Protection induced in mice against a lethal orthopox virus by the Lister strain of vaccinia virus and modified vaccinia virus Ankara (MVA).

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.

Pathogenicity and immunogenicity in mice of vaccinia viruses mutated in the viral envelope proteins A33R and B5R.

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.