Thermostability and efficacy of I-2 vaccine against Newcastle disease (ND) in Iran: a pilot study.

Thermostable vaccine against Newcastle disease (NO) is a potential alternative to chicken vaccination in villages, since cold chain is not needed in this process. The purpose of this study was to investigate thermostability and efficacy of I-2 vaccine against ND. The vaccine tested for sterility, intracerebral pathogenicity index (ICPI) and 50% embryo infectious dose (EID50). The wet vaccine stored at 20°C for 1, 2 and 4 weeks named A, B and D, respectively. Each preparation (10 (7.5) EID50) was used to inoculate twenty.4-week-old chicks via eye drop. All groups except the control were vaccinated twice in 2 weeks interval. Haemagglutination inhibition test used for evaluation of the antibody response. Two weeks after the first vaccination, a peak titer of about log.2 (6) and log.2 (4.6) was observed in A and B groups, but D group did not induce any antibody response in their sera. All the vaccinated groups responded to vaccination after second trial and produced mean titers of log.2 (6.2) , log.2 (6) and log.2 (5.4) were observed,respectively.