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Improved Piglet Performance and Reduced Antibiotic Use Following Oral Vaccination with a Live Avirulent Escherichia Coli F4 Vaccine against Post-Weaning Diarrhea

Authors:
Journal of Clinical Research and Medicine
Volume 3 Issue 2
Research Open
J Clin Res Med, Volume 3(2): 1–8, 2020
Introduction
Post-weaning diarrhea (PWD) in pigs is a worldwide economically
important disease [1], characterized by increased mortality, weight
loss, retarded growth, increased treatment costs, higher use of
antibiotics and batch variation [2-8]. Enterotoxigenic E. coli (ETEC)
is regarded the most important cause of PWD. e ETEC pathotype
is typically characterized by the presence of mbrial adhesins,
which mediate attachment to porcine intestinal enterocytes, and
enterotoxins, which disrupt uid homeostasis in the small intestine.
Research Article
Improved Piglet Performance and Reduced Antibiotic
Use Following Oral Vaccination with a Live Avirulent
Escherichia Coli F4 Vaccine against Post-Weaning Diarrhea
Frédéric Vangroenweghe1,2*, Olivier Thas3,4,5
1Elanco, BU Food Animals, Plantijn en Moretuslei 1 – 3rd oor, 2018 Antwerpen, Belgium.
2Ghent University, Faculty of Veterinary Medicine, Unit of Porcine Health Management, Merelbeke, Belgium
3I-BioStat, Data Science Institute, Hasselt University, Campus Diepenbeek, Agoralaan gebouw D, 3590 Diepenbeek, Belgium.
4Department of Data Analysis and Mathematical Modelling, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, 9000 Ghent, Bel-
gium.
5National Institute of Applied Statistics Research Australia (NIASRA), University of Wollongong, Northelds Ave, Wollongong, NSW 2522, Australia.
*Corresponding author: Frédéric Vangroenweghe, BU Food Animals, Elanco Benelux, Plantijn en Moretuslei 1 – 3rd oor, 2018 Antwerpen, Belgium; Tel : (+32)-3-334-
30-00; E-mail: vangroenweghe.frederic@telenet.be
Received: May 12, 2020; Accepted: May 21, 2020; Published: May 25, 2020
is results in mild to severe diarrhea within a few days post-weaning,
associated with clinical signs of dehydration, loss of body condition
(= disappearance of muscle volume) and mortality [9]. e adhesive
mbriae most commonly occurring in ETEC from pigs with PWD
are F4 (K88) and F18 [9]. Other mbriae such as F5 (K99), F6 (987P)
and F41 rarely occur in E. coli isolates from PWD [9-13]. e main
enterotoxins associated with porcine ETEC are heat-labile toxin (LT),
heat-stable toxin a (STa) and heat-stable toxin b (STb). In some cases,
both enterotoxins and a Shiga toxin (Stx2e) are produced by the
pathogenic stains [9].
Abstract
Background: Post-weaning diarrhea (PWD) in pigs is a worldwide economically important disease, which is frequently controlled using antibiotics.
However, emergence of antimicrobial resistance in E. coli strains urges the need for alternative control measures, such as adapted feeding strategies,
pre- and probiotics, organic acids, MCFAs or immunization. Dierent alternative control strategies such as active immunization of piglets against PWD
with an E. coli F4 vaccine combined with dierent feeding strategies, addition of nutraceuticals (medium chain fay acids (MCFAs), organic acids and
additional bers) or supplementation of ZnO were evaluated for their ecacy against PWD due to F4 enterotoxigenic Escherichia coli (F4-ETEC) under
eld conditions.
Results: ZnO-supplemented piglets had a lower overall end weight and lower average daily weight gain, as compared to E. coli vaccinated piglets
or piglets fed a diet with additional nutraceuticals. Piglets fed a ZnO-supplemented diet had optimal fecal and general clinical scores and the lowest
number of individual antibiotic treatments. All E. coli vaccinated groups had intermediate clinical scores and a relatively low number of antibiotic
treatments. However, clinical scores were much higher in the nutraceutical group, indicating more severe clinical diarrhea, which needed additional
antibiotic intervention. Mortality was also signicantly increased in the nutraceutical-supplemented group. The present study demonstrated the ecacy
of an oral live non-pathogenic E. coli F4 vaccine (Coliprotec® F4; Elanco) for active immunization of piglets against PWD due to F4-ETEC under eld
conditions. Dierent feeding strategies (1-, 2-, and 3-phase feeding) had no signicant eect on the clinical outcome and performance parameters of E.
coli vaccinated piglets.
Conclusions: In many parameters, E. coli vaccination performed equal compared to the ZnO-supplemented group. In contrast, the alternative control
strategy combining MCFAs, organic acids and additional bers resulted in signicant clinical diarrhea and mortality, requiring additional antibiotic
treatment to control, although many other performance parameters were very similar to E. coli vaccination or ZnO supplementation. Therefore, E. coli
vaccination could be one of the future preventive options to protect piglets against PWD due to pathogenic E. coli.
Keywords: F4-ETEC, PWD, E. coli F4 vaccine, performance, antibiotic reduction
J Clin Res Med, Volume 3(2): 2–8, 2020
Frédéric Vangroenweghe (2020) Improved Piglet Performance and Reduced Antibiotic Use Following Oral Vaccination with a Live Avirulent
Escherichia Coli F4 Vaccine against Post-Weaning Diarrhea
e disease is currently controlled using antimicrobials, although
the emergence of antimicrobial resistance in E. coli strains isolated
from cases of PWD urges the need for alternative control measures
[14-18].
Several alternative strategies have been explored to increase
intestinal health and decrease incidence of PWD due to E. coli in post-
weaned piglets [19-21]. Overall, inclusion of additional dietary ber
and reduction of crude protein levels in post-weaning diets seemed
to be an eective nutritional strategy that may counteract the negative
eects of protein fermentation in the pig gut [20, 22-24]. Although
specic fermentable carbohydrates combined with reduced crude
protein content altered the microora and fermentation patterns
in the gastro-intestinal tract of post-weaned piglets, these favorable
eects did not necessarily result in increased growth performance
[25]. Other feeding strategies were more focused on feed consistency,
thereby feeding more coarsely ground meal to the post-weaned
piglets [26]. Coarsely ground feed meals change the physico-chemical
conditions in the stomach, thereby increasing concentrations of
organic acids which lower the pH. is promoted growth of anaerobic
lactic acid bacteria and reduces survival of E. coli during passage
through the stomach [26]. Fermentation of undigested dietary protein
and endogenous proteins in the large intestines yield putative toxic
metabolites that can impair epithelial integrity and promote enteric
disorders such as PWD [27]. Incidence and severity of PWD may
also be inuenced by addition of probiotics to the diet, which may
change the fermentation prole and thus promote gut health [28].
