Augmentation of delayed-type hypersensitivity by vesicular stomatitis virus infection in mice

Effects of the infection with vesicular stomatitis virus (VSV) on delayed-type hypersensitivity (DTH) to heterologous erythrocytes were investigated in mice. Infection at the time of immunization resulted in production of high levels of DTH that were specific to the antigen used for immunization. The high level of DTH produced in VSV-infected mice could not be attributed to the nonspecific enhancement of the footpad swelling with the infection. Augmentation of DTH was observed in all strains of the mouse (CBA, BALB/c, C3H/He, and C57BL/6) used. The augmenting effect of VSV infection was not as apparent in adult thymectomized mice in which the level of VSV-replicating T cells was reduced. These results strongly suggest that DTH-mediating T cells are resistant to infection by VSV, and also that there are VSV-sensitive cells that may be engaged in the suppression of DTH. It seems improbable, however, that the cells sensitive to VSV infection represent the suppressor cells themselves, since the enhancing effect was not observed in mice in which the suppressor cells were induced by the administration of high doses of the antigen.