CD8A and infection: However, in rhesus macaques, using a novel soluble recombinant macaque PD-1 fused to a macaque Ig-Fc (rPD-1-Fc) an alternate strategy for blocking the PD-1/PD-L1 pathway, although found effective in rescuing the effector function of SIV-specific CD4+ and CD8+ T cells during the early chronic phase of infection, has limited clinical benefit [128].