<s>[INST] What is HIV? [/INST] HIV stands for human immunodeficiency virus. HIV is a retrovirus that infects cells of the human immune system (mainly CD4-positive T-cells and macrophages—key components of the cellular immune system) and destroys or impairs their function. Infection with this virus results in the progressive depletion of the immune system, leading to immunodeficiency.

The immune system is considered deficient when it can no longer fulfil its role of fighting off infection and diseases. People with immunodeficiency are much more vulnerable to a wide range of infections and cancers, most of which are rare among people without immunodeficiency. Diseases associated with severe immunodeficiency are known as opportunistic infections because they take advantage of a weakened immune system Source: UNAIDS. Link: https://www.unaids.org/en/frequently-asked-questions-about-hiv-and-aids. Field: Infectious Disease. Disease: HIV </s>