Furthermore, medium chain fatty acids (MCFAs) can neutralize
bacterial metabolites in the small intestine [29].
From the late 1980’s onwards, several studies on zinc supply to
post-weaned piglets have been performed. Several nutritional studies
demonstrated the eects of dietary zinc oxide (ZnO) in the prevention
and healing of PWD [30]. erefore, ZnO has been admitted in the
prevention and control of PWD at levels up to 3,000 parts per million
(ppm) through the feed for a maximum of 14 days post-weaning.
However, Committee for Veterinary Medicinal Products (CVMP) has
recently decided that the use of ZnO in post-weaning diets should be
phased out the latest by 2022 throughout the EU [31].
erefore, other preventive strategies have recently been explored
[1,32]. For an E. coli vaccination against PWD due to F4- and F18-
ETEC, the prerequisite is that active mucosal immunity against F4 and
F18 is mounted. is implies the local production of F4- and/or F18-
specic sIgA antibodies, which prevent pathogenic F4- and F18-ETEC
to attach to the intestinal F4- and F18-receptors and thus reduce clinical
signs of PWD [32]. Recently, vaccination with a live non-pathogenic E.
coli F4 or E. coli F4 and F18 vaccine has demonstrated ecacy against
PWD due to F4-ETEC and F4- and F18-ETEC [33,34]. Immunization
against the F4- and F18-ETEC pathogens resulted in decreased severity
and duration of PWD clinical signs and fecal shedding of F4- and F18-
ETEC [33,34]. Moreover, increased weight gain was demonstrated in
piglets vaccinated with E. coli F4 vaccine [33].
Here, we report results demonstrating the ecacy of an oral live
non-pathogenic E. coli F4 vaccine (Coliprotec® F4; Elanco; Greeneld,
IN) for active immunization of piglets against PWD caused by F4-
ETEC with dierent feeding strategies under eld conditions. We also
included a group using the current approach of 3,000 ppm ZnO during
14 days post-weaning and a group with addition of a nutraceutical
concept containing MCFAs, organic acids and additional bers.
Materials and Methods
Experimental farm description
e eld trial was performed on a conventional farrow-to-nish
pig farm with 600 DanBred sows in Flanders (Belgium). e farm was
managed in a 4-week batch-management system (with alternately
weaning) with 120 sows per production batch. is management
approach has been shown to improve the health status for several
respiratory pathogens [35]. Piglets were weaned at 23 days of age and
housed in specically equipped post-weaning facilities, where they
were raised for 7 weeks (50 days post-weaning). e post-weaning
facility was equipped with 40 pens, which could each house 16 post-
weaned piglets. Dry feeders with two waterers, one on each side, were
located at the pen division, thus feeding two pens with a total of 32
piglets. e pens were further equipped with fully slatted plastic oors
and were heated with hot water tubes on the side walls near the air
inlet. Ventilation was performed through 3 ventilation tubes and fresh
air entered into the compartment directly from the outside.
ETEC diagnosis and characterization at experimental farm
e farm was selected following ETEC diagnostics during the
post-weaning period. erefore, untreated piglets (n = 10) with typical
clinical signs of PWD, such as watery feces, thin belly and signs of
dehydration, were sampled using rectal swabs (Sterile Transport Swab
Amies with Charcoal medium; Copan Italia S.p.A., Brescia, Italy).
All sampled piglets were between 3 and 5 days post-weaning. e
diagnostic samples were sent to the laboratory (IZSLER, Brescia, Italy)
under cooled conditions for further processing.
Specimen were processed using standard procedures for isolation
and characterization of intestinal E. coli [18]. Briey, samples
were plated on selective media and on tryptose soy agar medium
supplemented with 5% of debrinated ovine blood and incubated
aerobically overnight at 37°C. Haemolytic activity was evaluated and
single coliform colonies were further characterized.
DNA samples were prepared from one up to ve haemolytic and/
or non-haemolytic E. coli colonies and used to perform a multiplex
PCR for the detection of mbrial and toxin genes, including those
encoding for F4 (K88), F5 (K99), F6 (987P), F18, F41, LT, STa, STb
and Stx2e, but not discriminating between F4ab, F4ac and F4ad. e
methodology used for the identication of these virulence genes has
been described previously [36]. All collected samples were positive for
F4 in combination with STa, STb and LT. No other virulence factors
could be detected.
Vaccination with a live non-pathogenic E. coli F4 vaccine
In order to vaccinate piglets at least 7 days before the clinical signs
to mount sucient protective local immunity in the gut [33], piglets
were vaccinated at 18 days of age (5 days prior to weaning), during
the suckling period. e live non-pathogenic E. coli F4 vaccine has a
J Clin Res Med, Volume 3(2): 3–8, 2020
Frédéric Vangroenweghe (2020) Improved Piglet Performance and Reduced Antibiotic Use Following Oral Vaccination with a Live Avirulent
Escherichia Coli F4 Vaccine against Post-Weaning Diarrhea
rapid onset of immunity (7 days) and a duration of immunity of 21
days post-vaccination, which covers the most critical period of PWD
[1]. An ecacy trial using an experimental E. coli F4 challenge at 3
days post-vaccination showed reduction of the severity and duration
of PWD and reduction in fecal shedding of pathogenic F4-ETEC
[33]. Sows were randomly assigned to treatment (Coliprotec® F4;
Elanco, Greeneld, IN) or control group based on their parity and sow
number. Parities were equally distributed to both treatment groups.
Piglets from sows assigned to the treatment group were vaccinated
orally through drenching with 2 ml of a live non-pathogenic E. coli F4
vaccine (Coliprotec® F4; Elanco, Greeneld, IN). Piglets from sows in
the control group were not treated nor vaccinated. No antibiotics were
administered to piglets from 15 days of age onwards, in order to omit
interference with development of protective local immunity by the E.
coli F4 vaccine during the 7 days following vaccination.
Experimental design
At weaning, E. coli vaccinated piglets were randomly assigned
to three groups with a dierent feeding strategy. e unvaccinated
control piglets were randomly assigned to two groups with dierent
preventive measures supplemented to the feed against PWD due to
E. coli. Each treatment group consisted of 128 piglets divided over
8 pens with 16 piglets each. Sexes were distributed equally within
and between dierent treatment groups. e treatment groups were
randomly allocated to the dierent pens within the compartment in
order to evenly distribute all treatments for potential interaction with
specic climatic subzones within the compartment (outer walls, air
inlet, central part). Details on the experimental design in relation to
feeding strategies and preventive measures are given in Table 1. Piglets
were weighed per pen (n = 16 piglets) at three dierent time-points:
d0 (start), d21 (mid-term) and d50 (end). Average piglets weights
were calculated based on pen weight and number of piglets present at
the moment of weighing. Piglet treatment identication was blinded
to both farmer and veterinarian involved in trial follow-up by letter
codes (A, B, C, D, and E).
