Vector competence of two Argentinean Culex mosquito species for West Nile virus (Flavivirus, Flaviviridae)

GIAYETTO, OCTAVIO; BERANEK, MAURICIO; NAZAR, FRANCO NICOLAS; DIAZ, L. ADRIÁN

National Harbor, Maryland USA

Congreso; ASTMH 68th Annual Meeting; 2019

American Society of Tropical Medicine and Hygiene

West Nile Virus (WNV) (Flavivirus; Flaviviridae) is a widely distributed arbovirus of medical and veterinary concern. It is maintained in an enzootic transmissionnetwork involving wild birds as hosts and ornithophilic mosquitoes as vectors. Due to its recent introduction in Argentina, the mosquito species vectoring thevirus are still not dilucidated. This study evaluates the vector competence of Cx. quinquefasciatus and Cx interfor mosquitoes from Cordoba city, for nativeArgentinean WNV Eq7229 strain. Mosquitoes were orally infected by feeding on viremic chicks (3.30; 3.70; 4.00; 6.00 and 7.00 log10 PFU/ml for Cxquinquefasciatus and 7.47 log10 PFU/ml for Cx. interfor) and maintained throughout the extrinsic incubation period at 28°C, 12:12 light/dark cycle and fed with a10% sucrose solution. At 10 days post infection, samples of body, legs and saliva were obtained and suspended in 300 μl of PBS and 10% FBS solution beforestorage at -80°C. Samples were analysed by plaque assay onto 24-well VERO cells monolyers tissue culture plates for viral detection. Infection, dissemination andtransmission rates were evaluated as the percentages of mosquitoes tested that contained virus in their body, legs or saliva respectively. Cx. quinquefasciatus (17-25 individuals per treatment) were susceptible to infection at all doses tested (47; 36; 36; 85 and 95 % respectively) and developed disseminated infections (50;50; 56; 76 and 100 % respectively). Only individuals exposed with over 6 and 7 log10 PFU/ml were able to transmit the virus (29 and 77 %). The 36% of Cx. interfortested (11) were competent to transmit the virus. All 11 mosquitoes were susceptible to infection and 8 developed disseminated infection. These results not onlybring information about what species might be involved in the, yet unknown, transmission network of WNV in Argentina but also, might indicate differences ininfection barriers between both species.