首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献，搜索用时 453 毫秒
1.
Apx toxins in Pasteurellaceae species from animals   总被引：6，自引：0，他引：6  
Pasteurellaceae species particularly of porcine origin which are closely related to Actinobacillus pleuropneumoniae were analyzed for the presence of analogues to the major A. pleuropneumoniae RTX toxin genes, apxICABD, apxIICA and apxIIICABD and for their expression. Actinobacillus suis contains both apxICABD(var.suis) and apxIICA(var. suis) operons and was shown to produce ApxI and ApxII toxin. Actinobacillus rossii contained the operons apxIICA(var.rossii) and apxIIICABD(var.rossii). However, only the toxin ApxII and not ApxIII could be detected in cultures of A. rossii. The Apx toxins found in A. suis and A. rossi may play a role in virulence of these pathogens. Actinobacillus lignieresii, which was included since it is phylogenetically very closely related to A. pleuropneumoniae, was found to contain a full apxICABD(var.lign.) operon which however lacks the -35 and -10 boxes in the promoter sequences. As expected from these results, no expression of ApxI was detected in A. lignieresii grown under standard culture conditions. Actinobacillus seminis, Actinobacillus equuli, Pasteurella aerogenes, Pasteurella multocida, Haemophilus parasuis, and also Mannheimia (Pasteurella) haemolytica, which is known to secrete leukotoxin, were all shown to be devoid of any of the apx toxin genes and did not produce ApxI, ApxII or ApxIII toxin proteins. However, proteins of slightly lower molecular mass than ApxI, ApxII and ApxIII which showed limited cross-reactions with monospecific, polyclonal anti-ApxI, anti-ApxII and anti-ApxIII were detected on immunoblot analysis of A. equuli, A. seminis and P. aerogenes. The presence of Apx toxins and proteins that imunologically cross react with Apx toxins in porcine Actinobacillus species other than A. pleuropneumoniae can be expected to interfere with serodiagnosis of porcine pleuropneumonia.  相似文献   

2.
Actinobacillus pleuropneumoniae (A. pleuropneumoniae) is the etiological agent of a porcine pleuropneumonia that threatens the global swine industry. The major pathogenic toxins of A. pleuropneumoniae include ApxI, ApxII, ApxIII, and ApxIV, which are serotype or serovar specific. Several techniques have been developed for the identification and typing of A. pleuropneumoniae. Serological assays are used to identify and serotype A. pleuropneumoniae, but factors such as cross-reactivity limit their specificity. Labor, time, and the requirement for specific antibodies are also drawbacks of these assays. Multistep polymerase chain reaction (PCR) techniques based on apx genes have been reported for the identification and typing of A. pleuropneumoniae. This study developed multiplex PCR for the identification and genotyping of A. pleuropneumoniae based on apx genes. This multiplex PCR technique was successful in differentiating 11 of 15 reference serotypes. Five different primer sets were used to amplify the 4 apx genes from each serotype in a single-step reaction. The multiplex PCR reported in this study was further used in genotyping 51 field isolates of A. pleuropneumoniae from different regions of Korea. The concomitant amplification of all 4 apx genes makes multiplex PCR more specific and convenient for the diagnosis and genotyping of A. pleuropneumoniae.  相似文献   

3.
We assessed and compared host cell specificity of the haemolytic and cytotoxic activity of the RTX toxins from Actinobacillus equuli, an equine pathogen, and Actinobacillus suis, which is pathogenic for pigs. The two bacterial species are closely related, phenotypically as well as phylogenetically, sharing the same 16S rRNA gene sequence. Both species contain specific protein toxins from the family of pore-forming RTX toxins, however, the two species differ in their RTX toxin profiles. Haemolytic A. equuli contains the operon for the Aqx toxin, whereas A. suis harbours genes for ApxI and ApxII. We tested the toxic activity of the corresponding proteins on erythrocytes as well as on lymphocytes isolated from horse and pig blood. The strength of the haemolytic activity for each of the toxins was independent of the origin of erythrocytes. When testing cytotoxic activity, the Aqx protein showed a higher toxic effect for horse lymphocytes than for porcine lymphocytes. On the other hand, ApxI and ApxII showed a strong cytotoxic effect on porcine lymphocytes and a reduced toxicity for horse lymphocytes; the toxicity of ApxII was generally much lower than ApxI. Our results indicate a host species specificity of the toxic activity of RTX toxins Aqx of A. equuli and ApxI and ApxII of A. suis.  相似文献   

