Vertical and venereal transmission of California group viruses by Aedes triseriatus and Culiseta inornata mosquitoes

Abstract

Aedes triseriatus and Culiseta inornata mosquitoes were compared in their ability to transmit vertically La Crosse (LAC) and snowshoe hare (SSH) viruses. LAC virus was transovarially transmitted by 53% of Ae. triseriatus, the natural vector, and by 22% of Cs. inornata mosquitoes. SSH virus was transovarially transmitted by 89% of Cs. inornata, a proposed natural vector, and by 29% of Ae. triseriatus. A genetic approach, using LAC, SSH, and LAC/SSH reassortant viruses was then used to elucidate viral genetic determinants of transovarial transmission of bunyaviruses by Ae. triseriatus mosquitoes. Viruses containing the LAC medium sized (M) RNA segment were most efficiently transovarially transmitted by Ae. triseriatus mosquitoes. LAC, SSH, and Tahyna (TAH) viruses were compared in their ability to be venerally transmitted. All three viruses replicated in the reproductive tract of male Aedes triseriatus and were venereally transmitted to female mosquitoes. LAC and TAH viruses infected previously blood fed (BF) but not non-blood fed (NBF) Aedes triseriatus female mosquitoes.