弓形虫免疫中脾转移因子对免疫细胞的影响

６只健康山羊分别连续注射普通脾转移因子（ＣｏｍｍｏｎＴｒａｎｓｆｅｒｏｒ，ＣＴＦ）及免疫脾转移因子（ＩｍｍｕｎｉｚｅＴｒａｎｓｆｅｒｏｒ，ＩＴＦ）３天后，发现转移因子能提高外周血白细胞总数，促使外周血嗜酸性粒细胞增加，增加外周血Ｔ淋巴细胞和促使外周血淋巴细胞活化等，证明转移因子具有提高机体免疫功能的作用。活虫攻击的结果显示，ＣＴＦ和ＩＴＦ均不能使机体获得完全的保护，但可使弓形虫急性感染向慢性感染转化。     

3种黄芩黄酮物质体外抗弓形虫效果比较试验

为探讨黄芩中主要成分对弓形虫的抑制效果,利用MTT法对黄芩乙醇提取物、黄芩苷、黄芩素进行体外抗弓形虫作用比较试验。结果表明:3种物质均能有效地抑制弓形虫的生长繁殖,其中黄芩素的抗虫效果最好,黄芩乙醇提取物次之,黄芩苷最弱,即黄芩黄酮主要物质中,黄芩素体外抗虫作用最好。     

Toxoplasma gondii-like organisms in skin aspirates from a cat with disseminated protozoal infection

An 8-year-old, male domestic shorthair cat was referred to the Matthew J. Ryan Veterinary Hospital of the University of Pennsylvania with a 3-day history of lethargy, inappetance, hyperemic skin nodules, coughing, and vomiting. Laboratory results included nonregenerative anemia, lymphopenia, thrombocytopenia, hypoalbuminemia, hyponatremia, and increased alanine aminotransferase and aspartate aminotransferase activities. Cytology of the skin nodules revealed many spindle- to crescent-shaped protozoal organisms, with morphology consistent with Toxoplasma gondii or Neospora caninum. Gross necropsy, histopathologic, immunohistochemical, and transmission electron microscopic findings confirmed a systemic protozoal infection; however, the organism exhibited characteristics of both N caninum and T gondii. Diagnosis of a T gondii-like infection was based on internal structures of the organism and positive reaction to rabbit polyclonal antibodies to T gondii. Reports of toxoplasmic dermatitis are rare in the cat and dog, and this is the first reported diagnosis of T gondii-like protozoa in skin aspirates.     

弓形虫ITS及5.8S序列的PCR扩增、克隆及分析

通过对国内来源于不同宿主的ZS人株、SH人株、CN猪株、QH绵羊株4个弓形虫虫株，以及国际标准强毒株RH株的核糖体DNA内转录间隔区(ITS)及5．8SDNA序列进行PCR扩增、克隆、测序和序列分析，旨在对国内不同宿主间弓形虫虫株的遗传变异情况进行分析和验证。为分子遗传学和分子诊断学研究提供资料。结果显示：QH绵羊株、ZS人株、SH人株、CN猪株的ITS及5．8S序列完全一致。且与GenBank上注册RH株的ITS及5．8S序列也一致；仅实验室传代保存的RH株的ITS2序列与其它4株的ITS2有2个碱基的差异。结果表明ITS可作为分子标记用于弓形虫与其它原虫的种间鉴定。但不适合用于弓形虫种内遗传变异的研究。     

弓形体抗原的纯化与分析

对几种提纯弓形体抗原的方法进行了比较。结果,分别经５０００ｒ、１００００ｒ、１５０００ｒ／ｍｉｎ离心３０分钟的粗抗原,用于检测弓形体抗体的Ｐ／Ｎ值依次为５．０５、５．６０、６．４３。用１００００ｒ／ｍｉｎ３０分钟处理的粗抗原（Ｒ１００００）,经凝胶柱层析分离洗脱,呈现２个蛋白峰（Ｆ１、Ｆ２）,经免疫学测定,其主要的抗原活性部分存在于Ｆ１中。Ｒ１００００抗原用５０％硫酸铵沉淀（Ｓ５０）的蛋白质得率达６４％;用７０％硫酸铵沉淀（Ｓ７０）的蛋白质率为３５％。Ｒ１００００与Ｆ１、Ｆ２、Ｓ５０、Ｓ７０５个抗原,经ＥＬＩＢ后用高免兔血清识别的条带数：Ｆ１和Ｆ２各１条、Ｓ５０Ｚ条、Ｓ７０和Ｒ１００００各３条。除Ｆ２之外,３９～４０ＫＤ为４种抗原的共同反应区带。用上述５种抗原致敏反应检测弓形体抗体,以Ｓ５０具有更高的敏感性和特异性。     