4.
OBJECTIVE: To evaluate the serological response of pigs receiving either the Porcilis APP vaccine or a modified live vaccine based on a streptomycin-dependent (SD) strain of Actinobacillus pleuropneumoniae, and then challenged with an Australian isolate of A. pleuropneumoniae of either serovar 1 or 15 as a means of understanding the protection provided by both vaccines against serovar 1 but not against serovar 15. DESIGN: The serological tests evaluated were serovar-specific polysaccharide ELISA tests (for serovar 1 and 15), ELISA tests for antibodies to three A. pleuropneumoniae toxins (ApxI, ApxII and ApxIII) as well as to a 42 kDa outer membrane protein (OMP), a haemolysin neutralisation (HN) assay and immunoblotting. The tests were used to detect antibodies in vaccinated pigs that had been shown to be protected against serovar 1 but not serovar 15. RESULTS: In the polysaccharide antigen ELISA assays, both vaccines resulted in a significant rise in the titre in the serovar 1 ELISA but not the serovar 15 ELISA. The Porcilis APP vaccinated pigs showed a significant response in the ApxI, ApxIII and 42 kDa OMP ELISA. In the ApxII ELISA, all pigs tested (the Porcilis APP vaccinates and the controls) were positive on entry to the trial. In the HN assay, the Porcilis APP vaccinated pigs showed a significant response after one dose while the SD vaccinated pigs required two doses of vaccine before a marked rise in titre was induced. Immunoblotting revealed that neither vaccine generated antibodies that recognised the ApxIII produced by serovar 15. CONCLUSIONS: The failure of these vaccines to provide protection against serovar 15 may be due to novel virulence factors possessed by serovar 15, significant differences between the ApxIII toxin of serovar 15 and those present in the Porcilis APP vaccine or failure by both vaccines to induce antibodies to the serovar 15 specific polysaccharide.  相似文献   

5.
Most serotypes of A. pleuropneumoniae produce more than one toxin in vivo. To determine the value of the production of more than one toxin in the development of disease, we tested the pathogenicity of isogenic strains of A. pleuropneumoniae serotype 1 that are mutated in the toxin genes apxIA and/or apxIIA or in the transport genes apxIBD. Bacteria mutated in both apxIA and apxIIA, or in apxIBD, were unable to induce pathological lesions, thereby confirming the conclusion that ApxI and ApxII are essential for the pathogenesis of pleuropneumonia. Infection with isogenic strains lacking either ApxI or ApxII did not consistently lead to pleuropneumonia unlike the parent strain S4074. ApxII seemed at least as important as ApxI for the development of clinical and pathological symptoms. Only one of the four pigs inoculated with a mutant strain unable to produce ApxII developed mild pneumonia whereas two out of the three pigs inoculated with a mutant strain unable to produce ApxI developed more severe lesions. The results indicate that both ApxI and ApxII of A. pleuropneumoniae serotype 1 are necessary for full virulence.  相似文献   

6.
Actinobacillus pleuropneumoniae, a gram-negative rod of the Pasteurellaceae family, causes pleuropneumonia in pigs. Establishing A. pleuropneumoniae free herds is difficult due to the occurrence of persistently infected animals. The ApxIV toxin is expressed by A. pleuropneumoniae in vivo and an ELISA based on the toxin is used to detect infection and to differentiate between infected and vaccinated animals. In this study, we have identified a 1070bp insertion element of the IS30 family, designated ISApl1, in the A. pleuropneumoniae serotype 7 strain AP76. ISApl1 contains a 924bp ORF encoding a transposase, which is flanked by 27bp inverted repeats showing six mismatches. We investigated the occurrence of ISApl1 in other A. pleuropneumoniae strains, and its possible interference with virulence associated factors. Four insertion sites were identified in AP76: within the apxIVA toxin ORF, within a putative autotransporter adhesin ORF, upstream of a capsular polysaccharide biosynthesis gene cluster, and downstream of a beta-lactamase gene. ISApl1 is also present in some serotype 7 field isolates, but not in reference or field strains of other serotypes. In A. pleuropneumoniae AP76, the transposase gene is transcribed in vitro. The insertion in the apxIVA toxin gene remains stable after animal passage. Since this insertion should disrupt toxin expression, we tested 7 pigs infected with AP76 at day 21 post-infection. All were negative in the ApxIV ELISA but four out of seven were positive in an ApxII toxin ELISA. These results show that insertion elements can affect the detection of A. pleuropneumoniae infected animals.  相似文献   

