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Biao Kan

Publications and source records attributed to Biao Kan.

At least 19 recordsLinked to original sources
PubMed2006

Identification of a new Neisseria meningitidis serogroup C clone from Anhui province, China.

BACKGROUND: Outbreaks of a new serogroup C meningococcal disease emerged during 2003-04 (five outbreaks with 43 cases) and in 2004-05 (five outbreaks with 29 cases), all in Anhui province, China. We describe the molecular epidemiology and features of the causative bacterial strains. METHODS: We used pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) to analyse the strains. FINDINGS: Of 34 strains of Neisseria meningitidis cultured during 2003-04 from Anhui province, 31 were group C meningococci, 28 of which were associated with three of five outbreaks; one from a patient and 27 from close contacts of eight patients. Of 30 strains isolated from Anhui province during 2004-05, 17 were identified as serogroup C meningococci, ten of which were associated with four of five outbreaks. In a nationwide survey, 542 strains were isolated during 2004-05; 58 were serogroup C meningococci interspersed among 11 other provinces where no serogroup C outbreak occurred. Of the 106 serogroup C strains analysed, 89 had identical PFGE patterns, designated AH1. Of 28 strains selected for MLST analyses, 25 were sequence type 4821 (ST-4821), which did not belong to any of the previously reported sequence types that can form a new hypervirulent lineage. INTERPRETATION: ST-4821 seems to be unique and caused the serogroup C meningitis outbreaks during the two seasons from 2003 to 2005 in Anhui province. The emergence of this sequence type has epidemiological importance that should be monitored for future spread in China and the rest of the world.

Child↗
PubMed2006

Streptococcus suis sequence type 7 outbreak, Sichuan, China.

An outbreak of Streptococcus suis serotype 2 emerged in the summer of 2005 in Sichuan Province, and sporadic infections occurred in 4 additional provinces of China. In total, 99 S. suis strains were isolated and analyzed in this study: 88 isolates from human patients and 11 from diseased pigs. We defined 98 of 99 isolates as pulse type I by using pulsed-field gel electrophoresis analysis of SmaI-digested chromosomal DNA. Furthermore, multilocus sequence typing classified 97 of 98 members of the pulse type I in the same sequence type (ST), ST-7. Isolates of ST-7 were more toxic to peripheral blood mononuclear cells than ST-1 strains. S. suis ST-7, the causative agent, was a single-locus variant of ST-1 with increased virulence. These findings strongly suggest that ST-7 is an emerging, highly virulent S. suis clone that caused the largest S. suis outbreak ever described.

Animals↗
PubMed2006

[Application of pulsed-field gel electrophoresis typing in tracing and carrying out surveillance programs on O139 cholera outbreaks].

OBJECTIVE: To study the characteristics of molecular typing and phylogenic relationship among the Vibrio cholerae serogroup O139 strains isolated from environment and sea food samples during cholera outbreaks, in Sichuan province in 2004 and to trace the source of infections so as to support the ascertainment of epidemic control strategy. METHODS: Cholera toxin gene was detected by polymerase chain reaction amplification. Pulsed-field gel electrophoresis (PFGE) was used for subtyping of isolates and clustering of patterns was analysed with the software BioNumerics. RESULTS: In all the 72 strains under analysis, 68 appeared to be toxigenic while 4 from river water derived isolates were toxin gene negative. Sixty-seven strains were clustered into 16 PFGE patterns when digested with Not I. The patterns of toxigeinc O139 strains isolated from turtles in the markets were identical with the patterns of strains appeared in the outbreaks respectively. The PFGE patterns of isolates from different outbreaks were inconsistent. CONCLUSION: The sources of infection causing these outbreaks were complicated. Contaminated turtles might also be one of the major sources of outbreaks when being served at the dinner parties in Sichuan in 2004.

Animals↗
PubMed2006

[Molecular typing of the pathogenic Yersinia enterocolitica strains with pulsed field gel electrophores isolated in China].

