Human immunodeficiency virus type 1 envelope, group-specific antigen, and polymerase proteins (HIV-1 Env, Gag, and Pol) (HIV-1 Env/Gag/Pol)

The HIV-1 Env, Gag, and Pol inserts expressed by the ALVAC-HIV vCP1521 vector are recombinant viral proteins used as immunogens in HIV vaccine development (Rerks-Ngarm et al., 2009, N Engl J Med). The Env (envelope) protein, specifically a gp120/gp41 fusion, is the primary target for neutralizing antibodies as it mediates viral entry into host cells (Haynes et al., 2012, N Engl J Med). Gag (group-specific antigen) and Pol (polymerase) are internal proteins that are highly conserved and serve as major targets for cytotoxic T-lymphocyte (CTL) responses, which are crucial for controlling viral replication (Robb et al., 2012, Lancet Infect Dis). In the vCP1521 construct, these proteins are derived from specific HIV-1 clades (clade B for Gag/Pol and clade E for Env) to provide protection against prevalent strains, particularly in Southeast Asia (NIH/NIAID, ClinicalTrials.gov NCT00006327). This antigenic combination was famously used in the RV144 'Thai Trial', where it was delivered via a canarypox vector to prime the immune system before boosting with a protein subunit vaccine. The goal of this target strategy is to elicit a dual-arm immune response capable of preventing initial infection and limiting the spread of the virus within the host.

Other names

ALVAC-HIV vCP1521 antigensHIV-1 gp120/gp41, Gag, and PolvCP1521 insertsHIV-1 clade B Gag/Pol and clade E Env

The antigens are expressed by the recombinant canarypox vector to prime the immune system by presenting viral epitopes via MHC class I and II pathways, leading to the generation of HIV-specific CD4+ and CD8+ T-cells and facilitating B-cell activation for antibody production (Rerks-Ngarm et al., 2009, N Engl J Med; Haynes et al., 2012, N Engl J Med).