Diversity and Global Epidemiology of HIV
Pp. 3-10 (8)
Kazem Baesi, Seyed Younes Hosseini, Ali Teimoori and Mohammad Gholami
HIV has probably originated from multiple zoonotic transmissions of Simian
Immunodeficiency Virus (SIV) from non-human primates to humans in West and
Central Africa. There are two HIV types: HIV type 1 (HIV-1) groups M, N, O and P
and HIV type 2 (HIV-2) groups A–H. Within the HIV-1 group M, nine subtypes are
found, designated by the letters A–D, F–H, J, and K. Within a subtype, changes in the
amino acid sequence is observed in the range of 8-17%, but it can be as high as 30%,
while differences between subtypes are generally found in the range of 17-35%.
In fact, when new combinations between different HIV-1 subtypes occurs, it results in
different Unique Recombinant Forms (URFs), some developed into Circulating
Recombinant Forms (CRFs) as propagated in three or more epidemiologically unlinked
individuals. The viruses fueling these epidemics vary according to geographical
regions, with clade C virus being the most prevalent worldwide, and clade B being
currently the most prevalent in the United States and Europe.
Thirty years after the first description of AIDS, an estimated 35.0 million [33.2
million–37.2 million] people were living with HIV at the end of 2013. 2.1 million
[1.9–2.4 million] had become newly contaminated with HIV in 2013, including 240000
children, and 1.5 million [1.4–1.7 million] HIV-infected persons died.
AIDS, CRF, Diversity, Epidemiology, HIV, Mutation,
Recombination, Sequence, Subtype, URF.
Hepatitis and AIDS Department, Pasteur Institute of Iran, Pasteur Ave., Tehran 1316943551, Tehran, Iran; Shiraz HIV/AIDS Research Center, Shiraz University of Medical Sciences, Zand, Iran.