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BACKGROUND: Whether anti-D produced by individuals with a weak D phenotype are allo- or autoantibodies remains a matter of debate even though blood transfusion practice is impacted. The aim of our study was to determine the serologic features of anti-D in individuals expressing the most frequent weak D type in Caucasians that are weak D Type 1 or weak D Type 2, to assess whether anti-D were allo- or autoantibodies. STUDY DESIGN AND METHODS: Serologic D typing and molecular analysis enabled the including of 121 weak D Type 1 individuals and 99 weak D Type 2 individuals in our study. Serologic features of anti-D included autologous controls, direct antiglobulin test, elution, and titration of anti-D before and after adsorption of serum on autologous red blood cells (RBCs). RESULTS: Serologic D typing showed a variable reactivity of RBCs expressing weak D Type 1 or weak D Type 2 (4+ to 0). Anti-D was identified in six weak D Type 1 and six weak D Type 2 individuals, respectively. The serologic data were in favor of autoantibodies. CONCLUSION: A complete anti-D investigation in individuals with a D variant (weak D or partial D identified by molecular analysis) should be systematically performed before any valid conclusion on the nature of the antibody. Transfusing weak D Type 1 or weak D Type 2 patients with D+ RBC units should be recommended. Weak D Type 1 or weak D Type 2 pregnant women do not need anti-D immunoprophylaxis.

Using the experimental infection of cynomolgus macaques with simian immunodeficiency virus (SIV) as a model of human immunodeficiency virus infection in humans, we studied the immunogenicity and protective efficacy of a vaccine strategy combining DNA, the modified recombinant vaccinia virus strain Ankara (MVA) and Semliki Forest virus (SFV) expressing gag, pol, env, tat, rev and nef from SIV. Although this immunization strategy induced moderate immune responses, the control of pathogenic SIVmac251 infection following mucosal challenge was clearly improved by vaccination. The viral load in vaccinated animals was reduced by 2 logs during the acute phase of infection and, in five of the six macaques, viral load fell below the detection limit at set point. No correlates of immune protection were identified, but SIV-specific T-cell responses were detected earlier in vaccinated animals than in controls. These results highlight the power of live attenuated virus vectors for vaccination strategies.