AP BIOLOGY

Detailed explanation-1: -HIV finds the white blood cells, called CD4 cells. HIV gets inside the CD4 cell and makes copies of itself. Then, HIV kills the CD4 cell and the new HIV copies find other CD4 cells to get inside and start the cycle again. HIV kills immune system cells that help the body fight infections and diseases.

Detailed explanation-2: -HIV binds to the CD4 molecule on the surface of helper T-cells and replicates within them. This results in destruction of CD4+ T-cells and leads to a steady decline in this population of T-cells.

Detailed explanation-3: -Human Immunodeficiency Virus (HIV) specifically attacks Helper T cells. Without an adequate supply of Helper T cells, the immune system cannot signal B cells to produce antibodies or Cytotoxic T cells to kill infected cells.

Detailed explanation-4: -In most HIV-infected individuals, the initiation of ART leads to a gradual increase in CD4+ T-cell counts and a decrease in CD8+ T-cell counts74. Although less is known about the effects of HIV infection on B-cell numbers, several studies have shown that B-cell numbers are decreased in HIV-infected individuals21, 75–77.

Detailed explanation-5: -CD4 T lymphocytes (CD4 cells) help coordinate the immune response by stimulating other immune cells, such as macrophages, B lymphocytes (B cells), and CD8 T lymphocytes (CD8 cells), to fight infection. HIV weakens the immune system by destroying CD4 cells.