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1.
In order to identify gene sequences unique to the virulent strains, suppression subtractive hybridization (SSH) was conducted using virulent Streptococcus suis type 2 (SS2) strain HA9801 and avirulent S. suis type 2 strain T15. Thirty genomic regions were absent in T15, and the DNA sequences of these regions in HA9801 were determined. These DNA fragments, containing putative virulence genes, encoded 28 proteins that were homologous to proteins involved in various aspects of cellular surface structure, molecular synthesis, energy metabolism, regulation, transport systems and others of unknown function. According to the published SS2 genomic sequence of the Chinese strain 98HAH33, PCR primers for 14 significant DNA fragments were designed and used for detection of the distribution of these fragments in S. suis strains from different sources, serotypes, regions, groups and times. The results showed that these 14 DNA fragments were widely distributed in 37 detected SS2 strains, yet were absent among the avirulent strain T15. Moreover, these fragments could be detected in other serotypes of S. suis, but each serotype had a different distribution of the fragments. 相似文献
2.
Pridgeon JW Aksoy M Klesius PH Li Y Mu X Srivastava K Reddy G 《Veterinary immunology and immunopathology》2011,144(1-2):111-119
To understand the molecular mechanisms involved in response of Nile tilapia (Oreochromis niloticus) to bacterial infection, suppression subtractive cDNA hybridization technique was used to identify upregulated genes in the posterior kidney of Nile tilapia at 6h post infection with Aeromonas hydrophila. A total of 31 unique expressed sequence tags (ESTs) were identified from 192 clones of the subtractive cDNA library. Quantitative PCR revealed that nine of the 31 ESTs were significantly (p<0.05) upregulated in Nile tilapia at 6h post infection with A. hydrophila at an injection dose of 10(5)CFU per fish (≈ 20% mortality). Of the nine upregulated genes, four were also significantly (p<0.05) induced in Nile tilapia at 6h post infection with A. hydrophila at an injection dose of 10(6)CFU per fish (≈ 60% mortality). Of the four genes induced by A. hydrophila at both injection doses, three were also significantly (p<0.05) upregulated in Nile tilapia at 6h post infection with Streptococcus iniae at doses of 10(6) and at 10(5)CFU per fish (≈ 70% and ≈ 30% mortality, respectively). The three genes induced by both bacteria included EST 2A05 (similar to adenylate kinase domain containing protein 1), EST 2G11 (unknown protein, shared similarity with Salmo salar IgH locus B genomic sequence with e value of 0.02), and EST 2H04 (unknown protein). Significant upregulation of these genes in Nile tilapia following bacterial infections suggested that they might play important roles in host response to infections of A. hydrophila and S. iniae. 相似文献
3.
K. M. Townsend H. J. S. Dawkins B. J. Zeng M. W. Watson J. M. Papadimitriou 《Research in veterinary science》1996,61(3):199-205
Two Carter type B Pasteurella multocida isolates, Izatnagar 52 and 25, isolated from cases of haemorrhagic septicaemia (
), were used in a modified subtractive hybridisation technique with the specific aim of cloning unique DNA sequences related to the pathogenesis of HS. Biochemical and protein analyses have shown these isolates to be similar, but reports indicate that they have differences in pathogenicity. The subtracted inserts were screened against genomic DNA from a wide range of P multocida isolates, with two distinct fragments demonstrating specific hybridisation with Carter type B isolates that cause
. No identity was observed with either Carter type E isolates or non-HS type B strains. The clones were sequenced and a search of the GenBank database revealed significant identity of the clone A3b (296 nt) to P haemolytica lipoprotein, whereas there was no significant identity with 6b (956 nt). Both these fragments had a high level of identity (72·8 to 76·9 per cent) to the H infuenzae Rd genome. 相似文献
4.
