旋毛虫Ts21重组蛋白的免疫诊断价值及免疫保护作用的研究

目的 探讨旋毛虫Ts21重组蛋白的免疫诊断价值及免疫保护作用。 方法 应用旋毛虫Ts21重组蛋白ELISA（Ts21-LISA）与肌幼虫ES抗原ELISA（ES-LISA）对旋毛虫病与其他寄生虫病患者血清及5种旋毛虫（T1、T2、T3、T4和T7）感染小鼠血清进行检测,并观察不同剂量旋毛虫感染小鼠后不同时间的血清抗体水平。将Ts21重组蛋白皮下注射免疫小鼠（20 μg/只,免疫3次,每次间隔10 d）,末次免疫后10 d,每只小鼠用300条旋毛虫肌幼虫经口攻击感染,3.5 d和42 d 后剖杀,观察肠道成虫与肌幼虫数并计算减虫率。 结果 Ts21-LISA检测旋毛虫病、并殖吸虫病、囊尾蚴病及棘球蚴病患者血清的抗体阳性率分别为94.7%（18/19）、15.8%（3/19）、9.1%（1/11）和7.7%（1/13）,与血吸虫病、华支睾吸虫病患者血清及健康人血清无交叉反应;Ts21重组蛋白与ES抗原ELISA检测旋毛虫病患者血清抗体的敏感性与特异性差异均无统计学意义（χ²=0,P＞0.05;χ²=0.358,P＞0.05）。Ts21重组蛋白与ES抗原检测T1感染小鼠血清的敏感性差异无统计学意义（χ²=0.104,P＞0.05）,与T2、T3、T4、T7感染小鼠血清的交叉反应率明显低于ES抗原（χ²=17.069,P＜0.05）。小鼠感染300条旋毛虫后4 周,应用Ts21-LISA检测的血清抗体阳性率为100%（10/10）;小鼠感染5条旋毛虫后6周,血清抗体阳性率为100%（10/10）。Ts21重组蛋白免疫小鼠用旋毛虫攻击感染后3.5 d和42 d,肠道成虫与肌幼虫减虫率分别为42.71%和49.8%。 结论 Ts21重组蛋白可用于旋毛虫病的血清学检测,但不能忽视与并殖吸虫病、囊尾蚴病及棘球蚴病患者血清的交叉反应。     

旋毛虫抗原基因Ts21的原核表达与重组蛋白鉴定

目的 原核表达旋毛虫相对分子质量（Mr）21 000抗原基因（Ts21）并对重组蛋白进行纯化和抗原性鉴定。 方法 将旋毛虫抗原基因Ts21亚克隆入原核表达载体pMAL-c2X，构建重组表达质粒pMAL-c2X-Ts21，经酶切鉴定正确后转化大肠埃希菌TB1，以异丙基-β-D硫代半乳糖苷（IPTG）诱导表达。亲和层析法纯化表达产物。应用十二烷基磺酸钠?鄄聚丙烯酰胺凝胶电泳（SDS-PAGE）和蛋白质印迹（Western blotting）分析鉴定重组蛋白的抗原性。将重组蛋白免疫小鼠制备免疫血清，ELISA检测抗体滴度，免疫荧光检测（IFA）确定Ts21蛋白在肌幼虫体内的分布。 结果 SDS-PAGE结果显示，表达产物为Mr 63 500的重组融合蛋白，IPTG诱导4 h后表达量最大，薄层凝胶光密度扫描显示表达的融合蛋白占菌体蛋白总量的18.2%。Western blotting结果显示该重组蛋白可被旋毛虫、纳氏旋毛虫感染小鼠血清及旋毛虫病患者血清识别，但不能被乡土旋毛虫、布氏旋毛虫及伪旋毛虫感染小鼠血清识别；与钩虫病、囊尾蚴病、日本血吸虫病患者血清无交叉反应，但与并殖吸虫病、华支睾吸虫病及棘球蚴病患者血清有交叉反应。重组蛋白免疫小鼠可产生高滴度的血清抗体，IFA显示Ts21蛋白主要分布于肌幼虫体壁。 结论 成功制备了旋毛虫Ts21基因的重组蛋白，该蛋白具有较好的抗原性。     

