猪链球菌2型的毒力因子及诊断方法

猪链球菌2型(Streptococcussuistype2)又称为猪链球菌血清2型或荚膜2型猪链球菌,是革兰氏阳性兼性厌氧菌,为条件性致病菌,是猪链球菌35种血清型中流行最广、毒力最强的一种。它所引起的猪链球菌病是影响全世界养猪业的重要问题之一,且属于人畜共患病。该菌通常引起猪脑膜炎、败     

猪链球菌2型抗体监测与防控

为了解本地生猪链球菌2型免疫情况,本文应用ELISA试验江苏省淮安市15个规模猪场共计300份血清样品进行猪链球菌2型抗体监测,结果显示:被检样品猪链球菌2型抗体阳性率为70%～95%,平均为85.33%,表明该地区猪链球菌2型免疫情况良好。     

猪流感H1亚型和猪链球菌2型临床分离血清的抗体检测

以各省份未免疫猪链球菌病疫苗和猪流感疫苗猪场的临床发病猪分离的4 661份猪血清作为检测对象,使用猪流感病毒(H1亚型)ELISA抗体检测试剂盒和猪链球菌2型ELISA抗体检测试剂盒分别检测猪流感病毒(H1N1)和猪链球菌2型(SS2)的抗体,将检测结果从时间、空间进行分析,以探究猪流感与猪链球菌感染的基本规律,从而为疾病的防治提供借鉴和指导。检测结果表明,初春4月左右是猪流感流行的季节,猪流感H1N1抗体平均阳性率为45.19%;猪链球菌一般在7-11月流行,猪链球菌2型(SS2)抗体平均阳性率为54.85%,双阳性的血清检出率在10-12月最高,双阳性的血清检出率最高的是湖南省。     

湖南省猪链球菌2型病流行情况调查

应用酶联免疫吸附法(EUSA)和细菌分离鉴定,对湖南省9个市33个猪场的631份血清样品和126份病死猪内脏组织样品进行猪链球菌2型病血清学调查和细菌分离鉴定,结果血清中猪链球菌2型的抗体阳性率为48.0%;所调查的9个市均有不同程度感染猪链球菌的猪场,场阳性率为84.8%;不同日龄猪群阳性率分别为种猪65.2%、肥猪51.3%、中猪39.8%、小猪25.2%;健康猪群与发病猪群抗体阳性率分别为41.8%和58.5%.分离出的12株猪链球菌2型分布在7个市的10个猪场,说明湖南省猪链球菌2型流行面广.     

猪链球菌病二联灭活疫苗生产菌株的筛选及培养条件的优化

1997年以来上海地区猪链球菌病的主要致病菌群为马链球菌兽疫亚种和猪链球菌2型，通过动物试验，从l0株马链球菌兽疫亚种和猪链球菌2型分离株中筛选出毒力强、免疫原性好的ATCC35246和HA9801株，作为制备疫苗用的生产菌株。对3种不同培养基、血清浓度、葡萄糖浓度、静置和振荡培养、培养基预热等对细菌生长的影响进行了比较。结果表明，用含有2％犊牛血清、0．2％葡萄糖的改良马丁肉汤培养基较为合适；温度对细菌生长的影响很大，培养基接种前预热可以提高细菌产量；振荡培养对细菌生长的影响不大。     

人畜共患新病原--猪链球菌2型的研究进展

猪链球菌2型（Streptococcus suis type 2,SS2）又称猪链球菌血清2型或荚膜2型猪链球菌,分类上属于兰氏（Lancefield）R群。1954年首先在英国从暴发败血症、脑膜炎和关节炎的乳猪中分离到,1968年Elliot按荚膜分类法将其命名为荚膜2型猪链球菌。SS2呈全球性分布,是许多国家导致猪链球菌病的主要病原,如荷兰、英国、美国、加拿大、澳大利亚、新西兰、比利时、巴西、丹麦、西班牙、德国、日本等国家均有报道。     

2016年四川省猪链球菌2型感染的血清流行病学调查

猪链球菌是一种重要的人兽共患病原菌,其中以猪链球菌2型致病性最强。本研究通过ELISA方法,对2016年采集自四川省21市(州)的1 604份猪血清样品进行猪链球菌2型的检测。结果表明:猪链球菌2型的阳性检出率为9.41%(151/1604),其中规模场阳性检出率为7.67%(66/860),散养户阳性检出率为11.42%(85/744)。本研究为四川地区猪链球菌病的防控提供了理论依据。     

临床分离猪链球菌的药物敏感性分析

血清2型猪链球菌不仅可以感染猪只发病,而且还可以感染特定人群并致死,是一种重要的人畜共患传染病。因此,如何防止猪链球菌的发生和传播,是当前猪病防控的一项重要课题。为了防止抗生素的滥用,要作好猪链球菌对抗生素的耐药性监测,并为     