Feeding strategies
Feeding strategies were based on practical eld situations, where a
limited number of dierent feeding phases can be fed to piglets during
the post-weaning period. erefore, we decided to test 1-phase,
2-phase and 3-phase feeding strategies in combination with E. coli F4
vaccination. Unvaccinated control group were also fed the 3-phase
strategy. One unvaccinated group was designed to resemble the current
eld situation with addition of 3,000 ppm ZnO to the feed during the
rst 14 days post-weaning, whereas the other unvaccinated group was
formulated with 2 kg of extra protective nutritional supplements, i.e.
nutraceuticals, consisting of a combination of MCFAs, organic acids
and additional bers.
Treatment
No group treatments were performed during the entire study
period. Individual piglets with severe clinical signs of PWD were
treated with an injectable antimicrobial, i.e. lincomycine. Other
disorders were treated by the farmer, following consultation of the
veterinarian, with the appropriate antimicrobial where needed. All
individual treatments were registered with date, pen, product type and
reason for treatment.
Performance parameters
e following performance parameters were collected during the
trial: piglet weight at d0, d21 and d50, feed intake during period 1 (0-
21 days), period 2 (22-50 days) and period 3 (0-50 days), individual
treatments with specic reason for treatment, mortality with date of death
(number of days in trial) and piglet weight. Average daily weight gain
(ADWG) was calculated based on piglet weight and number of days in
trial for period 1 (0-21 days), period 2 (22-50 days) and period 3 (0-50
days). Feed conversion rate (FCR), the amount of feed to add one kg of
bodyweight, was calculated based on average daily weight gain and feed
intake for period 1 (0-21 days), period 2 (22-50 days) and period 3 (0-50
days). Treatment incidence 50 (TI50) was calculated based on the number
of individual injections per treatment for a total of 100 piglets over the
trial duration of 50 days.
Pen fecal clinical score and general clinical score
Piglet feces consistency was scored daily from d0 to d21 using
pen fecal clinical score (FCS) as described in Table 2. FCS was
performed by the same person throughout the entire duration of
Score Interpre tation Clinical aspect
0 Normal Normal fecal consistency
1 Pasty So pasty consistenty
2 Mild Presence of uid, but more particles than uid
3 Moderate More uid than particles
4 Severe Fluid watery faeces
Table 2. Comprehensive description of the pen fecal clinical score with its interpretation
and the clinical aspect of the fecal clinical score.
Table 1. Schematic description of experimental trial set-up including treatment groups and their short comprehensive description and the respective dierences in feeding strategies (weaning
starter, starter and grow starter; blocks in the same colour have identical compositions), addition of ZnO (3,000 ppm), supplementary nutraceuticals (MCFAs, organic acids and additional bers)
and vaccination with a live non-pathogenic E. coli F4 vaccine.
Treatment groups
A B C D E
Treatment description 1-phase / vaccine 2-phase / vaccine 3-phase / vaccine 3-phase / nutriceutical 3-phase + ZnO
Weaning starter 2 kg 5 kg 5 kg 5 kg
Starter 8 kg 8 kg 8 kg
Grow starter ... ... ...
ZnO (14d) 0000 3,000 ppm
Nutraceuticals 000 2 kg / tonne 0
E. coli F4 vaccine yes yes yes no no
J Clin Res Med, Volume 3(2): 4–8, 2020
Frédéric Vangroenweghe (2020) Improved Piglet Performance and Reduced Antibiotic Use Following Oral Vaccination with a Live Avirulent
Escherichia Coli F4 Vaccine against Post-Weaning Diarrhea
the trial observation (0-21 days). Piglets were also scored on general
appearance using a general clinical score (GCS), ranging from 0 (=
severe clinical condition) to 10 (= excellent clinical condition). For
both pen FCS and GCS, one score per pen was attributed daily in the
morning at 9 am. For analysis, area under the curve (AUC) and time
to maximal score was calculated per pen for both pen FCS and GCS.
Clinical assessment of piglets with diarrhea was performed based on
appearance of uid watery stools in the anal and perineal region. e
number of piglets per pen with these clinical signs was counted daily
from d0 to d21 and reported as total number of piglets with diarrhea
per treatment group over the entire observation period (0-21 days).
Statistical analysis
For the continuous data, eect of treatment was assessed using
pairwise comparison using t-test with pooled standard deviations. For
the ordinal outcomes, eect of treatment was assessed using pairwise
comparison using Wilcoxon rank sum test. e P-values were adjusted
with the Bonferroni method for multiple comparison. All tests were
performed at the nominal level of 5%.
Results
Piglet weight and average daily weight gain
On d0, average individual piglet weight was not signicantly dierent
among treatment groups, indicating an equal starting weight in all groups.
At the mid-point weighing (d21), group E (ZnO) had a signicantly
higher (P < 0.05) weight as compared to the other treatment groups. In
contrast with its higher mid-point weight at d21, group E (ZnO) had
the lowest numerical average individual piglet weight at d50, although
no signicant dierences (P > 0.05) were present between all treatment
group (Figure 1).
For period 1 (0-21 days), group E (ZnO) had a signicantly higher (P
< 0.05) ADWG as compared to the other treatment groups. e piglets
vaccinated with the E. coli F4 vaccine grew equally well, whereas group
D (nutraceuticals) slightly, though not signicantly, underperformed, as
compared to the E. coli vaccinated groups A, B, and C. For period 2 (22-50
days), group E had a signicantly lower (P < 0.05) ADWG of 283 g/day
compared to all other treatment groups, whereas E. coli vaccinated piglets
in group A, B, and C grew 363 to 372 g/day. During this period, group E
also had a signicantly lower (P < 0.05) ADWG as compared to group
D. Overall ADWG (0-50 days) was not signicantly dierent among the
dierent treatment groups (Figure 2).
