First molecular detection and genomic characterization of West Nile virus associated with a naturally aborted sheep in Tunisia.

In September 2025, West Nile virus (WNV) RNA was detected for the first time in a sheep in Zaghouan Governorate, Tunisia. Following sheep abortions, fetal specimens were analyzed and one tested positive for WNV by RT-qPCR. The generated near-complete WNV genome sequence by Oxford Nanopore Technologies belonged to Lineage 1a, previously associated with locally reported human neuroinvasive cases in the same area. Amino acid analysis of the envelope (E) protein confirmed the presence of the conserved NYS glycosylation motif (E154-E156), a characteristic feature of Euro-Mediterranean Lineage 1 WNV strains. These findings further support the endemic circulation of WNV in Tunisia and underline its significance for both animal and public health.