广东地区猪链球菌宿主多样性调查

通过调查广东地区不同宿主(猪肉类、鱼类、禽类、宠物等)体内猪链球菌带菌情况,以期评估猪链球菌的流行风险。分别从不同地区采集不同种类样本,分离培养猪链球菌,经PCR鉴定为阳性后,进一步进行生化试验及药敏试验分析。从采集的848份样本中共分离到31株猪链球菌,其中血清9型11株(占35.5%),血清2型、8型、18型、26型及31型各1株,且所分离的菌株均呈现多重耐药性。猪链球菌在多种不同宿主中均能检测到,特别是血清9型,提示可能带来的猪链球菌流行风险应予以重视。     

猪链球菌2型的分离鉴定及致病性试验

从全国部分猪场采集疑似猪链球菌感染病例脑样品20份进行细菌分离,成功分离到10株细菌,通过猪链球菌及血清类型鉴定,最终确定其中一株为2型猪链球菌。应用猪链球菌7种主要毒力因子特异性基因扩增检测方法检测所分离到的2型猪链球菌的毒力因子分布情况,并应用小鼠攻毒试验对其致病性进行观察研究。结果表明:分离的2型猪链球菌具备7种毒力因子;动物试验表明SS2能引起小鼠的急性败血症及脑膜炎;细菌回归试验结果表明,试验组死亡小鼠的脑、心脏、肝脏、脾脏、肺脏、肾脏均有细菌定植,且能分离出攻毒菌。此分离菌株的研究为研制2型猪链球菌病疫苗奠定了基础。     

An indirect fluorescent antibody test for the detection of antibody to swine infertility and respiratory syndrome virus in swine sera.

An indirect fluorescent antibody (IFA) test was developed and standardized to detect and quantitate antibody for swine infertility and respiratory syndrome (SIRS) virus in swine sera. Test results were evaluated using sera of pigs infected both experimentally and naturally with SIRS virus. The IFA test used swine alveolar macrophage (SAM) monolayers prepared in 96-well microplates and infected with SIRS virus. The monolayers were incubated with test sera, washed, and stained with fluorescein isothiocyanate-labeled rabbit anti-swine IgG. After another wash step, the monolayers were examined under a fluorescent microscope. A noninfected SAM control well was included for each sample. The antibody titers for each serum sample were recorded as the highest serum dilutions with specific cytoplasmic fluorescence but no fluorescence in the control wells. To evaluate the test, sera of 4 6-week-old pigs that had been infected with SIRS virus, 2 contact pigs, and 13 experimentally infected sows were used. In the experimentally infected pigs, antibody was first detected at 7 days postexposure (PE) and peaked (1:256-1,024) between 11 and 21 days PE. All 13 sow sera were negative at time of infection but were positive (1:64- greater than or equal to 1:1,024) at 14-26 days PE. Seven hundred twenty sera collected from 25 different swine farms with or without a history of SIRS were also tested. Of 344 sera from 15 swine farms with a clinical history of SIRS, 257 (74.7%) sera had IFA titers greater than or equal to 1:4, whereas 371 (98.7%) of 376 sera from herds with no history of SIRS were negative.(ABSTRACT TRUNCATED AT 250 WORDS)     

Field evaluation of the enzyme-linked immunosorbent assay for swine trichinosis: efficacy of the excretory-secretory antigen

A field evaluation of an enzyme-linked immunosorbent assay (ELISA) for swine trichinosis was done with sera obtained from 5 herds experiencing ongoing transmission of Trichinella spiralis. Epizootiologic studies conducted on these herds offered an opportunity to evaluate the accuracy of an ELISA, using larval T spiralis excretory-secretory antigens. Sera from 162 infected pigs and 143 serum samples from noninfected pigs originating from the same farms were tested. The infection status of the pigs was determined by digestion of diaphragm or tongue muscle samples. Two criteria were established to classify the ELISA optical density (OD) readings: Criterion I stated that an OD greater than or equal to 5 times the mean OD of several normal swine sera pools was positive; criterion II stated that a OD greater than or equal to 4 times the normal sera values was positive. The results obtained did not reveal obvious serologic variations among infected herds located in the 4 states involved. Overall, the test detected 93% (criterion I) and 96% (criterion II) of infected pigs. The majority of false-negative sera was from hogs that had less than 5 larvae/g of muscle; 1 hog had 73.8 larvae/g of diaphragm muscle. The false-positive rates were 8% for criterion I and 9% for criterion II. The actual rate for these false-positive samples may have been overestimated, because generally, only small tissue samples (0.4 to 10 g) were digested; larger sample sizes might have altered the results. The relevance of this qualification is that these pigs originated from herds with prevalence rates greater than 50%. Other factors that may account for occasional false-positive sera or false-negative sera in the swine trichinosis ELISA are discussed.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of the microtitration agglutination test and the enzyme-linked immunosorbent assay for the detection of herds affected with swine dysentery

