Vector Competence of Peruvian Mosquitoes (Diptera: Culicidae) for Epizootic and Enzootic Strains of Venezuelan Equine Encephalomyelitis Virus

Abstract

Mosquitoes collected in the Amazon Basin, near Iquitos, Peru, were evaluated for their susceptibility to epizootic (IAB and IC) and enzootic (ID and IE) strains of Venezuelan equine encephalomyelitis (VEE) virus. After feeding on hamsters with a viremia of approximately 10(8) plaque-forming units of virus per milliliter, Culex (Melanoconion) gnomatus Sallum, Huchings, & Ferreira, Culex (Melanoconion) vomerifer Komp, and Aedes fulvus (Wiedemann) were highly susceptible to infection with all four subtypes of VEE virus (infection rates > or = 87%). Likewise, Psorophora albigenu (Peryassu) and a combination of Mansonia indubitans Dyar & Shannon and Mansonia titillans (Walker) were moderately susceptible to all four strains of VEE virus (infection rates > or = 50%). Although Psorophora cingulata (Fabricius) and Coquillettidia venezuelensis (Theobald) were susceptible to infection with each of the VEE strains, these two species were not efficient transmitters of any of the VEE strains, even after intrathoracic inoculation, indicating the presence of a salivary gland barrier in these species. In contrast to the other species tested, both Culex (Melanoconion) pedroi Sirivanakarn & Belkin and Culex (Culex) coronator Dyar & Knab were nearly refractory to each of the strains of VEE virus tested. Although many of the mosquito species found in this region were competent laboratory vectors of VEE virus, additional studies on biting behavior, mosquito population densities, and vertebrate reservoir hosts of VEE virus are needed to incriminate the principal vector species.

Vector Competence of Culex (Melanoconion) taeniopus for Equine-Virulent Subtype IE Strains of Venezuelan Equine Encephalitis Virus

“…taeniopus to oral infection by epizootic subtype IAB VEEV is the result of a midgut infection/ escape barrier and not a salivary gland infection barrier. 3,17,20 In contrast, epizootic vectors do not appear to exhibit subtypespecific infection barriers to the same extent as enzootic vector mosquitoes. 8,10,20 T able 2 Infection, dissemination, and transmission proportions for Culex taeniopus mosquitoes infected with enzootic and equine-virulent Venezuelan equine encephalitis virus subtype IE* The proportions of infection for the 68U201 VEEV strain in Cx.…”

Contrasting sylvatic foci of Venezuelan equine encephalitis virus in northern South America.

“…8,10 The CO-San Miguel forest exhibited higher mosquito diversity than any of the Catatumbo forests, but particularly it showed a richer fauna of Culex (Melanoconion) species ( That mixture of mosquitoes was also demonstrated to transmit VEE virus experimentally. 33 However, the titers of virus in the viremic hamsters used in those infection studies are far higher than those reported after experimental infection of natural reservoir hosts. 34,35 Our results suggest that the greater abundance, diversity, and constancy of suspected enzootic vectors (subgenus Melanoconion species) in CO-San Miguel site partly explain the regularity and higher rates of VEE virus isolations.…”

“…titillans seem to comply with the above criteria for all three forests. 33,[42][43][44][45][46] These species are also common in the forest and surrounding open areas in another enzootic foci of VEE virus in northern Venezuela. 36 Future studies should investigate the movement of VEE virus away from enzootic foci into open areas, and its interaction with equines and other potential amplifying hosts.…”

Mosquitos (Diptera: Culicidae) en el caserío de Chingalé, Santander, donde se registró un caso humano de encefalitis equina venezolana

“…Biomédica 2003;23 (Supl.1):125). Experimentalmente, en el área de Iquitos (Perú) se ha demostrado que es un vector competente del subtipo ID (30). Cx.…”