7.
Two unusual Actinobacillus isolates were recovered from pigs with no clinical signs, no lesions and no history of swine pleuropneumonia. Two representative strains (9953L55 and 0347) analyzed in this study were initially biochemically and antigenically identified as A. pleuropneumoniae serotypes 1 and 9, respectively, by traditional identification methods. Both strains presented, however, negative results with three A. pleuropneumoniae-specific PCR tests and revealed in particular the absence of the apxIV toxin genes. However, both strains produced and secreted ApxII toxin although they only harbored the toxin genes apxIICA, which is an uncommon feature for any of the known A. pleuropneumoniae serotypes. Upon experimental inoculation of pigs, these strains proved to be totally non-pathogenic. Animals infected with one of the strains produced antibodies that cross-react with A. pleuropneumoniae serotypes 1-9-11-specific LC-LPS ELISA. Phylogenetic analysis based on 16S rRNA gene sequence analysis revealed that these strains form a separate phylogenetic group that is distinct from other Actinobacillus species and is particularly different from A. pleuropneumoniae.  相似文献   

8.
Capsular polysaccharide antigens of serotypes 1, 2, 5 and 7 of Actinobacillus pleuropneumoniae were used in enzyme-linked immunosorbent assays (ELISAs) to test sera from experimentally infected and field pigs. Specific reactions were found in sera of experimental pigs with antigens of serotypes 1, 5 and 7 whereas the serotype 2 antigen was cross-reactive. A 1:200 serum dilution was used for testing of 300 sera from 21 swine herds in southern Ontario. Cases of pleuropneumonia had occurred in 11 of these herds, but not in the others. The negative cut-off value was the mean optical density at 405 nm (OD405) + three standard deviations (SD) for 16 negative reference sera. Sera from four pigs naturally infected with Actinobacillus suis were tested and found to react to varying degrees with each of the antigens. Therefore a second cut-off value was determined as the mean OD405 + 2 SD for the A. suis sera. Sera which, in the ELISA produced OD readings above the latter cut-off were considered positive for antibodies to A. pleuropneumoniae; those which were lower than the former cut-off were considered negative. Readings between the two cut-off values may have been due to low positive titers or cross-reactivity, possibly with A. suis, and could not be used to predict pleuropneumonia. Of the pleuropneumonia-free herds, none had positive reactors to serotypes 5 or 7, whereas one and two herds had positive reactors to serotypes 1 and 2, respectively. Of the pleuropneumonia positive herds, six had positive reactors to serotype 1, one to serotype 2, four to serotype 5, and eight to serotype 7.  相似文献   

9.
During serological screening of a closed SPF-herd free of pleuropneumonia, more than half of the pigs were positive for complement-fixing antibodies to Haemophilus pleuropneumoniae. Actinobacillus bacteria closely related to A. suis were isolated from tonsillar tissue of 14 out of 20 slaughtered pigs submitted for pathological and bacteriological evaluation. None of the pigs had evidence of respiratory disease. Two pigs inoculated endobronchially with a selected Actinobacillus strain developed mild focal pneumonia and complement-fixing antibodies cross-reacting with H. pleuropneumoniae. Five pigs exposed and vaccinated with the Actinobacillus strain and five pigs spontaneously infected with the strain also developed complement-fixing antibodies against H. pleuropneumoniae and appeared to be less susceptible to experimental Haemophilus pleuropneumonia than pigs not exposed to the Actinobacillus infection. The agglutination test applied on serum treated with 2-mercaptoethanol detected antibodies against H. pleuropneumoniae serotype 5 but not against serotype 1 in pigs exposed to the Actinobacillus strain. Antibodies reactive with the Actinobacillus strain were also found in pigs hyperimmunized against H. pleuropneumoniae serotypes 1-5 in 2-mercaptoethanol tube agglutination test and rabbits hyperimmunized against serotypes 1,2 and 7, and strain 73567 in the immunodiffusion test. Conversely rabbits immunized against the Actinobacillus strain had antibodies against H. pleuropneumoniae serotypes 1, 3, 4, 5 and 6. It is concluded that pigs infected with Actinobacillus organisms may become false positive reactors against H. pleuropneumoniae.  相似文献   

