The antigen marker most closely associated with the transmission of HBV infections is?

The antigen marker most closely associated with the transmission of hepatitis B virus (HBV) infections is HBsAg (Hepatitis B surface antigen). This is because HBsAg indicates the presence of the virus itself in the blood, which means that an individual is infectious. When HBsAg is present, it signifies that the person is actively infected, which is crucial for understanding and preventing the transmission of HBV to others.

HBeAg, while also related to HBV infection, is more indicative of viral replication and high infectivity rather than transmission itself. Anti-HBs represents the antibodies produced in response to the surface antigen and indicates recovery or vaccination, which means it is not associated with active transmission. Similarly, Anti-HBc reflects prior infection but does not indicate current infectiousness. Therefore, HBsAg is the primary marker used to assess acute or chronic infection and directly correlates with the ability to spread the virus, making it the correct choice in this context.