A TCR-mimic bispecific antibody reduces HIV-1 provirus and delays viral rebound in HLA-matched humanized mice

Bispecific antibodies that reroute cytotoxic effectors toward infected cells are promising HIV-1 cure agents, yet existing formats bind Env and are limited by antigenic variation and Env down-regulation. We engineered a TCR-mimic single-chain diabody, HI12, that recognizes a conserved Pol-derived peptide presented by HLA-A*02:01 and evaluated its effect in HLA-matched, HIV-infected humanized mice. When administered during early antiretroviral therapy (ART), HI12 was well tolerated, activated HIV-specific CD8+ T cells and accelerated plasma virus decay. Treatment produced four-to six-fold reductions in intact and total proviral DNA within lymph-node and splenic CD4+ T cells, indicating substantive reservoir clearance. After ART interruption, HI12-treated animals showed a significant delay in viral rebound compared with controls, linking reservoir reduction to improved post-therapy control. These findings provide the first in-vivo evidence that a peptide-HLA-directed bispecific antibody can both shrink the intact HIV reservoir and defer viral recrudescence, supporting further development of TCR-mimic bispecific antibodies for cure strategies. Significance StatementAn HIV-1 cure strategy will require novel therapeutics to facilitate immune-mediated elimination of infected cells and reduction of blood and tissue reservoirs. Here, we demonstrate that an TCR-mimic bispecific antibody that recognizes a conserved Pol epitope can promote CD8+ T cell-mediated clearance of infected cells in HLA-matched, HIV-infected humanized mice. The bispecific antibody therapy reduced HIV-1 proviral DNA in lymph node and splenic tissues and improved post-therapy viral control. This study highlights the potential of developing novel TCR-mimic bispecific antibodies in HIV cure-directed strategies.