Superantigen-Mediated Deletion of Specific T Cell Receptor Vβ Subsets in the SCID-hu Thy/ Liv Mouse Is Induced by Staphylococcal Enterotoxin B, but Not HIV-I

Infection by HIV-1 has been associated with perturbations in the TCR Vβ repertoire, suggesting the involvement of a superantigen. Among the hallmarks of superantigens is the capacity to delete T cells bearing specific TCR Vβ families in the developing thymus. To verify the presence of a superantigen in HIV-1, we analyzed the SCID-hu Thy/Liv TCR Vβ repertoire within CD4⁺CD8⁺, CD4⁺CD8^-, or CD4^-CD8⁺ thymocytes subsets by flow cytometry using a panel of Abs recognizing about 60% of the TCR repertoire following injection of SEB or infection by two different HIV-1 isolates. Seven days following SEB injection, thymocyte subsets bearing TCR Vβ3, Vβ12, Vβ17, and Vβ20, but not Vβ5 or Vβ8, were deleted relative to mock-injected mice. In contrast, no changes were observed in the TCR Vβ repertoire in CD4⁺CD8⁺, CD4⁺CD8^-, or CD4^-CD8⁺ thymocyte subsets after infection with HIV-1. The T cell depletion caused by HIV-1 infection is most likely not mediated by an HIV-encoded superantigen.