An Open-Label Study to Evaluate the Safety and Immunogenicity of 2 Doses of 100µg BG505 SOSIP.664 gp140 Vaccine, Adjuvanted, Given to a Population of Adults in Good General Health Who Have Received 3 Doses of 300µg BG505 SOSIP.GT1.1 gp140 Vaccine, Adjuvanted

This is an open-label study to evaluate the safety and immunogenicity of 2 doses of 100µg of BG505 SOSIP.664 gp140 Vaccine, Adjuvanted, given to HIV-1 uninfected adults in good general health who have received 3 doses of 300µg BG505 SOSIP.GT1.1 gp140 Vaccine, Adjuvanted, as part of Protocol IAVI C101 (NCT04224701).

Up to 14 participants, who had enrolled in and completed the phase 1 Protocol IAVI C101 "A Clinical Trial to Evaluate the Safety and Immunogenicity of Recombinant HIV-1 Envelope Protein BG505 SOSIP.GT1.1 gp140 Vaccine, Adjuvanted in Healthy, HIV-uninfected Adults (NCT04224701) and who received 3 doses of 300µg of BG505 SOSIP.GT1.1 gp140 Vaccine, Adjuvanted, will be recruited into the study. Protocol IAVI C101 evaluated the capacity of GT1.1 to prime desirable on-target responses against the CD4 binding site (CD4bs) of the HIV virion, including but not limited to VRC01 class responses, as well as against V2-apex.

This study, Protocol IAVI C107, will examine if maturation of anti-HIV antibody response occurs following boost immunizations with BG505 SOSIP.664 gp140 Vaccine, Adjuvanted. It is expected that this study will provide insight into if and how BG505 SOSIP.664 immunization can expand and mature desirable on-target CD4bs and V1V2-apex responses.