Immune responses in mice and pigs after oral vaccination with rabies virus vectored Nipah disease vaccines

Nipah virus (NiV) is a re-emerging zoonotic pathogen that causes high mortality in humans and pigs. Oral immunization in free-roaming animals is one of the most practical approaches to prevent NiV pandemics. We previously generated a recombinant rabies viruses (RABV) Evelyn-Rokitnicki-Abelseth (ERA) strain, rERAG, which contains a mutation from arginine to glutamic acid at residue 333 of glycoprotein (G) and serves as an oral vaccine for dog rabies. In this study, we generated two recombinant RABVs, rERAG/NiVG and rERAG/NiVF, expressing the NiV Malaysian strain attachment glycoprotein (NiV-G) or fusion glycoprotein (NiV-F) gene based on the rERAG vector platform. Both rERAG/NiVG and rERAG/NiVF displayed growth properties similar to those of rERAG and caused marked syncytia formation after co-infection in BSR cell culture. Adult and suckling mice intracerebrally inoculated with the recombinant RABVs showed NiV-G and NiV-F expression did not increase the virulence of rERAG. Oral vaccination with rERAG/NiVG either singularly or combined with rERAG/NiVF induced significant NiV neutralizing antibody against NiV and RABV, and IgG to NiV-G or NiV-F in mice and pigs. rERAG/NiVG and rERAG/NiVF thus appeared to be suitable candidates for further oral vaccines for potential animal targets in endemic areas of NiV disease and rabies.