Malaysia outbreak survivors retain detectable Nipah antibodies and memory B cells after 25 years

OBJECTIVE: To evaluate the long-term humoral immune response to Nipah virus (NiV) in a cohort of 25 survivors after 25 years of post-infection. METHODS: A total of 25 survivors of NiV infection from the 1998 outbreak were recruited for sample collection. The serum IgG antibody response to NiV antigens, specifically nucleocapsid (N), fusion glycoprotein (F) and attachment glycoprotein (G) was evaluated using ELISA. Additionally, the samples were tested for neutralizing antibodies and memory B cell responses. RESULTS: Detection rates of anti-NiV-F and anti-NiV-G were 56% and 60%, respectively, among the survivors at a 1:100 dilution, whereas only 20% were specifically reactive to rNiV-N. Notably, all samples that tested positive for NiV-F and NiV-G at this dilution also exhibited neutralizing antibodies, highlighting the specificity of these assays. Live virus neutralization assay showed that 72% of survivors had detectable neutralizing antibodies, with varying titers, indicating long-lasting immune memory. Furthermore, memory B cell responses specific to NiV-F and NiV-G were observed in six randomly selected survivors, suggesting the presence of enduring immunological memory. CONCLUSIONS: These findings highlight the potential of NiV-F and NiV-G as reliable markers for NiV exposure and underscore the need for continuous surveillance and research. Such efforts are crucial for advancing vaccine development and improving preparedness for future NiV outbreaks.