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.

Amphotericin B (AmB) is known to bind to ergosterol in fungal cell membranes, but the precise mechanism of its toxicity to cells is as yet poorly understood. AmB autooxidizes, and it is possible that its antifungal effects could result from oxidative damage. Exposure of protoplasts of Candida albicans to AmB under hypoxic conditions reduced protoplast lysis by as much as 80% compared with incubations in air. Protoplasts were protected from AmB-induced lysis by exogenous catalase and/or superoxide dismutase (SOD). Whole cells of C. albicans were protected by exogenous catalase from AmB-induced leakage of [3H]leucine and from killing by AmB. Cells grown on medium inducing high levels of endogenous catalase were resistant to AmB-induced growth inhibition. In contrast, AmB-induced K+ leakage was not hindered under hypoxic conditions or in the presence of catalase or SOD. Thus the lethal and lytic effects of AmB on C. albicans cells and protoplasts, but not prelethal AmB-induced K+ leakage, are mediated by oxidative damage.

A laboratory-derived mutant of Candida albicans B311 (L) and a clinical isolate (C) of C. albicans, both lacking membrane ergosterol, were less susceptible to amphotericin B (AmB)-induced cell membrane permeability to K+ and lethality than was the wild-type laboratory strain (B311) which contained ergosterol. The resistance of L and C to AmB-induced killing was much greater than the level of resistance to AmB-induced cell membrane permeability. L and C were also less susceptible to killing by H202 than was B311, and when treated with menadione, they each produced less H202 than did B311. In addition, their levels of catalase activity were 3.8-fold (L) and 2-fold (C) higher than that of B311. The ergosterol deficiency in L and C probably impaired AmB binding to the cells, thereby lowering AmB effectiveness as measured by both cell membrane permeability and killing. Resistance of strains L and C to oxidation-dependent damage likely contributed to a diminished response to AmB-induced lethality.

Background The increasing global prevalence of pulmonary nontuberculous mycobacteria (NTM) disease has called attention to challenges in NTM diagnosis and management. This study is conducted to understand management and outcomes of patients with pulmonary NTM disease at diverse centers across the US. Methods We conducted a 10-year (2005-2015) retrospective study at seven Vaccine and Treatment Evaluation Units to evaluate pulmonary NTM treatment outcomes in human immunodeficiency virus-negative adults. Demographic and clinical information were abstracted through medical record review. Microbiologic and clinical cure were evaluated using previously defined criteria. Results Of 297 patients diagnosed with pulmonary NTM, the most frequent NTM species were Mycobacterium avium-intracellulare complex (83.2%), M. kansasii (7.7%), and M. abscessus (3.4%). Two hundred forty-five (82.5%) patients received treatment, while 45 (15.2%) were followed without treatment. Eighty-six patients had available drug susceptibility results; of these, >40% exhibited resistance to rifampin, ethambutol, or amikacin. Of the 138 patients with adequate outcome data, 78 (56.5%) experienced clinical and/or microbiologic cure. Adherence to the American Thoracic Society/Infectious Diseases Society of America (ATS/IDSA) treatment guidelines was significantly more common in patients who were cured (odds ratio [OR] 4.5, 95% confidence interval [CI] 2.0-10.4, P < 0.001). Overall mortality was 15.7%. Conclusions Despite ATS/IDSA Guidelines, management of pulmonary NTM disease was heterogeneous and cure rates were relatively low. Further work is required to understand which patients are suitable for monitoring without treatment and the impact of antimicrobial therapy on pulmonary NTM morbidity and mortality.

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