Molecular Pathogens 2024, Vol.15, No.1, 9-16 http://microbescipublisher.com/index.php/mp 12 through the production of cytokines. Cytokines are secreted proteins that serve as signals and regulators between immune cells. In HIV infection, the production of certain cytokines is modulated, thereby affecting the activity and efficacy of immune cells (van Zyl et al., 2018) (Figure 2). Figure 2 Interaction between HIV and immune system (van Zyl et al., 2018) However, HIV has multiple mechanisms to evade the host immune response. The virus can change the structure of its surface proteins through diversity mutations and recombination, thereby avoiding recognition and attack by antibodies. Additionally, the virus can suppress the activity of the host immune system, disrupt the function of immune cells, or inhibit cytokine production. These evasion mechanisms make the host immune response to HIV infection complex and difficult, providing opportunities for sustained infection and immune escape by the virus. 3.2 Antibody Structure and Function Antibodies are a type of protein produced by the immune system, also known as immunoglobulins. Antibodies have a specific structure and function that play an important role in defending against infections and protecting the body from pathogenic invasion. The structure of antibodies is highly unique, typically consisting of two heavy chains and two light chains that form a Y-shaped molecule. They are connected together by disulfide bonds at their C-terminal ends. Each antibody has specificity due to the distinct amino acid sequence of its variable region (hypervariable region), which allows it to recognize and bind to a specific antigen. The variable region of antibodies is generated by genetic recombination and mutation, providing diversity that enables recognition and binding to various antigens (Sanchez et al., 2018). The function of antibodies is mainly manifested in two aspects. First, antibodies can directly neutralize the toxins or antigens of pathogens, preventing them from entering or invading host cells. When antibodies bind to a pathogen, they can block its attachment to host cells, thereby preventing invasion and damage. Second, antibodies can enhance the immune response of the body by activating other components of the immune system. This includes activating the complement system, inducing inflammatory responses through cytotoxic functions, and promoting the destruction and clearance of antigens by other immune cells. Antibodies also have other functions, such as regulating immune responses and mediating the activity of immune cells. They can interact with specific immune cells, such as macrophages, NK cells, and other immune cells, thereby regulating the activity and response of the host immune system. These functions make antibodies play a crucial role in various aspects of immune responses. 3.3 The impact of virus mutation on the recognition and binding ability of antibodies The high variability of HIV has a significant impact on the recognition and binding ability of antibodies, posing a significant challenge in the development of broad-spectrum, high-affinity antibody-based drugs and vaccines. The
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