imported>Ldominguez at 09:22, 3 May 2010

2010-05-03T09:22:16Z

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{{Element
|genbank=[http://www.ncbi.nlm.nih.gov/entrez/viewer.fcgi?db=nucleotide&val=31559679 AB097872]
|type=
Human lentiviruses
|genus=
Lentivirus
|subfamily=
Class 2
|family=
Retroviridae
|group=
LTR retroelements
|description=
''Human Immunodeficiency Viruses'' (HIVs) are complex retroviruses responsible of inducing Acquired Immunodeficiency Syndrome (AIDS) in human beings. Two major types of HIV have been described; HIV-1, predominant world-wide, and HIV-2, less virulent and prevalent in western Africa ([[Literature:85472|Barre-Sinoussi ''et al.'' 1983]]; [[Literature:85382|Gallo ''et al.'' 1984]]; [[Literature:43350|Levy and Simabukuro 1985]]; [[Literature:13689|Clavel ''et al.'' 1986]]). Both retroviruses are evolutionary related to different simian immunodeficiency viruses, nevertheless, HIV-2 has not evolved directly from HIV-1, or vice versa ([[Literature:31225|Hirsch ''et al.'' 1989]]; [[Literature:28410|Guyader ''et al.'' 1986]]; [[Literature:32689|Huet ''et al.'' 1990]]; [[Literature:24337|Gao ''et al.'' 1999]]).

HIV-1 comprises the following three groups: M group, O (outlier), and N (non-M, non-O). Group M is phylogenetically divided into 11 subtypes and responsible for the global HIV-1 pandemic. Recombination of M subtypes has resulted in the generation of multiple circulating recombinant forms (CRFs) consisting of mosaic lineages ([[Literature:58876|Perrin, Kaiser, and Yerly 2003]]; [[Literature:61965|Rambaut ''et al''. 2004]]). Most subtypes and CRFs are represented in Africa reflecting the origin of the epidemy. There are 40 million people at present worldwide infected by Human Immunodeficiency Viruses (HIVs) ([http://www.unaids.org/en/HIV_data/2006GlobalReport/default.asp Prevalence map. 2006 Report on the global AIDS epidemic, UNAIDS, May 2006)].

Pathologically, an HIV infection presents the following three distinguishable clinical stages ([[Literature:29751|Hazenberg ''et al''. 2000]]):

#Initial phase; Characterized by the first two months following infection, a viral peak and a sudden decrease of CD4+ lymphocytes in the peripheral blood.
#Chronic phase; Very variable in duration, with a mean around 10 years, and seemingly stable in CD4+ cells levels. Antiretroviral therapy has severe toxic site effects but is able to prolong this phase as long as the virus does not accumulate resistant mutations.
#Final phase; Identified by the classic symptomatology associated with the Immunodeficiency Syndrome.

The HIV-1 particle displays a similar morphology to that of C-type retroviruses, but due to its conical form it has not yet received a morphological classification letter. The genomic structure of HIV-1 is 9.6 Kb in size including LTRs of 633-546 nt. Its internal region displays a Primer Binding Site (PBS) complementary to a tRNA<sup>Lys3</sup>; Open Reading Frames (ORFs) for ''gag'', ''pol'' and ''env'' genes characteristic of retroviruses, ''tat'' and ''rev'' (both expanded in two exons) and ''vif'', which are three accessory genes common in other lentiviruses, ''vpx'', ''vpu'' and ''nef'' accessory genes specifical of primate lentiviruses, a Polypurine Tract (PPT) adjacent to the 3´LTR as well as another PPT found approximately in the central zone used as a secondary site in the beginning of the + DNA chain synthesis ([[Literature:62282|Ratner ''et al.'' 1985]]).

|structure=Hiv1.png
|host=Homo sapiens
|hostpic=Homo_sapiens.gif
|literature=
*[[Literature:14014|Retroviruses. (Coffin, Hugges and Varmus 1997)]]
|picowner=[http://www.biotechvana.com Image, Carlos Llorens, <br>Copyright, GyDB, Biotech Vana]
}}

Element:HIV-1 - Revision history

imported>Ldominguez at 09:22, 3 May 2010