Saber Jelokhani-Niaraki Majid Esmaelizad Morteza Daliri Rasoul Vaez-Torshizi Morteza Kamalzadeh Mohsen Lotfi 《Journal of veterinary science (Suw?n-si, Korea)》2010,11(3):243-247
The A Iran 05 foot-and-mouth disease virus (FMDV) subtype was detected in Iran during 2005 and has proven to be highly virulent. This study was undertaken to focus on molecular and phylogenetic analysis of 3A and 3B coding-regions in the A Iran 05 field isolate. To assess the genetic relatedness of A Iran 05 isolate the nucleotide and predicted amino acid sequences of the 3AB region of type A FMDV isolates were compared with twenty previously described type A FMDV isolates. The phylogenetic tree based on the 672 bp 3AB gene sequences of type A FMDV from thirteen different locations clustered them into five distinct lineages. The A Iran 05 isolate clustered in lineage A along with four type A variants and was closely matched with viruses isolated in Turkey and Pakistan during 2005~2006. The number of protein sequence differences exhibited by each of the isolates revealed that A Iran 05 isolate contains three amino acid substitutions at positions 47 and 119 of 3A and 27 of the 3B coding region. The nucleotide identity between A Iran 05 and the other four isolates of lineage A was estimated to be 98%. 相似文献
5.
Protozoan Ichthyophthirius multifiliis Fouquet (Ich) and bacterium Aeromonas hydrophila are two common pathogens of cultured fish, which cause high fish mortality. Currently there is no information available for the effect of parasitism by Ich on survival of channel catfish and invasion of A. hydrophila in fish tissues following exposure to A. hydrophila. A trial was conducted in this study to: (1) determine whether A. hydrophila increased fish mortality in Ich-parasitized channel catfish; and (2) compare the bacterial quantity in different tissues between non-parasitized and Ich-parasitized catfish by real-time polymerase chain reaction (qPCR). The results demonstrated that the Ich-parasitized catfish showed significantly (P<0.05) higher mortality (80%) when exposed to A. hydrophila by immersion than non-parasitized fish (22%). Low mortality was observed in catfish exposed to Ich alone (35%) or A. hydrophila alone (22%). A. hydrophila in fish tissues were quantified by qPCR using a pair of gene-specific primers and reported as genome equivalents per mg of tissue (GEs/mg). Skin, gill, kidney, liver and spleen in Ich-parasitized fish showed significantly higher load of A. hydrophila (9400-188,300 GEs/mg) than non-parasitized fish (4700-42,100 GEs/mg) after exposure to A. hydrophila. This study provides evidence that parasite infections enhance bacterial invasion and cause high fish mortality. 相似文献
6.
R A Joshua 《Veterinary parasitology》1990,36(3-4):303-309
Quantitative methods were adopted to study the course of Trypanosoma congolense infection in mice and goats. The ease of initiating infection with a single organism (clone) was found to show a smooth correlation with the virulence of 24 isolates. Virulence of T. congolense was found to be directly related to the degree of viability of the parasite but inversely proportional to the capacity of the host to limit parasitaemia. Isolates obtained from the goat in the early stage of the infection were found to be highly infective but moderately virulent; subsequent isolates were of low infectivity and low virulence. Organisms obtained at the terminal stage of the infection were highly virulent. Generally, the highly virulent clones produced rapidly high parasitaemia and mortality in the host. The low virulence clones were characterised by low parasitaemia but very pronounced remission of trypanosomaemia. 相似文献
7.
嗜水气单胞菌不同分离株生化特性及胞外蛋白酶的检测 总被引：2，自引：0，他引：2
嗜水气单胞菌可引起多种宿主患病,该菌致病性与其产生的多种毒力因子特别是胞外蛋白酶有关。本研究检测了26株嗜水气单胞菌不同分离株的生化指标,采用脱脂乳平板法检测了胞外蛋白酶的产生情况,并利用PCR技术检测了2种胞外蛋白酶基因ahp-A(编码丝氨酸胞外蛋白酶)和eprCAI(编码温敏胞外蛋白酶)。结果表明,大部分菌株生化指标表现为蔗糖(+)、阿拉伯糖(+)、葡萄糖(+)、甘露醇(+)、鸟氨酸脱羧酶(-)、肌醇(-)、七叶苷(+);脱脂乳平板法检测发现,91.7%(22/24)的致病菌株均能产生胞外蛋白酶,而2株无毒株则不能产生,对2个胞外蛋白酶基因的检测也得到相似的结果。本研究将为嗜水气单胞菌的流行病学调查和致病机制的深入研究奠定基础。 相似文献
8.