Feed conversion rate
For period 1 (0-21 days), group B (2-phase feeding) had a
signicantly higher (P < 0.05) FCR as compared to the other
a
b
a
a
a
a
a
a
a
b
a
ab
ac
ac
a
Figure 3. Feed conversion rate (FCR; expressed in kg of feed per kg of weight gain; mean
± SEM) for piglets during period 1 (0-21 days post-weaning), period 2 (22-50 days post-
weaning) and period 3 (0-50 days post-weaning). Dierent treatment groups diered
in feeding strategy and vaccination status against E. coli F4. Group A, B, and C were
vaccinated with Coliprotec® F4 at 18 days of age and combined with a 1, 2, or 3-phase
feeding strategy, respectively. Group D was fed a 3-phase feeding strategy combined
with additional nutraceutical protection and Group E was fed a 3-phase feeding strategy
with supplementation of 3,000 ppm ZnO for the rst 14 days post-weaning. Dierent
superscript letters indicate statistically signicant dierences (P < 0.05).
a
b
Figure 1. Average individual piglet weight (expressed in kg; mean ± SEM) for piglets at
d0 (start of trial), d21 (mid-point weighing) and d50 (end of trial). Dierent treatment
groups diered in feeding strategy and vaccination status against E. coli F4. Groups A,
B, and C were vaccinated with Coliprotec® F4 at 18 days of age and combined with a 1,
2, or 3-phase feeding strategy. Group D was fed a 3-phase feeding strategy combined
with additional nutraceutical protection, and Group E was fed a 3-phase feeding strategy
with supplementation of 3,000 ppm ZnO for the rst 14 days post-weaning. Dierent
superscript letters indicate statistically signicant dierences (P < 0.05).
a
a
a
a
b
a
a
a
a
b
a
a
a
a
a
Figure 2. Average daily weight gain (ADWG; expressed in g/d; mean ± SEM) for piglets
during period 1 (0-21 days post-weaning), period 2 (22-50 days post-weaning) and period
3 (0-50 days post-weaning). Dierent treatment groups diered in feeding strategy and
vaccination status against E. coli F4. Group A, B, and C were vaccinated with Coliprotec® F4
at 18 days of age and combined with a 1, 2, or 3-phase feeding strategy, respectively. Group
D was fed a 3-phase feeding strategy combined with additional nutraceutical protection,
and Group E was fed a 3-phase feeding strategy with supplementation of 3,000 ppm
ZnO for the rst 14 days post-weaning. Dierent superscript letters indicate statistically
signicant dierences (P < 0.05).
J Clin Res Med, Volume 3(2): 5–8, 2020
Frédéric Vangroenweghe (2020) Improved Piglet Performance and Reduced Antibiotic Use Following Oral Vaccination with a Live Avirulent
Escherichia Coli F4 Vaccine against Post-Weaning Diarrhea
treatment groups. During period 2 (22-50 days), both group B
(2-phase feeding) and group E (ZnO) had a signicantly higher
(P < 0.05) FCR as compared to groups A, C, and D. Overall FCR
(0-50 days) was signicantly higher (P < 0.05) in group B (2-phase
feeding) as compared to group C (3-phase feeding) and group D
(nutraceuticals). None of the other groups was signicantly dierent
from each other.
Pen fecal clinical score and general clinical score
Pen FCS was collected daily for each individual pen from 0 to 21
days post-weaning. Pen FCS, expressed as AUC, was not signicantly
dierent (P > 0.05) among E. coli vaccinated groups (A, B and C).
However, pen FCS of group E (ZnO) was signicantly lower (P <
0.05) as compared to group D (nutraceuticals). Pen FCS of group E
(ZnO) was signicantly lower (P < 0.05) as compared to all E. coli
vaccinated groups (Table 3). Although some numerical dierences
in time to maximal FCS occurred among dierent treatment groups,
no signicant dierences (P > 0.05) could be observed in the time to
maximal FCS (Table 3).
e number of piglets with clinical signs of diarrhea was
signicantly higher (n = 315; P < 0.05) in group D (nutraceuticals) as
compared to the E. coli vaccinated groups. No signicant dierences
were observed among the E. coli vaccinated groups (A, n = 76; B, n =
73; C, n = 105). Group E (ZnO) had a signicantly lower number (n =
11; P < 0.05) of piglets with clinical diarrhea as compared to all E. coli
vaccinated groups (A, B, and C) (Table 3).
Pen GCS was collected daily for each individual pen from 0 to
21 days post-weaning. AUC of pen GCS was signicantly better (P <
0.05) in group E (ZnO) as compared to all other treatment groups.
Group B (2-phase feeding) had a signicantly better (P < 0.05)
pen GCS as compared to group A (1-phase feeding), C (3-phase
feeding) and D (nutraceuticals) (Table 3). Although some numerical
dierences in time to maximal GCS occurred between the dierent
treatment groups, no signicant dierences (P > 0.05) could be
observed (Table 3).
Treatment incidence 50
TI50 was calculated as the total number of individual treatments per
100 piglets per group over 50 days of trial. In group D (nutraceuticals),
TI50 was signicantly higher (P < 0.05) as compared to the other
treatment groups. Group E (ZnO) had the lowest TI50, although
the addition of 3,000 ppm ZnO was not taken into account in this
calculation (Table 3). All E. coli vaccinated groups had equally low and
non-signicantly dierent (P > 0.05) TI50 values.
Mortality
Data related to mortality are given in Table 4. In summary, group
D (nutraceuticals) had the highest percentage of overall mortality with
12.5%, which was nearly double the mortality percentage of group E
(ZnO) and triple the mortality percentage in the vaccinated groups
(A, B, and C). Moreover, piglets in group D (nutraceuticals) died
early post-weaning (9.83 days post-weaning), mostly due to acute to
subacute PWD. Mortality in group E (ZnO) occurred in period 2 (22-
50 d), aer removal of 3,000 ppm ZnO from the diet at 14 days post-
weaning. is was characterized by the highest mortality weight (11.56
kg) for period 2 (22-50 d). Mortality in the E. coli vaccinated groups
(A, B, and C) was equally distributed among both periods and was
very limited in numbers (n = 4-6 dead piglets per group) compared to
both other groups (D and E).
Study period
Period 1 (0-21 d post-weaning) Period 2 (22-50 d post-weaning)
Treatment group Mortality - number (%) Average weight dead
piglets (kg; avg ± SEM)
Average days post-
weaning (d; avg ± SEM) Mortality - number (%) Average weight dead
piglets (kg; avg ± SEM)
Average days post-weaning
(d; avg ± SEM)
A 2 (1.56%) 6.00 ± 1.00 21.0 ± 0.0 4 (3.13%) 8.75 ± 1.11 35.2 ± 1.9
B 2 (1.56%) 4.50 ± 0.50 14.0 ± 5.0 3 (2.34%) 13.00 ± 5.00 40.7 ± 4.6
C 3 (2.34%) 4.00 ± 0.58 17.3 ± 2.7 1 (0.78%) 8.00 ± 0.00 25.0 ± 0.0
D 12 (6.67%) 4.17 ± 0.34 9.8 ± 1.6 4 (3.12%) 7.00 ± 3.67 30.4 ± 3.8
E 0 (0.00%) N/A N/A 9 (7.03%) 11.56 ± 1.32 39.8 ± 2.3
Table 4. Mortality results per treatment group and study period with number of dead piglets per group (percentage of total piglets enrolled in the group), average weight of the dead piglets (kg;
± SEM), and average day of post-weaning mortality (d; ± SEM).