A method was designed to evaluate and compare the microtitration agglutination test (MAT) and the enzyme-linked immunosorbent assay (ELISA) to detect antibodies in swine sera to Treponema hyodysenteriae and thereby establish a method for determining the prevalence of swine dysentery (SD) in herds. According to sampling criteria based on the hypergeometric distribution, sera were collected from 3 age groups of swine from farms having a history of SD on the premises (SD+) recently or being free of the disease (SD-). The highest degree of test sensitivity was obtained when sera from market age swine were evaluated with the ELISA. Of 14 SD+ herds from which sera were obtained from market-age swine, 13 were positive with the ELISA (93%); none of the 8 SD- herds was positive. The detection rates of individual swine in the SD+ herds for the 2 tests by age group were as follows: MAT--adult swine 1.4%, market-age swine 6%, and weaned pigs 0.8%; ELISA--adult swine 16%, market swine 31%, and weaned pigs 0.5%.     

A serological survey to determine the prevalence of infection with Treponema hyodysenteriae in Western Australia

A serological survey to detect antibody titres against Treponema hyodysenteriae was conducted on pigs from 106 herds in Western Australia. Titres indicating a positive result in the tests were determined by examining 400 sera from 4 herds known to be free of swine dysentery, and sera from immunised or experimentally infected pigs. Samples of serum from 40 bacon-weight pigs from each of the 106 herds were then collected at 2 abattoirs. Each serum was tested in enzyme-linked immunosorbent assays (ELISA) against the lipopolysaccharide of T hyodysenteriae of serogroups A, B and E, respectively. To assist in evaluating the test, 19 herds were resampled and retested, and faecal samples from 17 herds were cultured for T hyodysenteriae. Thirty-five of the 106 herds (33%) had serological evidence of infection when only one batch of sera from each herd was tested. The ELISA to detect T hyodysenteriae infection in herds using 40 sera was estimated as having a sensitivity of 77.3% and a specificity of 81.8% based on the owners' opinion of their herds disease status. Prevalence of infection within herds ranged from 2.5% to 47.5%, with a mean of 18%.     

Measurement of serum antibody in swine vaccinated with Bordetella bronchiseptica: comparison of agglutination and enzyme-linked immunosorbent assay methods

The immune responses of 514 pigs from 5 swine breeds (Chester White, Duroc, Hampshire, Landrace, Yorkshire) to vaccination with Bordetella bronchiseptica were measured by agglutination and enzyme-linked immunosorbent assay (ELISA) methods. Both assays showed higher antibody levels in sera of pigs after vaccination than in sera of the pigs before vaccination. The variability of the responses among breeds was greater for the agglutination method than for the ELISA method. The ELISA proved to be more sensitive than the agglutination method and could detect antibody in serum samples diluted at least 100-fold more than those used in the agglutination procedure. The correlation of antibody titers obtained by the 2 methods was small, but statistically (P less than 0.01) significant. The ELISA should be useful for determinations of antibody responses of swine to B bronchiseptica.     

Survey of trichinosis in breeding and cull swine, using an enzyme-linked immunosorbent assay

Serum samples obtained from 40,927 swine at various locations in North Carolina between Aug 1, 1987 and July 31, 1988, were tested for antibodies to Trichinella spiralis, using an ELISA based on a larval T spiralis excretory-secretory antigen. In the ELISA, samples were considered to have positive results if the optical density (OD) reading was equal to or 5 times greater than the mean OD value of 4 negative-control sera from trichina-free swine. Of the 40,927 serum samples tested, 154 (0.38%) were positive by ELISA; the rate for breeding swine was 0.35% (105/30,162), and the rate for cull swine was 0.45% (49/10,765). Of the 49 seropositive samples from cull swine, 11 were from out of the state, 22 had no identification, and 16 were known to originate from North Carolina. Seropositivity had a bimodally seasonal distribution, with peaks in March and September. There was no difference between the mean age of seropositive and seronegative swine, but males were at greater risk for seropositivity than were females. Pigs from lots with less than 100 sera tested were at increased risk for seropositivity, as were pigs from the central coastal region of North Carolina.     

