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Infection and Immunity, January 2007, p. 20-21, Vol. 75, No. 1
0019-9567/07/$08.00+0 doi:10.1128/IAI.01805-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.
| SPOTLIGHT |
Articles of Significant Interest Selected from This Issue by the Editors
Protein Combination Vaccine against Invasive Pneumococcal DiseasePneumococcal vaccines comprising conserved protein antigens are promising alternatives to polysaccharide conjugates that protect against a limited range of serotypes. Ogunniyi et al. (p. 350-357) have evaluated the efficacy of immunization of mice with PdB (pneumolysin toxoid) and the surface proteins PspA, PspC, PhtB, and PhtE, either alone or in various combinations. The relative protection elicited by a given antigen differed depending on the challenge strain. In general, combinations of two or more antigens provided stronger protection than any single antigen, the most efficacious formulation tested being PdB + PspA + PspC. Immunization with multiple pneumococcal proteins may be required to provide broad protection in humans.
Protective Blastomyces-Specific CD4+ T-Cell Clones Reveal Conserved Variable Gene Use of the 
ß T-Cell Receptor
T-Cell Receptor (TCR)-ß+ T cells are pivotal in acquired resistance to systemic dimorphic fungi, but few of these protective T cells have been investigated at the clonal level. Wüthrich et al. (p. 193-200) isolated and characterized antigen-specific CD4+ T cells that adoptively transfer protective immunity to experimental pulmonary infection with Blastomyces dermatitidis. Protective T-cell clones expressed a conserved TCR and produced high levels of gamma interferon. These findings indicate that the outgrowth of protective T-cell clones against immunodominant antigens of B. dermatitidis is biased by a combination of the TCR repertoire and Thl cytokine production.
Compartmentalization of Virulence Factor Activity Is Important for Listeria monocytogenes Virulence
During intracellular infection, the broad-range phospholipase C (PC-PLC) of Listeria monocytogenes is activated specifically in acidified vacuoles, improving the efficiency of vacuolar escape. Using a mutant that constitutively secretes active PC-PLC, Yeung et al. (p. 44-51) observed that secretion of active PC-PLC in the cytosol of infected cells compromises host cell membrane integrity and attenuates bacterial virulence in the mouse. These results highlight the importance for L. monocytogenes virulence to compartmentalize the activity of PC-PLC during infection.
Chemokine CXCL10 Detected in Intestinal Tissues in Human Cryptosporidiosis
Relatively little is known about the intestinal response to human infections. Wang et al. (p. 481-487) used mutliplex arrays and immunohistochemistry to detect cytokines and chemokines in small intestinal tissue from AIDS patients with cryptosporidiosis compared to healthy volunteers and AIDS patients without intestinal infections. They noted markedly increased levels of the chemokine CXCL10 in the cryptosporidiosis patients and also noted localization of cells expressing the CXCL10 receptor to the epithelial layer in those patients. These data suggest that CXCL10 may play a key role in control of intestinal infections by attracting immune effector cells to the site of infection.
Th-1 Immune Responses to Mycobacterial Antigens in Systemic Sarcoidosis
Sarcoidosis pathology is similar in appearance to mycobacterial infections; yet sarcoidosis specimens are negative for involvement by Mycobacterium species by histologic staining and culture. Drake et al. (p. 527-530) demonstrate that Mycobacterium ESAT-6 and KatG antigens induce a T-cell response in sarcoidosis patients at a frequency and magnitude of response comparable to subjects who are purified protein derivative positive (PPD+), and distinct from PPD-healthy volunteers. These results support the hypothesis that mycobacterial antigens may have a role in sarcoidosis pathogenesis through their ability to induce T-cell antigen-specific Th-1 responses known to be important in sarcoidosis granuloma formation.
Proteomics Reveal Antigenic and Compositional Differences between Coxiella burnetii Developmental Forms That Provide Insight into Their Unique Biological Properties
Coxiella burnetii, an obligate intracellular bacterium and the agent of Q fever, undergoes a biphasic developmental cycle that produces a small cell variant (SCV) form with spore-like environmental resistance. Using proteomic approaches coupled with immunoblotting, Coleman et al. (p. 290-298) identify up-regulated proteins consistent with an SCV that is structurally resistant and a large cell variant (LCV) form that is metabolically and replicatively active. Moreover, SCV and LCV synthesize unique antigens that are recognized in the context of both animal and human infections. These findings contribute to our understanding of the distinctive biological characteristics of C. burnetii and reveal new immunogenic properties of the pathogen's developmental forms that may be important in the pathophysiology of clinical Q fever and the induction of protective immunity.
Bedside to Bench in Women with Urinary Tract Infections: Uropathogenic Escherichia coli Utilizes Intracellular Bacterial Community Pathways
Urinary tract infections (UTI) are one of the most common causes of morbidity in women. Studies with mice have revealed that clinical isolates of uropathogenic Escherichia coli (UPEC) invades superficial umbrella cells that line the bladder, where they find safe haven from innate host responses. The bacteria rapidly replicate to form intracellular bacterial communities (IBCs) with biofilm-like properties. Garofalo et al. (p. 52-60) demonstrate the commonality of the IBC pathway among UPEC isolates from different syndromes of UTI. The evidence of the UPEC pathway in clinical isolates translates work from the bench to the bedside and suggests an alternative paradigm of UTI.
Infection and Immunity, January 2007, p. 20-21, Vol. 75, No. 1
0019-9567/07/$08.00+0 doi:10.1128/IAI.01805-06
Copyright © 2007, American Society for Microbiology. All Rights Reserved.
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