Important note: Information in this article was accurate in 1990. The state of the art may have changed since the publication date.
GENETIC VARIATION AMONG ISOLATES OF HIV-1 AND HIV-2
HIV Detection by Genetic Engineering Methods. Luciw PA and Steimer KS, eds. New York, Marcel Dekker, p. 257-73, 1989.. Unique Identifier : AIDSLINE ICDB/90660265 Hahn BH; Shaw GM; Univ. of Alabama, Birmingham, AL
Abstract:
Because of the obvious biologic similarities among HIV and simian immunodeficiency viruses (SIV), considerable attention is now being focused on their genetic organization, phylogenetic relatedness, and propensity for genomic variation. Current knowledge concerning the genetic variation of HIV/SIV and its biologic significance are reviewed, including relevant data from the authors' laboratory. Topics include extent of genetic variation among independent and sequential isolates of HIV, molecular dissection of HIV 'isolates,' relationship of cultured and uncultured HIV-1 virus populations, and biologic significance of HIV genetic variation. Genotypic variation of HIV-1 and HIV-2 in vivo is so rapid and extensive that numerous variant viral forms coexist and persist in vivo, and isolates of HIV-1 and HIV-2 actually consist of complex mixtures of genotypically distinct, but related, viruses. Amplification and propagation of viral cultures in vitro can result in genomic changes of viral sequences, but these variant viruses are not selected to replace existing viral populations in the culture. Thus, whereas cultured viruses truly reflect predominant viral forms as they exist in vivo, different mechanisms must be operative in vivo to produce and maintain such heterogeneity of viral forms. Host factors, immunologic or otherwise, must produce rather strong selective pressures on the virus. Such pressures could select for variants that can evade immunologic defenses, infect or persist in specific cell types, interact preferentially with certain major histocompatibility antigens, and so on. The possibility that immune pressures may be important in viral selection also is supported by the fact that plasma-derived HIV-1 isolates seem to lack the genomic diversity characterizing cell-derived isolates, suggesting that only one or a very limited number of viral strains is activated and released into the plasma at any one time in the infection. (33 Refs)
Keywords: Amino Acid Sequence Base Sequence Cloning, Molecular DNA, Viral/GENETICS Genotype Human HIV Infections/*DIAGNOSIS HIV-1/*GENETICS HIV-2/*GENETICS Molecular Sequence Data Variation (Genetics)/*GENETICS MONOGRAPH REVIEW REVIEW, TUTORIAL 900530
M9051017
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Important note: Information in this article was accurate in 1990. The state of the art may have changed since the publication date.
