Publications (6)20.61 Total impact
- [Show abstract] [Hide abstract] ABSTRACT: The objective of this study was to evaluate in native cattle the use of an in vitro derived attenuated live vaccine (Babesia bovis-Babesia bigemina). Three commercial farms located in a tropical region in Chiapas State, Mexico were included. For each ranch, 40 animals were selected as negative to Babesia spp. by using an immunofluorescent antibody test (IFAT) and PCR. Animals were distributed in four groups with 10 animals each: (i) <9 months, (ii) 9-18, (iii) 18-36 and (iv) >36 months old. From each group, two subgroups were formed with five animals each; one subgroup was vaccinated and the other served as control without vaccination. Monitoring and sampling were carried out initially at vaccination (day 0), at day 7 and then every 4 weeks for 12 months. During the study rectal temperature ( degrees C), packed cell volume (Ht %) and percentage of erythrocytes parasitized were registered, furthermore IFAT and PCR were performed. Prevalence rate at the beginning of the study was 83% by IFAT. During the survey, 26 non-vaccinated of the 120 selected animals (43%) showed clinical symptoms of babesiosis, confirmed by stained smears versus only four (6.6%) of the vaccinated ones. All Babesia-affected animals required specific treatment. Vaccinated cattle showed titres of up to 1 : 1840 and 1 : 1027 for B. bovis and B. bigemina, respectively by IFAT. Protection conferred by vaccination was about 93%. We propose that this vaccine should not only be used in cattle coming from babesiosis free zones, but also in native cattle kept in hyperendemic areas.
- [Show abstract] [Hide abstract] ABSTRACT: The purpose of this research was to evaluate the recombinant proteins MSA-1, MSA-2c and 12D3 as a combined immunogen for cattle. Fifteen steers were randomly assigned into three groups of five animals each (I, II and III). On day 0, cattle in group I were injected with 50 microg each of rMSA-1, rMSA-2c and r12D3 with the adjuvant Montanide 75; cattle in Group II received adjuvant-PBS, and Group III were untreated controls. On day 14, cattle in Group I received a second injection of the three recombinant proteins in adjuvant and cattle in Group II again received adjuvant alone. On day 28, all groups of cattle were challenged with a field strain of Babesia bovis. After challenge, the experimental cattle were clinically and serologically monitored. Three of the five steers immunized with the combined recombinant B. bovis proteins seroconverted on day 14 post-immunization (P.I.) and the maximum titre was 1 : 1600. All five immunized steers presented strong seropositivity to B. bovis antigens at day 21 P.I. The prepatent periods of vaccinated cattle were delayed until day 10 post-challenge exposure versus 8 and 7 days in Groups II and III, respectively. Cattle in all groups had fever above 41 degrees C; the reduction in packed cell volume was not significantly different (P > 0.05) in vaccinated group I compared with Groups II and III (29% versus 26% and 31%, respectively). Treatment was required for one steer in the control group. During the period of the study, the weight of cattle in Groups I and II increased an average of 9 and 7 kg, whereas the weight of the control cattle was reduced on average 4 kg. Immunization with rMSA-1-rMSA-2c-r12D3 proteins was not sufficient to prevent clinical symptoms against challenge, but the immunologic response was sufficient to protect steers against a mild virulent strain of B. bovis.
- [Show abstract] [Hide abstract] ABSTRACT: The 12D3 antigen present in Babesia bovis has been evaluated as a recombinant vaccine candidate and the 12d3 coding sequence has been reported for an Australian and an USA (Texas) isolate of B. bovis. However, no approach has been conducted to perform analysis of 12d3 sequence conservation on a larger number of B. bovis isolates. This could provide important information to determine whether a recombinant vaccine containing this antigen could be widely used. This study reports the cloning and sequencing analysis of the 12d3 coding region in 20 different B. bovis isolates collected from various geographical regions in the tropics and subtropics of Mexico. Comparative analysis of the consensus nucleotide sequences obtained for each isolate revealed a high degree of conservation (94-99% sequence identity) among the 12d3 alleles present in the Mexican isolates when compared with the 12d3 ORF sequences from the Texan (T2Bo) B. bovis isolate. Similarly, BLASTX sequence homology search showed a high percent identity (93-99%) of the deduced amino acid 12D3 sequence as compared with the T2Bo isolate sequence. The high level of sequence conservation in 12d3 among the 20 B. bovis isolates collected from geographically distant locations in Mexico suggests that there exists a minimal bovine-host immunological pressure which could be translated into antigenic diversity or variation, and most probably this is reflected in the non-inmunodominant characteristic of the 12D3 antigen as it has been previously described in the literature. 12D3 antigen can be considered as a viable candidate for inclusion in a recombinant vaccine for cattle babesiosis caused by B. bovis in Mexico.
