Human immunodeficiency virus type 1 Viral protein U (Vpu)

Human immunodeficiency virus type 1 Viral protein U (Vpu) is an 81-amino acid type I integral membrane protein that functions as both a viroporin and a multifunctional accessory protein [UniProt, 2024; González, 2015]. It plays a critical role in the HIV-1 life cycle by facilitating the release of new virions from infected cells and evading the host immune system [Khan et al., 2021]. Vpu achieves this by forming cation-selective ion channels and by acting as a molecular adapter to mediate the degradation of host proteins such as the CD4 receptor and the restriction factor BST-2 (Tetherin) [Wikipedia, 2024; González, 2015]. By antagonizing BST-2, Vpu prevents the physical tethering of virions to the cell surface, thereby promoting viral spread and protecting infected cells from antibody-dependent cellular cytotoxicity (ADCC) [Khan et al., 2021; Biotron, 2024]. Beyond its role in viral release, Vpu contributes to immune evasion by downregulating cell surface markers like MHCII, CD1d, and NTB-A, which reduces the visibility of infected cells to natural killer (NK) and T cells [Khan et al., 2021]. Therapeutic targeting of Vpu is an active area of research, as it offers a way to disrupt viral replication and potentially clear viral reservoirs in macrophages and monocytes [Biotron, 2024]. Small molecules such as BIT225 are currently in clinical development, aiming to inhibit Vpu's ion channel activity and its ability to counteract host restriction factors [Biotron, 2024; J Infect Dis, 2021]. However, therapeutic challenges remain due to the high sequence variability of Vpu across different HIV-1 strains and the need for high selectivity to avoid affecting host cell ion channels [González, 2015; SRI International, 2022].

Other names

Viral protein UU ORF proteinVpu proteinHIV-1 VpuHIV-1 Vpu viroporin

Inhibition of ion channel activity and blocking the degradation of host restriction factors such as CD4 and BST-2 to prevent viral release and immune evasion.