Newcastle disease virus has been classified into 2 classes (I & II), Class I is rarely detected in poultry, Class II is the most one affecting the poultry species. The class II nucleotides sequence of the F gene are divided into 18 genotypes (I–XVIII), in the region genotype (VII.1.1) is the most dominant NDV genotype, Genotype (VII.1.1) combining the former sub-genotypes VIIb, VIId, VIIe, VIIj, and VIIl. An exception is the former sub-genotype VIIf, which was classified as a separate sub-genotype, namely VII.1.2. The different genotypes have been showed antigenic and genetic diversity with multiple cases of vaccination failure and the reduced ability of classical vaccines (genotype II) to decrease virus replication and shedding of the virulent NDV. Recent NDV isolates are related to genotype VII.1.1 due to the presence of mutations at different sites of the F gene, that may affect virus pathogenicity and interfere with the protection offered by classical vaccines. Recently, the market available vaccines are from different genotypes genotype II and recent genotype VII recombinant RG ND vaccine on LaSota backbone-carrying F and/or HN genes and a whole virus of genotype VII.I.I (Valley Vac ND range).
When these vaccines are evaluated in commercial broilers and then challenged against ND genotype VII.I.I circulates virus, the result was that the birds which vaccinated with genotype II inactivated vaccine and challenged showed the highest respiratory manifestations along with the highest levels of digestive disorders and the lowest rate of recovery, the birds which vaccinated with recombinant G-VII and Challenged showed lower respiratory and digestive manifestations and the birds in which vaccinated with whole virus of NDV-GVII showed the lowest rates of respiratory and digestive manifestations.
When we examine the gross lesions and nervous manifestation, we found that the birds which vaccinated with genotype II inactivated vaccine and challenged showed the highest gross lesions and nervous manifestations comparing to the birds which vaccinated with recombinant G-VII and Challenged showed moderate to low gross lesions and nervous manifestations and birds in which vaccinated with whole virus of NDV-GVII showed the lowest rates of gross lesions and nervous manifestations.
The mortality rate in the birds which vaccinated with genotype II inactivated vaccine and challenged showed 7X and vaccinated with recombinant G-VII and Challenged 2X when comparing with birds in which vaccinated with whole virus of NDV-GVII.
Finally, the shedding control from trachea and cloaca was best in the group vaccinated with whole virus of NDV-GVII then in the recombinant G-VII and the lowest is in genotype II group.
In conclusion, NDV has 6 six encoded protein each one of them has a role in protection and viral shedding control. So, the whole inactivated GVII vaccine is the most suitable solution for protection against the circulating NDV in Middle East, Africa and Asia.