Diagnostics for Nipah virus: a zoonotic pathogen endemic to Southeast Asia

Abstract

Nipah virus (NiV) is an emerging pathogen that, unlike other priority pathogens identified by WHO, is endemic to Southeast Asia. It is most commonly transmitted through exposure to saliva or excrement from the Pteropus fruit bat, or direct contact with intermediate animal hosts, such as pigs. NiV infection causes severe febrile encephalitic disease and/or respiratory disease; treatment options are limited to supportive care. A number of in-house diagnostic assays for NiV using serological and nucleic acid amplification techniques have been developed for NiV and are used in laboratory settings, including some early multiplex panels for differentiation of NiV infection from other febrile diseases. However, given the often rural and remote nature of NiV outbreak settings, there remains a need for rapid diagnostic tests that can be implemented at the point of care. Additionally, more reliable assays for surveillance of communities and livestock will be vital to achieving a better understanding of the ecology of the fruit bat host and transmission risk to other intermediate hosts, enabling implementation of a ‘One Health’ approach to outbreak prevention and the management of this zoonotic disease. An improved understanding of NiV viral diversity and infection kinetics or dynamics will be central to the development of new diagnostics, and access to clinical specimens must be improved to enable effective validation and external quality assessments. Target product profiles for NiV diagnostics should be refined to take into account these outstanding needs.

Nipah Virus: Past Outbreaks and Future Containment

“…Diagnosis is performed in enhanced BSL3 (BSL3+) or BSL4 facilities. Diagnostic tests for detection of NiV include molecular and serological assays, immunohistochemistry, histopathology, virus isolation and neutralisation [58]. Vero cells are used to culture NiV with observable cytopathic effects in three days [57].…”

“…Though expensive, real-time RT-PCR, because of its extreme sensitivity, is employed extensively for NiV detection/diagnosis. Sensitivity of these techniques can be compromised if the viral genome undergoes rapid mutations [58,59].…”

“…Next generation sequencing is an alternative method aiding in effective identification of viral strain, however the method is not frequently used in diagnosis and when considering expenses. Another safe method for detecting NiV is immunohistochemistry since it uses formalin-fixed tissue samples [58,59]. ELISA is an effective serological assay which aids in the detection of NiV antigens and antibodies in serum samples.…”

“…ELISA is often followed by a serum neutralisation test or PCR. Virus isolation and neutralisation methods are also used for diagnosis but are constrained to BSL-4 facilities [57][58][59].…”

“…Studies towards understanding the bat environment, its susceptibility to being a carrier of NiV and its precise prevalence could help prevent the risk involved by human intervention into their habitat. Sampling and sero-surveillance for the NiV antibody and NiV with ELISA and PCR method in humans as well as bats will help to keep a check on the possibility of an outbreak in the prevalent regions [58].…”