genotype vii of newcastle disease virus: a global approach for a new vaccine

Newcastle disease virus (ndv) genotype vii (gvii) becoming predominant strain of ndv in poultry industry. it causes high mortality even in vaccinated chickens with a common ndv genotype ii vaccine (giivacc). the pathogenesis of the ndv-gvii is different than the other velogenic strains and mainly cause lymphocyte depletion and mortality within first 24 hours of infection in infected birds. to overcome this, killed gvii vaccine has been used to prevent ndv outbreaks. however, the debate about vaccine differences remains ongoing. hence, this study investigated the difference in chicken responses to the two vaccines at the molecular level. the spleen transcriptomes from vaccinated chickens reveal that gviivacc affected the immune response by down regulating neuro-inflammation. it also enhanced a synaptogenesis pathway that operates typically in the nervous system, suggesting a mechanism for the neurotrophic effect of this strain. we speculated that the down-regulated immune system regulation correlated with protecting the nervous system from excess leukocytes and cytokine activity. in contrast, giivacc inhibited apoptosis by downregulating perk/atf4/chop as part of the unfolded protein response pathway but did not affect the expression of the same synaptogenesis pathway. thus, the application of gviivacc needs to be considered in countries where gvii is the leading cause of ndv outbreaks. the predicted molecular signatures may also be used in developing new vaccines that trigger specific genes in the immune system in combating ndv outbreak.