Volume 4 Issue 4, April 2006

The genus Aspergillus comprises a group of ubiquitous filamentous fungi for which more than 185 species have been described, including many human and plant pathogens, as well as industrially relevant organisms. Recently, the genomes of three Aspergillus species have been analysed, providing a unique opportunity to compare a human opportunistic pathogen, an industrially important fungus and a model organism, all in a single genus.

Quorum sensing is a bacterial cell-to-cell communication process that involves secreted chemical-signalling molecules. Laurent Keller and Michael Surette discuss quorum sensing and cell?cell communication from an evolutionary and ecological perspective, and reveal that the nature of the interactions goes beyond simple cooperative communication.

This article focuses on phenotypic variation based on the feedback architecture of genetic networks, a type of variability that is epigenetic in nature, relies on direct or indirect autostimulation of pivotal transcription factors, and is observed in various bacterial systems.

Burkholderia pseudomalleiinfection can present with such a diverse array of clinical symptoms thatB. pseudomallei is known as the 'great mimicker'. Here, current knowledge of B. pseudomallei–host interactions is reviewed, and key topics for future research are highlighted.

The first effective cancer vaccine targeted Marek's disease, a virus-induced neoplastic disease in domestic chickens. Here, Osterrieder and colleagues discuss recent progress in research on the causative agent, Marek's disease virus (MDV), and how MDV could be a useful model system of virus-induced lymphoma.

Small colony variants (SCVs) constitute a slow-growing subpopulation of bacteria. This population has been most intensively studied inStaphylococcus aureus. Here, the authors discuss the clinical relevance of S. aureusSCVs and the available information on the metabolic deficiencies responsible for the SCV phenotype, and they highlight key areas for future research.

In this Opinion piece, Wiles and colleagues argue that a failure to address discrepancies between animal models and the natural disease process can adversely affect experimental outcomes. In particular, the inclusion of natural transmission routes in infection models can profoundly influence the phenotype and virulence of pathogens.

The restricted transmission of CXCR4-utilizing variants of HIV-1 compared with CCR5-utilizing variants has inspired a search for the 'gatekeeping' mechanism responsible. Here, Margolis and Shattock propose that there is no single mechanism and that, instead, the selective transmission depends on a series of imperfect gatekeepers.