Serological response of chicken to various Newcastle disease virus isolates

Immune response of chickens to Newcastle disease virus strains isolated from chicken, guinea fowl and pigeon was studied by various serological tests. Precipitating antibodies were detected at 7 DPI in all the 3 groups and birds remained positive till the end of the observation period. The HI antibody titre started rising after 7 DPI and the maximum titre was detected from 15-21 DPI. In guinea fowl and pigeon isolate infected groups, the titre was good whereas in chicken isolate infected group no bird was alive to monitor the response. ELISA titre was many-fold higher compared to HI titres of Newcastle disease virus, and it could also detect much low level of antibody than that of HI test. Serum neutralization titre in all the 3 groups was maximum between 15-21 DPI and then started declining. Overall, all the isolates elicited good immune response in chicken.