PATHOLOGY

Detailed explanation-1: -The hall mark of human immunodeficiency virus (HIV) infection is a gradual loss of CD4+ T-cells and imbalance in CD4+ T-cell homeostasis, with progressive impairment of immunity that leads ultimately to death. HIV infection in humans is caused by two related yet distinct viruses: HIV-1 and HIV-2 .

Detailed explanation-2: -CD4 count (or T-cell count) CD4 cells (also known as CD4+ T cells) are white blood cells that fight infection. CD4 cell count is an indicator of immune function in patients living with HIV and one of the key determinants for the need of opportunistic infection (OI) prophylaxis.

Detailed explanation-3: -HIV infects and deletes CD4+ T cells that normally coordinate the adaptive T-and B-cell response to defend against intracellular pathogens.

Detailed explanation-4: -HIV starts destroying T-lymphocytes, specifically the T-helper cells. Viruses generally lack the ability to replicate by themselves, outside a host cell.