RESUMEN
Vaccinia virus (VACV) has been associated with several bovine vaccinia outbreaks in Brazil, affecting cattle and humans. There are no available data about VACV environmental circulation or the role of wildlife in the emergence of an outbreak. Since VACV was isolated from rodents in Brazil, we investigated shedding and transmission of VACV strains in mice. The VACV excretion profile was assessed by PCR and chicken chorioallantoic membrane infection, revealing viral DNA and infectious virus in the faeces and urine of intranasally infected mice. Horizontal transmission was assessed by exposure of sentinel mice to wood shavings contaminated with excrement, to mimic a natural infection. Sentinel mice showed orthopoxvirus antibodies, and VACV DNA and infectious virus were detected in their faeces and intestines, even after six rounds of natural transmission. Together, these data suggest that murine excrement could play a relevant role in VACV spread and transmission, perhaps helping to explain how these viruses circulate between their natural hosts.
Asunto(s)
Modelos Animales de Enfermedad , Transmisión de Enfermedad Infecciosa , Virus Vaccinia/fisiología , Vaccinia/transmisión , Esparcimiento de Virus , Animales , Embrión de Pollo , Chlorocebus aethiops , Membrana Corioalantoides/virología , ADN Viral/análisis , ADN Viral/aislamiento & purificación , Heces/virología , Masculino , Ratones , Ratones Endogámicos BALB C , Reacción en Cadena de la Polimerasa , Orina/virología , Vaccinia/patología , Vaccinia/virología , Virus Vaccinia/genética , Virus Vaccinia/aislamiento & purificación , Virus Vaccinia/patogenicidad , Células VeroRESUMEN
Brazilian Vaccinia virus had been isolated from sentinel mice, rodents and recently from humans, cows and calves during outbreaks on dairy farms in several rural areas in Brazil, leading to high economic and social impact. Some phylogenetic studies have demonstrated the existence of two different populations of Brazilian Vaccinia virus strains circulating in nature, but little is known about their biological characteristics. Therefore, our goal was to study the virulence pattern of seven Brazilian Vaccinia virus strains. Infected BALB/c mice were monitored for morbidity, mortality and viral replication in organs as trachea, lungs, heart, kidneys, liver, brain and spleen. Based on the virulence potential, the Brazilian Vaccinia virus strains were grouped into two groups. One group contained GP1V, VBH, SAV and BAV which caused disease and death in infected mice and the second one included ARAV, GP2V and PSTV which did not cause any clinical signals or death in infected BALB/c mice. The subdivision of Brazilian Vaccinia virus strains into two groups is in agreement with previous genetic studies. Those data reinforce the existence of different populations circulating in Brazil regarding the genetic and virulence characteristics.