The Immune Response of Maternally Immune Chicks to Vaccination with Newcastle Disease Virus
This study was conducted to determine the persistence of maternally derived antibodies (MDA) to Newcastle disease virus (NDV) in newly hatched chicks and the effect of MDA on vaccination with a very potent vaccine (Avinew® (VG/GA)). Individual variations of chicks in acquiring and maintaining MDA and in their response to vaccination were also investigated. In order to study the persistence of MDA, 50 one-day-old Hisex breed chicks were divided into five groups based on their age at serum collection (one-day-old, seven days-old, fourteen-days-old, twenty- days-old and twenty eight-days-old), respectively. To assess interference of MDA with vaccination, 30 chicks were divided into three groups based on time of vaccination (days 1, 14, and 28). Haemagglutination inhibition test was used to measure antibody titer in sera. Chicks at 1, 7, 14, 21, and 28 days of age showed MDA titers of 9, 8.7, 5.8, 4.2, and 1.6 (log2) respectively. Vaccination at day 1, 14, and 28 of age elicited titers of 2.6, 3.98, and 4.75 respectively. It was noticed that among each group there was variations in titer. The minimum titer that interfered with vaccination was 4.2 (log2). This titer was obtained in day 18 of age which was considered the optimum time for vaccination with Avinew ®(VG/GA) strain.