Comparison of sensitivity and specificity in three commercial foot-and-mouth disease virus non-structural protein ELISA kits with swine sera in Taiwan

Three commercialized ELISA kits for the detection of antibodies to the non-structural proteins (NSPs) of FMD virus were compared, using sera from uninfected, vaccinated, challenged and naturally infected pigs. The kinetics of the antibody response to NSPs was compared on sequential serum samples in swine from challenge studies and outbreaks. The results showed that ELISA A (UBI) and ELISA B (CEDI) had better sensitivity than that of the 3ABC recombinant protein-based ELISA C (Chekit). The peak for detection of antibodies to NSPs in ELISA C was significantly delayed in sera from natural infection and challenged swine as compared to the ELISA A and B. The sensitivity of the three ELISAs gradually declined during the 6-month post-infection as antibodies to NSP decline. ELISA kits A and B detected NSP antibody in 50% of challenged pigs by the 9-10th-day and 7-8th-day post-challenge, respectively. ELISA B and C had better specificity than ELISA A on sequential serum samples obtained from swine immunized with a type O FMD vaccine commercially available in Taiwan. Antibody to NSPs before vaccination was not detected in swine not exposed to FMD virus, however, antibody to NSPs was found in sera of some pigs after vaccination. All assays had significantly lower specificity when testing sera from repeatedly vaccinated sows and finishers in 1997 that were tested after the 1997 FMD outbreak. However, when testing sera from repeatedly vaccinated sows or finishers in 2003-2004, the specificity for ELISAs A, B and C were significantly better than those in 1997. This effect was less marked for ELISA A. The ELISA B was the best test in terms of the highest sensitivity and specificity and the lowest reactivity with residual NSP in vaccinates.     

Serological Diagnosis of Classical Swine Fever: A Comparison of a Modified Direct Complement Fixation Test with an Immunofluorescence Plaque Neutralization Test in the Diagnosis of Experimental Subclinical Infection

Antibody levels in post-infection sera from a pig inoculated with a low virulent strain of classical swine fever virus (Hannover 62) and in sera from two pigs inoculated with another low virulent strain (Spielbach 66) and from an in-contact pig were assayed by complement fixation and immunofluorescence using classical swine fever virus (ALD strain) and bovine virus diarrhoea virus (UG 59 strain) as antigens. The complement fixation test used was modified by addition of a preparation of porcine Glq to the complement and by mercaptoethanol treatment of the immune serum before use. The mercaptoethanol treatment of the immune serum resulted in complete elimination of a haemolytic prozone often seen with porcine immune sera.In the sera from the inoculated animals complement-fixing antibodies appeared earlier than neutralizing antibodies. A few weeks after inoculation there was a correlation between the presence of complement-fixing and neutralizing antibodies.During the entire observation period of 13 weeks it was not possible to demonstrate complement-fixing or neutralizing antibodies in serum from a pig exposed to infection by contact with the two pigs inoculated with the Spièlbach 66 strain of classical swine fever virus.     

Sera-controlled preadipocyte growth in culture: an ontogeny study with sera from lean and obese pigs

Genetically lean and obese swine were used to investigate the control of preadipocyte growth in culture by porcine serum. Sera were collected from fetuses from obese and lean strains at 70, 90 and 110 d of gestation. Postnatal serum samples were collected from both lines of pigs at 23 to 27 kg. Rat preadipocytes were isolated and grown in culture. Preadipocyte and stromal-vascular cell proliferation was greater in cultures grown in sera obtained postnatally than in cultures grown in sera from fetuses. Sera from lean and obese fetuses were equipotent in promoting cell proliferation. Glycerol-phosphate dehydrogenase (GPDH) activity was higher in cultures fed serum from obese pigs and fetuses than in cultures fed serum from lean pigs and fetuses. Cultures grown in serum from obese fetuses and pigs had soluble protein levels similar to cultures grown with serum from lean pigs and fetuses. These results demonstrate that serum from genetically obese swine, in the pre-obese (fetal) and obese (postnatal) state, caused increased adipogenic activity in adipocytes in culture.     

In vitro muscle cell proliferation and protein turnover as affected by serum from pigs fed antimicrobials

The effect of antimicrobial supplementation of pigs on the capacity of their sera to influence proliferation and protein turnover in cultured muscle cells was evaluated. Mitogenic activity of sera increased when pigs were fed ASP250 (P less than .005) or carbadox (P less than .001), whereas the mitogenic activity of serum from pigs receiving the basal diet remained unchanged (P = .5). Additionally, sera from ASP250-fed pigs significantly decreased (P less than .001) total cellular protein degradation compared with sera obtained from the same pigs prior to supplementation. Neither ASP250 nor carbadox stimulated proliferation of myogenic cells when added to the culture media. Inclusion of ASP250 in swine diets altered the composition of their sera in a way that stimulated muscle cell proliferation and reduced the rate of protein degradation in cultured myogenic cells. Likewise, the inclusion of carbadox in swine diets increased the ability of their sera to stimulate cultured muscle cell proliferation.