Image_5_Immune Protection of SIV Challenge by PD-1 Blockade During Vaccination in Rhesus Monkeys.TIF Enxiang Pan Fengling Feng Pingchao Li Qing Yang Xiuchang Ma Chunxiu Wu Jin Zhao Hongbin Yan Rulei Chen Ling Chen Caijun Sun 10.3389/fimmu.2018.02415.s006 https://frontiersin.figshare.com/articles/figure/Image_5_Immune_Protection_of_SIV_Challenge_by_PD-1_Blockade_During_Vaccination_in_Rhesus_Monkeys_TIF/7241102 <p>Though immune correlates for protection are still under investigation, potent cytotoxic T lymphocyte responses are desirable for an ideal HIV-1 vaccine. PD-1 blockade enhances SIV-specific CD8+ T cells. However, little information has been reported about how it affects the immunogenicity and protection of prophylactic SIV vaccines in nonhuman primates. Here, we show that PD-1 blockade during vaccination substantially improved protective efficacy in SIV challenged macaques. The PD-1 pathway was blocked using a monoclonal antibody specific to human PD-1. Administration of this antibody effectively augmented and sustained vaccine-induced SIV-specific T cell responses for more than 42 weeks after first immunization in rhesus monkeys, as compared with SIV vaccination only. Importantly, after intrarectally repeated low-dosage challenge with highly pathogenic SIVmac239, monkeys with PD-1 blockade during vaccination achieved full protection against incremental viral doses of up to 50,000 TICD<sub>50</sub>. These findings highlight the importance of PD-1 blockade during vaccination for the development of HIV vaccines.</p> 2018-10-23 13:47:14 PD-1 blockade HIV vaccine CTL NHP model SIV challenge