scholarly journals Group AStreptococcusT Antigens Have a Highly Conserved Structure Concealed under a Heterogeneous Surface That Has Implications for Vaccine Design

2019 ◽  
Vol 87 (6) ◽  
Author(s):  
Paul G. Young ◽  
Jeremy M. Raynes ◽  
Jacelyn M. Loh ◽  
Thomas Proft ◽  
Edward N. Baker ◽  
...  
Keyword(s):  
Sequence Similarity ◽  
Sequence Divergence ◽  
Structural Similarity ◽  
T Antigen ◽  
T Antigens ◽  
Content Type ◽  
Group A ◽  
Efficacious Vaccine ◽  
High Level ◽  
Conserved Core

ABSTRACTGroup AStreptococcus(GAS) (Streptococcus pyogenes) is an important human pathogen associated with significant global morbidity and mortality for which there is no safe and efficacious vaccine. The T antigen, a protein that polymerizes to form the backbone of the GAS pilus structure, is a potential vaccine candidate. Previous surveys of theteegene, which encodes the T antigen, have identified 21 differentteetypes and subtypes such that any T antigen-based vaccine must be multivalent and carefully designed to provide broad strain coverage. In this study, the crystal structures of three two-domain T antigens (T3.2, T13, and T18.1) were determined and found to have remarkable structural similarity to the previously reported T1 antigen, despite moderate overall sequence similarity. This has enabled reliable modeling of all major two-domain T antigens to reveal that T antigen sequence variation is distributed along the full length of the protein and shields a highly conserved core. Immunoassays performed with sera from immunized animals and commercial T-typing sera identified a significant cross-reactive antibody response between T18.1, T18.2, T3.2, and T13. The existence of shared epitopes between T antigens, combined with the remarkably conserved structure and high level of surface sequence divergence, has important implications for the design of multivalent T antigen-based vaccines.

scholarly journals THE PROPERTIES OF T ANTIGENS EXTRACTED FROM GROUP A HEMOLYTIC STREPTOCOCCI

1946 ◽  
Vol 84 (5) ◽  
pp. 449-471 ◽  
Author(s):  
Rebecca C. Lancefield ◽  
Vincent P. Dole
Keyword(s):  
Proteolytic Enzymes ◽  
Enzymatic Digestion ◽  
T Antigen ◽  
Soluble Form ◽  
Bacterial Cells ◽  
T Antigens ◽  
Acid Media ◽  
Elementary Analysis ◽  
Group A

1. T antigens of group A hemolytic streptococci have been obtained in soluble form by digestion of the bacterial cells with pepsin or trypsin. Large quantities of this antigen were readily extracted from type 1 strains, whereas only small amounts could be obtained from strains of other types. 2. The T antigen, prepared in this way from a type 1 strain, was partially purified by chemical precipitation and further enzymatic digestion. An active fraction, apparently protein in nature, was separated electrophoretically at pH 7.00. The separated material, pooled and analyzed at the same pH, gave only a single peak. The isoelectric point of this substance was about pH 4.50. An elementary analysis was obtained. Although the T antigen was resistant to digestion with proteolytic enzymes and ribonuclease, it was readily inactivated by heat, especially in acid media and in strong salt solutions. The serological activity of this purified T substance was lost after exposure to ultraviolet radiation. 3. Analysis by means of the ultracentrifuge showed that the material was polydisperse and therefore probably impure. 4. The soluble form of the T substance was active in the precipitin reaction, in the fixation of complement, in inhibition of T agglutination, and as an antigen when injected into rabbits. The antibodies produced did not protect mice against infection with virulent strains of hemolytic streptococci containing the same T antigen. 5. The immunological specificity of T antigen in soluble form is the same as that of the T antigen in the intact streptococcus from which it was derived

scholarly journals Emergence of Escherichia coli Sequence Type 131 Isolates Producing KPC-2 Carbapenemase in China

2013 ◽  
Vol 58 (2) ◽  
pp. 1146-1152 ◽  
Author(s):  
Jia Chang Cai ◽  
Rong Zhang ◽  
Yan Yan Hu ◽  
Hong Wei Zhou ◽  
Gong-Xiang Chen
Keyword(s):  
Escherichia Coli ◽  
Carbapenem Resistance ◽  
Sequence Type ◽  
Content Type ◽  
E Coli ◽  
Predominant Type ◽  
Group A ◽  
Dna Fragment ◽  
High Level ◽  
Group D