旋毛虫成囊前期幼虫抗原结构基因TspE1的克隆与表达

目的　克隆和表达旋毛虫河南地理株成囊前期幼虫编码 3 1kDa抗原的结构基因 (TspE1)。　 方法　大鼠感染旋毛虫后第 17天收集成囊前期幼虫 ,提取虫体的总RNA。通过RT PCR特异性扩增目的基因 ,构建重组质粒pUC18 Ts HN3 ,将重组质粒 pUC18 Ts HN3中的目的基因亚克隆入原核表达载体pGEMEX 1,构建重组子 pGEMEX 1 Ts HN3 ,经IPTG诱导 ,在E .coliJM 10 9(DE3 )中表达。对表达产物进行SDS PAGE分析和Westernblotting鉴定。　 结果　SDS PAGE显示目的基因在大肠杆菌中获得高效表达 ,重组蛋白的分子量为 3 1kDa ,以诱导 4h时表达量最多。薄层凝胶光密度扫描分析结果显示 ,表达的融合蛋白量约占细菌总蛋白的 2 6%。Westernblotting证实 ,融合蛋白条带能被感染旋毛虫的大鼠血清及旋毛虫病患者血清识别。　结论　旋毛虫河南地理株成囊前期幼虫抗原结构基因TspE1克隆和原核表达成功。     

旋毛虫肌幼虫排泄分泌抗原诊断早期旋毛虫病的研究

目的评价旋毛虫肌幼虫排泄分泌(excretory-secretory,ES)抗原诊断早期旋毛虫病的价值。方法应用旋毛虫肌幼虫ES抗原Western blot对旋毛虫感染后6~11d的小鼠血清及19d的早期旋毛虫病人血清进行检测,并与感染后35d的晚期旋毛虫病人和其他寄生虫病人血清的检测结果进行比较。结果 Western blot分析显示,肌幼虫ES蛋白中的2条蛋白带(41.5、55kDa)可被旋毛虫感染后7~11d的小鼠血清识别,6条蛋白带(41.5、44.1、45、55、61和65.2kDa)能被早期和晚期旋毛虫病人血清识别,阳性反应率均为100%(15/15);这6条蛋白带与裂头蚴病人和健康人血清无交叉反应,但与其他寄生虫病(血吸虫病、并殖吸虫病、华支睾吸虫病、棘球蚴病及囊尾蚴病)患者血清具有明显的交叉反应(19.12%~38.23%)。结论旋毛虫肌幼虫ES抗原中的41.5kDa~65.2kDa蛋白带可与旋毛虫感染早期血清反应,但与其他蠕虫病患者有明显的交叉反应。     

旋毛虫编码新生幼虫p46 kDa抗原基因重组融合蛋白对小鼠的免疫保护性研究

目的 探讨旋毛虫编码新生幼虫p46 kDa抗原基因重组融合蛋白WN10对小鼠的免疫保护性。方法 将纯化的重组融合蛋白WN10以20μg/只的剂量分3次免疫小鼠后，攻击感染旋毛虫肌幼虫200条／只，检查旋毛虫7日龄成虫数、雌虫体外产生新生幼虫数、感染35d的肌幼虫数并计算减虫率，同时用ELISA法检测血清中抗WN10抗体IgG滴度。结果WN10免疫小鼠后获得旋毛虫7日龄成虫、肌幼虫的减虫率分别为64．28％和61．21％，均与感染对照组和佐剂对照组差异显著；获得雌虫产新生幼虫的减虫率为16．46％，与感染对照组和佐剂对照组差异不显著；WN10免疫组小鼠在第3次免疫后1周可检测到高滴度的抗WN10抗体IgG，在攻击感染旋毛虫9周后仍维持在较高水平。结论 编码旋毛虫新生幼虫p46 kDa抗原基因重组融合蛋白可诱导小鼠产生较强的抗旋毛虫保护性免疫。     

