HS vaccines have been developed from time to time using whole bacteria or their components The variation in duration of immunity, kinetics and isotype of antibody and humoral and cellular immune responses with regards to vaccine have been poorly understood. There are repeated incidences of vaccination failure inspite of vaccinations done at regular intervals. This work was envisaged to study the role of humoral immunity by emphasizing on levels of B lymphocytes in vitro and their markers in unvaccinated and vaccinated cattle and buffaloes against P. multocida B: 2 (strain P52) at different time intervals. On immunoflourescence staining using monoclonal antibodies for B lymphocytes and activated lymphocytes (IL-2R+), the distinct fluorescence pattern was seen on the periphery of both B lymphocytes and activated B lymphocytes. Flowcytometry was done to evaluate the levels of B lymphocytes and activated lymphocytes (IL-2R) in blood from 10 cattle and 10 buffaloes which were vaccinated with alum precipitated HS vaccine. There has been a decrease in the level of B Lymphocytes over a period of time from zero days to 90 days post vaccination. But there was no significant variation in B lymphocytes levels and activated lymphocyte (IL-2R+) levels between prevaccinated and post vaccinated cattle and buffaloes at different time intervals (30 day, 60 day, 90 days and 120 days) as revealed by ANOVA. However a significant increase was revealed by paired t-test in activated lymphocytes (IL-2R+) levels at 30 days and 120 days post vaccination.
Haemorrhagic septicaemia, IL-2, IL-2R+, B Lymphocytes, Flow Cytometry.