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Host Susceptibility and Resistance to HIV
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Relative hazards for genetic associations with progression to AIDS Non-HLA genetic associations with progression To AIDS Genetic associations including HLA effects, with progression To AIDS
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CCR5 32 allele ccr5/ccr5 81% of Caucasian Get infected normally Progress to AIDS normally ccr5/ ccr5 15-18% of Caucasians Get infected normally But progress to AIDS 2-4 years more slowly ccr5 / ccr5 1% of Caucasians Highly Resistant to Infection Loss of CCR5 function but otherwise normal (no side effects)
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CCR5 cell surface density on CD4+ T cells correlates with delayed disease progression
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Other genetic polymorphisms in CCR5 Extracellular Intracellular N-term ECL2 ECL3 ECL1
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Genetic Variants in CCR5
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HIV-infected CCR5 32 heterozygotes have lower viral loads wt/wt wt/ 32
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CCR2-V64I V64I is a conservative change in the first transmembrane domain of CCR2, a minor coreceptor 10% in Caucasians 15% in African-Americans 17% in Hispanics 25% in Asians Protective effect similar to ccr5 32 heterozygotes 2-4 years delayed disease progression Lower viral loads 9-12 months post- seroconversaion Mechanism of protective effect is unclear Never found on the same haplotype with ccr5 32 allele Effects of ccr2-64I and ccr5 32 are not additive May be found in complete linkage disequilibirum with CCR5 promoter point mutation
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CCR5 Promoter Polymorphism
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P1 promoter allele can accelerate disease progression P1 promoter effects can be overcomed by protective CCR2/CCR5 or sdf-1 allele
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P1 promoter allele frequency drops in long-term non- progressors ccr2-64I and ccr5 32 allele frequency increases in long-term non- progressor
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IL-10 promoter polymorphism accelerates disease progression IL-10 inhibits T cell cytokine secretion; immunosuppressive cytokine IL-10 may control virus proliferation in macrophages IL-10 promoter polymorphism (-592 C-->A) linked to diminished IL-10 production Would expect association with accelerated progression to AIDS Effect of IL-10 promoter polymorphism (5’A) is dominant Heterozygotes and homozygotes have same influence on disease progression
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CXCR4 SDF-1 CXCR4/SDF-1 Knock-Out Mouse phenotype is lethal Chemokine Ligand SDF-1[3’A/3’A] SDF-1[+/3’A] SDF-1[+/+] Polymorphism in 3’ untranslated region of SDF-1 gene may be associated with delayed progression to AIDS
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HLA and HIV: heterozygous advantage An individual who is homozygous at HLAA,HLA-B, and HLA-C displays a limited variety of class I molecules available for antigen presentation to cytotoxic T lymphocytes (CTLs) relative to an individual heterozygous for each class I locus. 10 20 00 Fraction AIDS Free years since seroconversion
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HLA and HIV: heterozygous advantage
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Overall Kaplan Meier survival analysis
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