Capsular Serotypes (capsular + serotype)

Distribution by Scientific Domains


Selected Abstracts


The genetic background of Streptococcus pneumoniae affects protection in mice immunized with PspA

FEMS MICROBIOLOGY LETTERS, Issue 2 2007
Xiangyun He
Abstract Anti-PspA antibodies are less efficient at protecting mice against certain pneumococcal strains. Immunization with PspA from EF5668 provided better protection against WU2 (a different capsular serotype and PspA family) than against EF5668. To understand the role of the pneumococcal genetic background in anti-PspA-mediated protection, we constructed a mutant of WU2 expressing pspA from EF5668. Both passive and active immunization demonstrated that the genetic background impacted the protection mediated by anti-PspA antibodies. We localized the protection-eliciting region to the first 122 amino acid residues of the N-termius of the ,-helical domain of PspA/EF5668. [source]


Novel vaccine strategies with protein antigens of Streptococcus pneumoniae

FEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 1 2003
Edwin Swiatlo
Abstract Infections caused by Streptococcus pneumoniae (pneumococcus) are a major cause of mortality throughout the world. This organism is primarily a commensal in the upper respiratory tract of humans, but can cause pneumonia in high-risk persons and disseminate from the lungs by invasion of the bloodstream. Currently, prevention of pneumococcal infections is by immunization with vaccines which contain capsular polysaccharides from the most common serotypes causing invasive disease. However, there are more than 90 antigenically distinct serotypes and there is concern that serotypes not included in the vaccines may become more prevalent in the face of continued use of polysaccharide vaccines. Also, certain high-risk groups have poor immunological responses to some of the polysaccharides in the vaccine formulations. Protein antigens that are conserved across all capsular serotypes would induce more effective and durable humoral immune responses and could potentially protect against all clinically relevant pneumococcal capsular types. This review provides a summary of work on pneumococcal proteins that are being investigated as components for future generations of improved pneumococcal vaccines. [source]


Genotype variation and capsular serotypes of Porphyromonas gingivalis from chronic periodontitis and periodontal abscesses

FEMS MICROBIOLOGY LETTERS, Issue 1 2007
Takashi Yoshino
Abstract Porphyromonas gingivalis is considered an important pathogen in periodontal disease. While this organism expresses a number of virulence factors, no study combining different virulence polymorphisms has, so far, been conducted. The occurrence of combined virulence (Cv) genotypes in 62 isolates of P. gingivalis was investigated from subjects displaying either chronic periodontitis or periodontal abscess. The Cv genotypes, based on gene variation of fimbriae (fimA), Lys-specific cystein proteinase (kgp) and Arg-specific cystein proteinase (prpR1/rgpA), were evaluated by PCR. The isolates were also subjected to capsular polysaccharide K-serotyping. A total of 18 Cv genotype variants based on fimA: kgp: rgpA were identified, of which II:I:A and II:II:A Cv genotypes (53.3%) were the two most frequently detected combinations. Moreover, 36% of the isolates were K-typeable, with the K6 serotype being the most prevalent (23%). Two isolates had the same genotype as the virulent strain W83. The results indicate that chronic periodontitis is not associated with a particularly virulent clonal type. A highly virulent genotype (e.g. strain W83) of P. gingivalis can be found in certain periodontitis patients. [source]


Differential cytokine expression by human dendritic cells in response to different Porphyromonas gingivalis capsular serotypes

JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 10 2009
Rolando Vernal
Abstract Aim: Capsular polysaccharides play an important role in the virulence of Gram-positive and Gram-negative bacteria. In Porphyromonas gingivalis, six serotypes have been described based on capsular antigenicity and its pathogenicity has been correlated both in vitro and in animal models. This study aimed to investigate the differential response of human dendritic cells (DCs) when stimulated with different P. gingivalis capsular serotypes. Materials and Methods: Using different multiplicity of infection (MOI) of the encapsulated strains K1,K6 and the non-encapsulated K, strain of P. gingivalis, the mRNA expression levels for interleukin (IL)-1,, IL-2, IL-5, IL-6, IL-10, IL-12, IL-13, interferon (IFN)- ,, tumour necrosis factor (TNF)- ,, and TNF- , in stimulated DCs were quantified by real-time reverse transcription-polymerase chain reaction. Results: All P. gingivalis capsular serotypes induced a T-helper type 1 (Th1) pattern of cytokine expression. K1- and K2-stimulated DCs expressed higher levels of IL-1,, IL-6, IL-12p35, IL-12p40, and IFN- , and at lower MOI than DCs stimulated with the other strains. Conclusions: These results demonstrate a differential potential of P. gingivalis capsular serotypes to induce DC responses and a higher capacity of strains K1 W83 and K2 HG184 than other K serotypes to trigger cytokine expression. [source]