Immunogenicity of commercial, formaldehyde and binary ethylenimine inactivated Newcastle disease virus vaccines in specific pathogen free chickens

Newcastle disease (ND) is one of the most important diseases that affect birds; the epizootic nature of the disease has caused severe economic losses in the poultry industry worldwide. In this experiment ND virus (NDV) was inactivated by two different chemicals binary ethylenimine (BEI) and formaldehyde. Formaldehyde was used at 0.1%, while BEI was used at concentrations of 1 to 4 mM. NDV inactivation with BEI was done in various incubation temperatures and periods and the best result (30 °C, 4 mM BEI and 21 hrs treatment) used as an experimental vaccine. Prepared inactivated NDV vaccines and a commercial vaccine were tested for their efficiency in generating humoral immune response in different groups of specific pathogen free (SPF) chicks. Test groups received 0.2 ml formaldehyde inactivated NDV (NDVF), BEI inactivated NDV (NDVEI) and Razi institute produced NDV vaccine (NDVR) subcutaneously respectively. HI Log 2 total mean titer of NDVEI group (8.42 ± 0.12) were significantly higher than NDVF (7.64 ± 0.16) and NDVR (7.86 ± 0.11) groups (p<0.05). BEI-inactivated vaccine gave higher antibody titers than formaldehyde-inactivated vaccine and preserves both structural integrity and antigenicity of the virus. Thus, it might be possible to use these compounds as an inactivator agent for commercial NDV inactivated vaccines in future.