Experimental efficacy evaluation of inactivated and live Newcastle 
disease virus vaccines of genotypes II and VII against wild type 
virus

Karim M Selim| Abdullah A Selim| abdelsattar Arafa| Hussein Aly Hussein| Ahmed A El-Sanousi

Abstract
Background: Different genotypes of Avian avulavirus 1, also known as Newcastle disease virus (NDV) and formerly known as Avian paramyxovirus 1(APMV-1), are circulating in many parts of the world. Currently, the used vaccine strains (mainly genotypes I and II) are three to seven decades old and are genetically distant from the currently circulating virulent Newcastle disease virus (NDV).
Objectives: In this study, we compared two vaccination programs against NDV in chickens, one using genotype VII inactivated and live NDV vaccine are available in the market, and the second group used genotype II inactivated LaSota vaccine with a live vaccine.
Method: NDV isolate designated NDV-GZ-986F-2015 was isolated from a commercial broiler farm in Egypt and characterized as a virulent strain that was used for the challenge. Contact chicks were added in both groups post-challenge.
Results: indicated that both programs can protect birds from mortalities (up to 100 %). The parameters used in this evaluation are the antibody immune response using hemagglutination inhibition (HI) assay, protection post-challenge, virus shedding and transmission in contact non-vaccinated chickens using the qRT-PCR test. The genotype VII (GVII) vaccine group induced higher HI titer by using GVII monospecific antigen and decreased virus shedding than other groups. The vaccinated group with genotype VII significantly reduced the virus shedding at 3, 5, 7, and 10 days post-challenge unlike the genotype II vaccinated group that did not reduce virus shedding and increased morbidity and mortality in contact birds.
Conclusion: The combined inactivated and live NDV vaccination programs have the potency to prevent mortalities of virulent genotype VII challenge virus. The vaccination program used genotype VII inactivated and live vaccines initiated a high level of antibody titers that can limit the transmission and virus shedding to the contact birds. These results may help in controlling the NDV of GVII virulent strain that is commonly circulating in the field.

Key words: Newcastle disease virus, homologues and heterologous Vaccination program, Virus shedding, GII, GVII, Recombinant Lasota vaccine

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