Infection and Vertical Transmission of Kamiti River Virus in Laboratory BredAedes aegyptiMosquitoes

Abstract

Kamiti river virus (KRV) is an insect-only Flavivirus that was isolated from field-collected Ae. macintoshi mosquitoes in 1999, and is closely related to cell fusing agent virus. Both of these viruses belong to the family Flaviviridae, which also contains other viruses of medical importance, such as yellow fever virus, West Nile virus and dengue. Because Ae. macintoshi is the only known natural host to KRV, the main objective of this study was to establish the possibility that other mosquito hosts of the virus exist, by determining its ability to infect Ae. aegypti mosquitoes under laboratory conditions. The study also sought to determine the rates of infection and, subsequently, vertical transmission as a possible means of its maintenance and propagation in nature, given that it neither grows in vertebrate cells or mice. The mosquitoes were infected by the virus either as larvae or adults. Virus assay was done by re-isolation in tissue culture and indirect immunofluoresce assay methods. KRV infected Ae. aegypti mosquitoes, with the observed rates as high as 74 to 96 %. The virus was also transmitted vertically in these mosquitoes. Vertical transmission rates of 3.90 % were observed for the 2nd and 3rd ovarian cycles combined. These results suggest that Ae. aegypti mosquitoes are likely to be infected with KRV in nature, and that vertical transmission is the natural means by which it is maintained and propagated in this host, and possibly others.

Isolation of a Novel Insect-Specific Flavivirus fromCuliseta melanurain the Northeastern United States

“…CsFV detection in larvae suggests that vertical transmission is occurring, and stable infection rates suggest that horizontal transmission is not occurring between larvae during the overwintering period. This reinforces observations of other ISFs, which indicate that vertical transmission is the major mode of transmission (Lutomiah et al 2007, Bolling et al 2012). …”

“…CxFV appears to perpetuate in mosquito populations by vertical transmission, the passing of the virus from an infected female to her progeny (Saiyasombat et al 2011, Bolling et al 2012, and venereal transmission may also play a minor role in viral maintenance (Bolling et al 2012). Evidence for vertical transmission has also been observed for other ISFs, including KRV (Lutomiah et al 2007), AeFV (Haddow et al 2013), and CLBOV , on the basis of virus detection in immature mosquitoes.…”

Wolbachia suppresses cell fusing agent virus in mosquito cells

“…In addition to flaviviruses pathogenic to vertebrates, a number of insect-specific flaviviruses (ISFs) have been described from mosquitoes that do not replicate in vertebrate cells but specifically in insect hosts (Blitvich & Firth, 2015). These are believed to be vertically transmitted as they are not infectious by oral feeding (Bolling et al, 2012;Cook et al, 2012;Lutomiah et al, 2007;Saiyasombat et al, 2011). Interestingly, a number of them have been shown to negatively affect replication of medically important flaviviruses in co-infected or superinfected mosquitoes (Bolling et al, 2012;Goenaga et al, 2014;Hall-Mendelin et al, 2016;Hobson-Peters et al, 2013;Kenney et al, 2014).…”

Insect-Specific Flaviviruses from Culex Mosquitoes in Colorado, with Evidence of Vertical Transmission

“…aegypti , infected with KRV by oral exposure, transmitted the virus to their offspring. 35 To investigate how insect-specific flaviviruses are maintained in mosquito populations, quantitative RT-PCR was performed on specimens from our laboratory colony of Cx. pipiens that was established from egg rafts collected in Fort Collins in 2005 and later found to be naturally and persistently infected with CxFV.…”