10.
The reference strains of the 12 serotypes of Actinobacillus pleuropneumoniae express one or two of three different RTX exotoxins designated Apx I, Apx II and Apx III. The toxins are important virulence factors. In the present study, ELISAs with purified Apx I, Apx II and Apx III, respectively, as antigen were evaluated as candidates for serological diagnosis of Actinobacillus pleuropneumoniae infection in pigs. The pigs were inoculated with biotype 1, serotypes 1-12, and biotype 2, serotype 14, respectively. A strong humoral antibody response was seen to all the three antigens in most pigs irrespective of the serotype used for inoculation. However, titers to the exotoxins secreted by the serotype used for inoculation were generally highest. The results show that toxin proteins of Actinobacillus pleuropneumoniae are antigenically related and that a correlation between serotype and secretion of exotoxin is not revealed serologically in the ELISA test.  相似文献   

11.
Xu F  Chen X  Shi A  Yang B  Wang J  Li Y  Guo X  Blackall PJ  Yang H 《Veterinary microbiology》2006,118(3-4):230-239
Actinobacillus pleuropneumoniae is the aetiological agent of porcine pleuropneumonia, a highly contagious and often fatal disease. A candidate live vaccine strain, potentially capable of cross-serovar protection, was constructed by deleting the section of the apxIA gene coding for the C-terminal segment of ApxI toxin of the A. pleuropneumoniae serovar 10 reference strain (D13039) and inserting a chloramphenicol resistance gene cassette. The mutant strain (termed D13039A(-)Chl(r)) produced an approximately 48kDa protein corresponding to the N-terminus of the ApxI toxin, and exhibited no haemolytic activity and lower virulence in mice compared with the parental strain. The mutant was evaluated in a vaccination-challenge trial in which pigs were given two intra-nasal doses of the mutant at 14 days intervals and then challenged 14 days after the last vaccination with either A. pleuropneumoniae serovar 1 (4074) or serovar 2 (S1536) or serovar 10 (D13039) reference strains. The haemolysin neutralisation titres of the pre-challenge sera were significantly higher in the vaccinated pigs than in the unvaccinated pigs. The mortalities, clinical signs and lung lesion scores in the vaccinated pigs were significantly lower than those in the unvaccinated pigs for the serovar 1 challenge. A significantly lower lung lesion score was also observed in the vaccinated pigs, compared with unvaccinated pigs, for serovar 2 challenge. Our work suggests that the mutant strain offers potential as a live attenuated pleuropneumonia vaccine that can provide cross-serovar protection.  相似文献   

12.
Pigs, asymptomatically infected with Actinobacillus pleuropneumoniae in their upper respiratory tract, can transmit the infection. Detection of such animals is indispensable to prevent the intake of the disease in a herd. This study was conducted to evaluate bacteriology, polymerase chain reaction (PCR) and serology for the detection of subclinically infected pigs. Pigs were inoculated onto the tonsils with an A. pleuropneumoniae serotype 9 strain (n=12, group 1) or phosphate buffered saline solution (PBSS) (n=5, group 2). To prevent infection of the lungs, pigs of group 1 were treated three times with sodium ceftiofur as an aerosol. A third group (n=5) was inoculated intranasally with the same strain. All animals were euthanized 30 days post-inoculation (dpi). In pigs of group 1, clinical signs were not observed. A small lung lesion was found in only one pig and A. pleuropneumoniae was isolated from this lesion. The bacterium was not isolated from the lungs of animals that did not develop lung lesions. A. pleuropneumoniae was demonstrated in tonsils of 9/12 animals using bacteriological isolation, whereas it was demonstrated in mixed bacterial cultures from tonsils of all 12 animals by PCR. In non-infected animals (group 2), clinical signs were not observed and A. pleuropneumoniae was not demonstrated in any sample. All intranasally infected animals (group 3) developed disease signs and lung lesions. High antibody titers against ApxI, ApxII and heat-stable antigens were detected in animals that developed lung lesions. Antibody titers against these antigens were low or absent in all other pigs. It was concluded that pigs carrying A. pleuropneumoniae in the upper respiratory tract generally do not show measurable antibodies in serum. Therefore, sensitive methods for the detection of the etiological agent such as PCR are required to identify carrier animals, while serological methods are not suitable.  相似文献   

