Document 3273
 DOCN  M94A3273
 TI    Unusual A/G ratio in HIV-1 gp120 V3 loop proviral sequences obtained in
       vivo.
 DT    9412
 AU    Gomez Carrillo M; Rabinovich R; Marquina S; Galvan V; Libonatti O; Natl.
       Centre of Ref. for AIDS, Buenos Aires, Argentina.
 SO    Int Conf AIDS. 1994 Aug 7-12;10(1):113 (abstract no. PA0072). Unique
       Identifier : AIDSLINE ICA10/94369302
 AB    OBJECTIVE: To analyze A/G ratio values of proviral V3 loop HIV-1
       sequences and correlate them with some phenotypic features of the
       corresponding variants. METHODS: After sequencing using the Sanger
       method, A/G ratio values were calculated for 28 in vivo, 2 isolate
       Argentine sequences and 21 published worldwide isolates. These values
       were correlated with the phenotypic characteristics of the corresponding
       variants. EIA assays were performed using synthetic peptides derived
       from HXB2 and MN isolates sequences. The G-->A hypermutation phenomenon
       was simulated for all sequences studied. RESULTS: Two distinct types of
       in vivo V3 loop sequences could be distinguished: 14 presented an
       unusually low A/G ratio value (lower than 2) and 14 beared
       characteristics similar to the standard worldwide isolates. Unusual
       sequences showed certain uncharged residues at positions 9 and 10 and a
       low overall positive charge. Patients' sera corresponding to these
       sequences showed higher reactivity against V3 loop peptides. Simulated
       G-->A transitions originated polar and positive residues, resulting in
       isolate-like charge distributions in usual sequences but not in unusual
       ones, while isolates remained relatively stable. DISCUSSION AND
       CONCLUSIONS: Unusual sequences might be present in patients with a
       functional immune response but would not be adapted to culture
       conditions. The G-->A hypermutation would occur less frequently in these
       variants, and the resulting increase in antigenicity would favour their
       elimination. The immune response and the G-->A hypermutation could act
       as two balanced mechanisms in the generation of variants differing in
       A/G contents.
 DE    Base Composition  DNA, Viral/CHEMISTRY/*GENETICS  Human  HIV
       Antibodies/BLOOD  HIV Envelope Protein gp120/*GENETICS/IMMUNOLOGY  HIV
       Infections/IMMUNOLOGY/MICROBIOLOGY  HIV-1/*GENETICS/IMMUNOLOGY/ISOLATION
       & PURIF  Mutation  Peptide Fragments/*GENETICS/IMMUNOLOGY  Phenotype
       Proviruses/*GENETICS/IMMUNOLOGY  Variation (Genetics)  MEETING ABSTRACT

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