Oral immunization is an alternative or supplementary approach that can significantly improve dog vaccination coverage, especially for free-roaming dogs. Safe and effective oral rabies vaccines for dogs are still being sought. In our previous studies, we generated a genetically modified rabies virus (RABV) ERA strain, rERAG_333E, containing a mutation from arginine (Arg, R) to glutamic acid (Glu, E) at residue 333 of the G protein (G_333E). Our previous results demonstrated that rERAG_333Ewas safe for adult mice and dogs, and oral vaccination with rERAG_333Einduced a strong and long-lasting protective immune response in dogs. Here, we further investigated the safety and immunogenicity of rERAG_333Ein non-target species, including suckling mice, rhesus monkeys, foxes, raccoon dogs, piglets, goats, and sheep. Suckling mice studies demonstrated that the G_333Emutation significantly reduced the virulence of the ERA strain. All of the suckling mice aged 10 days and above survived and showed no apparent signs of disease after intracerebral inoculation with rERAG_333E. Animal studies demonstrated that rERAG_333Ewas safe in rhesus monkeys, foxes, raccoon dogs, piglets, goats, and sheep. None of those animals inoculated orally with 10 times the intended field dose of rERAG_333Eshowed abnormal clinical signs before and after the booster immunization with Rabvac 3, an inactivated rabies vaccine. Meanwhile, oral inoculation with rERAG_333Einduced strong neutralizing antibody (NA) responses to RABV in rhesus monkeys, foxes, raccoon dogs, and piglets. These results demonstrated that rERAG_333Ehas the potential to serve as a safe oral rabies vaccine for dogs.

Toll-like receptors  /  TLR7 agonist  /  innate immunity  /  antiviral effect