OBJECTIVE: To investigate the epidemiological and molecular typing features of the pathogenic Yersinia enterocolitica strains isolated in China,using pulsed field gel electrophoresis(PFGE) and standardized PFGE method as well as typing database of Yersinia enterocolitica. METHODS: PFGE analysis was performed as Laboratory Directions for molecular subtyping of Salmonella by PFGE (PulseNet,USA) with some modifications and the results of PFGE were analyzed by BioNumerics soft (Version 4.0, Applied Maths BVBA, Belium). RESULTS: 114 O:3 Yersinia enterocolitica strains were typed by 25 patterns to have found that K6GN11C30012 (50 strains), K6GN11C30015(19 strains) and K6GN11C30016(10 strains) were the major patterns. K6GNllC30012 had 92.2% cluster similarity with K6GN11C30009-K6GN11C30023. This clone included 91.23% strains of 114 0:3 Yersinia enterocolitica strains. 51 0:9 Yersinia enterocolitica strains were typed by 14 patterns; K6GN11C90004 (22 strains) and K6GN11C90010 (13 strains)were the major patterns. K6GN11C90004 had 81.8% cluster similarity with K6GN11C90010 patterns. The major patterns of 0:3 and 0:9 serotypes were quite different. CONCLUSION: O:3 Yersinia enterocolitica strains might originate from the same clone and had very few variation in different years and provinces but O:9 Yersinia enterocolitica strains from two different clones with some changes.

China↗
PubMed2005

Resistance of the cholera vaccine candidate IEM108 against CTXPhi infection.

The cholera toxin (CT) genes ctxAB are carried on a lysogenic phage of Vibrio cholerae, CTXPhi, which can transfer ctxAB between toxigenic and nontoxigenic strains of bacteria. This transfer may pose a problem when live oral cholera vaccine is given to people in epidemic areas, because the toxin genes can be reacquired by the vaccine strains. To address this problem, we have constructed a live vaccine candidate, IEM108, which carries an El Tor-derived rstR gene. This gene encodes a repressor and can render bacterial resistance to CTXPhi infection. In this study, we evaluated the resistance of IEM108 against CTXPhi infection by using a CTXPhi marked for chloramphenicol (CAF) resistance and an in vivo model. We found that the cloned rstR gene rendered IEM108 immune to infection with the marked CTXPhi. In addition, the infection rate of IEM108 was even lower than that of the native CTXPhi-positive strain. These results suggest that the vaccine candidate IEM108 is resistant to infection by CTXPhi.

Animals↗
PubMed2005

Enteroaggregative Escherichia coli isolated from Chinese diarrhea patients with high-pathogenicity island of Yersinia is involved in synthesis of siderophore yersiniabactin.

AIM: To investigate the distribution of 12 high-pathogenicity island (HPI) genes and the relation between HPI genes and expression of yersiniabactin (Ybt) in enteroaggregative E.coli (EAggEC) isolated from Chinese diarrhea patients. METHODS: The distribution of 12 HPI genes was investigated by PCR and DNA hybridization in two prototype strains of EAggEC, EAggEC 17-2, EAggEC O42, and 6 clinical EAggEC isolates from China. The production of siderophore Ybt in HPI-positive strains was detected by reporter gene bioassay to determine the relation between HPI genes and expression of Ybt. Flow cytometry was used to detect fluorescent signal of the reporter strain that could designate production of Ybt. RESULTS: Seven strains were HPI-positive and one strain was HPI-negative. Six of seven HPI-positive strains were inserted into asnT-tRNA site. Moreover, seven EAggEC HPI-positive strains revealed enhanced fluorescence signal but the EAggEC HPI-negative strain did not. However, there was a difference in Ybt expression condition and level among these seven EAggEC HPI-positive strains. Although UFT073 strain, the prototype strain of uropathogenic E.coli (UPEC), carried the complete HPI core part, we did not detect the expression of Ybt in it. CONCLUSION: EAggEC HPI-positive strains can express the Ybt system, but the presence of HPI core part does not mean the functional expression of Ybt.

Animals↗
PubMed2005

Molecular evolution analysis and geographic investigation of severe acute respiratory syndrome coronavirus-like virus in palm civets at an animal market and on farms.