传染性法氏囊病病毒VP2基因高变区序列分析 总被引：3，自引：0，他引：3
根据传染性法氏囊病病毒（ＩＢＤＶ）ＶＰ２基因ＣＤＮＡ序列,在ＶＰ２基因高变区设计一对引物,用ＲＴ－ＰＣＲ方法扩增ＩＢＤＶ分离株ＪＳ３和ＪＳ４。将扩增片段克隆后以双脱氧链末端终止法测定核苷酸旬。ＪＳ３和ＪＳ４的同源性最高达９８％。与已发表的ｖｖＩＢＤＶ,ＩＢＤＶ变异要ＢＤＶ经典株为ＩＢＤＶ弱毒株核苷酸序列的同尖拨天９２￣９８％之间,根据ＩＢＤＶ的大ＯＲＦ推导出该片段蛋白的氨基酸序更,ＪＳ３和ＪＳ４的 相似文献
9.
Aeromonas hydrophila is a broad-host-range pathogen and its pathogenesis is multifactorial. A regulatory mechanism known as quorum sensing has been found to be involved in the regulation of virulence in many bacteria. In A. hydrophila the ahyR gene encodes LuxR-type response regulator. Here we describe the inactivation of the ahyR gene of A. hydrophila J-1 by the insertion of a DNA fragment containing a kanamycin resistance determinant and reintroduced by allelic exchange into the chromosome of A. hydrophila J-1 by means of the suicide plasmid pJP5603. Cytotoxic effects on EPC cells assay and LD(50) determinations in fish demonstrated that the ahyR mutant was highly attenuated relative to the wild-type strain. Compared with the parent strain, some characteristics, such as biochemical characters and outer membrane protein profiles, had changed. Some main virulent determinants could not be detected, including proteases, amylase, Dnase, hemolysin and S layer. This article confirmed the important function of AhyR in the pathogenesis of A. hydrophila J-1. 相似文献
10.
Presence of the Streptococcus suis suilysin gene and expression of MRP and EF correlates with high virulence in Streptococcus suis type 2 isolates 总被引：27，自引：0，他引：27
Nineteen Streptococcus suis type 2 isolates that had been analyzed previously for hemolysin production, ribotype, and virulence in pigs were examined for presence of the gene coding for suilysin by PCR amplification, and southern blot and hybridization techniques. Based on southern blot and hybridization analysis, all isolates tested contained at least a portion of the suilysin gene. PCR amplification of the entire gene resulted in gene fragments from five of the seven highly virulent isolates and none of the moderately virulent or avirulent isolates. Additional PCR analysis showed that mutation or deletions at the 5′ end of the suilysin gene in the less virulent isolates prevented amplification of the sly gene fragment from those isolates. The MRP+ (muramidase-released protein) EF+ (extracellular protein) phenotype was also expressed by the same five highly virulent/sly+ isolates. 相似文献
11.
The subtractive suppressive hybridization (SSH), a method that allows the identification of sequences that are present in one genome (tester) but not in the other (driver), is a promising technique for the comparison of Mycoplasma agalactiae pathogenic strains. The optimal conditions for SSH were established by subtracting the M. agalactiae type strain PG2 DNA from the M. agalactiae strain 5632 DNA. Because these two strains possess different vpma gene repertoires, 5632-specific vpma sequences (and possibly other 5632-specific sequences) were predicted to be retrieved by SSH. The subtracted tester DNA was PCR-amplified and cloned into the pGEM-T easy E. coli vector. Two independent libraries were generated and used to prepare individual probes that were tested by Southern blot with genomic DNA from various field isolates and mycoplasma reference strains. Sequence analysis of two overlapping clones showed that they potentially code for a large carboxyterminal portion of a new vpma ORF. Several DNA fragments homologous to insertion sequences were also found in 5632 and related strains. These preliminary data suggest that SSH is a powerful method to investigate differences between mycoplasma strains, and may be applied to molecular epidemiology, diagnostic, and host specificity or pathogenicity determinant discovery. 相似文献
12.
