Emerging zoonotic viral disease caused by Nipah virus; a spill over from fruit bats to human

Nipah virus (NiV), an emerging zoonotic virus, Nbelongs to the family Paramyxoviridae subfamily Paramyxovirinae and genus Henipavirus.

The natural reservoirs of the virus are fruit bats of the genus Pteropus (Thomas et al., 2019). NiV has 18,252 nucleotides long negative-sense ssRNA genome which is nonsegmented (Prescott et al 2012) packed in a helical nucleocapsid. The Henipavirus genus also includes pathogenic Hendra virus and nonpathogenic Cedar virus discovered in the years 1994 and 2009 respectively. Both Hendra virus and Nipah virus are enveloped and pleomorphic with an average diameter of about 500 nm (Ong and Wong, 2015). Six structural proteins are encoded by the NiV genome, namely, P (phosphoprotein), M (matrixprotein), F (fusion protein), G (receptor-binding glycoprotein), and L (RNA-dependent RNA polymerase). The interaction and attachment of the NiV G protein with the host cell ephrin B2 and/or B3 receptor activates the NiV F protein which lead to the internalisation of the virus through fusion of the viral envelope and host cell membrane (Ong and Wong, 2015).

Origin

NiV was discovered from an outbreak of respiratory and neurological disease in pigs and acute encephalitis with high mortality in workers handling those pigs in Malaysia during 1998-1999 (MacLachlan and Dubovi, 2010). The virus was first isolated by Chua et al. from the 1999 outbreak from the human cases with encephalitis from Sungai Nipah in Port Dickson, Malaysia and hence acquired the name "Nipah". The sample used for viral isolation was CSF of two patients and IgM antibodies against Hendra virus was found in the sample using IgM capture ELISA. The isolated virus caused syncytial formation after 5 days in Vero cell lines and was concluded as an undescribed virus related to Hendra virus of family Paramyxoviridae (Chua et al., 1999). Later the virus was isolated from the affected pigs also (MacLachlan and Dubovi, 2010).

Virus lineages