Sample blood collection tube with HIV test label on HIV infection screening test form.

AIDS, difference between HIV1 and HIV2

By Cristiano Antonino Last updated Aug 8, 2022

HIV1 and HIV2, what are the differences? The human immunodeficiency virus (also called HIV, an acronym from the English ‘human immunodeficiency virus’) is a retrovirus of the lentivirus genus, characterised by giving rise to chronic infections that are poorly responsive to the immune response and evolve slowly but progressively and can have a fatal outcome if left untreated

HIV is transmitted in many ways, for example through sexual intercourse (80% of cases), transfusions of contaminated blood and hypodermic needles, and through vertical transmission between mother and child during pregnancy, birth and breastfeeding.

HIV1 and HIV2, HIV is divided into two strains:

HIV-1: mainly localised in Europe, America and Central Africa. It is the first to be discovered; it is the most widespread and contagious strain and is responsible for a clinically more severe syndrome than the second strain. When people commonly refer to the ‘HIV virus’, they are generally referring to this strain and not to the second strain. HIV-1 generally leads to AIDS much more quickly than the second strain.

HIV-2: predominantly localised in West Africa and Asia, it is less widespread and infectious than the first strain and leads to a clinically more moderate syndrome than the previous strain. Only 166 cases of HIV-2 were identified between 1988 and 2010 in the US. HIV-2 generally leads to AIDS much more slowly than the first strain.