Treatment group
A B C D E
Pen FCS 42.9 ± 2.97 a 41.6 ± 2.08 ac 43.1 ± 2.18 ad 52.6 ± 1.84 ad 15.8 ± 1.72 b
Time to maximal FCS 6.25 ± 0.59 6.50 ± 0.68 7.25 ± 0.56 6.62 ± 0.60 5.62 ± 0.65
Pen GCS 175 ± 3.96 a 187 ± 1.55 ac 176 ± 2.76 a 164 ± 3.04 ac 204 ± 1.79 bd
Time to maximal GCS 8.12 ± 0.61 a6.12 ± 0.66 a7.12 ± 0.61 a7.62 ± 0.75 a5.50 ± 0.38 a
# piglets with diarrhea (0-21 d) 76 a73 a105 a315 b11 c
TI50 1.21 ± 0.18 a 1.16 ± 0.14 ab 1.67 ± 0.30 ab 5.00 ± 1.05 c 0.17 ± 0.01 b
Table 3. Area under the curve (AUC) of pen fecal clinical score and pen general clinical score (GCS), time to maximal FCS and GCS (mean ± SEM) for piglets during the rst 21 days post-weaning
and treatment incidence 50 (TI50; # individual treatment/100 piglets/50 days in trial; mean ± SEM). Pen FCS was scored daily on a score from 0 (= normal) to 4 (= watery diarrhea) and GCS was
scored daily on a score from 0 (= very bad) to 10 (= excellent). Dierent treatment groups diered in feeding strategy and vaccination status against E. coli F4. Group A, B, and C were vaccinated with
Coliprotec® F4 at 18 days of age and combined with a 1-2 or 3-phase feeding strategy, respectively. Group D was fed a 3-phase feeding strategy combined with additional nutraceutical protection and
Group E was fed a 3-phase feeding strategy with supplementation of 3,000 ppm ZnO for the rst 14 days post-weaning. Dierent superscript letters indicate statistically signicant dierences (P < 0.05).
J Clin Res Med, Volume 3(2): 6–8, 2020
Frédéric Vangroenweghe (2020) Improved Piglet Performance and Reduced Antibiotic Use Following Oral Vaccination with a Live Avirulent
Escherichia Coli F4 Vaccine against Post-Weaning Diarrhea
Discussion
From the current study, we can conclude that active immunization
of piglets against PWD caused by F4-ETEC performed at an acceptable
level as compared to the standard approach under eld conditions
with addition of 3,000 ppm ZnO during the rst 14 days post-weaning.
Although average individual piglet weight at 22 days post-weaning
was signicantly lower as compared to the ZnO-supplemented group
(E), piglets vaccinated with the E. coli F4 vaccine were numerically
heavier (1.0 to 1.4 kg extra) at the end of the nursery period (d50).
Under eld conditions, an extra kg of piglet weight during the nursery
period is considered to result in at least 2-3 kg extra weight during
the fattening period. is implies earlier slaughter at the same weight
or heavier fattening pigs at the same slaughter age. Both scenarios
mean economic benet to the swine farmer. Average daily weight
gain behaved in the same trend, although the ADWG for period 2
(22-50 d) was signicantly lower in the ZnO-supplemented group (E).
Under eld conditions, most farmers only have access to start and
end-point data related to post-weaning performances, therefore the
signicantly higher mid-term performance in the ZnO-supplemented
group (E) is not considered relevant to practice. Nevertheless, the
higher weight and better ADWG indicate that piglets supplemented
with ZnO at 3,000 ppm for 14 days post-weaning might have a stable
intestinal integrity and pathogenic E. coli bacteria have less impact on
the performance of these piglets during the early post-weaning phase
[30]. However, CVMP has recently decided that the use of ZnO in
post-weaning diets should be phased out the latest by 2022 throughout
the EU [31]. erefore, alternative approaches to control PWD due to
pathogenic E. coli should be explored. Several alternative strategies,
such as adapted nutritional strategies (feed consistency, lower
crude protein, digestible bers and other dietary bers), prebiotics,
probiotics, organic acids, MCFAs, specic IgA antibodies and oral
vaccination have been explored [19-29,33,34,37-40].
In the current study, a nutraceutical approach, including a
mixture of MCFAs, organic acids and additional ber, was evaluated.
Although performance parameters (weight, ADWG and FCR) were in
line with the E. coli vaccinated groups and supplementation of ZnO,
other parameters related to health (pen FCS, mortality and TI50) were
signicantly worse, indicating this approach did not provide as much
protection as ZnO supplementation or E. coli F4 vaccination. Indeed,
intestinal pathogens have many dierent mechanisms to interact
with the host, which makes complete inhibition of their pathogenesis
through specic feed additives or a combination of these additives
quite challenging [21,41].
Recently, vaccination with a live non-pathogenic E. coli F4 or E.
coli F4 and F18 vaccine has demonstrated ecacy against PWD due
to F4-ETEC, and F4- and F18-ETEC [33,34]. Immunization against
the F4- and F18-ETEC pathogens resulted in decreased severity and
duration of PWD clinical signs and fecal shedding of F4- and F18-
ETEC [33,34]. Moreover, increased weight gain was demonstrated
in piglets vaccinated with E. coli F4 vaccine [33]. Our results are in
line with these observations, indicating that feeding regime (1-, 2-
or 3-phase feeding strategy) had no impact on results induced by
immunization with an E. coli F4 vaccine under eld conditions. is
implies that farms suering from PWD due to F4-ETEC do not have to
alter their specic feeding strategy. is is an advantage, since in most
cases there are limitations in the number of available feed bins for the
on-farm post-weaning facilities. From an economical point of view,
however, 3-phase feeding strategies provide optimal performance
parameters related to FCR.
As expected, supplementation of ZnO resulted in the lowest pen
FCS and TI50 although time to maximal fecal clinical score did not dier
among treatment groups. Nevertheless, from 14 days post-weaning
onwards, at removal of the ZnO from the feed, pen FCS increased
again, in contrast to the other groups, where pen FCS remained stable
during that specic period. In practice, this phenomenon is referred to
as ‘post-ZnO diarrhea’ and sometimes even needs antibiotic treatment
to control. E. coli vaccinated piglets had similar pen FCS and GCS,
which remain important evaluation parameters in practice, due to
lack of many other directly available data for evaluation of preventive
or clinical interventions to prevent or control PWD due to E. coli.
