RESUMO
The Lister (Elstree) strain of vaccinia virus, used in Israel for vaccination against smallpox, was studied in tissue cultures and in a mouse model. The virus failed to reach the brain of the mice when inoculated intranasally at a dose of 500,000 plaque forming units, but was lethal for 50% of them, when injected intracranially. Lower doses of virus injected intracranially caused some weight loss initially, but later the mice completely recovered. Modified vaccinia virus Ankara (MVA), when infected intranasally, did not spread beyond the lungs to other organs of the mice. Even when the mice were inoculated with MVA intracranially, they were not affected. Significant protection against a lethal dose of an orthopoxvirus was obtained in mice following immunization with the Lister strain, while larger doses and repeated vaccination procedure, were required with MVA. The Lister virus stock applied in Israel, was found to be heterogeneous in its plaque morphology. Two variants isolated from it, showed significant attenuation for mice, when inoculated intranasally and intracranially, as compared to a third variant and to the unpurified stock of the virus.
Assuntos
Orthopoxvirus/imunologia , Orthopoxvirus/patogenicidade , Infecções por Poxviridae/prevenção & controle , Vaccinia virus/imunologia , Animais , Encéfalo/virologia , Feminino , Humanos , Israel , Camundongos , Camundongos Endogâmicos BALB C , Infecções por Poxviridae/imunologia , Infecções por Poxviridae/virologia , Varíola/imunologia , Varíola/prevenção & controle , Vacina Antivariólica/farmacologia , Vacinas Atenuadas/farmacologia , Vaccinia virus/classificação , Vaccinia virus/isolamento & purificação , Vaccinia virus/patogenicidade , Virulência , Cultura de Vírus/métodosRESUMO
The pathogenicity and immunogenicity in mice of WR.cl and WR.c3, two mutants of the Western Reserve (WR) strain of vaccinia virus, mutated in the A33R and B5R proteins of the outer envelope of the virus, respectively, were studied. WR.c1 was the most attenuated virus, WR.c3 was somewhat more pathogenic, while WR was the most virulent of the three. While the WR and the WR.c3 viruses, intranasally inoculated into mice, spread efficiently to the different internal organs of the animal, including the brain, WR.c1 was restricted to the lungs only. Mice, intranasally infected with 500 plaque forming units of the WR, WR.c1, or WR.c3 viruses, were protected against infection with a lethal dose of the WR strain.