通过毒力测定、RT-PCR及F基因的序列测定与遗传进化分析,对2005-2008年从河北省部分地区的发病鸡群中分离到的10株新城疫病毒（NDV）进行了研究。各分离株经典毒力测定结果显示：MDT在37.6～54.4h之间,ICPI在1.71～2.0之间,IVPI值在2.16～2.8之间,均为新城疫病毒强毒株特征。F基因的序列测定表明,分离株之间的核苷酸序列具有77.4%～98.0%的同源性,与疫苗株Lasota的同源性为87.0%～98.9%,与国内标准强毒株F48E9同源性为89.7%～98.9%。推导其氨基酸序列分析表明,8个分离株的F蛋白的裂解位点氨基酸组成为112 R-R-Q-K-R-F117,具有NDV强毒株特征,与毒力测定结果相符,2个分离株的F蛋白的裂解位点氨基酸组成为112 G-R-Q-G-R-L117,与弱毒株特征相符。F基因分型和同源性比较显示：目前河北新城疫的流行以基因Ⅶ型为主（占70%）,同时兼有基因Ⅱ型（占20%）和基因Ⅸ型（占10%）。 相似文献
13.
A synthetic deoxyribonucleotide probe for virulent Listeria monocytogenes, designated ADO7, was evaluated for its ability to identify restriction fragments of L. monocytogenes with nucleic acid sequences homologous with the beta-hemolysin gene by Southern blot hybridization of clinical and food isolates. The synthetic probe hybridized with three restriction fragments (approximately 1.1, 0.86, and 0.76 kb) of the serotype 1/2A isolates. Southern blot hybridization of the serogroup 4B isolates indicated that the nucleic acid sequences homologous with the beta-hemolysin gene probe were limited to a single restriction fragment of approximately 1 kb. 相似文献
14.
Tan C Tang X Zhang X Ding Y Zhao Z Wu B Cai X Liu Z He Q Chen H 《Veterinary journal (London, England : 1997)》2012,192(3):483-488
Extraintestinal pathogenic Escherichia coli (ExPEC) isolates were detected in 315/3127 (10.1%) diseased pigs from 19 provinces of China; the frequency of isolation increased from 3.1% in 2004 to 14.6% in 2007. All isolates were characterised for O serogroups, haemolysis, phenotypic and genotypic antimicrobial resistance, virulence genes and pathogenicity. The most prevalent serogroups were O161, O8, O11, O138, O101 and O26; 83/315 (26.3%) isolates were haemolytic. Forty percent of isolates in phylogenetic groups B2 and D were highly virulent porcine ExPEC strains. Thirty-three putative extraintestinal virulence factor genes that are normally associated with human and/or avian ExPEC strains were widely present in porcine isolates. These results indicate that ExPEC are prevalent in pigs in China and represent a potential public health threat. 相似文献
15.
Keawcharoen J Theamboonlers A Jantaradsamee P Rungsipipat A Poovorawan Y Oraveerakul K 《Veterinary microbiology》2005,105(2):137-142
The C-terminal part of the nucleocapsid protein gene of 13 canine distemper virus (CDV) isolates from Thailand, were analyzed. The nucleotide sequences were assigned to two clusters; cluster A exhibited a high degree of homology with the vaccine strain Onderstepoort, 99.10 and 97.61%, respectively, in the two isolates examined. Cluster B appeared closely related to virulent strains registered in the GeneBank database and to the virulent reference strain (A75/17); a total of 11 samples were analyzed, with 94.63-99.10% homology at the same position. The deduced amino acid sequences correlated with the two-nucleotide sequence clusters. However, there was no association among the CDV groups with histories of vaccination, sex, ages, clinical findings and evidence of viral antigen in tissues. 相似文献
16.
