Articles of Significant Interest Selected from This Issue by the Editors

doi:10.1128/IAI.00600-08

DOI: 10.1128/IAI.00600-08

Effect of Polymorphisms on Antigen Presentation and Susceptibility to Mycobacterium tuberculosis Infection

Particular polymorphisms have been associated inconsistently with susceptibility to Mycobacterium tuberculosis. Examining the antigen presentation pathway, Chang et al. (p. 3221-3232) developed a multiscale mathematical model incorporating events such as peptide-major histocompatibility complex binding and gamma interferon expression that are known to be affected by host polymorphisms and tracked changes occurring at the intracellular, cellular, and tissue levels. They then used this framework to show that some polymorphisms may counteract or augment each other in their effects during M. tuberculosis infection. This suggests that the accuracy and consistency of association studies could be increased by concurrently examining pairs or groups of polymorphisms.

Don't Just Ignore That “Cross-Reactive” Band on Your Western Blot

While characterizing a polyclonal antibody against a well-known Bordetella virulence factor, Williams et al. (p. 2966-2977) noticed what appeared to be a large, cross-reactive polypeptide that was produced only by virulent-phase bacteria. The protein turned out to be a previously uncharacterized autotransporter, BatB, that binds immunoglobulin and is required to overcome B- and/or T-cell-mediated clearance mechanisms during the first week of infection. The results suggest that nonspecific antibodies play an important role in protecting the lungs against bacterial infection. Comparative analyses suggest further that BatB may have contributed to evolution of host adaptation and/or virulence among the bordetellae that infect mammals.

Shiga Toxin-Producing Escherichia coli Causes Acute Renal Failure in Germ-Free Mice

Hemolytic-uremic syndrome secondary to Shiga toxin-producing Escherichia coli (STEC) infection is a potentially life-threatening syndrome of hemolysis and acute renal failure that often affects young children. Eaton et al. (p. 3054-3063) characterize a germ-free mouse model of acute renal failure due to STEC infection. Germ-free Swiss Webster mice readily become colonized by large numbers of bacteria and develop acute renal failure with tubular necrosis and glomerular thrombosis as well as cecal luminal fluid accumulation. Disease is dependent on the bacterial strain, and bacterial production of Shiga toxin 2 is necessary but not sufficient to induce renal and enteric disease.

New Adhesin of Enteroaggregative Escherichia coli Related to the Afa/Dr/AAF Family

Enteroaggregative Escherichia coli (EAEC) is an emerging diarrheal pathogen thought to cause disease by mucosal colonization followed by elaboration of cytotoxins and enterotoxins. Heretofore, only a minority of EAEC strains were found to possess one of the known adhesins, the aggregative adherence fimbriae (AAF). Boisen et al. (p. 3281-3292) now report a fourth member of this family and show that virtually all EAEC strains apparently possess a member of the AAF group. Moreover, they suggest that the Afa/Dr adhesins, together with the AAF, form a superfamily with three major branches, which may have distinct biophysical and pathogenic characteristics.