Immunogenic potential and protective efficacy of formalin inactivated circulating Indian strain of West Nile virus

摘要

Objective:To assess the best suitable condition for virus inactivation, and to study the immunogenic potential and protective efficacy of a circulatingWestNile virus(WNV) strain in Assam.Methods:Bulk preparation of circulatingWNV:WNIRGC07(GeneBankID:HQ246154), was undertaken in a bioreactor using cytodex-1.VirusInactivation was done in three different conditions;22 ℃,4 ℃ and room temperature.The virus preparations were evaluated for antigenicity byELISA and toxicity by cell proliferation kit.Virus efficacy was donein-vivo on swiss albino mice against standardIndianWNV andJapanese encephalitis virus(JEV) strain.Humoral and cell mediated immune response was evaluated in mice sera byELISA and neutralization assay.Results:Inactivation at22 ℃ was found to be more suitable in terms of less toxicity and high antigenicity.The same was selected to study the immune response and efficacy in mice.It induced neutralizing antibody titre of1:625 and highIgG response.In vivo experiment showed100% protective efficacy againstWNV and20.8% cross protective efficacy againstJEV. Further assessment of cellular immunity through immunized mice revealed augmentation of high levels of pro-inflammatory cytokines and moderate levels of anti-cytokines indicating a mixed balance ofTh1 andTh2 response.Conclusions:Findings suggest that formalin inactivated IndianWNV strain has a good immunogenic potential.This is the first study on assessment of immunogenic potential of a lineage5 strain ofWNV.Our study reveals that it would be a promising and effective candidate for vaccine studies which warrants furtherevaluation.