Rabies-based vaccine induces potent immune responses against Nipah virus

Nipah Virus (NiV) is a re-emerging zoonotic pathogen in the genus Henipavirus of the Paramyxoviridae family of viruses. NiV is endemic to Bangladesh and Malaysia and is highly fatal to both livestock and humans (human case fatality rate = 74.5%). Currently, there is no approved vaccine against NiV on the market. The goal of this study was to use a recombinant RABV vector expressing NiV glycoprotein (NiV G) to develop a bivalent candidate vaccine against NiV disease and rabies virus (RABV) disease, which is also a significant health burden in the regions where NiV is endemic. The rabies vector is a well-established vaccine strain that lacks neurovirulence and can stably expresses foreign antigens that are immunogenic in various animal models. Mice inoculated intranasally with the live recombinant RABV/NiV vaccine (NIPARAB) showed no signs of disease. To test the immunogenicity of the vaccine candidate, groups of C57BL/6 mice were immunized intramuscularly with a single dose of live vaccine particles or two doses of chemically inactivated viral particles. Both vaccination groups showed NiV G-specific seroconversion, and the inactivated (INAC) vaccine group yielded higher titers of NiV G-specific antibodies. Furthermore, cross-reactivity of NiV G-specific immune sera against Hendra virus (HeV), was confirmed by immunofluorescence (IF) and indirect ELISA against soluble recombinant HeV glycoprotein (HeV G). Both live and killed vaccines induced neutralizing antibodies. These results indicate that NIPARAB may be used as a killed virus vaccine to protect humans against NiV and RABV, and possibly as a preventative measure against HeV as well. Viral vaccines: bivalent vaccine immunizes mice against Nipah virus The Nipah virus (NiV) infects livestock and humans with high mortality, but to date no vaccine has been approved that protects against NiV. Here, Matthias Schnell and colleagues developed a bivalent vaccine based on a highly immunogenic rabies virus vector and on expression of NiV glycoprotein. The vaccine led to the formation of neutralizing antibodies against the NiV glycoprotein in inoculated mice, which developed no disease as a consequence of immunization. Notably, the researchers also show that NiV neutralizing antibodies generated in the inoculated mice were cross-reactive to the Hendra virus, broadening the spectrum of the vaccine. The work provides a candidate for a NiV vaccine that uses a highly immunogenic vector and that has the potential to induce protection against not only NiV, but to rabies virus and Hendra virus as well.