Another important evaluation parameter to assess the success of
dierent intervention strategies in relation to PWD due to E. coli is
mortality [33]. Mortality data were dierent among treatment groups,
with acceptable levels (3.12 to 4.69%) in E. coli vaccinated piglets,
and much higher levels of 7.03% to 12.5% in ZnO-supplemented
and nutraceutical-supplemented groups, respectively. Analysis of
mortality data per period showed early death in the nutraceutical-
supplemented piglets, whereas ZnO-supplemented piglets died much
later during the post-weaning period, i.e. aer the removal of ZnO
at 14 days post-weaning. In the E. coli vaccinated piglets, mortality
was more equally distributed throughout the entire study period and
signicantly lower as compared to both other alternative treatments
(nutraceutical- and ZnO-supplementation).
In conclusion, the present study demonstrated the ecacy of an
oral live non-pathogenic E. coli F4 vaccine (Coliprotec® F4; Elanco)
for active immunization of piglets against PWD due to F4-ETEC.
Dierent feeding strategies had no signicant impact on the clinical
outcome and performance parameters of these vaccinated piglets. In
many parameters, E. coli vaccination performed equally or better as
compared to the ZnO- supplemented group. However, this approach
is no longer future-proof due to EU-regulations on total ban of ZnO
by 2022. erefore, E. coli vaccination could be one of the preventive
options to protect piglets against PWD due to E. coli in the near future.
In contrast, the alternative strategy combining MCFAs, organic acids
and additional bers resulted in signicant clinical diarrhea and
mortality, requiring additional antibiotic treatment to control the
disease. Nevertheless, in the nutraceutical-supplemented group, other
performance parameters were similar to E. coli vaccination or ZnO
supplementation.
Acknowledgements
e authors greatly acknowledge the technical sta of Innsolpigs
(Aalter) for their assistance in randomization, weighing and data
collection.
J Clin Res Med, Volume 3(2): 7–8, 2020
Frédéric Vangroenweghe (2020) Improved Piglet Performance and Reduced Antibiotic Use Following Oral Vaccination with a Live Avirulent
Escherichia Coli F4 Vaccine against Post-Weaning Diarrhea
Declarations
Ethics approval and consent to participate: Field trial with
Veterinary Medicinal Product approved for use in swine. No additional
ethical approval needed. Consent to participate was obtained following
full information of farmer on the protocol to be carried out.
Consent for publication: Not applicable.
Availability of data and material: e datasets analysed during
the current study are available from the corresponding author on
reasonable request.
Competing interests: e authors declare that they have no
competing interests.
Funding: e study was funded by Elanco Animal Health, which
facilitated the conduct of the eld trial.
Author’s contributions: FV coordinated the entire study from
study design to data collection and analysis to the manuscript. OT was
involved in data analysis and manuscript preparation. All authors read
and approved the nal manuscript.
Acknowledgements: e author greatly acknowledges the swine
farmer and his swine veterinarian participating in the study.
Author’s information: FV is currently a Sr. Technical Advisor
Swine for Benelux / UK&ROI within Elanco Animal Health. He holds
a DVM, a Master in Veterinary Public Health and Food Safety, a PhD
in Veterinary Sciences and a PhD in Applied Biological Sciences,
and is a Diplomate in the European College of Porcine Health
Management. He has a specic interest in swine intestinal health
and the specic approach to improve intestinal health through non-
antibiotic solutions.
Abbreviations
AUC: area under the curve
CVMP: Committee for Veterinary Medicinal Products
ETEC: enterotoxigenic Escherichia coli
EU: European Union
FCS: fecal clinical score
GCS: general clinical score
LT: heat-labile toxin
MCFAs: medium chain fatty acids
ppm: parts per million
PWD: post-weaning diarrhea:
STa: heat-stabile toxin a
STb: heat-stabile toxin b
Stx2e: shiga-toxin 2e
ZnO: zinc oxide
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Citation:
Frédéric Vangroenweghe, Olivier as (2020) Improved Piglet Performance and Reduced Antibiotic Use Following Oral Vaccination with a Live Avirulent Escherichia
Coli F4 Vaccine against Post-Weaning Diarrhea. J Clin Res Med Volume 3(2): 1-8.
... Recently, vaccination with a live non-pathogenic E. coli F4, or E. coli F4 and F18 vaccine has demonstrated efficacy against PWD due to F4-ETEC, and F4-ETEC and F18-ETEC [26,27]. Immunization against the F4-ETEC and F18-ETEC pathogens resulted in decreased severity [26,27,29,30] and duration of PWD clinical signs and fecal shedding of F4-ETEC and F18-ETEC [26,27]. Moreover, increased weight gain was demonstrated in piglets vaccinated with E. coli F4 vaccine [26,29,30]. ...
... Immunization against the F4-ETEC and F18-ETEC pathogens resulted in decreased severity [26,27,29,30] and duration of PWD clinical signs and fecal shedding of F4-ETEC and F18-ETEC [26,27]. Moreover, increased weight gain was demonstrated in piglets vaccinated with E. coli F4 vaccine [26,29,30]. ...
... Immunization against the F4-ETEC and F18-ETEC pathogens resulted in decreased severity and duration of PWD clinical signs and fecal shedding of F4-ETEC and F18-ETEC [26,27]. Moreover, increased weight gain was demonstrated in piglets vaccinated with an E. coli F4/F18 vaccine [26,29,30]. The current field results are in line with these observations, indicating that different farm management practices (BMS, weaning age, feeding regime) had no impact on results induced by immunization with an E. coli F4/F18 vaccine under field conditions. ...
Article
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Background: Post-Weaning Diarrhoea (PWD) in pigs is a worldwide economically important disease, which is frequently controlled using antimicrobials. However, emergence of antimicrobial resistance in E. coli strains and new EU regulations urge the need for alternative control measures, such as adapted feeding strategies or immunization. Oral vaccination of suckling piglets using a live non-pathogenic E. coli F4/F18 vaccine was performed in 10 farrow-to-finish sow farms to prevent against post-weaning diarrhoea due to F4-Enterotoxigenic E. coli (ETEC) or F18-ETEC. The vaccination strategy was compared to the standard therapeutic approach in each farm, meanwhile collecting data on Average Daily Weight Gain (ADWG), Feed Conversion Rate (FCR), mortality rate and treatment incidence with antimicrobial drugs (TI100) during the post-weaning period. Results: Vaccine-treated groups demonstrated a significant improvement in FCR, mortality rate and TI100 as compared to the Control group. The ADWG only marginally and non-significantly improved in the Vaccine-treated group. Conclusions: In conclusion, the present study demonstrated the efficacy of an oral live non-pathogenic E. coli F4/F18 vaccine (Coliprotec® F4/F8; Elanco Animal Health) for active immunization of piglets against PWD due to F4-ETEC and F18-ETEC under field conditions. For several economically important performance parameters, such as FCR, mortality rate and TI100, E. coli vaccination performed significantly better as compared to the standard therapeutic approach. Therefore, vaccination against PWD due to F4-ETEC or F18-ETEC using an oral live non-pathogenic E. coli F4/F18 vaccinated may be considered a good alternative to consolidate post-weaning piglet performance results while meeting the new European requirements concerning prudent use of antimicrobials in intensive pig production.
