Viral budding

At the cell membrane, the immature viruses bud off the cell and enter the bloodstream. The newly produced, immature viruses are non-infectious. The CD4 cells are often destroyed by the HIV virus infection which can result in profound immunodeficiency.

The viral components gather at the cell membrane. The cell membrane then begins to form mini-bubbles, which eventually bud out of the cell taking with it all viral proteins and RNA needed to form a virus particle (a "virion").

The newly assembled virions are still immature as they enter the bloodstream. At this stage they are unable to infect other cells. The virions must undergo a process of maturation in order to become infectious.

CD4 cells do not usually survive invasion by HIV. Either they disintegrate because of the large number of viruses budding off, or the body's immune system will recognise the viral envelope proteins in the cell membrane and destroy the damaged cells. As CD4 cells themselves are an essential part of the immune system their destruction can cause profound immunodeficiency.