Massive numbers of palm civets were culled to remove sources for the reemergence of severe acute respiratory syndrome (SARS) in Guangdong Province, China, in January 2004, following SARS coronavirus detection in market animals. The virus was identified in all 91 palm civets and 15 raccoon dogs of animal market origin sampled prior to culling, but not in 1,107 palm civets later sampled at 25 farms, spread over 12 provinces, which were claimed to be the source of traded animals. Twenty-seven novel signature variation residues (SNVs) were identified on the spike gene and were analyzed for their phylogenetic relationships, based on 17 sequences obtained from animals in our study and from other published studies. Analysis indicated that the virus in palm civets at the live-animal market had evolved to infect humans. The evolutionary starting point was a prototype group consisting of three viral sequences of animal origin. Initially, seven SNV sites caused six amino acid changes, at positions 147, 228, 240, 479, 821, and 1080 of the spike protein, to generate low-pathogenicity viruses. One of these was linked to the first SARS patient in the 2003-2004 period. A further 14 SNVs caused 11 amino acid residue changes, at positions 360, 462, 472, 480, 487, 609, 613, 665, 743, 765, and 1163. The resulting high-pathogenicity groups were responsible for infections during the so-called early-phase epidemic of 2003. Finally, the remaining six SNVs caused four amino acid changes, at positions 227, 244, 344, and 778, which resulted in the group of viruses responsible for the global epidemic.

Amino Acid Sequence↗
PubMed2005

Construction and characterization of a thyA mutant derived from cholera vaccine candidate IEM101.

A naturally cholera toxin gene negative Vibrio cholerae (O1, El Tor, Ogawa) strain, named IEM101, was isolated in China. The human volunteer tests showed that this strain was safe, able to colonize the intestinal mucosa, and able to induce a strong immune response. Also other studies indicated that it was an efficient live vector to deliver heterologous antigens. In this article, a thymidylate synthase gene (thyA)-defined mutant was constructed using homologous recombination. Except for the morphological changes in minimal medium and slightly reduced colonization capacity, mutant strain IEM101-T maintained most of the desirable features as the wild-type strain IEM101 in terms of growth rate and immunogenicity. However, the mutant was more biosafe than its parent strain. In conclusion, IEM101-T may be a promising strain to develop live vaccine candidate of cholera or an attractive vaccine vector to deliver heterologous antigens in vivo.

Animals↗
PubMed2005

SARS-CoV infection in a restaurant from palm civet.

Epidemiologic investigations showed that 2 of 4 patients with severe acute respiratory syndrome (SARS) identified in the winter of 2003-2004 were a waitresss at a restaurant in Guangzhou, China, that served palm civets as food and a customer who ate in the restaurant ashort distance from animal cages. All 6 palm civets at the restaurant were positive for SARS-associated coronavirus (SARS-CoV). Partial spike (S) gene sequences of SARS-CoV from the 2 patients were identical to 4 of 5 Sgene viral sequences from palm civets. Phylogenetic analysis showed that SARS-CoV from palm civets in the restaurant was most closely related to animal isolates. SARS cases at the restaurant were the result of recent interspecies transfer from the putative palm civet reservoir, and not the result of continued circulation of SARS-CoV in the human population.

Adult↗
PubMed2005

[Surveillance on severe acute respiratory syndrome associated coronavirus in animals at a live animal market of Guangzhou in 2004].

OBJECTIVE: To study the prevalence of severe acute respiratory syndrome coronavirus (SARS-CoV) like virus in animals at a live animal market of Guanzhou in 2004 before and after culling of wild animal action taken by the local authority, in order to predict the re-emerging of SARS from animal originals in this region. METHODS: Animals at live animal market were sampled for rectal and throat swabs in triplicate. A single step realtime reverse transcription-polymerase chain reaction (RT-PCR) diagnostic kit was performed for screening SARS-CoV like virus, the manual nested RT- PCR and DNA sequencing were performed for confirmation. Only specimens which tested positive for both of the N and P genes by nested RT-PCR were scored as positive. RESULTS: In 31 animals sampled in January 5 2004 before culling of wild animals at Guangdong Province, including 20 cats (Felis catus), 5 red fox (Vulpes vulpes) and 6 Lesser rice field rats (Rattus losea), 8 (25.8%) animals were tested positive for SARS-CoV like virus by RT-PCR methods, of which 4 cats, 3 red fox and one Lesser rice field rats were included. However, two weeks after culling of animals and disinfection of the market were implemented, in 119 animals sampled in January 20 2004, including 6 rabbits (Oryctolagus cuniculus), 13 cats, 46 red jungle fowl (Gallus gallus), 13 spotbill duck (Anas platyrhynchos), 10 greylag goose (Anser anser), 31 Chinese francolin (Franclinus pintadeanus), only rectal swab from one greylag goose was tested positive for SARS-CoV like virus. Furthermore, in 102 animals that including 14 greylag gooses, 3 cats, 5 rabbits, 9 spotbill duck (Anaspoecilorhyncha), 2 Chinese francolin (Franclinus pintadeanus), 8 common pheasant (Phasianus colchicus), 6 pigeons, 9 Chinese muntjac (Muntiacus reevesi), 19 wild boar (Sus scrofa), 16 Lesser rice field rats, 5 dogs, 1 mink (Mustela vison), 3 goats, 2 green peafowl (Pavo muticus) sampled in April, May, June, July, August and November, only rectal swab from one pig was tested positive. However, of 12 and 10 palm civets sampled in November and December including five of which had been at the live animals market for 2 days, none of them was tested positive. CONCLUSION: This findings revealed that animals being sampled in April, May, June, July, August and November of 2004, only one rectal swab from a pig was tested positive as SARS-CoV like virus, much lower than the results from the previous year, suggesting that the possibility of re-emerging of human infection from animal origins is low for the winter of 2004-2005.

