Biological and immunological studies of five Brazilian rabies virus isolates

Abstract

Aspects of biological behavior of Brazilian rabies virus isolated from canine, bovine, equine, vampire and insectivorous bats were studied in mice. The oral infection occurred in mice fed with infected brain of insectivours bat (8.82%), canine (8.57%) and equine (3.03%). The mean period of incubation to all the isolates was 6 days after mice intracerebral inoculation, however, symptoms were variable, since hyperexcitability (canine sample), progressive paralysis of lower limbs and prolonged clinical course until death (equine sample), and mice without clinical signs before death (insectivorous bat). By immunohistochemistry IFN was detected in brains of mice inoculated with bovine and insectivorous bat samples, TNF and iNOS were detected in brains of those inoculated with insectivorous bat, bovine and canine samples, and positive GFAP astrocytes were found in all five samples. Two commercial inactivated rabies vaccines, one imported (vaccine 1) and another manufactured in Brazil (vaccine 2) were compared to evaluate their efficacy to protect against experimental rabies infection in mice, through the NIH and the CDC potency tests, using these street isolates as challenge virus. There was no statistical significant difference between the efficaccy of both vaccines, when comparing the same potency test and challenge virus strain suggesting no need to produce specific vaccines with street isolates.