Imen Larbi

Pasteur Institut of Tunis,
Tunisia

Abstract Title: First Report of West Nile virus Infections in Horses in Tunisia from 2018 to 2023

Biography: Dr. Imen Larbi is Head of the Veterinary Microbiology Laboratory at the Institut Pasteur de Tunis and an expert for the Food and Agriculture Organization of the United Nations / EMC. She holds a PhD in Biology and a Doctorate in Veterinary Medicine, with training from the École Nationale Vétérinaire de Sidi Thabet, the University of Florida, and the École Nationale Vétérinaire d'Alfort. Her research focuses on zoonotic viral diseases, particularly arboviruses such as West Nile and Usutu viruses. Her work includes virus isolation, molecular characterization, and phylogenetic analysis to better understand West Nile virus transmission dynamics and their impact on animal and human health in Tunisia. She has authored over 20 publications in peer-reviewed journals.

Research Interest: West Nile virus (WNV) is an arthropod borne virus, the most widely distributed of the encephalitic Orthoflaviviruses. It can cause severe neurological symptoms in both humans and horses. It poses an emerging threat to both public and animal health. In this study, we retrospectively screened 25 suspected WNV samples collected from 2018 to 2023. A total number of 25 samples (brain tissue and blood) were collected from clinicallyaffected horses and those already deceased across several locations in Tunisia. All samples were tested for the presence of WNV NS2A gene using qRT-PCR. Eleven positive samples underwent virus isolation in Vero cells andpartial sequencing of their envelope (E) glycoprotein gene. The resulting sequences were analyzed to gain molecular and phylogenetic insights.Eleven of the 25 (44%) samples were WNV positive and 11 partial E protein sequences were taken. The phylogenetic analysis revealed that all Tunisian isolates belonged to lineage 1a and were closely related to each other and formed a distinct group within the Mediterranean subtype of clade 1a. Tunisian WNV were characterized by the presence of a potential N-linked glycosylation site at residue 154–156 (Asn-Tyr-Ser) (NYS) and did not have the mutation E-I159V or E-I159A. Genomic monitoring of horses has revealed the circulation of WNV in several regions of Tunisia. Our findings highlight the critical need for prompt investigation of WNV infections in horses, as these cases may precede outbreaks of human cases in the country.