       Document 0301
 DOCN  M9620301
 TI    Natural selection on the gag, pol, and env genes of human
       immunodeficiency virus 1 (HIV-1).
 DT    9602
 AU    Seibert SA; Howell CY; Hughes MK; Hughes AL; Department of Biology,
       Pennsylvania State University, University; Park 16802, USA.
 SO    Mol Biol Evol. 1995 Sep;12(5):803-13. Unique Identifier : AIDSLINE
       GENBANK/K03454
 AB    Natural selection on polymorphic protein-coding loci of human
       immunodeficiency virus-1 (HIV-1), the more geographically widespread of
       the two viruses causing human acquired immune deficiency syndrome
       (AIDS), was studied by estimating the rates of nucleotide substitution
       per site in comparisons among alleles classified in families of related
       alleles on the basis of a phylogenetic analysis. In the case of gag,
       pol, and gp41, the rate of synonymous substitution generally exceeded
       that of nonsynonymous substitution, indicating that these genes are
       subject to purifying selection. However, in the case of several of the
       variable (V) regions of the gp120 gene, especially V2 and V3,
       comparisons within and between families often showed a significantly
       higher rate of nonsynonymous than of synonymous nucleotide substitution.
       This pattern of nucleotide substitution indicates that positive
       Darwinian selection has acted to diversify these regions at the amino
       acid level. The V regions have been identified as probable epitopes for
       antibody recognition; therefore, avoidance of such recognition seems
       likely to be the basis for positive selection on these regions. By
       contrast, regions of HIV-1 proteins identified as epitopes for T cell
       recognition show no evidence of positive selection and are often highly
       conserved at the amino acid level. These results suggest that selection
       favoring avoidance of T cell recognition has not been a major factor in
       the history of HIV-1 and thus that avoidance of T cell recognition is
       not likely to be a major factor in the pathogenesis of AIDS.
 DE    Acquired Immunodeficiency Syndrome/VIROLOGY  Alleles  Amino Acid
       Sequence  Comparative Study  Epitopes/ANALYSIS  *Genes, env  *Genes, gag
       *Genes, pol  Human  HIV Envelope Protein gp120/BIOSYNTHESIS/GENETICS
       HIV Envelope Protein gp41/BIOSYNTHESIS/GENETICS  HIV-1/*GENETICS
       HIV-2/*GENETICS  Molecular Sequence Data  *Phylogeny  *Selection
       (Genetics)  Support, U.S. Gov't, P.H.S.  T-Lymphocytes/IMMUNOLOGY
       JOURNAL ARTICLE

       SOURCE: National Library of Medicine.  NOTICE: This material may be
       protected by Copyright Law (Title 17, U.S.Code).

