Effects of vaccinia virus-expressed interleukin 2 on the immune system of sublethally irradiated mice

A recombinant vaccinia-rabies virus in the immunocompromised host: oral innocuity, progressive parenteral infection, and therapeutics

With the emergence of raccoons (Procyon lotor) as the primary rabies reservoir in the United States of America, a recombinant vaccinia-rabies glycoprotein (V-RG) virus vaccine was developed that protected raccoons by the oral route from rabies infection. Despite extensive laboratory evaluation, vaccine safety concerns remained about free-choice distribution for wildlife rabies control. In this study, the oral innocuity of V-RG virus was demonstrated in immunodeficient mice but parenteral exposure resulted in systemic and progressive infection, albeit significantly abrogated in severity in comparison to vaccinia virus. Treatment with vaccinia immune globulin and hydroxyphosphonylmethoxy-propyl-cytosine resulted in significantly longer survival and minimized V-RG viral gross lesions.

Biological effects of recombinant vaccinia virus-expressed interleukin 4

Recombinant vaccinia viruses expressing murine interleukin 4 (IL-4), either alone or together with interleukin 2 (IL-2) or gamma interferon (gamma-IFN), were constructed. Unlike IL-2, IL-4 expressing viruses were not cleared from immunodeficient mice and the mice died. As they died more rapidly than immunodeficient mice inoculated with a control virus, it appeared that IL-4 contributed to their death and the IL-4 mediated toxicity was confirmed in normal immunocompetent mice. The toxicity was reversed by co-expression of either IL-2 or gamma-IFN, probably due to virus clearance and therefore lower levels of circulating IL-4. Vaccinia virus-expressed IL-4 did not increase antibody or natural killer cell levels and caused a slight decrease in cytotoxic T lymphocyte levels.