IMMUNOLOGY

Detailed explanation-1: -To infect cells, the HIV protein envelope (Env) binds to the primary cellular receptor CD4 and then to a cellular coreceptor. This sequential binding triggers fusion of the viral and host cell membranes, initiating infection.

Detailed explanation-2: -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-3: -HIV primarily targets a type of cell in the immune system called the CD4+ T cell. However, many types of these cells exist, and they are not all equally susceptible to infection by HIV.

Detailed explanation-4: -Most people who get HIV get it through anal or vaginal sex, or sharing needles, syringes, or other drug injection equipment (for example, cookers). But there are powerful tools that can help prevent HIV transmission.

Detailed explanation-5: -CD4 cell counts are obtained from bloodwork as part of laboratory monitoring for HIV infection. CD4+ cell counts are usually measured when you are diagnosed with HIV (at baseline), every 3 to 6 months during first 2 years or until your CD4 count increases above 300 cells/mm3.