13.
Actinobacillus pleuropneumoniae is a causative agent of porcine pleuropneumonia, a highly contagious endemic disease of pigs worldwide, inducing significant economic losses worldwide. Apx toxins, which are correlated with the virulence of A. pleuropneumoniae, were expressed in Saccharomyces cerevisiae and its possible use as an oral vaccine has been confirmed in our previous studies using a murine model. The present study was undertaken to test the hypothesis that oral immunization using S. cerevisiae expressing either ApxI or ApxII could protect pigs against A. pleuropneumoniae as an effective way of inducing both mucosal and systemic immune responses. The surface-displayed ApxIIA#5 expressing S. cerevisiae was selected as an oral vaccine candidate by finding on induction of higher immune responses in mice after oral vaccination. The surface-displayed ApxIIA#5 expressing S. cerevisiae and the ApxIA expressing S. cerevisiae were developed to serve as an oral vaccine in pigs. The vaccinated pigs showed higher specific IgG- and IgA-related antibody activities than the non-treated control and vector control pigs. Additionally, the induced immune responses were found to protect pigs infected with A. pleuropneumoniae according to the analysis of clinical signs and the gross and microscopic pulmonary lesions. These results suggested that the surface-displayed ApxIIA#5 and ApxIA in S. cerevisiae might be a potential oral vaccine to protect pigs against porcine pleuropneumonia. Thus the present study is expected to contribute to the development of a live oral vaccine against porcine pleuropneumonia as an alternative to current conventional vaccines.  相似文献   

14.
A blocking enzyme-linked immunosorbent assay (ELISA) detecting antibodies against Actinobacillus pleuropneumoniae (Ap) serotype 6 was developed. The blocking ELISA was based on the inhibition of a polyclonal antibody raised against Ap serotype 6. Purified lipopolysaccharide from Ap serotype 6 was used as antigen. The blocking ELISA was tested against sera from pigs experimentally infected with the 12 serotypes of Ap biotype 1. Cross-reaction with serotypes 3 and 8 but not with other serotypes was observed. The sensitivity and specificity of the test on a herd level were evaluated with sera from herds naturally infected with serotypes 2, 6, 8 or 12 and with sera from herds free of infection with any Ap serotype. The blocking ELISA showed a high herd sensitivity (1.00 (0.79-1.00)) and specificity (0.97 (0.93-0.99)).  相似文献   

15.
根据荚膜多糖和脂多糖抗原表位的不同，猪胸膜肺炎放线杆菌分为15个血清型，某些血清型问存在交叉反应，不同血清型甚至同一血清型不同菌株间的毒力大小不一样，致病性也有强弱之别。该菌的致病性与多种毒力因子密切相关，主要有外毒素、外膜蛋白、脂多糖、英膜多糖、转铁蛋白、脲酶等。本文综述了国内外对胸膜肺炎放线杆菌的几种主要毒力因子及血清型的研究进展。  相似文献   

16.
Equine Actinobacillus species were analysed phylogenetically by 16S rRNA gene (rrs) sequencing focusing on the species Actinobacillus equuli, which has recently been subdivided into the non-haemolytic A. equuli subsp. equuli and the haemolytic A. equuli subsp. haemolyticus. In parallel we determined the profile for RTX toxin genes of the sample of strains by PCR testing for the presence of the A. equuli haemolysin gene aqx, and the toxin genes apxI, apxII, apxIII and apxIV, which are known in porcine pathogens such as Actinobacillus pleuropneumoniae and Actinobacillus suis. The rrs-based phylogenetic analysis revealed two distinct subclusters containing both A. equuli subsp. equuli and A. equuli subsp. haemolyticus distributed through both subclusters with no correlation to taxonomic classification. Within one of the rrs-based subclusters containing the A. equuli subsp. equuli type strain, clustered as well the porcine Actinobacillus suis strains. This latter is known to be also phenotypically closely related to A. equuli. The toxin gene analysis revealed that all A. equuli subsp. haemolyticus strains from both rrs subclusters specifically contained the aqx gene while the A. suis strains harboured the genes apxI and apxII. The aqx gene was found to be specific for A. equuli subsp. haemolyticus, since A. equuli subsp. equuli contained no aqx nor any of the other RTX genes tested. The specificity of aqx for the haemolytic equine A. equuli and ApxI and ApxII for the porcine A. suis indicates a role of these RTX toxins in host species predilection of the two closely related species of bacterial pathogens and allows PCR based diagnostic differentiation of the two.  相似文献   