Animals↗
PubMed2005

[Construction and characterization of mutant Enteroaggregative E. coli O42 strain with high-pathogenicity island deletion].

OBJECTIVE: To construct and characterize a mutant Enteroaggregative E. coli(EAggEC) O42 strain with in-frame deletion of high-pathogenicity island (HPI). METHODS: The kanamycin resistance gene (kan) was inserted between the sequences of irp8 and irp5 genes as the two homologous sequences for construction of the recombinant plasmid pCO85 by subcloning the recombined sequence into the suicide vector pCVD442. By homologous recombination and conjunction mobilization, EAO85 mutant with deletion of the core region of HPI about 24 kb spanning from irp8 to irp5 sequences was screened. RESULTS: Irp8 and irp5 genes of EAggEC O42 were exchanged by pCO85 by conjunction mobilization with the selection by sucrose. The EAO85 mutant was identified by their failure to yield PCR products with primers specific for the internal regions of HPI. CONCLUSION: We have successfully constructed a mutant of EAggEC O42 strain with HPI in-frame deletion, which may facilitate the exploration of the role of HPI in EAggEC strain.

Bacterial Adhesion↗
PubMed2005

[Sequence analysis of the mutated genes in CTXEVC Phi and nct-CTXnew Phi genomes in Vibrio cholerae JS94484 strain].

OBJECTIVE: To analyze the sequences of the mutated genes in CTX(EVC)Phi and nct-CTX(new)Phi genomes in Vibrio cholerae JS94484 strain. METHODS: The mutated genes in CTX(EVC)Phi and nct-CTX(new)Phi genome were obtained by PCR, sequenced and analyzed. RESULTS: ig1, rstR, ig2, and ctxAB genes in CTX(EVC)Phi genome of V. cholerae strain JS94484 were highly homologous with those of standard EVC strain N16961, while ig1, rstR and ig2 genes in nct-CTX(new)Phi genome of the strain JS94484 shared low homology with those of the other 3 biotypes of V. cholerae. Considerable difference was detected in the last 60 bp of zot genes between CTX(EVC)Phi and nct-CTX(new)Phi genomes, indicating possible difference in the amino sequences of the Zot proteins encoded by these two genes. The sequence of toxin-coregulated pilus A subunit gene (tcpA) of the strain JS94484 was identical with that of strain N16961. CONCLUSION: ig1, rstR and ig2 genes of nct-CTX(new)Phigenome are of a novel type, and their functions await further investigation.

Cholera Toxin↗
PubMed2005

[Study on infection of different strains of Vibro cholerae O1 by El Tor CTXPhi].

To study the horizontal transfer efficiencies of filamentous bacteriophage CTXPhi in different V. cholera O1 strains and the phage immunities of these strains. The infectious El Tor CTXPhi particles genetic marked by chloramphenicol resistance gene were used to infect four different V. cholerae O1 strains in vivo and in vitro. Selected the infected clones based on its character of chloramphenicol resistance and identified and judged the exist form of CTXPhi genome through Southern bolt and other hybridization methods. Calculated the infection rates of different strains and compared each other. Then we analyzed the mechanism of infection and phage immunity. The infection rate of classic strain 1119 with the genetic marked CTX(ET)Phi in vivo is much higher than that in vitro. In vitro experiment, the rate of 1119 is higher than other three El Tor strains. And in El Tor strains, the infection frequency of IEM101 that had no rstR gene is 100 to 1000 times higher than other two strains containing rstR. Classical biotype strain is more susceptible to CTX(ET)Phi particles than El Tor strains. Expression of TCP and the phage immunity mediated by rstR gene affect the horizontal transfection of CTXPhi in V. cholerae strains.