旋毛虫新生幼虫可溶性抗原的免疫蛋白组学分析

目的 鉴定能被旋毛虫感染血清识别的新生幼虫蛋白，为抗新生幼虫疫苗筛选候选抗原。方法 从感染旋毛虫的BALB/c小鼠肠道收集成虫，培养后收集新生幼虫，制备新生幼虫可溶性性抗原，通过蛋白质免疫印迹（Western blotting）筛选出能被旋毛虫感染小鼠血清识别的新生幼虫可溶性抗原蛋白带进行液相色谱串联质谱（LC-MS/MS）鉴定，并与Uniprot数据库中的旋毛虫数据进行比对，利用生物信息学在线网站分析所鉴定的旋毛虫蛋白的理化性质，使用WEGO在线软件对匹配的蛋白进行基因本体（GO）分类。收集旋毛虫肌幼虫、肠道感染性幼虫（感染后6 h）、成虫（感染后2 d）和新生幼虫等不同发育期的虫体，提取虫体总RNA，反转录为cDNA。qPCR扩增旋毛虫C型凝集素（CTL）、钙网蛋白（CRT）、锌指蛋白（ZFP）和丙酮酸激酶（PK）基因，以甘油醛-3-磷酸脱氢酶（GAPDH）基因为内参，以肌幼虫的相对转录水平为对照，比较4个旋毛虫基因在不同发育期的相对转录水平。不同发育期相对转录水平的比较采用单因素方差分析。结果 Western blotting结果显示，新生幼虫可溶性抗原的11条蛋白条带中有4条被...     

以重组蛋白为抗原的ELISA法检测旋毛虫抗体

目的 寻求特异性强、敏感性高的旋毛虫病诊断抗原。 方法 以旋毛虫新生幼虫期特异性T668基因在E.coli高效表达的重组蛋白为抗原，分别以兔、猪和健康者血清及旋毛虫病阳性血清为一抗，以辣根过氧化物酶（HRP）标记的山羊抗兔IgG、山羊抗猪IgG和山羊抗人IgG为二抗，建立检测旋毛虫抗体的间接ELISA方法，并以旋毛虫肌幼虫排泄?鄄分泌（ES）抗原作为检测对照。 结果 以T668重组蛋白为抗原，对兔、猪和人旋毛虫病血清进行检测，阳性检出率为100 ％，且敏感性高（0.016 μg / 孔），与ES抗原检测结果完全一致。 结论 T668重组抗原有望替代ES抗原检测旋毛虫抗体。     

旋毛虫肌幼虫排泄分泌物中特异性诊断抗原的研究

目的　寻找旋毛虫肌幼虫排泄分泌(ES)物中的特异性诊断抗原。　方法　应用SDSPAGE和Western印迹对旋毛虫肌幼虫体外培养18、30h后的ES抗原中的蛋白组分进行研究。　结果　旋毛虫肌幼虫培养18、30h后得到的ES抗原组分大致相同,两种ES抗原中主要蛋白带的分子量为112、110、108、97、53、49、45、42、35、23和16kDa。18hES抗原中的102、97、95和53kDa以及30hES抗原中的53、49、45和43kDa均与并殖吸虫病、华支睾吸虫病、日本血吸虫病及囊尾蚴病患者血清发生明显的交叉反应。ES抗原中的23kDa蛋白组分只与旋毛虫感染的大鼠、小鼠及患者血清反应,而不与上述其它寄生虫感染者、正常大鼠和小鼠及正常人血清发生交叉反应。　结论　旋毛虫肌幼虫ES抗原中的23kDa蛋白组分为旋毛虫肌幼虫的特异性抗原,可用于旋毛虫病的血清学诊断及血清流行病学调查。     

旋毛虫新生幼虫p46000抗原基因的表达与抗原性分析

目的　对旋毛虫新生幼虫p46000抗原基因进行原核表达并检测重组抗原的抗原性。　方法　利用聚合酶链反应 (PCR)扩增目的基因 ,克隆到原核表达载体 pET-28a ,构建重组表达质粒 ,经酶切及测序鉴定后转化大肠埃希菌BL21(DE3 ),以异丙基-β-D 硫代半乳糖苷诱导表达。十二烷基磺酸钠-聚丙烯酰胺凝胶电泳 (SDS-PAGE)、酶联免疫吸附测定 (ELISA)和蛋白质印迹法 (Western blotting)分析表达产物。　结果　 SDS-PAGE结果显示表达产物的分子量约为Mr 48000 ,与理论值相符。ELISA和Western blotting结果表明 ,重组蛋白可被旋毛虫感染的猪血清和兔抗重组蛋白血清识别 ;兔抗重组蛋白血清可识别旋毛虫新生幼虫抗原Mr 46000蛋白。　结论　成功表达了旋毛虫新生幼虫p46000抗原基因 ,重组抗原具有良好的抗原性。     

