Oropouche virus RNA persistence and antibody kinetics: a multi-specimen, genomic and serological analysis

BACKGROUND: Oropouche virus (OROV) is an emerging orthobunyavirus causing febrile illness in South America, yet data on viral kinetics, diagnostic samples and serological responses remain limited. AIM: We performed a comprehensive longitudinal analysis of OROV RNA detection, antibody responses and viral genomics in a returned traveller from Brazil to better characterize infection dynamics and inform diagnostic strategies. METHODS: Multiple clinical specimens, including serum, plasma, whole blood, coagulated blood, urine, saliva and a vaginal swab, were collected from Day 3 to Day 126 post-symptom onset (p.s.o.) and tested using reverse transcription polymerase chain reaction and OROV-specific Immunoglobulin M (IgM) and Immunoglobulin G (IgG) enzyme-linked immunosorbent assay (ELISA). Near-complete viral genome sequencing (99.6% coverage) enabled genotyping and phylogenetic analysis. RESULTS: OROV RNA exhibited compartmental specificity. Whole blood showed prolonged and stable RNA detection for over 120 days p.s.o., representing one of the longest documented periods of OROV RNA persistence to date. Coagulated blood also remained positive at multiple time points, whereas serum and plasma demonstrated only short-term detectability. Urine showed detectable viral RNA from Day 4 to Day 30. Saliva tested positive at Day 7 p.s.o., while the vaginal swab was negative. Serologically, IgM peaked early and waned by Day 79, whereas IgG remained detectable through Day 126. In addition, sequencing confirmed infection with an American-lineage virus carrying reassorted genome segments clustering with Brazilian strains from 2024. CONCLUSION: This case provides a detailed view of OROV infection kinetics in multiple compartments, demonstrating prolonged whole-blood RNA persistence, and complete genomic characterization. These findings have direct implications for diagnostics, surveillance and understanding OROV pathogenesis, particularly in returned travellers and settings with co-circulating arboviruses.