Opinion in 2006

Charles Dorman discusses recent data that indicate that the nucleoid-associated protein H-NS might have a role in silencing the expression of horizontally transferred genes.

Telomeres are specialized DNA–protein complexes that are required for protection and replication of chromosome ends. In this Opinion, George Cross and colleagues discuss the biology of telomere function in trypanosomes and propose an intriguing role for these structures in regulating antigenic variation.

Understanding the factors that contribute to the evolution and maintenance of virulence is crucial for a full understanding of infectious disease biology. Focusing onStaphylococcus aureus and Staphylococcus epidermidis, the authors argue that host-to-host transmission is a key factor in determining the level of bacterial virulence.

The field of landscape ecology links the biotic and abiotic factors of an ecosystem. In this Opinion article, the authors argue that using the tools of landscape ecology would improve the accuracy of ecological studies of antibiotic resistance.

Humans vary in their susceptibility to HIV infection, and identifying the host genetic factors that cause this variation is a priority for vaccine development. Progress in high-throughput genotyping and in knowledge about human genetic variation allows systematic searching for genetic variants that influence the human response to HIV-1.

Comparative genomic analysis can be a powerful tool to investigate the molecular and genetic mechanisms responsible for bacterial niche specialization. Here, the clues that can be gleaned from the complete genome sequences of five different Vibrionaceae species are discussed.

To survive in various niches, bacteria must effectively integrate a multiplicity of signals from their environment. In this Opinion article, the authors discuss whether recent reports that theSalmonella typhimuriumPhoP/PhoQ system recognizes antimicrobial peptides are likely to be biologically significant.

In this Opinion article the authors propose that peptidoglycan is not only an essential structural component of the bacterial cell wall, but is also involved in diverse biological processes, such as microbial pathogenesis, symbiotic associations and a range of interactions between bacteria and other organisms.

It is well known that multidrug-resistance efflux pumps can confer antibiotic resistance on bacteria. Now, it is becoming evident that certain classes of these pumps also increase bacterial pathogenicity. Laura Piddock proposes that, owing to this dual function, such efflux pumps have greater clinical relevance than has previously been thought.

Cowman and colleagues present their analysis of the repertoire of actin-binding proteins and actin-regulatory proteins in apicomplexan parasites. They integrate their observations with recent progress in understanding actin, actin-binding proteins and actin-regulatory proteins to propose a modified model of apicomplexan gliding motility, in which actin dynamics have a central role.

Bacteria can have genetically determined mechanisms for resistance to antibiotics, but can also be phenotypically refractory to their action — known as 'non-inherited antibiotic resistance'. A mathematical model and computer simulations show how non-inherited resistance could translate to treatment failure and increase the likelihood of inherited resistance in treated patients.

Source–sink models of adaptive evolution were initially used to study the population ecology of animals and plants. Here, the authors propose that such models can also be applied to the bacterial world and can help to understand how bacterial pathogens adapt to their human hosts.

Trypanosoma brucei rhodesienseis one of the causative agents of sleeping sickness, owing to its ability to resist lysis by human serum. In this Opinion article, the authors contend that a pore-forming apolipoprotein known as APOL1 is the factor that is responsible for the trypanolytic activity of human serum.

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.

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.

In this Opinion article, Carlos Buscaglia and colleagues discussTrypanosoma cruzi mucins and the intriguing possibility that the heterogeneity of the mucin core polypeptides in the mammal-dwelling stages of the T. cruzilife cycle might be an immune-evasion mechanism.

It is estimated that 50% of the world's population is persistently colonized byHelicobacter pylori. In this Opinion article, Ben Appelmelk and colleagues argue that for most patients, controlled modulation of the host immune response by H. pylorifacilitates an asymptomatic, persistent infection.

Amy Gladfelter discusses our current knowledge of the functions and regulation of the septins and formins in filamentous fungi, and makes the case that a concerted research effort on these proteins in these organisms could yield significant insights into fundamental eukaryotic cellular processes.