Animals↗
PubMed2005

[Functional analysis of promoters of Vibrio cholerea typing phage VP1 with reporter system].

Phage VP1 infects and lyses Vibrio cholerae. The VP1 genome is a circular double-strand DNA and its size is 32176 base pairs. Analysis of the sequence of the VP1 genome revealed the presence of 15 putative promoter sequence. The activities of these putative promoters in V. cholerae were assayed by transformation of reporter gene plasmid and phage infection together. Promoter regions were ligated into pRS1274/BamH I/EcoR I. Then transformed into E. coli JM109 and all of clone display blue. The recombinant plasmids were transformed into V. cholerae 7743 deltaZ by electroporation, then bacteriophage VP1 infect transformant. The time-course expressing lacZ gene and detecting change of beta-galactosidase enzyme activity in V. cholerae transformants at latent period, indicated P17 probably is a early promoter; P2 and P3 and P9 etc are medium-term promoters; P18 is a late promoter.

Bacteriophage Typing↗
PubMed2005

[Sequencing and analysis of Vibrio cholerae typing phage VP3 genome].

DNA sequence and the genome of phage VP3 (a typing phage of V. cholera) were analyzed. A random library of VP3 DNA was constructed by shot-gun library method. The VP3 genome sequence was assembled with contigs sequences, the gaps between different contigs were filled with sequencing data from primer walking. ORFs were predicted; Phylogeny of DNA polymerase sequences was analyzed to determine the class of VP3; The activity of putative promoter genes were analyzed using lacZ report system. VP3 genome is a 39504bp of circular double-stranded DNA. Twenty-seven out of forty-nine putative ORFs were annotated; twenty gene products were homologous with T7-like phages, including DNAP, DNA replicative protein, capsid, tail tubular, tail fiber protein, and DNA packaged protein. The activity of the putative promoter regions was confirmed through cloning those regions to LacZ-fuse plasmid pRS1274 and analysis of the expression of beta galactosidase. The complete genomic sequence of VP3 and phylogenetic tree analysis suggests VP3 is a member of T7 phage family.

Bacteriophage T7↗
PubMed2005

[Study on the distribution of Yersinia enterocolitica in Nantong, Jinagsu Province].

OBJECTIVE: To study the distribution of Yersinia enterocolitica and its virulence factors in Nantong, Jiangsu. METHODS: Yersinia strains were isolated from livestock and poultry. Conventional PCR was used to detect the virulence factors of all strains and strain 0:8 was analyzed by pulsed-field gel electrophoresis(PFGE). RESULTS: The combined isolation rate of Yersinia enterocolitica from livestock and poultry was 31.06% and the gene distribution characters were: 39.57% of them were ail-, ystA- , ystB-, yadA- , virF-; 60.43% were ail- , ystA- , ystB + , yadA- , virF- respectively. The two reference strains from America and Denmark showed similar electrophoresis patterns but were significantly different with O:8 strains isolated from China while the serotypes of Yersinia enterocolitica O:3 and O:9 which were the main epidemic strains in China, were not found in this area. CONCLUSION: The pathogenic Yersinia enterocolitis O:3 and O:9 were not found in Nantong,Jiangsu province.

Animals↗
PubMed2004

Proteome comparison of Vibrio cholerae cultured in aerobic and anaerobic conditions.

The pathogen Vibrio cholerae causes severe diarrheal disease in humans. This environmental inhabitant has two distinct life cycles, in the environment and in the human small intestine, in which it differs in its multiplication behavior and virulence expression. Anaerobiosis, limitation of some nutrient elements, and excess burden from host metabolism reactants are the major stresses for V. cholerae living in intestine, in comparison to conditions in the environment and laboratory medium. For an insight into the response of V. cholerae to different microenvironments, we cultured the bacteria in aerobic and anaerobic conditions, and compared the whole cell proteome by two-dimensional electrophoresis. Among the protein spots identified, some protein species involved in aerobic respiration and the nutrient carbohydrate transporters were found to be more abundant in aerobic conditions, and some enzymes for anaerobic respiration and some stress response proteins were found more abundant in anaerobic culture. One spot corresponding to flagellin B subunit was decreased in anaerobic conditions, which suggests correlation with the meticulous regulation of bacterial motility during infection in the host intestine. This proteome analysis is the starting point for in-depth understanding of V. cholerae behavior in different environments.

Bacterial Proteins↗