Guinea pigs experimentally infected with vaccinia virus replicate and shed, but do not transmit the virus

Abstract

<jats:p>The origin of vaccinia viruses (VACV) associated with vesicular disease in cattle and humans in Southeast Brazil remains uncertain, yet the role of wild species in virus transmission has been suggested. This study investigated the susceptibility and transmission potential by guinea pigs (Cavia porcellus) - phylogenetically close to an abundant Brazilian rodent (Cavia aperea) - to two VACV strains (P1V and P2V) isolated from an outbreak of cutaneous disease in horses in Southern Brazil. Eight guinea pigs inoculated intranasally with P1V and P2V (10(6) TCID50.ml-1) did not develop clinical signs, but six animals shed virus in nasal secretions (day 1 to 9 post-inoculation - pi), developed viremia (between days 1 and 10 pi) and seroconverted to VACV. In spite of virus replication and shedding, the virus was not transmitted to sentinel animals by direct or indirect contact (aerosols) or through food and water contaminated with virus. These results demonstrate that, in spite of replicating and shedding the virus, guinea pigs do not transmit the virus upon experimental inoculation. This finding makes unlikely a possible participation of related species in VACV maintenance and transmission in nature.</jats:p>