Final answer:
HIV resists host defenses by targeting immune cells, particularly CD4+ T cells, which are a vital component of the immune system. The virus uses its envelope glycoprotein, gp120, to bind to the CD4 receptor on the surface of these cells, facilitating entry and subsequent infection. Additionally, HIV has the ability to mutate rapidly, leading to diverse viral strains that can evade the host immune response.
Step-by-step explanation:
HIV (Human Immunodeficiency Virus) has evolved sophisticated mechanisms to evade the host immune defenses, allowing it to establish and persist in the human body.
One key strategy involves the virus's interaction with CD4+ T cells, which are crucial for coordinating the immune response. The envelope glycoprotein gp120 on the surface of HIV binds specifically to the CD4 receptor on the surface of these immune cells, initiating a series of events that culminate in viral entry and replication. This interaction not only facilitates viral entry but also impairs the normal functioning of CD4+ T cells, compromising the overall immune response.
Furthermore, HIV exhibits a high mutation rate due to the error-prone nature of its reverse transcriptase enzyme. This rapid mutation leads to the generation of diverse viral variants within an infected individual, a phenomenon known as genetic diversity.
This diversity poses a significant challenge for the immune system to mount an effective and sustained defense, as it must contend with a constantly changing viral landscape. The ability of HIV to escape immune recognition through genetic variability contributes to the persistence of the virus in the host.
In summary, HIV's resistance to host defenses involves the specific targeting of CD4+ T cells through the interaction of gp120 with the CD4 receptor and the virus's ability to rapidly mutate, creating a diverse viral population. These evasion strategies contribute to the chronic nature of HIV infection and the challenges in developing effective vaccines or cures.