... Since onset of immunity by this vaccine is 7 days, the piglets were vaccinated timely in relation to the onset of clinical signs of PWD. Without E. coli vaccination, at least 10 days of antimicrobial treatment would be necessary and mortality would rise up to 4-5%, as observed in previous trials with a non-vaccinated control group [26,27]. The E. coli vaccination had been administered as standard for several years prior to the trial. ...
... Pigs were evaluated daily and any unusual observations were recorded, including but not limited to altered behavior and disease. Diarrhea scores were assessed for each pen by scoring five droppings per pen based on the fecal clinical score (FCS) shown in Table 7 [26,27]. The scoring was done by the same observer on days 0 to 11 post weaning and on day 49 (end of trial). ...
... Therefore, we selected a field trial facility with a substantial intestinal challenge related to PWD due to E. coli, which was partly tackled using an oral live non-pathogenic E. coli vaccine (Coliprotec® F4/ F18; Elanco, Greenfield, IA). In order to quantify intestinal and general health aspects, we recorded a fecal clinical score (FCS; adapted from [26,27]) and a general clinical score (GCS; adapted from [26,27]) during the most critical period post-weaning (from weaning until 11 dpw). Although some differences in kinetics could be observed for FCS, the treatment did not differ significantly their AUC and time to maximum FCS during the entire period from 0 to 11 dpw. ...
Article
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Enzyme supplementation with a β-mannanase to degrade β-mannan fibers present in the diet has been shown to restore and improve performance in swine. The current study was conducted on a farm which had historical episodes of post-weaning diarrhea. In total, 896 newly weaned piglets were enrolled in two consecutive trials. Each trial consisted of 32 pens of 14 piglets housed in one large post-weaning compartment. Piglets at the same feeder were randomly assigned to the two treatment groups. The study compared the performance of post-weaned piglets fed either a commercial 3-phase nursery diet (Control) or an adapted diet supplemented with a β-mannanase (Hemicell HT; Elanco) (Enzyme), with some of the more expensive proteins replaced by soy bean meal in phase 1 and 2, and net energy (NE) content reduced by 65 kcal/kg in phase 3. All data analyses were performed using R version 3.6.3 (R Core Team, 2020). All tests were performed at the 5% level of significance. When multiple testing was involved, the nominal 5% Familywise Error Rate (FWER) was used. The study showed similar performance on the alternative diet with β-mannanase and the common commercial diets ( P > 0.05). However, the Enzyme treated group had a significantly better general clinical score. Moreover, the number of individual treatments was a factor exp (0.69441) or 2 (CI 95% [1.46; 2.74]) higher ( P < 0.001) in the Control group as compared to the Enzyme treated group. The number of treated animals was a factor exp (0.62861) or 1.87 (CI 95% [1.43; 2.53]) higher ( P < 0.001) and the number of pigs with a repeated treatment was a factor exp (0.9293) or 2.53 (CI 95% [1.26; 5.09]) higher ( P = 0.009) in the Control group as compared to the Enzyme treated group. In total, 7 (1.56%) piglets died in the Control group, whereas only 2 (0.45%) piglets died in the Enzyme treated group. The hazard ratio for mortality in the Control group relative to the Enzyme treated group was and estimated as 1.74 (CI 95% [0.51; 5.96]). Thus, the Control group had a non-significantly ( P = 0.375) increased mortality. In conclusion, the results suggest that the use of an exogenous heat-tolerant β-mannanase allowed reduced levels of expensive protein sources to be used in the first two diets fed post-weaning, and 65 kcal/kg lower net energy content to be used in the third diet without adverse effects on intestinal health or overall performance. In fact, the occurrence of PWD and number of individual treatments during the post-weaning period were significantly reduced on the β-mannanase supplemented diets.
... Feeding strategies were based on previous results [37], showing that a 3-phase feeding strategy has proven the most optimal production results. Additionally, different combinations of normal or high energy and protein diets in the 3-phase approach were tested together with E. coli F4 vaccination and addition of 2 kg per tonne of extra protective nutritional supplements, i.e. nutraceuticals, consisting of a combination of MCFAs, organic acids and additional fibers. ...
... Nevertheless, piglets vaccinated with the E. coli F4 vaccine were numerically heavier (1.3 to 1.6 kg extra) at the end of the nursery period (d50) as compared to piglets in group A (ZnO). This is in accordance with a previous study demonstrating the same effect of ZnO supplementation during 14 days post-weaning on piglet performances [37]. Under field conditions, an extra kg of piglet weight during the nursery period is considered to result in at least 2-3 kg extra weight during the fattening period. ...
... Average daily weight gain behaved in the same trend, although the ADWG for period 2 (21-50 d) was numerically lower in the ZnO-supplemented group (A). This is in accordance with a previous study where ADWG in the ZnO-supplemented group was significantly lower as compared to the E. coli vaccinated groups in period 2 (21-50 days) [37]. Under field conditions, most farmers only have access to start-and end-point data related to post-weaning performances, therefore the numerically higher mid-term performance in the ZnO-supplemented group (A) is not considered relevant to practice. ...
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Introduction: Post-weaning diarrhea (PWD) in pigs is a worldwide economically important disease, which is frequently controlled using antibiotics. However, emergence of antimicrobial resistance in Escherichia coli strains urges the need for alternative control measures, such as adapted feeding strategies, pre- and probiotics, organic acids, MCFAs or immunization. Methods: Different alternative control strategies such as active immunization of piglets against PWD with an E. coli F4 vaccine (Coliprotec® F4; Elanco) combined with high energy and protein diets, addition of nutraceuticals (medium chain fatty acids (MCFAs), organic acids and additional fibers) or supplementation of ZnO were evaluated for their efficacy against PWD due to F4 enterotoxigenic E. coli (F4-ETEC) under field conditions. Results: ZnO-supplemented piglets had a lower overall end weight and lower average daily weight gain, as compared to E. coli vaccinated piglets. The E. coli vaccinated group with normal energy and protein diet had the lowest clinical scores, whereas piglets fed a ZnO-supplemented diet had intermediate fecal clinical scores. All E. coli vaccinated groups had a low number of antibiotic treatments. In the nutraceutical group, clinical scores were much higher, indicating more severe clinical diarrhea, which needed additional antibiotic intervention. Conclusions: The present study demonstrated the efficacy of an oral live non-pathogenic E. coli F4 vaccine for active immunization of piglets against PWD due to F4-ETEC under field conditions. Different feeding strategies had no significant effect on the clinical outcome and performance parameters of E. coli vaccinated piglets.
