[The influence of vaccination on immunological reactivity and efficiency of serological diagnosis of bovine leucosis]
2009
Ivanov, O.V., Ivanovo State Agricultural Academy (Russian Federation) | Ivanova, O.Yu. | Fedorov, Yu.N., Ivanovo Regional Veterinary Laboratory (Russian Federation) | Verkhovskij, O.A., Research and Development Inst.of Diagnosis and Prophylaxis of Human and Animal Disease, Moscow (Russian Federation) | Verkhovskaya, A.E.
At one of leucosis-affected farms in the Ivanovo region there was studied influence of a live lyophilized vaccine (LLV) Taurus-B on humoral immunity in calves infected with BLV. All experimental calves (30 heads – IDT-negative and 10 heads – IDT-positive) were once immunized with LLV from attenuated strains of infectious rhinotracheitis (IRT) virus, viral diarrhea (VD) and parainfluenza. The study of blood sera 1 month after vaccination has shown that LLV stimulated B-cell immunity, however, the level of virus-specific antibodies to all 3 virus in IDT-positive calves was much lower than in IDT-negative calves: 21.2 (38.7) – to IBR; 93.7 (118.8) – to parainfluenza-3 and 96.3 (121.4) – to VD, respectively. In all experimental animals there was found an increase in the total content of immunoglobuline concentration: in IDT-positive calves – up to 23.7/2.8 mg/ml, in IDT-negative calves – 23.4/2.1 mg/ml, respectively. The observed difference in IGM proved an immunosuppressive effect of leucosis virus on B-lymphocytes secreting immunoglobulins of this isotope. The study of blood sera of calves for antibodies to BLV in EIA has shown that all 10 IDT-positive calves were EIA-positive, and of 30 IDT-seronegative, 6 were positively responsive in EIA. As was found by analysis, the immunization of seropositive calves with LLV had an immunosuppressive effect on the synthesis of antibodies to BLV resulted in pseudo-negative EIA results in earlier positive animals with low their content. The presence of interference between BLV and IBR, VD and partially parainfluenza-3 viruses in susceptible calves promoted mutual inhibition of virus-specific B-cell immune response, immunosuppression and lowering the indices of humoral immunity
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