Influence of divergent selection for response to sheep RBC on immunoresponsiveness to Newcastle disease vaccine in White Leghorn Chicken*

Abstract

An investigation was carried out to evaluate the effect of divergent selection for antibody respons eto sheep RBCs on immunoresponsiveness of birds against Newscastle disease virus (ND) vaccine. Chicks (20)) belonging to first generation of divergily selected lines, 10 at high extreme in high SRBC response line (HRSBC) and 10 at low extreme in low SRBC line (LSRB), identified by assesing their antibody responses to sheep RBCs at 5-6 weeks of age, were evaluated for immunoresponsiveness ND vaccine. Chicks were vaccinated with 'F' strain of ND vaccine at day '0' and a booster dose was given on 28th day. Sera were collected at 7.14,11, 28.35 and 42 dpi after primary inoculation and antibody titres against NU (vaccine strain) were determined using ELISA. IISRBC line exhibited peak antibody tire at 14 dpi, but LSRBC line revealed no specific trend in antibody titres. Significant differences betwen line observed at 14 dpi, 21.35 and 32 dpi. Effect of sex was significant at 11 and 28 dpi. Interaction of sex and line was significant in the early weeks (7 and 14 dpi) only. The finding demonstrated that antibody production to NU vaccine was influenced by divergent selection for antibody response to sheep RBC. It may be suggested that selection for higher humoral response along with other economioc traits could be used in layer chicken to genetically improve their immunoresponsiveness towards vaccines like ND vaccine.