Immunization with baculovirus-expressed recombinant rotavirus proteins VP1, VP4, VP6, and VP7 induces CD8⁺ T lymphocytes that mediate clearance of chronic rotavirus infection in SCID mice

Clearance of chronic murine rotavirus infection in SCID mice can be demonstrated by adoptive transfer of immune CD8⁺ T lymphocytes from histocompatible donor mice immunized with a murine homotypic rotavirus (T. Dharakul, L. Rott, and H. B. Greenberg, J. Virol. 64:4375-4382, 1990). The present study focuses on the protein specificity and heterotypic nature of cell-mediated clearance of chronic murine rotavirus infection in SCID mice. Heterotypic cell-mediated clearance was demonstrated in SCID mice infected with EDIM (murine) rotavirus after adoptive transfer of CD8⁺ T lymphocytes from BALB/c mice that were immunized with a variety of heterologous (nonmurine) rotaviruses including Wa (human, serotype 1), SAH and RRV (simian, serotype 3), and NCDV and RF (bovine, serotype 6). This finding indicates the serotypic independence of T-cell-mediated rotavirus clearance. To further identify the rotavirus proteins that are capable of generating CD8⁺ T cells that mediate virus clearance, donor mice were immunized with SF-9 cells infected with a baculovirus recombinant expressing one of the following rotavirus proteins: VP1, VP2, NS53 (from RF), VP4, VP7, NS35 (from RRV), VP6, and NS28 (from SA11). SCID mice stopped shedding rotavirus after receiving CD8⁺ T cells from mice immunized with VP1, VP4, VP6, and VP7 but not with VP2, NS53, NS35, NS28, or wild-type baculovirus. These results suggest that heterotypic cell-mediated clearance of rotavirus in SCID mice is mediated by three of the major rotavirus structural proteins and by a putative polymerase protein.