What does IgG primarily contribute to in the immune system?

IgG, or Immunoglobulin G, plays a crucial role in the immune system by contributing significantly to both antibacterial and antiviral activities. It is the most abundant antibody in the bloodstream and is particularly effective at opsonization, which enhances the ability of immune cells to identify and eliminate pathogens. When the body encounters harmful microorganisms, IgG binds to these pathogens, marking them for destruction by phagocytes and complement proteins. Additionally, IgG can neutralize toxins and viruses by blocking their ability to infect cells.

This antibody is key in providing long-term protection and memory against infections, as it is produced after initial exposure to an antigen and can respond rapidly upon subsequent exposures. This ability to recognize and neutralize both bacteria and viruses underlines the comprehensive protective function of IgG in the immune response, making it a central component in fighting infections and diseases.

Other options, while relevant to different aspects of the immune system, do not capture the primary role of IgG as effectively. The focus on its antibacterial and antiviral functions encapsulates its diverse and essential contributions to immune protection.