ABSTRACT
@#Nipah virus (NiV), a highly pathogenic henipavirus of the family Paramyxoviridae, which causes fatal encephalitis in 40-70% of affected patients, was first reported in Malaysia over 20 years ago. Pteropid bats are the natural hosts of henipaviruses, and ticks have been proposed as a possible link between bats and mammalian hosts. To investigate this hypothesis, infection of the tick cell line IDE8 with NiV was examined. Presence of viral RNA and antigen in the NiV-infected tick cells was confirmed. Infectious virions were recovered from NiV-infected tick cells and ultrastructural features of NiV were observed by electron microscopy. These results suggest that ticks could support NiV infection, potentially playing a role in transmission.
ABSTRACT
Nipah Virus is a recently emerging zoonotic virus with disease causing potential in both animals and humans. Nipah virus belongs to the family of paramyxovirida, genus Henipavirus along with Hendra virus. (1) The knowledge of human infection with Henipavirus was limited to a very small number of cases infected with Hendra virus in Australia during 1994-1999 which was responsible for deaths of two humans and seventeen horses. (2) Nipah virus was first identified and isolated in 1999 in Malaysia during an outbreak of febrile illness among pig farmers and people who were in close contacts with pigs. (3) In 2001, Nipah virus was identified as the causative agent of outbreak in Bangladesh. Since then number of outbreaks has been reported in various districts of Bangladesh. (4) In India, a total of three outbreaks of Nipah have been reported, latest being on 19th May 2018, from Kozhikode district of Kerala. (5) With a fatality rate of 58%, Nipah virus is primarily seen to cause encephalitis and severe respiratory distress. Despite of the severe pathogenicity and high pandemic potential there is no specific treatment for Nipah virus encephalitis except for supportive and symptomatic treatment.
ABSTRACT
The henipaviruses, represented by Nipah virus and Hendra virus, are emerging zoonotic viral pathogens responsible for repeated outbreaks associated with high morbidity and mortality in Australia, Southeast Asia, India and Bangladesh. These viruses enter host cells via a class I viral fusion mechanism mediated by their attachment and fusion envelope glycoproteins; efficient membrane fusion requires both these glycoproteins in conjunction with specific virus receptors present on susceptible host cells. The henipavirus attachment glycoprotein interacts with a cellular B class ephrin protein receptor triggering conformational alterations leading to the activation of the viral fusion (F) glycoprotein. The analysis of monoclonal antibody (mAb) reactivity with G has revealed measurable alterations in the antigenic structure of the glycoprotein following its binding interaction with receptor. These observations only appear to occur with full-length native G glycoprotein, which is a tetrameric oligomer, and not with soluble forms of G (sG), which are disulfide-linked dimers. Single amino acid mutations in a heptad repeat-like structure within the stalk domain of G can disrupt its association with F and subsequent membrane fusion promotion activity. Notably, these mutants of G also appear to confer a postreceptor bound conformation implicating the stalk domain as an important element in the G glycoprotein's structure and functional relationship with F. Together, these observations suggest fusion is dependent on a specific interaction between the F and G glycoproteins of the henipaviruses. Further, receptor binding induces measurable changes in the G glycoprotein that appear to be greatest in respect to the interactions between the pairs of dimers comprising its native tetrameric structure. These receptor-induced conformational changes may be associated with the G glycoprotein's promotion of the fusion activity of F.