ABSTRACTTwenty-two KPC-2-producingEscherichia coliisolates were obtained from three hospitals in Hangzhou, China, from 2007 to 2011. One isolate, with OmpC porin deficiency, exhibited high-level carbapenem resistance. Pulsed-field gel electrophoresis showed that few isolates were indistinguishable or closely related. Multilocus sequence typing indicated that sequence type 131 (ST131) was the predominant type (9 isolates, 40.9%), followed by ST648 (5 isolates), ST405 (2 isolates), ST38 (2 isolates), and 4 single STs, ST69, ST2003, ST2179, and ST744. Phylogenetic analysis indicated that 9 group B2 isolates belonged to ST131, and 5 of 11 group D isolates belonged to ST648. Only one group B1 isolate and one group A isolate were identified. A representative plasmid (pE1) was partially sequenced, and a 7,788-bp DNA fragment encoding Tn3transposase, Tn3resolvase, ISKpn8transposase, KPC-2, and ISKpn6-like transposase was obtained. TheblaKPC-2-surrounding sequence was amplified by a series of primers. The PCR results showed that 13 isolates were consistent with the genetic environment in pE1. It is the first report of rapid emergence of KPC-2-producingE. coliST131 in China. TheblaKPC-2gene of most isolates was located on a similar genetic structure.

Hyphomicrobium nitrativorans sp. nov., isolated from the biofilm of a methanol-fed denitrification system treating seawater at the Montreal Biodome

2013 ◽  
Vol 63 (Pt_10) ◽  
pp. 3777-3781 ◽  
Author(s):  
Christine Martineau ◽  
Céline Villeneuve ◽  
Florian Mauffrey ◽  
Richard Villemur
Keyword(s):  
16S Rrna ◽  
Type Species ◽  
Sequence Similarity ◽  
Open Reading Frames ◽  
Nitrite Accumulation ◽  
Rrna Gene ◽  
Content Type ◽  
Link Type ◽  
Serine Pathway ◽  
High Level

A budding prosthecate bacterial strain, designated NL23T, was isolated from a methanol-fed denitrification system treating seawater at the Montreal Biodome, Canada. Phylogenetic analysis based on 16S rRNA (rRNA) gene sequences showed that the strain was affiliated with the genus Hyphomicrobium of the Alphaproteobacteria and was most closely related to Hyphomicrobium zavarzinii with 99.4 % sequence similarity. Despite this high level of 16S rRNA gene sequence similarity, DNA–DNA hybridization assays showed that strain NL23T was only distantly related to H. zavarzinii ZV-622T (12 %). Strain NL23T grew aerobically, but also had the capacity to grow under denitrifying conditions in the presence of nitrate without nitrite accumulation. Growth occurred at pH 7.0–9.5, with 0–1 % NaCl and at temperatures of 15–35 °C. Major fatty acids were C18 : 1ω7c or ω6c (84.6 %) and C18 : 0 (8.5 %), and major quinones were Q8 (5 %) and Q9 (95 %). The complete genome of the strain was sequenced and showed a DNA G+C content of 63.8 mol%. Genome analysis predicted open reading frames (ORF) encoding the key enzymes of the serine pathway as well as enzymes involved in methylotrophy. Also, ORF encoding a periplasmic nitrate reductase (Nap), a nitrite reductase (Nir), a nitric oxide reductase (Nor) and a nitrous oxide reductase (Nos) were identified. Our results support that strain NL23T represents a novel species within the genus Hyphomicrobium , for which the name Hyphomicrobium nitrativorans sp. nov. is proposed. The type strain is NL23T ( = ATCC BAA-2476T = LMG 27277T).

Streptomyces endophyticus sp. nov., an endophytic actinomycete isolated from Artemisia annua L.

2013 ◽  
Vol 63 (Pt_1) ◽  
pp. 224-229 ◽  
Author(s):  
Jie Li ◽  
Guo-Zhen Zhao ◽  
Wen-Yong Zhu ◽  
Hai-Yu Huang ◽  
Li-Hua Xu ◽  
...  
Keyword(s):  
16S Rrna ◽  
16S Rrna Gene ◽  
Artemisia Annua ◽  
Sequence Similarity ◽  
Diaminopimelic Acid ◽  
Rrna Gene ◽  
Content Type ◽  
Link Type ◽  
High Level ◽  
Physiological Tests

