Final answer:
CD4 cells are vital for immune defense as they enable antibody production by facilitating B cell maturation, and their destruction by HIV leads to increased susceptibility to opportunistic infections. Treatments focus on targeting viral replication but vaccine development is complicated by HIV's rapid mutation.
Step-by-step explanation:
HIV selectively destroys CD4 cells, which are a type of helper T cell crucial to the immune response. A person with AIDS, therefore, is highly susceptible to life-threatening infections and diseases. Given that these cells are targeted and destroyed by HIV, an individual's immune system becomes severely compromised, leading to an inability to mount an effective defense against pathogens.
When CD4+ T cells are destroyed by HIV, there is a consequent loss in the body's ability to produce antibodies because CD4+ T cells facilitate the maturation of B cells, which are responsible for antibody production. Thus, the destruction of CD4+ T cells impedes this critical function, leaving the body vulnerable to various opportunistic infections.
Treatment for HIV involves drugs that target viral proteins to inhibit viral replication and help preserve CD4+ T cell populations. Such antiretroviral treatments have significantly prolonged the lives of those with HIV, yet the development of a vaccine remains a challenge due to the virus's rapid mutation rate.