Sand flies and Toscana virus: intra-vector infection dynamics and impact on Phlebotomus perniciosus life-history traits

Toscana virus (TOSV) is a leading cause of summer viral meningitis in central Italy and south of France, and can cause severe neurological cases. Within the Mediterranean basin, it is transmitted by hematophagous sand flies belonging to the Phlebotomus genus. Despite the identification of the primary TOSV vectors, the virus’s developmental cycle in vector species remains largely unknown. Limited research has been conducted on transmission dynamics and the vectorial competence and capacity of the principal TOSV vector, Phlebotomus perniciosus . In this context, we investigated the intra-vector TOSV infection dynamics in Ph. perniciosus , as well as its impact on the vector’s life history traits. Female sand flies were experimentally infected with TOSV though an artificial blood meal. Systemic dissemination of the virus was observed approximately three days post-infection, potentially resulting in a shorter extrinsic incubation period. Moreover, the study revealed a longer hatching time for eggs laid by infected females. This research not only confirmed the vector competence of Ph. perniciosus but also provided the first insight into TOSV’s developmental cycle and its impact on the vector. These findings prompt further exploration of TOSV transmission dynamics, raise new hypotheses on the virus transmission and highlight the importance of follow-up studies.