- [Show abstract] [Hide abstract] ABSTRACT: Variable merozoite surface antigens of Babesia bovis are exposed glycoproteins having a role in erythrocyte invasion. Members of this gene family include msa-1 and msa-2 (msa-2c, msa-2a(1), msa-2a(2) and msa-2b). To determine the sequence variation among B. bovis Mexican isolates using msa-2b as a genetic marker, PCR amplicons corresponding to msa-2b were cloned and plasmids carrying the corresponding inserts were purified and sequenced. Comparative analysis of nucleotide and deduced amino acid sequences revealed distinct degrees of variability and identity among the coding gene sequences obtained from 16 geographically different Mexican B. bovis isolates and a reference strain. Clustal-W multiple alignments of the MSA-2b deduced amino acid sequences performed with the 17 B. bovis Mexican isolates, revealed the identification of three genotypes with a distinct set each of amino acid residues present at the variable region: Genotype I represented by the MO7 strain (in vitro culture-derived from the Mexico isolate) as well as RAD, Chiapas-1, Tabasco and Veracruz-3 isolates; Genotype II, represented by the Jalisco, Mexico and Veracruz-2 isolates; and Genotype III comprising the sequences from most of the isolates studied, Tamaulipas-1, Chiapas-2, Guerrero-1, Nayarit, Quintana Roo, Nuevo Leon, Tamaulipas-2, Yucatan and Guerrero-2. Moreover, these three genotypes could be discriminated against each other by using a PCR-RFLP approach. The results suggest that occurrence of indels within the variable region of msa-2b sequences can be useful markers for identifying a particular genotype present in field populations of B. bovis isolated from infected cattle in Mexico.
- [Show abstract] [Hide abstract] ABSTRACT: To evaluate the effect of Lactobacillus casei on the effectiveness of the Mexican bovine babesiosis mixed vaccine, 20 bovines were randomly allocated into four groups of five animals (I, II, III, and IV). At day -2 animals in groups I and II were inoculated with saline solution by intramuscular route (i.m.) and animals in groups III and IV were inoculated with L. casei. At day 0 bovines in groups I and III were inoculated i.m. with bovine normal erythrocytes and animals of groups II and IV were inoculated with the babesiosis vaccine. Twenty-four days later each bovine was challenged with Babesia bovis- and B. bigemina-infected erythrocytes. The average rectal temperature in groups I and III was higher (P < 0.05) than that in the vaccinated groups after challenge. The average packed cell volume was lower (P < 0.01) in the control groups than in the vaccinated groups. At day 10 after challenge, the average anti-Babesia antibody level was higher in group IV than in group II. At day 7 after vaccination, the percentage of bovines positive to gamma interferon, as determined by real-time PCR, was 20, 0, 40, and 80 for groups I, II, III, and IV, respectively. All animals in control groups (I and III) were treated against babesiosis to avoid their death because they showed signs of babesiosis. The results indicate that L. casei, inoculated 2 days before the inoculation of the Mexican bivalent bovine babesiosis vaccine, improves the vaccine's efficiency.
- [Show abstract] [Hide abstract] ABSTRACT: Gamma irradiation on bovine serum and red blood cells (RBC) allows proliferation and growth of in vitro-cultured Babesia sp., and has potential application to inactivate contaminating viruses and bacteria from the substrate. Gamma irradiation with 25 kGy in a source of (60)Co was able to inactivate infectious bovine rinotracheitis (IBR) and bovine viral diarrhea (BVD) viruses in artificially contaminated serum; besides, bacteria were also eliminated. In vitro culture of Babesia bovis (B. bovis) in modified substrate, by adding irradiated serum with (60)Co at 25 kGy was propagated from 24-well culture plates to 225 cm(2) tissue culture flasks, and percentages of parasitized erythrocytes (PPE) from 2.4% to 8.8% were obtained. Infected RBC adapted to Irrad S were transferred to the irradiated substrate in vitro culture system, by using serum irradiated at 25 kGy and RBC from 10 to 70 Gy. The PPE ranged from 3.1 to 11. Culture of Babesia bigemina (B. bigemina) was established with Irrad S (25 kGy); its propagation was achieved in tissue culture flasks reaching PPE from 0.5 to 4.3 with no statistical difference (P > 0.05) when compared to the nonirradiated control culture (1.2-4.8). B. bigemina-infected RBCs were transferred to the modified culture system by adding irradiated serum and RBC (25 kGy and 70 Gy, respectively). PPE obtained in culture flasks were from 0.8 to 4.2. The results indicate that gamma irradiation is a suitable method to inactivate potential viral contamination and eliminate bacteria from bovine serum, to produce a live attenuated vaccine through the in vitro culture.