Seroprevalence of Nipah virus specific antibodies in pigs from regions with reported human cases using recombinant nucleocapsid protein based indirect-ELISA

Nipah virus (NiV) is an emerging bat-borne zoonotic pathogen of significance causing fatal encephalitis in South-East and South-Asia including India. This study describes the in-house development and application of a recombinant nucleocapsid (rN) protein based indirect-ELISA for the detection of NiV specific antibodies in pigs from an Indian state. The NiV-rN-iELISA exhibited 84.85% and 85.37% agreement for positive and negative sera, respectively, with a commercial counterpart (AsurDx™ i-ELISA). The NiV-rN-iELISA based sero-surveillance of pigs (n = 741) across seven districts of Kerala state for two time periods (retrospective: 2018–2019 and current: 2024–2025) indicated varying sero-prevalence for NiV specific IgG antibodies with the highest (24.03%) in Ernakulam district and an average positivity of 5.67% across five districts. Further, the hotspot analysis revealed significant spatial clustering of Nipah virus sero-positivity in specific taluks of Kerala, with the most pronounced aggregation concentrated in Ernakulam district. The study demonstrated the potential application of NiV-rN-iELISA for routine sero-surveillance of pigs in areas with close interfaces among fruit bat, pigs, and humans to assess the potential spillover risk, develop more robust and accurate risk maps of NiV infection threat to humans and facilitate implementation of strategic control measures.