After entering the body, HIV infects and enters macrophages. The RNA genome of the virus replicates to form viral DNA with the help of reverse transcriptase, an enzyme found in the virus. This viral DNA then gets incorporated into the host cell’s DNA, directing the infected cells to produce new virus particles. These newly produced virus particles can then infect other cells, leading to further replication and spread of the virus throughout the body. The macrophages continue to produce virus, acting like a “factory”, and over time this can lead to a decline in the person’s immune function and the development of AIDS.