Comparative analysis of emm type pattern of Group A Streptococcus throat and skin isolates from India and their association with closely related SIC, a streptococcal virulence factor

<p>Abstract</p> <p>Background</p> <p>Group A streptococcus (GAS) causes a wide variety of life threatening diseases in humans and the incidence of such infections is high in developing countries like India. Although distribution of <it>emm </it>types of GAS in India has been described, there is a lack of data describing either the comparative distribution of <it>emm </it>types in throat versus skin isolates, or the distribution of certain virulence factors amongst these isolates. Therefore in the present study we have monitored the <it>emm </it>type pattern of Group A streptococcus throat and skin isolates from India. Additionally, the association of these isolates with closely related <it>sic </it>(<it>crs</it>), a multifunctional compliment binding virulence factor, was also explored.</p> <p>Results</p> <p>Of the 94 (46 throat and 48 skin) isolates analyzed, 37 <it>emm </it>types were identified. The most frequently observed <it>emm </it>types were <it>emm</it>49 (8.5%) and <it>emm</it>112 (7.5%) followed by 6.5% each of <it>emm</it>1-2, <it>emm</it>75, <it>emm</it>77, and <it>emm</it>81. Out of 37 <it>emm </it>types, 27 have been previously reported and rest were isolated for the first time in the Indian Community. The predominant <it>emm </it>types of throat (<it>emm</it>49 and <it>emm</it>75) samples were different from those of skin (<it>emm</it>44, <it>emm</it>81 and <it>emm</it>112) samples. After screening all the 94 isolates, the <it>crs </it>gene was found in six <it>emm</it>1-2 (<it>crs</it>1-2) isolates, which was confirmed by DNA sequencing and expression analysis. Despite the polymorphic nature of <it>crs</it>, no intravariation was observed within <it>crs</it>1-2. However, insertions and deletions of highly variable sizes were noticed in comparison to CRS isolated from other <it>emm </it>types (<it>emm</it>1.0, <it>emm</it>57). CRS1-2 showed maximum homology with CRS57, but the genomic location of <it>crs</it>1-2 was found to be the same as that of <it>sic</it>1.0. Further, among <it>crs </it>positive isolates, <it>spe</it>A was only present in skin samples thus suggesting possible role of <it>spe</it>A in tissue tropism.</p> <p>Conclusion</p> <p>Despite the diversity in <it>emm </it>type pattern of throat and skin isolates, no significant association between <it>emm </it>type and source of isolation was observed. The finding that the <it>crs </it>gene is highly conserved even in two different variants of <it>emm</it>1-2 GAS (<it>spe</it>A +ve and -ve) suggests a single allele of <it>crs </it>may be prevalent in the highly diverse throat and skin isolates of GAS in India.</p

Cell Surface and Cytosolic Proteins of Group B Streptococcus Adding New Dimensions in Its Colonization and Pathogenesis

Streptococcus agalactiae or Group B streptococcus (GBS) is an opportunistic human pathogen known for their invasive diseases caused in newborns, pregnant women, and nonpregnant adults. This pathogen even being an asymptomatic colonizer of adult humans, still they result in a broad range of disease manifestations starting from mild skin diseases to pneumonia, meningitis, and septicemia. Of the 10 GBS capsular types, the majority of invasive neonatal diseases are associated with the serotype III. GBS is a pathogen that has developed some strategies to resist host immune defenses. The formidable array of GBS virulence factors makes this bacterium at the forefront of neonatal pathogens. The involvement of bacterial components in the host-pathogen interaction of GBS pathogenesis and its related diseases is thought to be due to a variety of virulence factors expressed by Streptococcus agalactiae. Pathogenic factors of streptococcus promote infections by their coordinated activity. These factors/determinants initially get a stimulus by the communication between specific ligands and their respective receptors in a host-pathogen interaction. These in turn activate adhesion and invasion mechanisms by mediating the attachment of pathogen via cell wall associated/secretory proteins, e.g., adhesins followed by their entry into the host cell eventually deciding their fate to live by activation of mechanisms like phagocytosis. These mediators/determinants also modulate the immune responses by the host toward the pathogen. A number of new GBS surface-exposed or secreted proteins have been identified (GBS immunogenic bacterial adhesion protein, leucine-rich repeat of GBS, serine-rich repeat proteins), the three-dimensional structures of known streptococcal proteins (αC protein, C5a peptidase) have been solved, and an understanding of the pathogenetic role of “old” and new determinants has been better defined in recent years. Recently, a 39kDa Invasion Inhibitory Factor (IIF) was isolated from GBS playing an important role in its invasion. A homogeneous non-toxic 39 kDa factor from the cytosol of GBS showing a homology with xenobiotic response element type transcriptional regulator protein adds another quill to the GBS protein panama, thus indicating that such protein molecules can be efficiently explored as suitable vaccine candidates. These observations add a novel aspect to bacterial pathogenesis where bacteria’s own intracellular protein component can act as a potential therapeutic candidate by decreasing the severity of disease thus promoting its invasion inhibition

