Leucocyte counts and subpopulations were studied in peripheral blood from calves experimentally infected in the respiratory tract with either bovine virus diarrhoea virus (BVDV) or Mannheimia haemolytica (Mh), or with a combination of both agents (BVDV/Mh). A non-inoculated control group was included. Peripheral blood samples were obtained for total leucocyte counts, and for neutrophil, lymphocyte and monocyte counts. The numbers of blood lymphocytes expressing the surface antigens CD4, CD8, WC1, B and IL-2R were analysed using flow cytometry. The results showed that BVDV inoculation induced a significant decrease in total leucocyte counts and in neutrophil and lymphocyte numbers, while Mh inoculation induced significant increases in total leucocyte counts and neutrophils, while the lymphocyte count decreased. In the BVDV/Mh group, the total leucocyte count and the lymphocyte numbers decreased significantly. In this group, the lymphocyte numbers remained on a very low level throughout the rest of the study. The numbers of CD4+, CD8+ and WC1+ lymphocytes decreased significantly compared with before inoculations mainly in the BVDV and BVDV/Mh groups. The drops were most pronounced in the BVDV/Mh group. The numbers of B+ lymphocytes and IL-2R+ cells did not change significantly.
"M. haemolytica is an opportunestic pathogen that inhabits the nasopharynx and tonsils of cattle and sheep (Radostits et al., 2006) and is capable of causing infection when the body's defense mechanisms are impaired (Haig, 2011). Environmental stress factors like inclement weather, shipment, weaning, overcrowding and complex interactions among several infectious agents can serve as cofactors for pathogenesis of pneumonic pasteurellosis (Kraabel and Miller, 1997; Ganheim et al., 2005). A major problem in the control of pneumonic pasteurellosis is the lack of vaccine which consistently induces protective immunity against M. haemolytica (Dyer, 1982). "
[Show abstract][Hide abstract] ABSTRACT: This experimental study was done on a total of 40 male lambs with the objectives of developing
experimental vaccines from Mannheimia haemolytica serotypes A2 and A7 that express iron regulated
outer membrane protein and in vivo evaluation of their efficacy. Lambs were categorized in to four
experimental groups and vaccinated with 1 ml of vaccine containing 5 × 108 CFU/ml. Group 1 was
vaccinated with M. haemolytica A2, group 2 with A7, group 3 with serotype A2 and A7 combination, and
group 4 received saline as control. They were challenged intratracheally by the respective homologous
serotype after 35 days of vaccination. Post challenge clinical investigation showed that significant
higher rate of morbidity was seen in control group which was demonstrated by raised rectal
temperature (by 0.5-1°C) and respiratory signs. From the total of 26 lambs challenged with live M.
haemolytica A2 and A7, 6 (23.1%) and 4 (15.3%) lambs were found dead and sick, respectively. Higher
mortality and morbidity were observed in unvaccinated control group; however, lesser was recorded in
combined vaccinated group. Lung lesions of variable severity were observed in 13 (50.0%) lambs
following challenge. From vaccinated groups, 5 (27.8%) lambs were found to have a +1 lung lesion
score. All of the lambs in unvaccinated control group had scores between +2 and +3. There was a
statistically significant difference (p < 0.05) between control and vaccinated groups, while no
statistically significant difference (p > 0.05) was seen among vaccinated groups concerning lung lesion
scores. Furthermore, the respective serotypes of M. haemolytica were successfully re-isolated from
pneumonic lungs at a mean titre range of 102.2 – 108.1 CFU/g. In conclusion, lambs which received
combined vaccine confer relatively good protective efficacy than M. haemolytica A2 or A7 vaccinated
groups. Therefore, further study should be done on evaluation of antibody titer at different time points.
African journal of microbiology research 03/2014; 8(11):1237-1244. DOI:10.5897/AJMR2013.6371 · 0.54 Impact Factor
"In a BVDV type 2 challenge, Kelling et al. (2007) reported that nonvaccinated animals had greater rectal temperatures on d 9 to 11 after intranasal challenge compared with a vaccinated group. Calves challenged with noncytopathic type 1 BVDV (Gånheim et al., 2005) had a mild fever (>39.5°C) from d 1 through 5 after viral inoculation compared with nonchallenged controls. "
[Show abstract][Hide abstract] ABSTRACT: Remote rumen temperature monitoring is a potential method for early disease detection in beef cattle. This experiment was conducted to determine if remotely monitored rumen temperature boluses could detect a temperature change in steers exposed to bovine viral diarrhea virus (BVDV) and challenged with a common bovine respiratory disease pathogen, Mannheimia haemolytica (MH). Twenty-four Angus crossbred steers (BW = 313 ± 31 kg) were allotted to 1 of 4 treatments: 1) no challenge (control); 2) challenge by a 72-h exposure to 2 steers persistently infected with BVDV; 3) bacterial challenge with MH; and 4) viral challenge by a 72-h exposure to 2 steers persistently infected with BVDV followed by bacterial challenge with MH (BVDV + MH). Remotely monitored rumen temperature boluses programmed to transmit temperature every minute were placed in the rumen before the time of exposure to steers persistently infected with BVDV. Rectal temperatures were taken before MH challenge (0) and at 2, 4, 6, 12, 18, 24, 36, 48, 72, and 96 h after MH challenge. Rumen temperatures were recorded 3 d before (-72 h; period of BVDV exposure) through 14 d after (336 h) MH challenge. Rumen temperatures were analyzed as a randomized complete block design with a 2 × 2 factorial arrangement of treatments and a first-order autoregressive covariance structure for repeated measures. A treatment × day interaction was observed for average daily rumen temperature (P < 0.01). A treatment difference (P < 0.01) was observed on d 0, when MH-challenged steers had greater rumen temperatures than steers not challenged with MH. There was no BVDV × day interaction (P > 0.01). Rumen temperatures averaged every 2 h resulted in a BVDV × hour interaction (P < 0.01) and an MH × hour interaction (P < 0.01). The BVDV × hour differences occurred at h -18 to -14, 40 to 46, 110, 122, and 144 to 146 (P < 0.01). The MH × hour difference occurred at h 4 to 24 (P < 0.01). Maximum rumen temperature was increased (P < 0.01) for BVDV (0.8 °C), MH (1.2 °C), and BVDV + MH (1.3 °C) compared with the control. On average, rumen temperatures measured by the boluses at the same time points as the rectal temperatures were 0.13 °C less than rectal temperatures, and the 2 body temperatures were highly correlated (r = 0.89). Rumen temperature boluses appear to have potential as a tool for detecting temperature changes associated with adverse health events such as exposure to bovine respiratory disease and BVDV.
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