Viral surface protein

Viral surface proteins are virus-encoded structural glycoproteins or antigens that are embedded in the viral envelope (enveloped viruses) or displayed on the viral capsid (nonenveloped viruses)[6]. These proteins mediate the initial steps of viral infection: binding to specific host cell receptors and often catalyzing membrane fusion or endocytosis, thereby enabling viral genome delivery to the host cell cytoplasm[1][4][5][6]. Examples include the spike (S) protein of SARS-CoV-2, hemagglutinin (HA) of influenza, gp120/gp41 envelope proteins of HIV, and the glycoproteins of other enveloped viruses[3][4][5]. Viral surface proteins are the main antigens recognized by the host immune system, forming the basis of neutralizing antibody responses and most vaccine strategies. Due to their extracellular location and critical role in pathogenesis, they are primary therapeutic targets for antiviral drugs and neutralizing antibodies. However, high sequence variability and immune evasion strategies (such as glycan shields and rapid mutation) present major hurdles to interventions[3][4][7]. Note on correctness and specificity: - “Viral surface proteins and antigens on infected host cells” is a non-specific, umbrella term rather than a single, canonical target. - Each virus has distinct surface proteins (e.g., SARS-CoV-2 spike, HIV gp120, influenza HA), and each may be referenced more precisely by its official protein name. - Antigens on infected host cells typically refer to viral proteins presented in the context of MHC molecules or expressed on the plasma membrane post-infection, enabling recognition and clearance by immune cells[7]. - For structured databases or drug-target mapping, it is better to specify the individual viral protein and, if relevant, the viral species (e.g., “SARS-CoV-2 spike glycoprotein”), rather than using a collective term. - This entry would be considered too broad and not a single target, which limits its utility for structured annotation in drug discovery or clinical databases.

Other names

Viral spike proteinViral envelope glycoproteinViral fusion proteinViral antigen (context-dependent: "viral surface antigen")

Blocking receptor binding (antibodies or small molecules compete for receptor or critical conformational sites)[1][4] Preventing membrane fusion (fusion inhibitors target conformational changes in fusion peptides or HR1/HR2 domains)[1][4] Immune-mediated clearance (antibodies enable neutralization, cellular cytotoxicity, complement activation)[7]