Immune response against M protein-conserved region peptides from prevalent group A Streptococcus in a North Indian population

BackgroundGroup A streptococci (GAS) cause infections with a high prevalence in most developing countries. A GAS vaccine under trial that is based on the amino-terminus of the M protein provides type-specific immunity, and hence seems ineffective in India because of heterogeneous emm types. However, the conserved C-terminal region of the M protein protects against multiple serotypes. In this paper, the immune response generated against the conserved C-repeat region of the M protein was checked in an Indian population to establish their vaccine candidature.MethodsWhen screened for GAS, patients with pharyngitis, rheumatic fever/rheumatic heart disease (RF/RHD), and invasive disease showed heterogeneous emm types, out of which five prevalent types (1-2, 11, 49, 75 and 112) were selected for the study. The C-terminal region of their M proteins showed conserved C1-, C2-, and C3-repeats. The C1-repeat was more diverse and had two different J14-like sequences. Peptides to these C-terminal regions (J14.1 and J14-R6) were designed. Antibodies against these peptides were analyzed using the sera of 130 GAS-infected volunteers.ResultsSerum antibodies were significantly higher in patients with acute rheumatic fever, RHD, and invasive disease than in patients with pharyngitis or the healthy controls. The serum antibodies to these peptides was higher in teenagers and adults than in children.ConclusionResults showed an association between streptococcal disease progression and the age-related development of immunity to the conserved regions. Hence, these peptides could be considered protective in impeding streptococcal infections worldwide

Characterization of adhesin variants in Indian isolates of enteroaggregative Escherichia coli

Enteroaggregative Escherichia coli (EAEC) are causative agents of diarrhea, being characterized by aggregative adherence to cultured epithelial cells. In this study, phenotypic properties of EAEC were analyzed with respect to AA, hemagglutination, clump and biofilm formation, all of which are mediated by aggregative adherence fimbriae (AAF). The strains were also screened for AAF types, AAF adhesin variants and Dr adhesin by PCR. Of the three known AAF types, AAF/I and AAF/II adhesin variants were identified. An association between the AAF/adhesin genotypes and the subtypes/scores of phenotypic properties was sought and it was observed that strains harboring same adhesins displayed different subtypes/scores and vice versa

Genetic diversity and differentiation among populations of the Indian eri silkworm, Samia cynthia ricini, revealed by ISSR markers

Samia cynthia ricini (Lepidoptera:Saturniidae), the Indian eri silkworm, contributes significantly to the production of commercial silk and is widely distributed in the Brahmaputra river valley in North-Eastern India. Due to over exploitation coupled with rapid deforestation, most of the natural populations of S. cynthia ricini are dwindling rapidly and its preservation has become an important goal. Assessment of the genetic structure of each population is a prerequisite for a sustainable conservation program. DNA fingerprinting to detect genetic variation has been used in different insect species not only between populations, but also between individuals within a population. Since, information on the genetic basis of phenotypic variability and genetic diversity within the S. cynthia ricini populations is scanty, inter simple sequence repeat (ISSR) system was used to assess genetic diversity and differentiation among six commercially exploited S. cynthia ricini populations. Twenty ISSR primers produced 87% of inter population variability among the six populations. Genetic distance was lowest between the populations Khanapara (E5) and Mendipathar (E6) (0.0654) and highest between Dhanubhanga (E4) and Titabar (E3) (0.3811). Within population, heterozygosity was higher in Borduar (E2) (0.1093) and lowest in Titabar (E3) (0.0510). Highest gene flow (0.9035) was between E5 and E6 and the lowest (0.2172) was between E3 and E5. Regression analysis showed positive correlation between genetic distance and geographic distance among the populations. The high GST value (0.657) among the populations combined with low gene flow contributes significantly to the genetic differentiation among the S. cynthia ricini populations. Based on genetic diversity, these populations can be considered as different ecotypes and in situ conservation of them is recommended

Single Amino Acid Changes in the Murine Leukemia Virus Capsid Protein Gene Define the Target ofFv1Resistance

AbstractThe mouseFv1genetic locus controls resistance to subgroups of ecotropic, MCF, and amphotropic murine leukemia viruses (MuLVs). In addition to the four previously defined alleles ofFv1(Fv1n, Fv1b, Fv1nr, Fv10), we present evidence that the novel restriction pattern characteristic of DBA/2J mice maps to theFv1locus and therefore represents a novel allele, here designatedFv1d.Previous studies had demonstrated that theFv1-mediated viral tropism is determined within the capsid protein gene, and that N- and B-tropic virus capsids differ only in two adjacent amino acids. We introduced various amino acid substitutions at these two sites in the N-tropic AKV MLV capsid gene, and typed resulting viruses for host range on cells carrying all fiveFv1alleles as well as on cells from additional wild mouse species withFv1-like differences in virus susceptibility. Results indicate that alteration of the first of the two amino acids does not alter tropism, but alteration of the second alone is sufficient to convert the N-tropic AKV MLV to a B-tropic virus. Substitution of leucine for arginine at this site produced a virus with an unusual tropism not characteristic of any of the naturally occurring or laboratory strains of MuLV

