Enhancement of murine sarcoma virus (Moloney) infection in mice by Guaroa virus.

Mice dually infected with murine sarcoma virus (Moloney) [MSV(M)] and Guaroa virus (GV), an arbovirus of the Bunyamwera group, showed enhanced MSV(M) infection, reflected by progressive tumor growth, reduced median survival time, increased virus yield from tumor, and increased mortality with tumor as compared to mice inoculated with MSV(M) alone. Temporal studies indicated that GV-mediated enhancement of MSV(M) was optimum in mice infected with GV 3 days before or simultaneously with MSV(M) challenge. The en hancement of MSV(M) infection in GV-infected mice appeared to be independent of the route of GV inoculation. Dose-response studies indicated that the GV-mediated potentiation of MSV(M) infection in mice appeared to be an all or none phenomenon from the standpoint of dose of GV inoculated, while the potentiation appears to be dependent on the dose of MSV(M) used to challenge GV-infected mice. Attempts to define the mechanism by which GV poten tiated MSV(M) infection in mice were successful, but the data obtained revealed that neither the humoral or cellular immune responses nor the Interferon synthesis was affected in GV-infected mice. Other possible mechanisms by which GV potentiates MSV(M) in mice are discussed.