title: Blood groups and susceptibility to virus infection: new developments.
abstract: OBJECTIVE
  Histo-blood group antigens belonging to the P1PK and GLOB blood group systems are involved in bacterial infections, but a substantial body of evidence is emerging that some of these glycosphingolipids play a role in HIV infection. These recent findings have raised additional questions regarding the possible role of the P/Gb3 histo-blood group antigen in HIV-1 infection.
  
  
  RESULTS
  Early studies implicated a number of glycosphingolipids able to interact with HIV envelope glycoprotein 120. It has been recently reported that cellular or soluble P/Gb3 histo-blood group antigen provides protection from HIV-1 infection. This resistance mechanism appears to be mediated through inhibition of fusion of the HIV-1 envelope to the cell target membrane. Protection has been shown to be provided to both HIV-1 X4 and R5 tropic strains. Indeed, an inverse correlation has been documented between the expression of P/Gb3 on the cellular membrane and susceptibility to HIV infection. Moreover, soluble P/Gb3 analogues have been shown to inhibit HIV infection.
  
  
  CONCLUSIONS
  The P/Gb3 histo-blood group antigen is the first described cell surface expressed natural resistance factor for prevention of HIV infection. Increased expression of P/Gb3 correlates to decreased HIV infection, whereas decreased or absent P/Gb3 increases HIV susceptibility. Soluble P/Gb3 analogues can inhibit HIV by two mechanisms: direct inhibition of the free virus and inhibition of viral entry. Future development of soluble P/Gb3 analogues, pharmacologic means of increasing cell surface expression of P/Gb3 on HIV susceptible target cells or both may result in novel therapeutic modalities for the prevention and eradication of HIV/AIDS.
authors.affiliation: Research and Development, Canadian Blood Services, Department of Medicine, Division of Cell and Molecular Biology, Toronto General Research Institute, University of Toronto, Toronto, Ontario, Canada. don.branch@utoronto.ca
authors.forename: Donald R
authors.initials: DR
authors.lastname: Branch
mesh_terms: D001789:Blood Group Antigens / Q000276:immunology*; D006028:Glycosphingolipids / Q000276:immunology*; D015658:HIV Infections / Q000097:blood* / Q000188:drug therapy / Q000276:immunology* / Q000821:virology; D015497:HIV-1 / Q000276:immunology* / Q000378:metabolism; D006801:Humans
chemical_list: D001789:Blood Group Antigens; D006028:Glycosphingolipids