Immunogenicity of virosome vaccine from Komarov mesogenic strain against Newcastle disease in chicken

Immunogenic potential of virosome vaccine prepared from Komarov-mesogenic Newcastle disease virus (NDV) was evaluated in chicken against Newcastle disease (ND). Mesogenic NDV strain-Komarov virus stock was bulk propagated in embryonated chicken eggs (ECE) and the allantoic fluid was harvested, purified and concentrated by density gradient ultracentrifugation. Virosomes were prepared from purified virus by following Triton X-100 treatment and SM 2 bio-beads method. A total of 144 day-old Vanaraja chicks were used in immunization trial. First group was immunized with virosome vaccine through subcutaneous (S/C) route on 5^th day; Second group was primed with same dose followed by booster of virosomes on 14^th day. Third group wasimmunizedwith LaSota on 5^thand 14^thdayand fourth group was kept as unimmunized control. ND specific antibody response was measured by haemagglutination inhibition assay (HI) at different weekly intervals. Cell mediated immune response was analysed on 4^th and 10^th week by lymphocyte transformation test (LTT). Virosome vaccine prime-boost group induced HI titres equivalent to Lasota vaccine during first and second week of postimmunization. However, during third and fourth week Lasota vaccine induced higher antibody titres. On 9^th and 10^th week virosome prime-boost vaccine could induce equivalent antibody response to LaSota vaccine. No significant differences were observed between the three groups in stimulation indices on 4^th and 10^th week post-immunization. Prime-boost immunization with virosome vaccine from mesogenic NDV induces antibody titres equivalent to multiple doses of lentogenic live vaccine.