Three filamentous actinomycetes, strains YIM 65594T, YIM 65638 and YIM 65642, were isolated from the surface-sterilized roots of Artemisia annua L. collected from Yunnan province, south-west China. These strains were found to have morphological and chemotaxonomic characteristics typical of the genus Streptomyces . The organisms formed an extensively branched substrate mycelium, with abundant aerial hyphae that differentiated into spores. The cell wall of the isolates contained ll-diaminopimelic acid and the menaquinones were MK-9(H8) and MK-9(H6). The major fatty acids were anteiso-C15 : 0, anteiso-C17 : 0 and iso-C16 : 0. Phylogenetic analysis of the 16S rRNA gene sequences of these strains revealed that the strains clustered together and were most closely related to Streptomyces kunmingensis NBRC 14463T, with 98.5–98.6 % 16S rRNA gene sequence similarity. The results of DNA–DNA hybridization and physiological tests allowed the genotypic and phenotypic differentiation of strains YIM 65594T, YIM 65638 and YIM 65642 from related species. However, the high level of DNA–DNA relatedness between them showed that these three strains belong to the same species. Strain YIM 65594T ( = DSM 41984T = CCTCC AA 209036T) was selected as the type strain to represent this novel species, for which the name Streptomyces endophyticus sp. nov. is proposed.

scholarly journals The Histone-Like Protein Hlp Is Essential for Growth of Streptococcus pyogenes: Comparison of Genetic Approaches To Study Essential Genes

2011 ◽  
Vol 77 (13) ◽  
pp. 4422-4428 ◽  
Author(s):  
Julia V. Bugrysheva ◽  
Barbara J. Froehlich ◽  
Jeffrey A. Freiberg ◽  
June R. Scott
Keyword(s):  
Streptococcus Pyogenes ◽  
Group A Streptococcus ◽  
Constitutive Expression ◽  
Essential Genes ◽  
Differential Growth ◽  
Content Type ◽  
Group A ◽  
Approaches To Study ◽  
Control Translation ◽  
High Level

ABSTRACTSelection of possible targets for vaccine and drug development requires an understanding of the physiology of bacterial pathogens, for which the ability to manipulate expression of essential genes is critical. ForStreptococcus pyogenes(the group A streptococcus [GAS]), an important human pathogen, the lack of genetic tools for such studies has seriously hampered research. To address this problem, we characterized variants of the inducible Ptetcassette, in both sense and antisense contexts, as tools to regulate transcription from GAS genes. We found that although the three-operator Ptetconstruct [Ptet(O)3] had low uninduced expression, its induction level was low, while the two-operator construct [Ptet(O)2] was inducible to a high level but showed significant constitutive expression. Use of Ptet(O)3in the chromosome allowed us to demonstrate previously that RNases J1 and J2 are required for growth of GAS. Here we report that the uninduced level from the chromosomally inserted Ptet(O)2construct was too high for us to observe differential growth. For the highly expressed histone-like protein (Hlp) of GAS, neither chromosomal insertion of Ptet(O)2or Ptet(O)3nor their use on a high-copy-number plasmid to produce antisense RNA specific tohlpresulted in adequate differential expression. However, by replacing the ribosome binding site ofhlpwith an engineered riboswitch to control translation of Hlp, we demonstrated for the first time that this protein is essential for GAS growth.

scholarly journals A multivalent T-antigen-based vaccine for Group A Streptococcus

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jacelyn M. S. Loh ◽  
Tania Rivera-Hernandez ◽  
Reuben McGregor ◽  
Adrina Hema J. Khemlani ◽  
Mei Lin Tay ◽  
...  
Keyword(s):  
Recombinant Protein ◽  
Recombinant Proteins ◽  
Group A Streptococcus ◽  
Vaccine Coverage ◽  
Protective Efficacy ◽  
Invasive Disease ◽  
T Antigen ◽  
Major Protein ◽  
T Antigens ◽  
Group A

AbstractPili of Group A Streptococcus (GAS) are surface-exposed structures involved in adhesion and colonisation of the host during infection. The major protein component of the GAS pilus is the T-antigen, which multimerises to form the pilus shaft. There are currently no licenced vaccines against GAS infections and the T-antigen represents an attractive target for vaccination. We have generated a multivalent vaccine called TeeVax1, a recombinant protein that consists of a fusion of six T-antigen domains. Vaccination with TeeVax1 produces opsonophagocytic antibodies in rabbits and confers protective efficacy in mice against invasive disease. Two further recombinant proteins, TeeVax2 and TeeVax3 were constructed to cover 12 additional T-antigens. Combining TeeVax1–3 produced a robust antibody response in rabbits that was cross-reactive to a full panel of 21 T-antigens, expected to provide over 95% vaccine coverage. These results demonstrate the potential for a T-antigen-based vaccine to prevent GAS infections.

scholarly journals Studies on two methods for extraction of streptococcal T antigens

1973 ◽  
Vol 71 (1) ◽  
pp. 131-138 ◽  
Author(s):  
H. H. Erwa
Keyword(s):  
Specific Antigen ◽  
T Antigen ◽  
M Protein ◽  
T Antigens ◽  
Specific Polysaccharide ◽  
Protein Group ◽  
Group A ◽  
Streptococcal Antigens ◽  
Method Of Extraction

