Pathogenicity of different rabies virus isolates and protection test in vaccinated mice Patogenicidade de diferentes isolados do vírus da raiva e teste de proteção em camundongos vacinados

Abstract

This study was aimed to evaluate and compare the pathogenicity of rabies virus isolated from bats and dogs, and to verify the efficacy of a commercial rabies vaccine against these isolates. For evaluation of pathogenicity, mice were inoculated by the intramuscular route (IM) with 500MICLD50/0.03mL of the viruses. The cross-protection test was performed by vaccinating groups of mice by the subcutaneous route and challenged through the intracerebral (IC) route. Isolates were fully pathogenic when inoculated by the IC route. When inoculated intramuscularly, the pathogenicity observed showed different death rates: 60.0% for the Desmodus rotundus isolate; 50.0% for dog and Nyctinomops laticaudatus isolates; 40.0% for Artibeus lituratus isolate; 9.5% Molossus molossus isolate; and 5.2% for the Eptesicus furinalis isolate. Mice receiving two doses of the vaccine and challenged by the IC route with the isolates were fully protected. Mice receiving only one dose of vaccine were partially protected against the dog isolate. The isolates from bats were pathogenic by the IC route in mice. However, when inoculated through the intramuscular route, the same isolates were found with different degrees of pathogenicity. The results of this work suggest that a commercial vaccine protects mice from infection with bat rabies virus isolates, in addition to a canine rabies virus isolate.O estudo avaliou e comparou as propriedades patogênicas de cinco isolados do vírus da raiva de morcegos e um isolado do vírus da raiva de cão e analisou a eficácia de vacina comercial contra estes isolados, em camundongos. Para o estudo de patogenicidade camundongos foram inoculados pela via IM com 0,1 mL contendo 500MICLD50/0,03mL das amostras de vírus. Quando inoculados pela via IC, os isolados do vírus da raiva provocaram a morte de 100% dos camundongos. No entanto, 500MICLD50/0,03mL das mesmas amostras, inoculadas pela via IM, ocasionaram mortalidade de: 60,0% quando a amostra era de Desmodus rotundus; 50,0% de cão e de Nyctinomops laticaudatus; 40,0% de Artibeus lituratus; 9,5% de Molossus molossus; e 5,2% de Eptesicus furinalis. Camundongos que receberam duas doses de vacina foram protegidos quando desafiados pela via IC, com todas as amostras testadas. Quando os camundongos receberam uma dose da mesma vacina, houve proteção parcial daqueles desafiados com a amostra de cão. Todos os isolados do vírus da raiva testados foram patogênicos para camundongos, inoculados pela IC. No entanto, pela via IM, os mesmos isolados mostraram diferentes graus de patogenicidade. Concluiu-se também que a vacina comercial contra raiva protegeu os camundongos desafiados com amostras de vírus isolados de morcegos e de cão.

Keywords

• Rabies virus
• Pathogenicity
• Vaccine