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Infection and Immunity, October 2007, p. 4673-4674, Vol. 75, No. 10
0019-9567/07/$08.00+0     doi:10.1128/IAI.01135-07
Copyright © 2007, American Society for Microbiology. All Rights Reserved.

SPOTLIGHT

Articles of Significant Interest Selected from This Issue by the Editors

Vibrio cholerae El Tor strains produce several secreted cytotoxic proteins in addition to cholera toxin. These include the pore-forming toxin hemolysin and the V. cholerae multifunctional autoprocessing RTX toxin, which causes cell rounding and actin cross-linking. Olivier et al. (p. 5035-5042) associate these toxins with virulence, showing that they cause rapid death in adult mice after oral infection. However, after immunization with a strain lacking these toxins, mice were protected from a subsequent lethal challenge, suggesting that a deletion of these toxins from vaccine strains has no effect on vaccine efficacy.

A Glucosylceramide-Deficient Mutant Provides a Key for Possible New Therapeutic Approaches against Cryptococcosis

The key to finding effective therapy for infections caused by pathogenic organisms arises from a better understanding of their behavior and survival preferences. Kechichian et al. (p. 4792-4798) show that a Cryptococcus neoformans mutant lacking glucosylceramide (gcs1) is able to grow only in acidic niches, such as within alveolar macrophages, as opposed to the wild-type organism, which survives both intra- and extracellularly. Depletion of alveolar macrophages in T- and NK-immunodeficient mice infected with the gcs1 mutant was an efficient way of prolonging host survival. This study introduces the possibility of combination therapy for cryptotcoccosis targeting glucosylceramide and alveolar macrophages.

Profiling a Killer: DNA Microarrays of Malaria Parasites Infecting Pregnant Women

Plasmodium falciparum parasites infecting pregnant women differ from other parasites in binding chondroitin sulfate A in placentas. A placental malaria (PM) vaccine could prevent thousands of mother-child deaths, but only one protein (VAR2CSA) has been associated with PM parasites. Using DNA microarrays to study fresh parasites from Tanzanian donors, Francis et al. (p. 4838-4850) identified five novel genes that distinguish PM parasites at both early and late developmental stages. The parasite developmental stage was determined by a novel transcriptomic approach that will facilitate future studies of clinical samples. Products of the genes identified in this study are promising potential vaccine or drug targets.

Intranasal Immunization with Gal-Lectin Combined with CpG Oligodeoxynucleotide Adjuvant Protects against Entamoeba histolytica Challenge

A challenge to protect against the colonic pathogen Entamoeba histolytica is to develop an appropriate mucosal vaccine that stimulates a protected antibody and Th1 immune response. Ivory and Chadee (p. 4917-4922) utilized the surface Gal-lectin (adhesin) of the parasite formulated with CpG oligodeoxynucleotide adjuvant for intranasal immunization. The immunized animals developed a strong Th1 immune response accompanied by protection in the liver against challenge and stool immunoglobulin A, which blocked parasite adherence to target cells in vitro. These studies are the first to highlight the importance of blocking antibodies in E. histolytica colonization and Th1 responses for systemic host defense in immunization regimens.

Dynamics of Type IV Pilus-Mediated Neisseria gonorrhoeae Infection

Neisseria gonorrhoeae type IV pilus (Tfp) mediates twitching motility and attachment. Previous fixed-cell studies gave rise to the belief that attachment proceeds in distinct stages. To investigate how this model fits within the framework of bacterial motility and host cell signaling, Higashi et al. (p. 4743-4753) used live-cell videomicroscopy to demonstrate that attachment is a continuum of microcolony motility, microcolony fusion, and force induction of host cell signaling. Tfp retraction force is exerted over a large area of the epithelium as microcolonies crawl across the cell surfaces. As microcolonies enlarge, their retraction force is predicted to increase. Dynamic changes in force (strength and intermittency) may elicit dynamic changes in host responses.

Respiration of Escherichia coli in the Mouse Intestine

It is generally accepted that the intestine is anaerobic. However, Escherichia coli grows in the mucus layer adjacent to the intestinal epithelium, where oxygen is known to be present. Jones et al. (p. 4891-4899) demonstrate that mutants of commensal and pathogenic E. coli lacking the ability to respire oxygen, nitrate, or fumarate fail to compete effectively for colonization of the mouse intestine. Thus, respiratory flexibility is a key to the success of E. coli colonization in the intestine. This makes sense because respiration maximizes bacterial cell yield on relatively scarce nutrients.

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via Google Scholar Google Scholar Search for Related Content