Hepatitis B virus small surface protein S (HBsAg (S protein))

The "Hepatitis B virus S open reading frame transcript" refers to the mRNA transcribed from the S region of the hepatitis B virus genome. This transcript encodes the small surface antigen known as HBsAg or S protein. The major function of this viral membrane glycoprotein is to form both infectious virion envelopes and non-infectious subviral particles that circulate in high quantities during infection[5][8]. The presence of HBsAg in blood is a hallmark diagnostic marker for acute or chronic hepatitis B infection[6]. Recombinant forms of this antigen are used as immunogens in all current prophylactic HBV vaccines, which work by inducing protective antibody responses against this surface component[5][8]. **Note on correctness:** The query target "Hepatitis B virus S open reading frame transcript" describes an mRNA rather than a canonical therapeutic target such as a receptor or enzyme. However, its translation product—the small surface antigen/protein—is widely recognized as both an immunological biomarker and vaccine/drug target. For structured data purposes, it is best mapped to "Hepatitis B virus small surface protein S" or simply "HBsAg," not just its transcript[5][6][8]. If you need information about other related proteins encoded by different ORFs—such as pre-S1/pre-S2/L/M proteins—please specify further.

Other names

Hepatitis B virus S proteinHBV S antigenSmall hepatitis B surface antigenSHBsAg

Vaccines induce neutralizing antibodies against HBsAg, preventing viral entry into hepatocytes and conferring immunity.