SUMMARYThe extraction of group A streptococcal antigens by group C phage-associated lysin has been confirmed. In addition to the T antigen the extract contained M-protein, group-specific polysaccharide and mucopeptide antigen which was difficult to remove. This method of extraction of the T antigen was compared with the trypsin method. The latter method was found to be of advantage in giving a pure specific antigen.

scholarly journals STUDIES ON THE ANTIGENIC COMPOSITION OF GROUP A HEMOLYTIC STREPTOCOCCI

1944 ◽  
Vol 79 (1) ◽  
pp. 79-88 ◽  
Author(s):  
Rebecca C. Lancefield ◽  
Walter A. Stewart
Keyword(s):  
T Antigen ◽  
T Antigens ◽  
Antigenic Composition ◽  
Group A

1. Group A hemolytic streptococci have been described which do not agglutinate in anti-T serum because they lack T antigen. 2. Other strains occur which contain T antigen yet do not agglutinate in anti-T serum because T agglutination is blocked by the presence of large amounts of M substance in the streptococci. 3. Strains belonging to a number of types have been analyzed to determine their antigenic composition with respect to M and T antigens.

scholarly journals STUDIES ON THE ANTIGENIC COMPOSITION OF GROUP A HEMOLYTIC STREPTOCOCCI

1944 ◽  
Vol 79 (1) ◽  
pp. 99-114 ◽  
Author(s):  
Walter A. Stewart ◽  
Rebecca C. Lancefield ◽  
Armine T. Wilson ◽  
Homer F. Swift
Keyword(s):  
T Antigen ◽  
T Antigens ◽  
Antigenic Composition ◽  
Slide Agglutination ◽  
Cross Reactions ◽  
Specific Antisera ◽  
Group A ◽  
The Cross

1. The occurrence of closely related T antigens in the series composed of types 15, 17, 19, 23, and 30 accounts for most of the cross reactions observed among these types. Similarly T antigens, unrelated to the first series but mutually related, occur in a second series comprising types 4, 24, 26, 28, 29, and 46. 2. Matt variants of each of the eleven types studied possess type-specific M antigens demonstrable either by precipitin or agglutinin reactions. 3. In seven of these types, strains have been encountered which do not possess the T antigen usually associated with the type in question. 4. Procedures are outlined in the appendix for preparing specific antisera for the classification of these types by the slide agglutination technique.

scholarly journals Rhodanobacter caeni sp. nov., isolated from sludge from a sewage disposal plant

2012 ◽  
Vol 62 (Pt_12) ◽  
pp. 2815-2821 ◽  
Author(s):  
Sung-Geun Woo ◽  
Sathiyaraj Srinivasan ◽  
Myung Kyum Kim ◽  
Myungjin Lee
Keyword(s):  
Sequence Similarity ◽  
Phylogenetic Analyses ◽  
Rrna Gene ◽  
Sewage Disposal ◽  
Respiratory Quinone ◽  
Content Type ◽  
Dna Relatedness ◽  
Link Type ◽  
Major Respiratory Quinone ◽  
High Level

Two Gram-reaction-negative, motile bacteria, designated strains MJ01T and MJ14, were isolated from sludge collected from the Daejeon sewage disposal plant in South Korea. The taxonomic positions of both strains were determined using a polyphasic approach. In phylogenetic analyses based on 16S rRNA gene sequences, strains MJ01T and MJ14 appeared indistinguishable and to be most closely related to members of the genus Rhodanobacter in the family Xanthomonadaceae of the Gammaproteobacteria (96.4–98.8 % sequence similarity). Strain MJ01T exhibited a relatively high level of DNA–DNA relatedness with strain MJ14 (89.3 %) but relatively low DNA–DNA relatedness values with established species in the genus Rhodanobacter (<60 %). The genomic DNA G+C contents of strains MJ01T and MJ14 were 65.3 and 64.8 mol%, respectively. The major respiratory quinone of both novel strains was the ubiquinone Q-8. The major fatty acids of both strains were iso-C15 : 0, iso-C16 : 0, iso-C17 : 0 and iso-C17 : 1ω9c, and the polar lipid profiles of the two strains contained diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine and minor amounts of unidentified aminophospholipids and phospholipids. Based on the phenotypic, genotypic and phylogenetic evidence, strains MJ01T and MJ14 represent a single novel species in the genus Rhodanobacter , for which the name Rhodanobacter caeni sp. nov. is proposed. The type strain is MJ01T ( = KCTC 22449T = JCM 16242T), with MJ14 ( = KCTC 22460 = JCM 16243) as a reference strain.

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