Heterologous reassortment of bunyaviruses in Aedes triseriatus mosquitoes and transovarial and oral transmission of newly evolved genotypes

Aedes triseriatus mosquitoes were orally infected with two different California serogroup bunyaviruses (La Crosse and snowshoe hare viruses) and high frequency reassortment occurred in these mosquitoes. Increased viral replication and subsequent gene segment reassortment was noted in the ovaries of mosquitoes that had ingested multiple blood-meals. To determine whether newly generated reassortant viruses could be transmitted transovarially to progeny mosquitoes, adult female mosquitoes were inoculated with the two temperature-sensitive (ts) parental viruses, and allowed to blood-feed and oviposit. Of 58 infected progeny mosquitoes assayed, six (10%) contained non-ts viruses, and three of these transmitted non-ts viruses to a susceptible host. Selected viruses of the non-ts phenotype, which were isolated from mosquitoes and from mice fed upon by the mosquitoes, were demonstrated to be reassortant viruses by oligonucleotide fingerprinting.