Experimental Infection of North American Mammals with Epidemic Venezuelan Encephalitis Virus

Abstract

Eighty-three wild mammals of ten species were inoculated with a first mouse passage level Venezuelan encephalitis (VE) virus isolated from south Texas in 1971 during the VE outbreak. Rodents were highly susceptible to VE infection and circulated VE virus at levels ranging from 10(7.7) to 10(11.5) suckling mouse intracranial lethal doses per ml for 2 to 4 days. These levels of virus could easily infect vector mosquitoes. Mortality was high in all species of rodents except Sigmodon hispidus, adult Neotoma micropus, and adult Peromyscus leucopus. Lagomorphs were susceptible to VE infection but circulated VE virus at or near mosquito threshold levels for 1 day only. Raccoons and opossums were relatively resistant to VE infection or circulated low levels of virus in the blood. Juvenile animals of four species were more susceptible and experienced higher viremias than did adults. In two of the four, mortality was higher in the juveniles than in adults. A consideration of results obtained during this study and those of other investigators led to the conclusion that equines were of major importance, that canines, lagomorphs and rodents were of minor importance, and that other species tested were of no importance as virus amplifiers in VE epizootics.

Experimental Infection of Potential Reservoir Hosts with Venezuelan Equine Encephalitis Virus, Mexico

“…In that study, mammals of 10 genera had VEEV-specifi c antibodies. In 2 follow-up studies in which wild mammals and wild birds were infected with a strain of VEEV-IB isolated during the outbreak, viremia and mortality rates for rodents were high (21,22). In a longitudinal fi eld study performed concurrent with the study reported here, seroprevalance for wild rodents was found to be much lower than previously found for this area (11).…”

Safety and protective efficacy of INA-inactivated Venezuelan equine encephalitis virus: Implication in vaccine development

“…In our previous study [26] we demonstrated that V3000 virus, rescued from a cDNA of VEEV [8], can be completely inactivated with INA in vitro. In this study we tested the safety and protective efficacy of INA-inactivated V3000 in mice.…”

“…Virus: Molecularly cloned virulent strain of VEEV, V3000 [8] and an attenuated strain, V3526 [34] were used in the present study.…”

“…VEEV has been designated a Category B priority pathogen by the National Institute of Allergy and Infectious Disease. VEEV is transmitted by mosquito in nature [5][6][7] and causes disease of varying severity in horses and humans [8,9].…”

Candidate Vectors and Rodent Hosts of Venezuelan Equine Encephalitis Virus, Chiapas, 2006–2007

“…[13][14][15][16] Laboratory studies have shown that a variety of wild rodents from several different genera survive experimental infection, develop high viremia, and strong antibody responses after infection with various VEEV strains. [17][18][19][20] Understanding which vertebrate species serve as the primary amplifying/reservoir hosts can help to elucidate the natural transmission cycle and may inform how arboviruses can emerge from enzootic precursors to cause human and animal disease. Determining the roles of mosquitoes as enzootic and/ or epizootic vectors is also needed to anticipate and respond to epizootic VEEV emergence.…”