The full medical name for AIDS is Acquired Immune Deficiency Syndrome (AIDS), an immunodeficiency syndrome caused by human infection with the human immunodeficiency virus, HIV. Most people who are infected with HIV remain healthy and can live for many years with no symptoms or only mild illness. Even when they appear healthy and feel healthy themselves, they are still able to transmit HIV to others and remain infectious throughout their lives.
HIV is strictly host-specific and can infect humans and cause AIDS; under experimental conditions, HIV-1 can infect chimpanzees and HIV-2 can infect rhesus monkeys, resulting in sick blood and positive serum antibodies, but it does not cause disease in animals. The virus can be isolated from peripheral blood, semen, milk, cerebrospinal fluid, saliva, tears and other body fluids of HIV-infected patients, but there are no reports of HIV infection through tears, saliva and juices.
HIV is generally transmitted through blood and semen, and the main ways of transmission include: 1, sexual transmission: through sexual intercourse between gay men and heterosexuals, but also through artificial insemination; 2, blood transmission: through receiving blood or organs donated by HIV-infected people, using HIV-contaminated blood products or sharing injection needles with HIV-infected people and being infected, in addition, contact with HIV In addition, medical and laboratory personnel who are exposed to HIV-infected body fluids or HIV cultures are at occupational risk of HIV infection; 3. Mother-to-child transmission: HIV infection can be transmitted from mother to newborn in utero or during delivery (Connor, 1997). Other than that, general human-to-human contact does not lead to HIV transmission, so there is no need to be overly sensitive and fearful about it.
In vitro, HIV can infect CD4+ T lymphocytes (T4 cells) and monocytes-macrophages, where they proliferate and cause cytopathic lesions, suggesting that CD4+ T lymphocytes and monocytes-macrophages are the main target cells of HIV. In addition, HIV can also infect normal B lymphocytes, B lymphoblastoid cell lines formed by EBV transformation, microglia, glial cells, neuroglia, neutrophils and various cell lines (O’Brien, 1997) In vivo, HIV infects CD4+ T lymphocytes, monocytes-macrophages, B lymphocytes, neutrophils and follicular dendritic cells in connective tissues, in addition to HIV has such a wide range of cellular and histophilic properties, which is consistent with its ability to cause CD4+ T lymphocytes, monocyte-macrophages, B lymphocytes, neutrophils, astrocytes and endothelial cells in the skeleton, thymus, brain, heart, lung, intestine, eye, kidney, skin and gonads (Dittmar, 1997a). HIV has such a wide range of cellular and histophilic properties that are consistent with the multi-organ symptoms it causes such as CD4+ T-lymphocyte deficiency, lymphadenopathy, Kaposi’s sarcoma and neurological damage.
A high degree of mutagenicity is a distinctive feature of HIV and other retroviruses. The mutations are mainly derived from the reverse transcription process, with the largest mutations in genes such as env and nef, while gag and pol are relatively conserved, less mutated, and mostly silent point mutations. Based on the mutations of env and gag genes, HIV-1 can be classified into at least 2 groups with 11 subtypes. The M(main) group consists of 10 subtypes, i.e. subtypes A-J. The M(main) group consists of 10 subtypes, i.e. A-J subtypes. The B subtype is predominant in Europe and America, while the A, C, D, E subtypes are popular in Africa. According to the same method, HIV-2 can be classified into subtypes A, B, etc. (UNAIDS, 1997). HIV varies greatly not only between regions or individuals, but also within the same individual. In fact, each HIV-infected person carries a heterogeneous population of viruses, with various mutant strains coexisting in the body. This high level of variability helps HIV evade host immune surveillance and creates significant barriers to the prevention, diagnosis and treatment of HIV infection.
How to prevent HIV?
1. Self-love Maintain faithful and single sexual relationships; use condoms correctly when having risky sex; treat STDs promptly.
2.Prevent the blood transmission of AIDS Do not use untested blood and blood products. Do not use drugs or share needles with others. Ear or body piercing, tattoos, needle therapy or any procedure that requires invasive skin piercing all carry a certain risk of HIV transmission.
HIV can be transmitted during pregnancy, childbirth, or breastfeeding after the child is born. Women who are infected with HIV should avoid pregnancy and abort if they become pregnant. The use of antiviral drugs before and after delivery can reduce the chance of mother-to-child transmission. The use of artificial feeding can also reduce the risk of HIV infection.