       Document 0089
 DOCN  M9590089
 TI    Repeated exposure of rhesus macaques to low doses of simian
       immunodeficiency virus (SIV) did not protect them against the
       consequences of a high-dose SIV challenge.
 DT    9509
 AU    Dittmer U; Stahl-Hennig C; Coulibaly C; Nisslein T; Luke W; Fuchs D;
       Bodemer W; Petry H; Hunsmann G; Deutsches Primatenzentrum, Gottingen,
       Germany.
 SO    J Gen Virol. 1995 Jun;76 ( Pt 6):1307-15. Unique Identifier : AIDSLINE
       MED/95302026
 AB    As part of an in vivo titration study of the macaque simian
       immunodeficiency virus (SIVmac) strain 251/spl, macaques were inoculated
       intravenously with various dilutions of this infectious SIVmac. Seven
       animals received dilutions from 10(-3) to 10(-6) of SIVmac251/spl. Two
       monkeys infected with the 10(-3) dilution of SIVmac exhibited a
       productive infection as indicated by seroconversion, detection of
       genomic RNA and proviral DNA and positive virus isolation. These animals
       showed a cytotoxic T cell (CTL) response against different SIVmac
       proteins without any measurable T cell proliferation. The five macaques
       receiving higher virus dilutions did not seroconvert and were negative
       for both viral RNA and for infectious virus, although proviral DNA was
       detected in their peripheral blood mononuclear cells. In contrast to the
       animals receiving the 10(-3) virus dilution, these five silently
       infected monkeys developed an SIV-specific proliferative T cell response
       but SIV-specific CTL could not be observed. The SIV-specific T cell
       proliferation of the silently infected animals could be boosted by a
       second low-dose exposure with a 10(-4) or 10(-5) dilution of
       SIVmac251/spl. The virological status of the animals was not changed
       following this second virus inoculation. Four months later these
       macaques were challenged intravenously with 2 ml of a 10(-4) dilution of
       SIVmac251/32H containing 10 monkey ID50. After this challenge all
       SIV-pre-exposed animals and three naive controls became productively
       infected. In addition, all infected animals developed typical signs of
       an immunodeficiency within 6 months after infection. These observations
       indicate that macaques infected silently by a low-dose exposure to
       infectious virus generated a virus-specific cellular immune response.
       However, SIV-specific T cell proliferation alone could not protect the
       monkeys against an intravenous challenge with SIVmac and the subsequent
       development of AIDS-like symptoms.
 DE    Animal  Base Sequence  Cytotoxicity, Immunologic  DNA Primers
       Lymphocyte Transformation  Macaca mulatta  Molecular Sequence Data
       Polymerase Chain Reaction/METHODS  Proviruses/ISOLATION &
       PURIF/PHYSIOLOGY  RNA, Viral/ANALYSIS  Simian Acquired Immunodeficiency
       Syndrome/*IMMUNOLOGY  SIV/*IMMUNOLOGY/ISOLATION & PURIF/PHYSIOLOGY
       T-Lymphocytes/*IMMUNOLOGY  T-Lymphocytes, Cytotoxic/*IMMUNOLOGY  Time
       Factors  Virus Replication  JOURNAL ARTICLE

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

