ABSTRACT
Background & objectives: Nipah virus (NiV) is a zoonotic paramyxovirus that causes fatal encephalitis in humans. Enzyme Linked Immunosorbent Assay (ELISA) is a safe, sensitive, specific, and affordable diagnostic tool that can be used during screening of large-scale epidemiological investigations. Development and evaluation of IgM and IgG ELISA for screening serum samples of NiV suspected cases would also help in planning public health interventions. Methods: An IgM capture (MAC) ELISA and an indirect IgG ELISA were developed using NiV antigen to detect IgM and IgG antibodies against NiV in human sera. The sensitivity, specificity, and cross- reactivity of the assays were evaluated using NiV IgM, IgG positive, negative human sera and measles, mumps, rubella, Crimean-Congo haemorrhagic fever, Kyasanur forest disease IgM, IgG positive sera, respectively. Results: The developed anti-NiV IgM and IgG ELISAs have shown specificity of 99.28 per cent and sensitivity of 100 per cent compared to reference test from Centers for Disease Control and Prevention, USA. Assays demonstrated negative predictive value of 100 per cent and positive predictive value as 90 and 93.94 per cent for anti-Nipah IgM ELISA and IgG ELISA respectively with test accuracy of 99.33 per cent. Interpretation & conclusions: Timely diagnosis of NiV is crucial for the management of cases, which could prevent further spread of infection in the community. IgM ELISA can be used as primary diagnostic tool followed by polymerase chain reaction. These assays have advantages of its applicability during outbreak investigations and surveillance activities at hospital or onsite laboratories with basic biosafety practices.
ABSTRACT
Background & objectives: Pipistrellus ceylonicus bat species is widely distributed in South Asia, with additional populations recorded in China and Southeast Asia. Bats are the natural reservoir hosts for a number of emerging zoonotic diseases. Attempts to isolate bat-borne viruses in various terrestrial mammalian cell lines have sometimes been unsuccessful. The bat cell lines are useful in isolation and propagation of many of the viruses harboured by bats. New stable bat cell lines are needed to help such investigations and to assist in the study of bat immunology and virus-host interactions. In this study we made an attempt to develop a cell line from P. ceylonicus bats. Methods: An effort was made to establish cell line from embryo of P. ceylonicus species of bat after seeding to Dulbecco’s modified eagle medium (DMEM) supplemented with 10 per cent foetal bovine serum; a primary cell line was established and designated as NIV-BtEPC. Mitochondrial DNA profile analysis was done using cyt-b and ND-1 gene sequences from the cell line. Phylogenetic tree was constructed using neighbour-joining algorithm for cyt-b and ND-1 genes with 1000-bootstrap replicates. Results: NIV-BtEPC cell line was susceptible to Chandipura (CHPV) and novel adenovirus (BtAdv-RLM) isolated from Rousettus leschenaulti from India but did not support multiplication of a number of Bunyaviruses, Alphaviruses and Flavivirus. This might be useful for isolation of a range of viruses and investigation of unknown aetiological agents. Interpretation & conclusions: In this study, a new bat cell line was developed from P. ceylonicus. This cell line was successfully tested for the susceptibility to Chandipura and BtAdv-RLM virus isolated from bats. The approach developed and optimised in this study may be applicable to the other species of bats and this established cell line can be used to facilitate virus isolation and basic research into virus-host interaction.