Immunosuppressive effect of Babesia bovis immunogens on immunization against foot and mouth disease

The impact of natural infection with Babesia bovis on the immune response to FMD vaccine in calves was studied. Three groups of calves, group [1] were Babesia bovis free and vaccinated with inactivated FMD vaccine, group [2] naturally Babesia bovis infected and vaccinated with inactivated FMD vaccine, while group [3] was kept as non infection non vaccinated control. The humoral immune response of each group was measured by serum neutralization test [SNT] for a period of 16 weeks. Babesia [B.] bovis naturally infected group of calves [gp. 2] showed tendency of lower antibody responses in comparison with uninfected [gp. 1] post vaccination with Foot and Mouth Disease [FMD] vaccine. Parasitaemia of B.bovis infected calves were ranged from 1.5% to 2.5% at time of vaccination accompanied with reduction in packed cell volumes [PCV] up to 23% less than control group. The parasite persisted in the blood of infected calves as carriers with low parasitaernia. Three isolates of B.bovis have been identified. Protein characterization of the three isolates of B.bovis immunogens resulting in immunosuppressive effect was investigated. The isolates identified and propagated in cell culture using microaerophilus stationary phase and characterized by sodium dedocyle sulphate polyacrylamide gel electrophoresis [SDS-PAGE] and Western immunoblot. The molecular weights of antigens were varied froml2 to 165 Kilo Daltons [KDa]. The isolates showed totally 30 polypeptide antigens. Nineteen antigens were detected as homologous and common between the isolates, their molecular weights were 160, 152, 132, 110, 85, 77, 70, 67, 60, 49, 45, 40, 39, 35, 33, 30, 23, 18 and 12 KDa. While the other 11 antigenic bands were detected as heterologous and differ between the isolates, their molecular weights were 165, 155, 153, 144, 140, 120, 115, 112, 62, 37 and 20 KDa. Isolates no. I, 2 and 3 contained 24, 28 and 24 out of the 30 immunogens respectively. The immune suppressive effect by reduction in serum neutralizing antibody titers of B.bovis infected calves might be due to one or more of B.bovis common antigens

Trial to increase the duration of neutralizing antibodies in cattle vaccinated with inactivated FMD vaccine

Inactivated FMD vaccine is weakly immunogenic and multiple vaccinations at four-month intervals are necessary for the prevention of the disease. Our results revealed that in cyclophosphamide treated animals, the antibody titers remained protecting up to 35 weeks post vaccination, while in non treated group, the animals became susceptible to infection 19 weeks post vaccination. So, it is possible to increase the duration of neutralizing antibodies in serum when a low single dose of cyclophosphamide is administered four days before vaccination with aluminum hydroxide-saponin FMD vaccine and this will increase the intervals between vaccinations and decrease the commercialization costs of vaccination programs