17.
A saline boiled extract (SBE), capsular polysaccharides (CPS) and long-chain lipopolysaccharides (LC-LPS) of Actinobacillus pleuropneumoniae serotype 7 have been evaluated in ELISA for the serodiagnosis of swine pleuropneumonia caused by this serotype. Mean optical densities (ODs) obtained with the 3 antigens using sera from negative herds as well as from animals experimentally and naturally exposed to A. pleuropneumoniae serotypes 7 or 4 were not statistically different. The positive ELISA reaction with anti-serotype 4 sera was unexpected with the CPS, which are supposed to be serotype-specific; LPS traces present in the CPS appeared to be responsible for this reaction. In addition, sera from animals exposed to A. pleuropneumoniae serotypes 5 or 10 presented cross-reactions with the SBE and the CPS, but not with the LC-LPS. Cross-reactions were mainly due to rough LPS, as shown by immunoblotting. The LC-LPS is easily obtainable and can be used for the detection of antibodies in animals infected with A. pleuropneumoniae serotypes 7 and 4.  相似文献   

18.
RTX toxins are bacterial pore-forming toxins that are particularly abundant among pathogenic species of Pasteurellaceae, in which they play a major role in virulence. RTX toxins of several primary pathogens of the family of Pasteurellaceae are directly involved in causing necrotic lesions in the target organs. Many RTX toxins are known as haemolysins because they lyse erythrocytes in vitro, an effect that is non-specific, but which serves as a useful marker in bacteriological identification and as an easily measurable signal in vitro in experimental studies. More recent studies have shown that the specific targets of most RTX toxins are leukocytes, with RTX toxins binding to the corresponding β-subunit (CD18) of β2 integrins and then exerting cytotoxic activity. After uptake by the target cell, at sub-lytic concentrations, some RTX toxins are transported to mitochondria and induce apoptosis. For several RTX toxins the binding to CD18 has been shown to be host specific and this seems to be the basis for the host range specificity of these RTX toxins. Observations on two very closely related species of the Pasteurellaceae family, Actinobacillus suis, a porcine pathogen particularly affecting suckling pigs, and Actinobacillus equuli subsp. haemolytica, which causes pyosepticaemia in new-born foals (sleepy foal disease), have revealed that they express different RTX toxins, named ApxI/II and Aqx, respectively. These RTX toxins are specifically cytotoxic for porcine and equine leukocytes, respectively. Furthermore, the ApxI and Aqx toxins of these species, when expressed in an isogenetic background in Escherichia coli, are specifically cytotoxic for leukocytes of their respective hosts. These data indicate the determinative role of RTX toxins in host specificity of pathogenic species of Pasteurellaceae.  相似文献   

19.
At the end of the national eradication program for Enzootic Pneumonia (EP) and Porcine Actinobacillosis (APP) in Switzerland (2003), A. pleuropneumoniae serotype 2 is considered to have been eradicated. There is no current information about the distribution of the other serotypes available. The ApxIV ELISA detects antibodies against all serotypes of A. pleuropneumoniae, without cross-reaction with other bacterial species. The aim of this study was to achieve actual data concerning the seroprevalence of A. pleuropneumoniae in breeding-herds and to validate the ApxIV ELISA under field conditions, especially for the diagnosis of latently infected breeding-herds without clinical signs, and to achieve more information about the role of herd book farms for the spread of the infectious agent. A total of 2068 serum samples from 96 pig herds in Switzerland were examinated. Over half of the examinated herd book farms showed positive results in this ELISA. 93% of the breeding herds were positive. On single animal level sensitivity was 96% and specifity 100%. Herd sensitivity ranged between 67% and 99%. Herd specifity was 100%. The results show that the ApxIV ELISA is a valuable tool for the detection of latently infected herds.  相似文献   

20.
Choi C  Kwon D  Min K  Chae C 《Veterinary pathology》2001,38(4):390-395
In situ hybridization techniques that employed a nonradioactive digoxigenin-labeled probe were used to detect and localize ApxI, II and III genes in tissue sections of pneumonic lung naturally infected with Actinobacillus pleuropneumoniae. In pigs infected with either serotype 2 or 6, a hybridization signal for apxIICA, apxIIICA, apxIBD, and apxIIIBD was detected, and in pigs infected with serotype 5, a hybridization signal for apxICA, apxIICA, and apxIBD was detected in the pneumonic lesions. A hybridization signal for apxIICA and apxIBD was detected in pigs infected with serotype 7. A strong hybridization signal for apx genes was seen in streaming degenerate alveolar leukocytes bordering zones of coagulative necrosis. Simultaneous detection of hybridization signals for the apxCA and apxBD genes provided scientific evidence that the expression of the apx genes could be potential indicators of the production of corresponding Apx toxins. This study demonstrates the expression of ApxI, II, and III genes in pneumonic lesions caused by A. pleuropneumoniae.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号