Henipavirus

Henipavirus is a genus in the family Paramyxoviridae, order Mononegavirales. These enveloped, negative-sense, single-stranded RNA viruses have genomes of about 18,000 nucleotides. The genome encodes six major structural proteins—N, P, M, F, G, L—with additional products (V and W) produced by editing of the P gene. The virions use the G glycoprotein for attachment and the F glycoprotein for fusion; the receptors implicated in cell entry are ephrin-B2 and ephrin-B3.

Natural reservoirs are fruit bats of the genus Pteropus. Spillover to humans occurs through intermediate hosts such as horses (Hendra virus) or pigs (Nipah virus), or directly from bats via contact with infectious fluids or contaminated materials (for example, date palm sap). Nipah virus was first identified in 1998 during outbreaks in Malaysia, and has caused outbreaks in Bangladesh and India; Hendra virus was identified in 1994 in Australia. Human illness ranges from fever and pneumonia to severe encephalitis; Nipah infections have high fatality rates, while Hendra infections are less common but can be fatal.

Diagnosis is by molecular testing (RT-PCR) and serology; virus isolation is performed in high-containment laboratories. Management is supportive. There are no licensed human vaccines as of now; control focuses on preventing exposures and vaccinating horses against Hendra virus in regions where spillover occurs. A vaccine against Hendra virus is available for horses in some jurisdictions; Nipah vaccine candidates are in development.

Taxonomy and research: The genus is in the subfamily Orthoparamyxovirinae of Paramyxoviridae. Ongoing surveillance has identified additional henipaviruses in bats and other mammals, expanding understanding of the diversity and spillover risk within this group.