... In order to score fecal consistency during PWD, a Fecal Clinical Score (FCS) was developed with a fecal consistency score from 0 to 4 with and appropriate description [32,33] and applied under field conditions to objectively assess the fecal consistency during the post-weaning period (Table 1) throughout time and in the presence of multiple persons assessing the clinical fecal consistency [34][35][36]. The fecal clinical score is extensively described and illustrated in Table 1. ...
... The fecal clinical score is extensively described and illustrated in Table 1. Under field conditions, clear advantages have been observed in using the FCS to evaluate the effect of specific preventive or prophylactic interventions during the post-weaning period [34][35][36]. Table 1: Fecal clinical score from 0 to 4 with a realistic picture and a generic description of the consistency and the ratio between the liquid and solid fraction within the fecal material. coli F4 or E. coli F4 and F18 vaccine has demonstrated efficacy against PWD due to F4-ETEC or F4-ETEC and F18-ETEC [32,33]. ...
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Oral antibodies that interfere with gastrointestinal targets and can be manufactured at scale are needed. Here we show that a single-gene-encoded monomeric immunoglobulin A (IgA)-like antibody, composed of camelid variable single domain antibodies (VHH) fused to IgA Fc (mVHH-IgA), prevents infection by enterotoxigenic Escherichia coli (F4-ETEC) in piglets. The mVHH-IgA can be produced in soybean seeds or secreted from the yeast Pichia pastoris, freeze- or spray-dried and orally delivered within food. This link will guide you to the full text: https://lnkd.in/dbDqZJj
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F4- and F18-positive enterotoxigenic E. coli strains (F4-ETEC and F18-ETEC) are important causes of post-weaning diarrhea (PWD) in pigs. F4 (antigenic variant ac) and F18 (ab and ac) fimbriae are major antigens that play an important role in the early stages of infection. Herein, the efficacy of a live oral vaccine consisting of two non-pathogenic E. coli strains, one F4ac- and one F18ac-positive, was evaluated using F4ac-ETEC and F18ab-ETEC challenge models. A randomized, masked, placebo-controlled, block design, parallel-group confirmatory study with two different vaccination-challenge intervals (7 and 21 days) was conducted for each challenge model. The vaccine was administered in one dose, to ≥18-day-old piglets via drinking water. Efficacy was assessed by evaluating diarrhea, clinical observations, weight gain and fecal shedding of F4-ETEC or F18-ETEC. Anti-F4 and anti-F18 immunoglobulins in blood were measured. The vaccination resulted in significant reductions in clinical PWD and fecal shedding of F4-ETEC and F18-ETEC after the 7- and 21-day-post-vaccination heterologous challenges, except for after the 21-day-post-vaccination F4-ETEC challenge, when the clinical PWD was too mild to demonstrate efficacy. A significant reduction of mortality and weight loss by vaccination were observed following the F18-ETEC challenge. The 7-day protection was associated with induction of anti-F4 and anti-F18 IgM, whereas the 21-day protection was mainly associated with anti-F4 and anti-F18 IgA. The 7-day onset and 21-day duration of protection induced by this vaccine administered once in drinking water to pigs of at least 18 days of age were confirmed by protection against F4-ETEC and F18-ETEC, and induction of F4 and F18-specific immunity. Cross protection of the vaccine against F18ab-E. coli was demonstrated for both the 7- and 21-day F18-ETEC challenges.
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Enterotoxigenic Escherichia coli strains expressing F4 (K88) fimbriae (F4-ETEC) are one of the most important causes of post-weaning diarrhea (PWD) in pigs. F4, a major antigen, plays an important role in the early steps of the infection. Herein, the efficacy of a live oral vaccine consisting of a non-pathogenic E. coli strain expressing F4 for protection of pigs against PWD was evaluated. Three blinded, placebo-controlled, block design, parallel-group confirmatory experiments were conducted, using an F4-ETEC PWD challenge model, each with a different vaccination-challenge interval (3, 7, and 21days). The pigs were vaccinated via the drinking water with a single dose of the Coliprotec® F4 vaccine one day post-weaning. Efficacy was assessed by evaluating diarrhea, clinical observations, intestinal fluid accumulation, weight gain, intestinal colonization and fecal shedding of F4-ETEC. The immune response was evaluated by measuring serum and intestinal F4-specific antibodies. The administration of the vaccine resulted in a significant reduction of the incidence of moderate to severe diarrhea, ileal colonization by F4-ETEC, and fecal shedding of F4-ETEC after the heterologous challenge at 7 and 21days post-vaccination. The 7-day onset of protection was associated with an increase of serum anti-F4 IgM whereas the 21-day duration of protection was associated with an increase of both serum anti-F4 IgM and IgA. Significant correlations between levels of serum and intestinal secretory anti-F4 antibodies were detected. Maternally derived F4-specific serum antibodies did not interfere with the vaccine efficacy. The evaluation of protection following a challenge three days after vaccination showed a reduction of the severity and the duration of diarrhea and of fecal shedding of F4-ETEC. The 7-day onset and the 21-day duration of protection induced by Coliprotec® F4 vaccine administered once in drinking water to pigs of at least 18days of age were confirmed by protection against F4-ETEC and induction of F4-specific protective immunity.
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Background Post-weaning diarrhoea (PWD), due to Escherichia coli, is an important cause of economic losses to the pig industry primarily as a result of mortality and worsened productive performance. In spite of its relevance, recent data about the prevalence of virulence genes and pathotypes among E. coli isolates recovered from cases of PWD in Europe are scarce. ResultsThis study investigates the prevalence of fimbrial and toxin genes of E. coli by PCR among 280 farms with PWD across Europe. A total of 873 samples collected within the first 48 h after the onset of PWD (occurring 7–21 days post weaning) were submitted to the laboratory for diagnostic purposes. Isolation and identification of E. coli were performed following standard bacteriological methods and PCR assays for the detection of genes encoding for fimbriae (F4, F5, F6, F18 and F41) and toxins (LT, STa, STb and Stx2e). The prevalence of fimbriae and toxins among E. coli isolates from cases of PWD was: F4 (45.1 %), F18 (33.9 %), F5 (0.6 %), F6 (0.6 %), F41 (0.3 %), STb (59.1 %), STa (38.1 %), LT (31.9 %) and Stx2e (9.7 %). E. coli isolates carrying both fimbrial and toxin genes were detected in 52.5 % of the cases (178 out of 339 isolates), with 94.9 % of them being classified as enterotoxigenic E. coli (ETEC). The most common virotype detected was F4, STb, LT. Conclusions This study confirms that ETEC is frequently isolated in pig farms with PWD across Europe, with F4- and F18-ETEC variants involved in 36.1 % and 18.2 % of the outbreaks, respectively.
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