The major genetic determinants of HIV-1 control affect HLA class I peptide presentation

Infectious and inflammatory diseases have repeatedly shown strong genetic associations within the major histocompatibility complex (MHC); however, the basis for these associations remains elusive. To define host genetic effects on the outcome of a chronic viral infection, we performed genome-wide association analysis in a multiethnic cohort of HIV-1 controllers and progressors, and we analyzed the effects of individual amino acids within the classical human leukocyte antigen (HLA) proteins. We identified >300 genome-wide significant single-nucleotide polymorphisms (SNPs) within the MHC and none elsewhere. Specific amino acids in the HLA-B peptide binding groove, as well as an independent HLA-C effect, explain the SNP associations and reconcile both protective and risk HLA alleles. These results implicate the nature of the HLA-viral peptide interaction as the major factor modulating durable control of HIV infection.

Human immunodeficiency virus infection, the acquired immunodeficiency syndrome, and inflammatory bowel disease

The objective of this study was to determine the effect of human immunodeficiency virus (HIV) infection/acquired immunodeficiency syndrome (AIDS) on inflammatory bowel disease (IBD). A retrospective survey of the medical records of St. Paul's Hospital and its AIDS-care physicians/gastroenterologists searching for patients with both HIV/AIDS and IBD was conducted. Of 1,839 hospitalized patients (4,459 hospital admissions) from 1989 to 1993, two patients with AIDS/HIV and IBD were found. The physician survey revealed four patients for a total of six patients. Four patients developed de novo IBD--two ulcerative colitis (UC), one Crohn's disease (CrD), and one indeterminate colitis (IC)--after HIV infection. Two patients had UC predating HIV seroconversion. The absolute CD4 count of patients with de novo IBD was 210-700 cells/ml at the time of IBD. The patient with IC maintained quiescent IBD from a CD4 count of 190-30 cells/ml. The other had many relapses before HIV seropositivity. With CD4 count depletion, disease activity improved. IBD medications were discontinued at a CD4 count of 130 cells/ml. Diarrhea returned at a CD4 count of 20 cells/ml; however, sigmoidoscopy was unremarkable, and mucosal biopsy revealed cryptosporidiosis without active UC. No patient had an AIDS-related illness during active IBD. Two patients followed to CD4 counts of < 30 cells/ml suffered AIDS-related infections with quiescent IBD. With a progressive decline in CD4 count, IBD disease activity may improve and remit. The CD4 count at which remission occurs may reflect severe immunodeficiency such that risk for AIDS-related infection is high. Active IBD may occur with lesser degrees of immunodeficiency.