Cell fusing agent virus (Flavivirus) infection in Aedes aegypti in Texas: seasonality, comparison by trap type, and individual viral loads.

South Texas has experienced local transmission of Zika virus and of other mosquito-borne viruses such as chikungunya virus and dengue virus in the last decades. Using a mosquito surveillance program in the Lower Rio Grande Valley (LRGV) and San Antonio, TX, from 2016 to 2018, we detected the presence of an insect-specific virus, cell fusing agent virus (CFAV), in the Aedes aegypti mosquito population. We tested 6,326 females and 1,249 males from the LRGV and 659 females from San Antonio for CFAV by RT-PCR using specific primers. Infection rates varied from 0 to 261 per 1,000 mosquitoes in the LRGV and 115 to 208 per 1,000 in San Antonio depending on the month of collection. Infection rates per 1,000 individuals appeared higher in females collected from BG Sentinel 2 traps compared to Autocidal Gravid Ovitraps, but the ratio of the percentage of infected pools did not differ by trap type. The natural viral load in individual males ranged from 1.25 x 102 to 5.50 x 106 RNA copies and in unfed females from 5.42 x 103 to 8.70 x 106 RNA copies. Gravid females were found to harbor fewer viral particles than males and unfed females.

Aedes aegypti densonucleosis virus amplifies, spreads, and reduces host populations in laboratory cage studies.

Aedes densonucleosis virus (family Parcoviridae, genus Brevidensovirus, AeDNV) is a mosquito pathogen that increases Aedes aegypti larval mortality and reduces adult life span. We conducted three laboratory population cage trials, each lasting 16-25 wk. We tested two broad hypotheses. First, Ae. aegypti raised in containers seeded with 10(8) AeDNV genome equivalents/ml (geq/ ml), a concentration feasible for field application, increase AeDNV to concentrations that cause significant adult and larval mortality. Second, infected female mosquitoes disperse AeDNV to uninfected larval habitats. In hypothesis 1, we addressed the rate at which infected larvae secrete virus, how AeDNV titers change in seeded containers over time, whether AeDNV decays over time, and whether AeDNV exposed populations are reduced. In hypothesis 2, we monitored AeDNV concentrations in novel containers after oviposition by infected females. Both hypotheses were supported. Larvae increased AeDNV, secreting virus at a rate of 2.14 x 10(6) geq/larva/d when exposed to 10(8) geq/ml. AeDNV titers reached an asymptote of 10(10) geq/ml by week 10 in seeded containers. AeDNV decayed by 1 log every 4 d as indicated by a reduction in larval mortality. Adult population size was reduced in treated populations. Infected females dispersed AeDNV to novel containers, with titers reaching 10(8) geq/ml. The parameters were used in a Leslie-Lewis matrix model. This model predicted that AeDNV negatively affects Ae. aegypti densities and population structure and thus vectorial capacity.