The effects of chronic infection with a superantigen-producing virus

C3H/HeJ mice transmit a mouse mammary tumor virus from mother to pup in milk. The retrovirus infects mice shortly after birth and, when expressed in recipient mice, produces a Vβ14-specific superantigen. The consequences of such expression on Vβ14-bearing T cells are examined in this paper. Most cells bearing Vβ14 and either CD4 or CD8 are eliminated in the thymus. Some Vβ14-bearing cells escape to the periphery, however. Those bearing CD8 are unaffected by expression of the viral superantigen. The percentage of peripheral CD4⁺ T cells bearing Vβ14 drops with time after birth. In large part this seems to be due to the fact that many of these cells become anergic because of exposure to the viral superantigen. Unlike normal T cells, these anergic cells cannot undergo peripheral postthymic expansion. Consequently, they drop in percentage even during a time when their total numbers are constant.