Ts21重组蛋白斑点免疫金渗滤法检测旋毛虫抗体的研究

目的应用旋毛虫Ts21基因重组蛋白建立诊断人体旋毛虫病及动物旋毛虫感染的快速血清学方法。方法以胶体金标SPA、旋毛虫Ts21重组蛋白与肌幼虫排泄-分泌(excretory-secretory,ES)抗原包被硝酸纤维素膜(NCM),分别建立Ts21重组蛋白-斑点免疫金渗滤法(Ts21-dot immunogold-filtration assay,Ts21-DIGFA)与ES-DIGFA,对旋毛虫病及其他寄生虫病患者血清和感染动物血清进行检测,并与ELISA检测结果进行比较。结果Ts21-DIGFA检测旋毛虫病患者血清抗体的敏感性和特异性分别为94.73%和86.96%,ES-DIGFA的敏感性和特异性分别为89.47%和86.96%,差异无统计学意义(χ2敏感=0.368,χ2特异=0,P>0.05);Ts21-ELISA的敏感性和特异性分别为94.73%和94.20%,与Ts21-DIGFA相比差异无统计学意义(χ2敏感=0,χ2特异=1.272,P>0.05)。Ts21-DIGFA检测旋毛虫感染猪血清的敏感性和特异性分别为88.89%和100%,ES-DIGFA的敏感性和特异性分别为94.44%和95.00%,差异均无统计学意义(χ2敏感=0,χ2特异=0,P>0.05)。小鼠感染300条旋毛虫后4周Ts21-DIGFA的血清抗体检出率为100%(10/10);感染10条及5条旋毛虫后6周血清抗体检出率均为100%(10/10)。DIGFA可在3 min内肉眼观察结果,抗原包被后的NCM和金标SPA在4℃至少保存6个月。结论Ts21-DIGFA检测旋毛虫抗体具有较高的敏感性和特异性及良好的稳定性和重复性,可用于旋毛虫病的血清学诊断及血清流行病学调查。     

抗旋毛虫肌幼虫ES抗原IgY的制备及鉴定

目的制备抗旋毛虫肌幼虫排泄-分泌(excretory-secretory,ES)抗原的鸡卵黄免疫球蛋白(IgY),测定其效价及用于检测抗原的敏感性。方法 4只24w龄罗曼母鸡用旋毛虫肌幼虫ES抗原经大腿外侧与胸部肌肉免疫4次(首次剂量为500μg/只,加强剂量为250μg/只),每次间隔10d。取免疫前和首次免疫后42d的鸡蛋卵黄,用水稀释法提取IgY,考马斯亮蓝法测定蛋白含量,十二烷基磺酸钠-聚丙烯酰胺凝胶电泳(SDS-PAGE)、蛋白质印迹(Western blot)及间接荧光抗体试验(IFAT)对IgY进行分析,ELISA检测纯化后IgY的效价及检测抗原的敏感性。结果罗曼鸡经ES抗原免疫后,每枚鸡蛋经提纯后均可得到约70mg抗体,SDS-PAGE表明纯化的IgY有2条主要蛋白带,分子量为67kDa、23kDa,Western blot与IFAT发现提纯的IgY可识别肌幼虫虫体与ES抗原。IgY的抗体效价为1∶107,IgY-夹心ELISA检测旋毛虫抗原的敏感性为1.17ng/mL。结论制备的抗旋毛虫ES抗原的IgY具有较高的效价与敏感性。     

Characterization of a Trichinella spiralis 31 kDa protein and its potential application for the serodiagnosis of trichinellosis

The Trichinella spiralis 31 kDa protein (Ts31) was screened from the excretory-secretory (ES) proteins of muscle larvae (ML) by immunoproteomics using serum from mice infected with T. spiralis at 18 days post infection (dpi). The aim of this study was to characterize the Ts31 protein and to evaluate the potential of the recombinant Ts31 protein (rTs31) for serodiagnosis of human trichinellosis. Ts31 gene was cloned and rTs31 was produced in an E. coli expression system. An anti-rTs31serum recognized the native protein migrating in a 25–55 kDa range by Western blotting of ML crude or ES antigens. Expression of Ts31 gene was observed at all developmental stages of T. spiralis (adult worms, newborn larvae, pre-encapsulated larvae and ML). An immunolocalization analysis identified Ts31 in the cuticle and stichocytes of the parasite. The sensitivity of rTs31-ELISA and ES antigen ELISA for detecting anti-Trichinella IgG antibodies in sera of patients with trichinellosis was 97.83% (45/46) and 86.78% (39/46), respectively (P > 0.05); The specificity of rTs31-ELISA was 99.13% (114/115), which was significantly higher than 85.22% (98/115) of ES antigen ELISA (P < 0.01). The rTs31 protein of T. spiralis could be considered as a potential diagnostic antigen for trichinellosis.     

