SIV infection, or simian immunodeficiency virus infection, is a viral infection that affects various species of non-human primates, including monkeys and apes. SIV is closely related to HIV, the human immunodeficiency virus, and is often used as a model for studying the transmission, pathogenesis, and treatment of HIV infection in humans. SIV infection can lead to immunodeficiency in primates, similar to the progression of HIV infection in humans. It is transmitted through direct contact with infected bodily fluids, such as blood or semen, and can also be passed from mother to infant during breastfeeding. Symptoms of SIV infection can include weight loss, diarrhea, and susceptibility to other infections, and can ultimately progress to AIDS if left untreated. Research in the area of SIV infection often focuses on developing vaccines, studying the mechanisms of viral replication and immune response, and testing potential antiviral therapies. By understanding how SIV infects and affects non-human primates, researchers hope to gain insights that can inform strategies for preventing and treating HIV infection in humans.