ROLE OF SUGARS IN SURFACE MICROBE-HOST INTERACTIONS IN GROUP B STREPTOCOCCUS INVASION: Simple sugars and their role in GBS invasion

Objective: Metabolic sources for food play a very important role in developing a niche for a microbe to invade and cause infection in the host. The influence of various sugars on invasion of Streptococcus agalactiae or Group B streptococcus (GBS) into HeLa and A549 cells in vitro were evaluated. Methods: The cell lines and the bacteria were pretreated separately with different sugars before invasion. These observations were also corroborated with light microscopy. Results: Our results showed that the maximum GBS invasion observed at 2h, decreased significantly (p&lt;0.05) when the cells were pretreated with N-acetyl galactosamine (GlcNAc), D-xylose, sucrose, lactose, D-mannose, and D-glucose. In contrast, mannitol was seen to support the invasion of GBS. In addition, when a combined effect of GlcNAc and xylose was studied, 87.5%–91% inhibition to GBS invasion was observed in HeLa and A549 cell lines, respectively. A sizeable reduction in invasion was observed when the bacteria were pretreated with 10 mM of D-Glucose (79.32%), GlcNAc (69.66%), and mannose (48.28%). In conclusion, GlcNAc, D-xylose, and D-glucose proved to be excellent inhibitors to GBS invasion. Furthermore, bacterial pretreatment results might indicate that these sugar specific receptors might be present on the epithelial cells which possibly gets blocked and thus inhibits the entry of GBS. Conclusion: These findings are the first to suggest the role of these sugars as a way to alternative therapies to GBS infection by altering the host-pathogen environment during invasion

Severity of Hepatitis C Virus (Genotype-3) Infection Positively Correlates with Circulating MicroRNA-122 in Patients Sera

Introduction. Hepatitis C virus (genotype-3) causes acute and chronic hepatitis infection predomination in India. The infectious phase of the virus requires various host factors for its survival and subsequent viral particle production. Small RNA molecules like microRNA-122 (miR-122) are one such factor mostly present in the liver and play a supportive role in viral replication. Objective. In this study, diagnostic potential of miR-122 is evaluated in the sera of chronic hepatitis C patients. Methods. miRNAs were isolated from the sera samples of patients as well as controls and miR-122 expression was quantified by real-time PCR. Results. A significant augmentation was observed in the level of circulating miR-122 (median level, 0.66 versus 0.29, P=0.001) in patients compared to controls with ROC value of 0.929±0.034 (P<0.001). Interestingly, miR-122 level also depicted a significant positive correlation with serum ALT (r=0.53), AST (r=0.44), and viral load (r=0.52). Conclusion. The study thus unveiled the role of miR-122 as a plausible diagnostic biomarker during HCV genotype-3 infection in India

Asp299Gly and Thr399Ile polymorphism of TLR-4 gene in patients with prostate cancer from North India

Background: The etiological factors associated with prostate cancer (CaP) have not been completely understood as yet. Genetic predisposition and inflammation is fast emerging as risk factors for CaP is a key player in the innate immune response and plays role in immune- surveillance and inflammation. The present study was conducted to evaluate TLR-4 gene polymorphism in patients with CaP. Material and Methods: DNA was isolated from blood samples of 198 patients with CaP, 200 cases of Benign Prostatic Hyperplasia (BPH) and 119 controls. TLR-4 gene polymorphisms Asp299Gly and Thr399Ile were determined by Restriction Fragment Length Polymorphism (RFLP) technique using Nco1 and Hinf 1 restriction enzymes. All statistical calculations were performed using SPSS for windows, version 13 (SPSS Inc., Chicago, Illinois, USA) Results: A significantly high proportion of patients with CaP had AG genotype (16.6%) as compared to control (4.2%) [OR-4.4, 95% CI (1.57-13.26), P =0.0013] with respect to Asp299Gly single nucleotide polymorphism (SNP). AA genotype showed a protective effect towards CaP development [OR-0.39, 95% CI (0.18-0.83), P=0.007). A trend was observed towards development of BPH with respect to AG genotype (P=0.06). Thr399Ile SNP was not significantly different among the population groups studied. Conclusions: This finding highlights the genetic predispositions to CaP with respect to TLR-4 gene. Individuals with Asp299Gly polymorphism having AG genotype appear to have four fold higher risk for development of Prostate cance