旋毛虫氨基肽酶的表达及其血清学诊断价值的研究

目的构建旋毛虫氨基肽酶（TsAP）基因重组质粒,表达重组TsAP蛋白,评价该蛋白的血清学诊断价值。方法通过RT-PCR扩增TsAP基因。构建重组质粒pGEX-6p-1-TsAP,测序及酶切鉴定后转化E．coliBL21,用异丙基-G-D-硫代半乳糖苷（IPTG）诱导,表达产物经GSTSefinoseResin（BBI）亲和层析纯化后应用SDS-PAGE和Westernblot进行鉴定。应用旋毛虫重组rTsAP蛋白EusA（rTsAP-ELISA）对旋毛虫感染小鼠血清进行检测,观察旋毛虫感染小鼠后不同时间的血清抗体阳性率,并与旋毛虫肌幼虫ES抗原ELISA（ES-EIJIsA）的检测结果进行比较。结果构建的重组表达载体pGEX-6p-1-TsAP能表达TsAP蛋白。SDS-PAGE结果显示,rTsAP的分子质量单位约为80ku,以IPTG诱导4h后表达量最大。rTsAP-ELISA及ES-ELIS对旋毛虫感染小鼠血清的抗体检出率均为100％（40／40）,与曼氏裂头蚴、弓形虫感染小鼠及正常小鼠血清均无交叉反应,与日本血吸虫感染小鼠血清的交叉反应率分别为93．75％（15／16）和50．00％（8／16）（P〈0．05）。rTsAP-ELISA与ES-ELISA对旋毛虫感染2周的小鼠血清抗体检出率分别为50．00％（11／22）和81.82（18／22）,差异无统计学意义（P〈0．05）,至感染后6周抗体检出率均达100％。结论重组TsAP蛋白具有良好的反应原性,但与日本血吸虫感染小鼠血清有较高的交叉反应。     

旋毛虫排泄分泌抗原对小鼠的保护性免疫

目的比较旋毛虫成虫排泄分泌抗原(ES抗原)、肌幼虫ES抗原、成虫和肌幼虫ES混合抗原对小鼠的免疫保护作用。方法用生理盐水培养法从培养液中提取成虫ES抗原、肌幼虫ES抗原,分别用成虫ES抗原、肌幼虫ES抗原、成虫和肌幼虫ES混合抗原免疫小鼠,同时设佐剂组和对照组,间隔7d共免疫3次。末次免疫后7天,每只小鼠用200条旋毛虫感染期幼虫经口进行攻击感染。感染后7天和30天检查各组小鼠肠道成虫数和肌幼虫数。结果旋毛虫成虫ES抗原组、肌幼虫ES抗原组、成虫和肌幼虫ES混合抗原组的成虫减虫率分别为87.95%、69.48%、84.34%,肌幼虫减虫率分别为74.79%、87.97%、86.87%。成虫ES抗原组、成虫与肌幼虫ES抗原混合组的成虫减虫率均高于肌幼虫ES抗原组(P均<0.05)。肌幼虫ES抗原组、成虫与肌幼虫ES抗原混合组的肌幼虫减虫率均高于成虫ES抗原组(P均<0.01)。结论旋毛虫成虫和肌幼虫ES混合抗原均能诱导小鼠产生抗成虫及肌幼虫较强的免疫力。     

The influence of the procedure of excretory-secretory L1 trichinella spiralis antigen preparation on the efficiency of an ELISA test in pigs

