In recent years, bats have been identified as a natural reservoir for a diverse range of viruses. Nelson Bay orthoreovirus (NBV) was first isolated from the heart blood of a fruit bat (Pteropus poliocephalus) in 1968. While the pathogenesis of NBV remains unknown, other related members of this group have caused acute respiratory disease in humans. Thus the potential for NBV to impact human health appears plausible. Here, to increase our knowledge of NBV, we examined the replication and infectivity of NBV using different mammalian cell lines derived from bat, human, mouse and monkey. All cell lines supported the replication of NBV; however, L929 cells showed a greater than 2 log reduction in virus titre compared with the other cell lines. Furthermore, NBV did not induce major cytopathic effects in the L929 cells, as was observed in other cell lines. Interestingly, the related Pteropine orthoreoviruses, Pulau virus (PulV) and Melaka virus (MelV) were able to replicate to high titres in L929 cells but infection resulted in reduced cytopathic effect. Our study demonstrates a unique virus-host interaction between NBV and L929 cells, where cells effectively control viral infection/replication and limit the formation of syncytia. By elucidating the molecular mechanisms that control this unique relationship, important insights will be made into the biology of this fusogenic virus.
Hendra virus and Nipah virus are bat-borne paramyxoviruses that are the prototypic members of the genus Henipavirus. The henipaviruses emerged in the 1990s, spilling over from their natural bat hosts and causing serious disease outbreaks in humans and livestock. Hendra virus emerged in Australia and since 1994 there have been 7 human infections with 4 case fatalities. Nipah virus first appeared in Malaysia and subsequent outbreaks have occurred in Bangladesh and India. In total, there have been an estimated 582 human cases of Nipah virus and of these, 54% were fatal. Their broad species tropism and ability to cause fatal respiratory and/or neurologic disease in humans and animals make them important transboundary biological threats. Recent experimental findings in animals have demonstrated that a human monoclonal antibody targeting the viral G glycoprotein is an effective post-exposure treatment against Hendra and Nipah virus infection. In addition, a subunit vaccine based on the G glycoprotein of Hendra virus affords protection against Hendra and Nipah virus challenge. The vaccine has been developed for use in horses in Australia and is the first vaccine against a Biosafety Level-4 (BSL-4) agent to be licensed and commercially deployed. Together, these advances offer viable approaches to address Hendra and Nipah virus infection of livestock and people.