Protection against infections of group II Japanese encephalitis virus strains in mice

Twenty-one strains of Japanese encephalitis (JE) virus analyzed earlier for the epitopes employing a panel of monoclonal antibodies (MAbs) raised against glycoprotein ‘E’ of an Indian strain of JE virus, showed 15 strains having complete Hs epitope functional (protective) activity (group I). The remaining six strains depicted only partial Hs epitope activity (group II). Five of the six group II JE virus strains i.e., 3 Indian strains-G9473, 641686 and 755468; one each of Japanese–Yoken and Sri Lankan-691004 strain were studied for in vivo neutralization and passive protection by the MAbs as well as protection by active immunization with four group II strains against lethal virus challenge in Swiss mice. Group II strains were neutralized; especially strains G9473 and 755468 by some of the Hs MAbs and the mice were protected against lethal virus challenge due to active immunization or by the MAbs transferred passively. Also an additional role of NHs epitopes along with those of partially expressed/functional Hs epitopes in protection was clearly indicated. These findings might help in evaluating a better strategy of vaccination for inducing an optimal immune response, thereby protecting the individuals against infections with JE virus showing strain variations.