Serological survey of Toxoplasma gondii infection in domestic cats from northeastern Portugal

Cats are very important hosts in the epidemiological cycle of Toxoplasma gondii, a zoonotic protozoan parasite that can infect humans and many other animal species worldwide. We report a serological survey of antibodies to T. gondii in domestic cats from northeastern Portugal, by means of the modified agglutination test. Three cats had titres of 20 (3.9%), 18 had titres of 40 (23.7%) and 55 animals had titres of > or =800 (72.4%). Results of three seropositive kittens with less than 4 months were not considered for determining the seroprevalence of infection, which was found to be 35.8% (73/204). Differences in the seroprevalence levels were not statistically significant between males (35.6%) and females (36.0%) or pure non-European (26.7%) and European or mixed-breed cats (39.6%). Animals aged 36-71 months and 72-180 months had the highest seroprevalences of infection, i.e. 51.7% and 51.2%, respectively, which significantly differ from the values observed in cats with 2-11 months (14.6%) and 12-35 months (26.3%). Infection levels were also significantly different between cats that lived totally indoors (7.7%) and those that had access to outdoors (45.4%), as well as between cats living alone (13.8%) and those that had contact with other cats (39.4%). Seroprevalence values in cats fed only commercial canned or dried food (22.9%) and animals whose diet included raw or undercooked viscera and/or meat (53.5%) were also significantly different. Furthermore, considering only 108 cats, differences of seropositivity to T. gondii were significant between feline immunodeficiency virus infected and non-infected animals, but this was not observed for feline leukaemia virus. Age, habitat and diet were identified as risk factors for the feline T. gondii infection by logistic regression analysis. Some control measures are suggested based on these findings.     

Genotyping studies of Toxoplasma gondii isolates from Africa revealed that the archetypal clonal lineages predominate as in North America and Europe

Until recently, Toxoplasma gondii was considered to be clonal with very little genetic variability. Recent studies indicate that T. gondii isolates from Brazil are genetically and biologically different from T. gondii isolates from USA and Europe. However, little is known of the genetics of T. gondii strains from Africa. In this study, we genotyped 19 T. gondii isolates from chickens from six African countries (Egypt, Kenya, Nigeria, Congo, Mali, and Burkina Fasco) using 10 PCR-RFLP markers (SAG1, SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico). The results revealed four genotypes. Thirteen isolates belong to the Type III lineage, five isolates have Type II alleles at all loci except apico and they belong to the Type II lineage. One isolate from Nigeria had atypical genotype. In general, these isolates were mostly clonal Type III and II strains that predominate in North American and European. DNA sequencing at several loci for representative isolates confirmed the results of PCR-RFLP genotyping. Taken together with recent studies of T. gondii isolates from Africa, it is clear that the three clonal lineages (Types I, II and III) predominate not only in North America and Europe, but also in Africa.     

Ovine toxoplasmosis: Seroconversion during pregnancy and lamb birth rate in Uruguayan sheep flocks

Specific anti-Toxoplasma gondii antibodies were analyzed by latex agglutination during the 5 months of pregnancy in the serum of sheep from two flocks in the Uruguayan north-west: one flock (79 sheep) kept under an intensive management system and the other (494 sheep) kept under an extensive management system. Titers obtained using the latex test correlated with those obtained by indirect immunofluorescence. Pregnancy was confirmed by laparoscopy in all sheep from the smaller flock and by determination of serum progesterone levels in the seroconverted sheep from the larger flock. The percentage of sheep originally exhibiting significant serum levels of anti-T. gondii anti-bodies (13.9% in the smaller flock and 28.5% in the larger one) as well as the observed levels of seroconversion (22.8% and 7.7%, respectively), indicated a high prevalence of this infection in the north-west of Uruguay. In addition, birth rates of seroconverted sheep in the larger flock were significantly different from those of non-seroconverted animals. These results, although preliminary, suggest that Toxoplasma infection would produce considerable economic losses in extensive ovine production in Uruguay.     

蛋白AG检测多种动物弓形虫抗体AG-ELISA的效果评价

利用建立的可检测多种动物弓形虫抗体的AG-ELISA方法,检测了人工感染及自然感染4种动物血清中的弓形虫抗体.对人工感染猪血清的检测结果表明,AG-ELISA法可于感染后第10天全部检出阳性,早于MAT方法的第14天,其检出率、敏感性及准确度等指标亦优于MAT法.在对临床上304份动物血清检测中,AG-ELISA法对猪、羊血清的阳性检出率高于MAT法,而对犬、猫血清的栓出率则与MAT法相同.Kappa一致性试验表明,AG-ELISA法与MAT法符合良好.上述结果证实AG-ELISA法可用于多种动物弓形虫抗体的检测.