Insights into long-term antibody response in Lassa fever: A five-year follow-up study of Lassa fever survivors in Nigeria

Résumé fourni par la source

Introduction: Lassa fever (LF), a viral hemorrhagic fever caused by Lassa virus (LASV), remains a persistent public health threat in West Africa. Despite anecdotal reports of immunity following infection, no licensed vaccine or therapeutic exists. Understanding the immune response, especially the antibody dynamics in LF survivors, is essential for guiding vaccine development and public health interventions. This study aimed to assess long-term serologic responses, specifically the kinetics and neutralization capacity of antibodies, including cross-neutralization of LASV strains over 60 months post-convalescence. Methods: This longitudinal, prospective study was conducted at Irrua Specialist Teaching Hospital in collaboration with the Bernhard Nocht Institute for Tropical Medicine (BNITM), Germany. A cohort of 159 LF survivors was followed for 60 months post-discharge. Sera were collected at up to 12 time points and assessed for anti-LASV IgG antibodies using ELISA (targeting glycoproteins (GP) and nucleoproteins (NP)). Neutralization assays using live virus were performed under BSL-4 conditions at BNITM. Results: IgG titers against LASV GP increased during late convalescence, while anti-NP IgG was detectable early during acute infection. Antibody levels remained high for up to five years. Sera demonstrated robust neutralizing activityagainst native LASV (Lineage II) and cross-neutralization against LASV Lineages II, III, IV, V, and VII. However, cross-neutralization was limited against Lineage V. Despite stable IgG titers, a late decline in neutralization capacity was observed. Conclusion: LASV-specific antibodies persist in survivors for up to five years, with substantial neutralizing and cross-neutralizing activity against most LASV lineages, excluding Lineage V. However, a potential late decline in functional neutralization capacity was noted. An extended follow-up cohort is underway to further evaluate long-term immunity and implications for vaccine strategies.

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