Document 0279
 DOCN  M9590279
 TI    Effect of CD4(D2-D3)mutations on HIV entry.
 DT    9509
 AU    Blanc-Zouaoui D; Signoret N; Rocca-Serra J; Sattentau Q; Dpt of
       Microbiology, UQ, St Lucia, Brisbane.
 SO    Annu Conf Australas Soc HIV Med. 1994 Nov 3-6;6:243 (unnumbered poster).
       Unique Identifier : AIDSLINE ASHM6/95291820
 AB    CD4 is the first receptor for HIV on human cells, and the primary
       binding site has been mapped on domain 1, in the CDR2 region. Other
       domains of CD4 are thought to be important between the step of gp
       120-CD4 binding and the fusion of gp 41 with a host cell membrane
       component. From a panel of anti-CD4 antibodies (abs), only the anti
       D1(CDR2) and anti D2-D3 abs were able to prevent virus entry. Although
       the former abs prevent HIV binding, the laters do not affect this step
       but inhibit viral and cell membrans fusion. Circumstantial evidences
       suggest that there is a hinge in this D2-D3 region and our hypothesis is
       that its integrity is required for inducing gp120 conformational changes
       driving the exposure of the cryptic fusogenic epitope of gp 41. We have
       generated a series of mutants in this region by directed mutagenesis,
       expressed them in human Hela cells and analysed the level of expression
       of those mutants, done an epitope mapping by using an extensive panel of
       anti-CD4 abs and a binding study of gp 120. We have then assessed HIV
       binding, fusion and entry for these hinge mutants. Our results show that
       although gp120 and virus binding are not affected, fusion between
       infected and non infected cells is undetectable for the hinge deleted
       mutants and HIV entry dramatically reduced, whilst the extended hinge
       mutants are not affected. We are currently studying the effects of these
       mutations on gp 41 exposure in order to understand the mecanistic events
       preventing fusion. We will also produce soluble form of these mutated
       molecules to help elucidate the 3D structure of the mutants versus the
       wild-type form of CD4.
 DE    Antigens, CD4/*GENETICS  Gene Expression Regulation, Viral/PHYSIOLOGY
       Hela Cells  Human  HIV/*GENETICS  HIV Envelope Protein gp120/*GENETICS
       HIV Envelope Protein gp41/*GENETICS  *Mutation  Viral Fusion
       Proteins/*GENETICS  Virus Replication/*GENETICS  MEETING ABSTRACT

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