BACKGROUND: Trichinellosis is a parasitic zoonosis transmitted to humans by consumption of raw or undercooked meat from animals infected by worms of the Trichinella genus. Every year seropositive cases are found among the human population and thus trichinellosis still remains an epidemiologically important disease in Poland. The usefulness of ELISA for anti-T. spiralis IgG detection in pigs is still limited by the nature of antigen. The objective in the present study was to compare the usefulness of excretory-secretory antigens of L1 T. spiralis for the serological detection of IgG antibodies in pigs. MATERIAL AND METHODS: The antigens were prepared in different laboratories: Ag ES L1 T. spiralis (N) in Germany, Ag ES L1 T. spiralis (W) in Italy and Ag ES L1 T. spiralis in Poland. Conventional, Iberian pigs were infected with 200, 1000 and 20 000 muscle larvae of T. spiralis. Serum samples were obtained at 5 and 1 dbi (day before infection), and 5, 10, 15, 20, 25, 30, 40, 50, 60 dpi (day post infection) and screened for specific IgG antibodies to excretory-secretory L1 T. spiralis antigens. Serum samples were obtained from the EU project TRICHIPORSE. The cut-off value of ELISA was determined on serum samples from 248 Trichinella-free pigs from Poznaii and Boza Wola, that were examined by artificial digestion. RESULTS: In pigs infected with 200 L1 T. spiralis larvae, specific IgG were detectable from 50 dpi, when the Ag ES L1 T. spiralis (N) was used, whereas when Ag ES L1 T. spiralis (W) and Ag ES L1 T. spiralis were used, the specific IgG were detectable from 40 dpi. In pigs infected with 1000 LI T. spiralis larvae, specific IgG was observed from 30 dpi when Ag ES L1 T. spiralis (W) and Ag ES L1 T. spiralis were used, but when Ag ES L1 T. spiralis (N) was used specific IgG were detectable from 40 dpi. In the group infected with the highest dose of T. spiralis larvae, specific IgG were detectable from 30 dpi when Ag ES L1 T. spiralis (N) and Ag ES L1 T. spiralis (W) were used, whereas when Ag ES L1 T. spiralis was used specific IgG were detectable from 20 dpi. The results strongly indicated that in the examined pigs, the specific IgG response against T. spiralis infection is dose dependent. Furthermore, it was shown that the high infectious dose induced earlier increasing of specific IgG response. Statistical analysis revealed a significant positive correlation between OD values obtained in procedures based on the three antigens. The results were statistically repeatable for procedures and for single pigs (P<0.01).     

旋毛虫与伪旋毛虫肌幼虫抗原的SDS-PAGE和双向电泳分析

目的鉴定旋毛虫(Trichinella spiralis,T1)与伪旋毛虫(T.pseudospiralis,T4)肌幼虫的差异蛋白。方法应用SDS-PAGE和双向电泳(two-dimensional gel electrophoresis,2-DE)对T1、T4肌幼虫的可溶性抗原与培养24h的ES抗原的蛋白组分进行分析。结果SDS-PAGE显示,T1肌幼虫可溶性抗原有22条蛋白带(221.62kDa～14.88kDa),其中6条为T1特异性蛋白带(59.72、44.37、23.66、22.36、18.26、16.34kDa);T4可溶性抗原蛋白有18条带(185.28kDa～14.27kDa),其中4条为T4特异性蛋白带(132.60、119.30、35.26、31.02kDa)。T1的ES抗原有10条蛋白带(113.21kDa～14.37kDa),T4的ES抗原有9条蛋白带(104.71kDa～14.51kDa),T1、T4肌幼虫ES抗原的蛋白带均不相同。2-DE显示,T1可溶性抗原有193±12个蛋白点,分子量主要为11kDa～22kDa、25kDa～64kDa及100kDa～144kDa,所对应的等电点(pI)分别为4.7～8.2、4.5～6.5及5～7;T4可溶性抗原有175±9个蛋白点,分子量主要为12kDa～21kDa及25kDa～90kDa,所对应的pI分别为4～9.5与4.5～9.6。T1的ES抗原具有82±6个蛋白点,分子量主要为13kDa～16kDa、18kDa～22kDa及40kDa～55kDa,所对应的pI分别为4～7、3.8～6.2及5～9;T4的ES抗原具有69±5个蛋白点,分子量主要为10kDa～15kDa、17kDa～25kDa及29kDa～55kDa,所对应的pI分别为4.7～6.5、4.6～6及5～7。结论旋毛虫肌幼虫可溶性抗原及ES抗原的蛋白组分与伪旋毛虫的明显不同。     