Calus D Baele M Meyns T de Kruif A Butaye P Decostere A Haesebrouck F Maes D 《Veterinary microbiology》2007,120(3-4):284-291
Sodium-dodecyl-sulphate polyacrylamide gel electrophoresis (SDS-PAGE) was used to study the protein variability of Mycoplasma hyopneumoniae isolates. Fifty-six M. hyopneumoniae isolates from 6 different countries and 37 different herds were used. From eight herds, more than one isolate was available. All SDS-PAGE patterns of isolates originating from different herds were clearly divergent. Intra-species protein variability was quantified using the reference strain J and seven field strains all obtained from different herds and classified according to virulence. Between the field strains, a variability of 25% was found, while the culture-adapted strain J was clearly divergent and showed 30% variability with the field strains. No clustering according to virulence was obtained, but a protein band of about 181 kDa was present in the two highly virulent isolates whereas this protein band was absent in the moderately and low virulent isolates. Protein patterns of isolates derived from different animals from the same herd, were identical or differed in only a few protein bands. This study clearly indicates that, in agreement with previous studies on genomic diversity of M. hyopneumoniae isolates, proteomic variability within the species is high. Our study did not find clear evidence that more than one M. hyopneumoniae isolate circulates within a herd at a specific time point. The minor differences found between M. hyopneumoniae isolates from the same herd might reflect the organism's ability to alter its proteomic expression profile under field conditions. 相似文献
17.
Twenty-eight expressed sequence tags (ESTs) were isolated from a Nile tilapia (Oreochromis niloticus) vaccinated vs non-vaccinated subtractive library at 12-h post injection of a formalin killed Streptococcus iniae ARS-98-60 vaccine. The 28 ESTs were classified in terms of their putative functions. Half of the ESTs identified were unknown proteins. Of the remaining half ESTs, 17% have putative functions in protein biosynthesis and 11% have putative functions in immunity, energy production, and signal transduction, respectively. Immunity-related ESTs identified included high density lipoprotein-binding protein vigilin, immunoglobulin heavy chain, and QM-like protein. Quantitative PCR revealed that one EST (cytochrome c oxidase subunit II) was highly upregulated (1825 ± 336 fold) in vaccinated fish compared to that in non-vaccinated fish. Of the remaining 27 ESTs, nine were significantly (P<0.05) upregulated (<20 fold) in vaccinated fish. The nine significantly upregulated genes included five unknown or hypothetical proteins and four known proteins (high density lipoprotein-binding protein vigilin, QM-like protein, ribosomal protein S13, and ribosomal protein L5). The upregulation of these genes induced by killed S. iniae vaccines suggest that they might play important role in Nile tilapia defense against S. iniae infection. 相似文献
18.
Feline Immunodeficiency Virus (FIV) is a Lentivirus responsible for an immunodeficiency like disease in domestic cats. Based on the genetic diversity of the V3-V5 region of env gene FIV is divided in five phylogenetic subtypes (A, B, C, D and E) with a world-wide distribution. To understand the subtype diversity of FIV in Portugal a serological survey was conducted during 1 year in the Veterinary Faculty Hospital, Lisbon, Portugal to identify seropositive animals. Two viral genomic regions were amplified by a nested PCR, sequenced and the phylogenetic relationships between 24 new Portuguese FIV sequences and other previously published FIV isolates were assessed. The introduction of these sequences induced a subclustering in subtype B including most of the new Portuguese sequences. Moreover, a new cluster emerged, with two highly divergent new sequences that might represent a new subtype. The study of these new FIV isolates showed the presence in Portugal of a unique viral population subclustering within subtype B and of sequences clearly divergent from the five known subtypes, providing a contribution for the understanding of FIV's genetic diversity. 相似文献
19.
Putative immunoglobulin VH genes of the goldfish, Carassius auratus, detected by heterologous cross-hybridization with a murine VH probe 总被引：3，自引：0，他引：3
M R Wilson D Middleton C Alford J T Sullivan G W Litman G W Warr 《Veterinary immunology and immunopathology》1986,12(1-4):21-28
By using a defined cDNA probe for the VH region of a murine phosphocholine-binding myeloma protein (S107) we have defined a family of distinct cross-hybridizing DNA sequences in genomic DNA of the goldfish. The estimated number of the goldfish putative VH family detectable by the S107 probe is about 36. By using two putative goldfish VH probes to analyze, by hybridization, the relationships among seven of the goldfish genomic clones, we have determined that the putative goldfish VH genes recognized by the S107 probe comprise at least several distinct families that are not closely related. 相似文献
20.
Nucleotide sequence analysis of VP2 hypervariable domain of infectious bursal disease virus detected in Japan from 1993 to 2004 总被引：2，自引：0，他引：2
Yamaguchi T Kasanga CJ Terasaki K Maw MT Ohya K Fukushi H 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2007,69(7):733-738