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

PLoS Negl Trop Dis. 2024 Sep 25;18(9):e0012509. doi: 10.1371/journal.pntd.0012509. eCollection 2024 Sep.

Abstract

Toscana virus (TOSV) is a leading cause of summer viral meningitis in Southern Europe (Central Italy, south of France, Spain and Portugal) 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 viral developmental cycle in vector species remains largely unknown. Limited research has been conducted on transmission dynamics and the vector competence and vectorial 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 life history traits. Female sand flies were experimentally infected with TOSV through an artificial blood meal. Systemic dissemination of the virus was observed approximately three days post-infection, potentially resulting in a short extrinsic incubation period. Moreover, the study revealed a longer hatching time for eggs laid by infected females. This research brought additional experimental insights regarding the vector competence of Ph. perniciosus but also provided the first insight into TOSV 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.

MeSH terms

  • Animals
  • Female
  • Insect Vectors* / physiology
  • Insect Vectors* / virology
  • Life History Traits
  • Male
  • Phlebotomus* / physiology
  • Phlebotomus* / virology
  • Sandfly fever Naples virus*

Grants and funding

This research was funded by the IRD (Institut de Recherche pour le Développement) to LL, CNRS (Centre National de la Recherche Scientifique) to LL, UM (Université de Montpellier) to LL and INFRAVEC2 (https://infravec2.eu/, grant agreement N° 731060 2017-2022) to LL. L.L. was financially supported by an UM doctoral fellowship and obtained a grant Key Initiative Montpellier: Risks and Vectors (KIM RIVE), supported by Montpellier University of Excellence (MUSE) and défi clé RIVOC, supported by Région Occitanie), with J.P. as PI, which fund part of the material for this study. This work was also supported by the European Commission (European Virus Archive Global project (EVA GLOBAL, grant agreement No 871029) of the Horizon 2020 research and innovation programme (european-virus-archive.com/). LL received salary from University of Montpellier and J.P received salary from INFRAVEC2 project. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.