showing the encased purple core.
HIV virus particles or virions. Human Immunodeficiency Virus is the retrovirus that causes AIDS (Acquired Immune Deficiency Syndrome). The virus has an RNA genome contained within a bullet shaped capsid (pinkish-purple and glimpsed in the depths of the particles). This conical nucleocapsid sits snugly within a cage of matrix proteins (blue cage). The matrix is covered by an envelope (translucent greenish blue) which was derived from the host cell during viral budding. Anchored in the matrix, and passing through the viral envelope, are the spikes (golden) which enable the virus to attach to host cells. Having attached, the envelope merges with the cell membrane and the contents of the virus enter the cell. The RNA genome is ferried to the nucleus. During this journey, the viral RNA is reverse transcribed into DNA. The DNA viral genome then enters the nucleus through a nuclear pore and becomes integrated into the host genome.