Henipaviruses: Gaps in the Knowledge of Emergence

Abstract

Over the past 10 years many “new” viruses have been identified in Australia and the Asian region. The viruses have been isolated from, and/or identified in, a range of animals; some of these viruses are of veterinary and medical importance while others are new threats to biodiversity. Of these viruses, Hendra and Nipah viruses have emerged as significant zoonotic agents belonging to the family Paramyxoviridae and genus Henipavirus. These agents cause fatalities in a range of animals including horses, pigs, and humans. Both viruses have been isolated from flying foxes (genus Pteropus; suborder Megachiroptera), which are accepted as their natural hosts. Although some research has been undertaken on the viruses and their hosts, little is known about how these viruses emerge. We have attempted to investigate the current knowledge of the bat-Henipavirus ecology by discussing the range of bat viruses that exist (viral assemblage), the significance of evolving viruses, possible functional role(s) of viruses, the ecology of viruses and their hosts, and identifying possible drivers (selection pressures) that may culminate with the overlap of new potential viral hosts thereby facilitating the replication of fit viral populations in a new host–virus continuum(s). By undertaking such an analysis, we have attempted to identify key questions, which should be investigated if the factors involved in “driving” Henipavirus emergence are to be understood.