Jyoti S Kumar, Divyasha Saxena and Manmohan Parida
West Nile virus is an emerging arthropod borne flavivirus with increasing distribution worldwide that is responsible for severe and fatal encephalitis in humans. Currently, there is no licensed human vaccine or specific therapy to prevent WNV infection. Present study was aimed to assess the immunogenicity and protective efficacy of recombinant whole envelope (rEnv) and domain III (rDIII) in mice model. Briefly, the gene coding for the envelope and domain III protein of WNV was cloned and expressed in pET 28a expression vector followed by purification. Balb/C mice were immunized with the purified recombinant proteins of rEnv and rDIII with a conc. of 25 and 50μg with Freund' s adjuvant. Booster injections with same formulation were given on 14 and 28 days after first immunization. Two booster doses were given subsequently. Humoral and cell mediated immune responses were determined by ELISA titer, PRNT assay and cytokine ELISA. Further assessment of cell mediated immune response from immunized mice revealed higher levels of both pro- and anti- inflammatory cytokines indicating a balance of Th1/Th2 type of immune response. All the mice were challenged with 100LD50 dose of WNV after 30 days of last booster and observed for 1 month. Mice immunized with recombinant whole envelope protein showed 100 % protection whereas domain III only confers 83 % protection. These results indicate that WNV whole envelope protein can be better candidate molecule for vaccinestudies.
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