The usefulness of ELISA test for early serological detection of Trichinella spp. infection in pigs

Trichinellosis is a parasitic zoonosis transmitted to humans through consumption of raw or undercooked meat from animals infected with nematodes of the Trichinella genus. Every year seropositive cases are found among the human population and thus trichinellosis still remains an epidemiologically important disease. The first step of the study was the optimization of a new ELISA method enabling an early and specific serological diagnosis of trichinellosis in pigs and wild boars using excretory-secretory (ES) antigens obtained from in vitro cultures of L1 T. spiralis. Serum samples were assayed for anti-T. spiralis IgG antibodies using the new ELISA protocol and a reference test--Standard manufactured by Institut Pourquier. The optimization involved the selection of suitable plates for antigen coating, dilution of sera and antibodies and their time of incubation. On the basis of the optimization a new ELISA procedure for the detection of IgG and IgM against T. spiralis was elaborated. Conventional, Iberian pigs and SPF (Specific Pathogen Free) pigs were infected with 200, 1000 and 20,000 muscle larvae of T. spiralis. Serum samples were obtained at 5 and 1 dbi (day before infection), and 5, 10, 15, 20, 25, 30, 40, 50, 60 dpi (day post infection) and screened for specific IgG antibodies against excretory-secretory L1 T. spiralis antigens. Serum samples were obtained from the EU project Trichiporse: "Safe pork and horse meat on EU markets: early and unbiased diagnostic tests for Trichinella". Field samples of conventional pigs (1474) and wild boars (1784) were obtained from slaughter houses in different parts of Poland. Pigs were examined for the presence of Trichinella spp. using the artificial digestion method. Only four pigs were naturally infected with T. spiralis, the remaining were Trichinella larvae free. ELISA was used to examine IgG levels against L1 T. spiralis in pig and wild boar sera. The usefulness of ELISA for anti-IgG detection in pigs is usually limited by the nature of the antigen. The antigens were prepared in different laboratories: in Germany--Ag ES L1 T. spiralis (N), Italy--Ag ES L1 T. spiralis (W)) and in Poland--Ag ES L1 T. spiralis. Cut-off values for ELISA along with the estimated sensitivity and specificity were calculated using different methods: S/P%, M+3SD and ROC (Receiver Operating Characteristic). In SPF and Iberian pigs inoculated with 200, 1000 and 20,000 L1 T. spiralis, specific antibodies were detected 40, 30 and 25 dpi, respectively, with the use of the Standard (reference test). The analysis of the two ELISA procedures demonstrated a high sensitivity and specificity for the newly elaborated test utilizing the Ag ES L1 T. spiralis. In conventional pigs infected with 20,000 L1 T. spiralis specific antibodies were detected from 20 dpi when employing the new protocol. Similar results for the Standard and new ELISA test were obtained for serum samples of conventional pigs infected with 200 and 1000 larvae, which became positive from 40 dpi and 30 dpi, respectively. The results showed that both: the Standard and new protocols were comparable, and based on this, the new test was applied for further research. Results obtained adopting the new protocol with three antigens showed that two of them: Ag ES L1 T. spiralis (W) and Ag ES L1 T. spiralis are similar. The specific IgG antibodies for infective doses of 200 and 1000 larvae for these antigens were detectable 40 and 30 dpi respectively. In pigs infected with the highest dose of T. spiralis larvae IgG antibodies were detectable from 20 dpi when Ag ES L1 T. spiralis was used. These results strongly indicate that in examined pigs, the specific IgG response to T. spiralis infection is dose dependant. Of 1474 examined pig sera only 0.99% gave a positive signal against ES L1 T. spiralis antigen. Of 1784 examined wild boars sera only 0.68 % gave positive results using the new ELISA protocol. ELISA is a useful method for detecting specific IgG antibodies in pigs experimentally infected with different doses of T. spiralis and naturally infected pigs. In pigs the specific IgG response is dose dependant. The Ag ES L1 T. spiralis increases the specifity of the method and reduces false positive results. Simultaneous use of both methods: digestion and ELISA for the diagnosis of Trichinella in naturally infected pigs and wild boars may increase the chances of eliminating meat infected with T. spiralis larvae.