Vaccine Potential of Nipah Virus-Like Particles

Nipah VLP Since it was first recognized in 1998, Nipah virus (NiV) has caused several outbreaks in humans of encephalitic disease associated with high lethality. In the first outbreak, which was in Malaysia and Singapore, 265 humans became sick and some 40% of them died. Epidemiological links pointed to human contact with sick pigs in commercial piggeries, and the outbreak was brought under control through culling of approximately 1.1 million pigs. Since then, the virus has re-emerged in Bangladesh and neighboring India, starting in 2001, and between then and now, has caused several smaller but even deadlier disease outbreaks with case fatality rates ranging between 60 and 90%. Unlike the Malaysian outbreak, the route of transmission in these outbreaks was considered to be bat-to-human via food contaminated with bat saliva. In some cases, nosocomial transmissibility and person-to-person spread was also noted. An additional concern is that NiV is also potentially an agent of agro-terror since the rate of transmission of this virus in the pig population is close to 100%. Effective vaccine and therapies are needed to combat the threats posed by NiV.

2011 Vaccine Potential of Nipah Virus-Like Particles. 2011 PLoS ONE 6(4): e18437. doi:10.1371/journal.pone.0018437
Nipah virus (NiV) was first recognized in 1998 in a zoonotic disease outbreak associated with highly lethal febrile encephalitis in humans and a predominantly respiratory disease in pigs. Periodic deadly outbreaks, documentation of person-to-person transmission, and the potential of this virus as an agent of agroterror reinforce the need for effective means of therapy and prevention. In this report, we describe the vaccine potential of NiV virus-like particles (NiV VLPs) composed of three NiV proteins G, F and M. Co-expression of these proteins under optimized conditions resulted in quantifiable amounts of VLPs with many virus-like/vaccine desirable properties including some not previously described for VLPs of any paramyxovirus: The particles were fusogenic, inducing syncytia formation; PCR array analysis showed NiV VLP-induced activation of innate immune defense pathways; the surface structure of NiV VLPs imaged by cryoelectron microscopy was dense, ordered, and repetitive, and consistent with similarly derived structure of paramyxovirus measles virus. The VLPs were composed of all the three viral proteins as designed, and their intracellular processing also appeared similar to NiV virions. The size, morphology and surface composition of the VLPs were consistent with the parental virus, and importantly, they retained their antigenic potential. Finally, these particles, formulated without adjuvant, were able to induce neutralizing antibody response in Balb/c mice. These findings indicate vaccine potential of these particles and will be the basis for undertaking future protective efficacy studies in animal models of NiV disease.

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