弓形虫天然免疫影响因素的研究进展

弓形虫与宿主免疫系统之间存在着精妙的平衡,而弓形虫天然免疫在这个平衡中发挥着重要的作用,因此了解弓形虫天然免疫的影响因素对于控制疾病、开发有效的疫苗具有重要的意义。本文对影响天然免疫的8种主要因素进行了综述,主要包括IL-12、IFN-γ、NO、活性氧中间物、铁、色氨酸、p47GTP酶和抗炎性细胞因子。     

Protective immunity to toxoplasmosis in pigs vaccinated with a nonpersistent strain of Toxoplasma gondii

The RH strain of Toxoplasma gondii is highly virulent; 1 infective organism is uniformly lethal for mice. Three pigs inoculated SC with 10(3) tachyzoites of the RH strain developed fever, but otherwise remained normal, and T gondii was not demonstrated in their tissues by bioassay into mice. To determine whether vaccination with the RH strain could induce protective immunity to oral challenge with T gondii oocysts, 12 pigs were divided into 3 groups (A, B, C) of 4 pigs each. Pigs in groups A and B were inoculated IM with 10(6) tachyzoites of the RH strain and 4 pigs in group C served as uninoculated controls. Except for fever, the pigs remained clinically normal after inoculation with the RH strain and T gondii was not found by bioassay in mice of tissues from 4 pigs euthanatized 64 days after inoculation. Pigs in groups B and C were challenge-inoculated orally with 10(4) (4 pigs) or 10(5) (4 pigs) T gondii oocysts 72 days after vaccination with the RH strain. The previously uninoculated pigs developed fever, anorexia, and diarrhea from 3 to 8 days after the oocyst challenge. One of the 2 pigs given 10(5) oocysts became moribund because of toxoplasmosis and was euthanatized 9 days after inoculation. Pigs vaccinated with the RH strain remained free of clinical signs after challenge with oocysts. Results of the bioassays indicated that fewer tissue cysts developed in the RH strain-vaccinated pigs than in the previously uninoculated control pigs.     

弓形虫疫苗研究进展

弓形虫是细胞内寄生的一种原虫,弓形虫病是由弓形虫引起的一种重要人兽共患寄生虫病,弓形虫疫苗作为防控弓形虫病的重要措施是目前研究的热点。弓形虫进入机体后以细胞免疫为主,使得疫苗可以发挥最大功用。疫苗的免疫效果与候选抗原和佐剂的使用密切相关,不同类型的抗原和佐剂用于疫苗中能够产生不同的免疫效果。目前,弓形虫疫苗的候选抗原主要以虫体特异组分蛋白和新型表位基因为主,佐剂也从传统的弗氏佐剂拓展到了霍乱毒素、透明质酸酶和CpG-ODN等。综合考虑各方面因素进行疫苗研制,将成为生产具有理想保护性弓形虫疫苗的研究方向。     

Farmed wild boars exposed to Toxoplasma gondii and Trichinella spp

The meat of wild boar (Sus scrofa L.) can be a source of human infections with zoonotic parasites Toxoplasma gondii and Trichinella spp. We screened 197 wild boar sera collected at slaughter from 25 Finnish farms in 2007-2008 for serological evidence of infections with these parasites. Using a commercial direct agglutination test at a serum dilution of 1:40, T. gondii-specific IgG antibodies were detected in 65 (33.0%) samples, on 14 (56.0%) farms. Females, animals older than 24 months, animals of small herds, and animals originating from south-western parts of Finland were more often T. gondii-seropositive than were males, younger animals, animals of larger herds, and animals originating from the north and east, respectively. Four (2.0%) of the sera, originating from three (12.0%) farms, tested Trichinella-seropositive with an in-house ELISA and a conservative cut-off for seropositivity. One farm had both T. gondii- and Trichinella-seropositive animals. Taken together, an infection source had been present on 16 (64.0%) farms, and 69 (35.0%) of the 197 farmed wild boars intended for human consumption had specific serological evidence of exposure to a zoonotic parasite.     

弓形虫膜囊的生物发生

弓形虫(Toxoplasma gondii)属于囊泡虫类(alveolate)顶复门(Apicomplexa)原虫的一种,能够在几乎所有人和恒温动物(鸟类和哺乳动物)的有核细胞内寄生并建立感染。这种原生细胞的胞质膜下有双层膜囊(Alveoli)结构称为内膜复合体(Inner membrane complex)。弓形虫是专性细胞内寄生原虫,内膜复合体对弓形虫体外滑动、入侵、宿主细胞内存活及逸出发挥至关重要的作用。然而内膜复合体的生物发生机制还知之甚少。近期研究表明,内膜复合体蛋白是由高尔基体分泌且网格蛋白包裹的囊泡运输到内膜组装生成。     

Intracranial Toxoplasma gondii granuloma in a cat

An 8-year-old cat with recent-onset generalized seizures was diagnosed with a right forebrain mass using magnetic resonance imaging. The mass was excised and upon histologic and immunohistochemical examination shown to be a Toxoplasma gondii granuloma. Serology supported active T gondii infection. The cat was treated with phenobarbital to control seizures. After definitive diagnosis of toxoplasma granuloma, clindamycin was administered for approximately 1 month. Seizures recurred 8 months after initial presentation, and the cat was euthanased at the owner's request. This is a previously unreported manifestation of feline central nervous system toxoplasmosis. When a mass lesion is present in the brain of a cat and serologic test results support active infection with T gondii, toxoplasma granuloma must be a differential diagnosis. If the patient is suffering from clinical disease, surgical resection of the mass (if possible) can be complimented with medical treatment until definitive diagnosis is obtained. Immunocompromising factors should be identified and addressed if possible.     

Toxoplasma gondii infection in Polish farmed mink

The aim of this study was to determine the seroprevalence of Toxoplasma gondii antibodies in Polish farmed mink according to way of feeding as well as to confirm the role of toxoplasmosis in reproductive losses in mink farms. The serological examinations were carried out on 961 mink randomly selected from 12 Polish farms. Blood sera were examined for the presence of T. gondii antibodies with the use of the latex agglutination test. The examinations for the presence of T. gondii in organ tissues were performed on five neonatal mink kits with the use of immunofluorescence method. In total 133 (13.9%) out of 961 examined mink had T. gondii antibodies. In large farms the seropositivity was lower (2.9%), than in small farms (26.33%) (P < 0.001). Significant difference was found in seroprevalence according to way of feeding. In farms feeding fish, percentage of seropositivity was lower (2.2%), than in farms based on non-frozen slaughter offal (43.4%). Titres of T. gondii antibodies were usually lower than 120 IU/ml. Using the immunofluorescence method, T. gondii was detected in impression smears from liver and brain of two neonatal mink kits derived from one seropositive female.     

Toxoplasma gondii antibodies in California swine.

In a serologic survey for Toxoplasma gondii in 891 swine from 20 California counties, 478 (54%) were seronegative, 153 (17%) were nonspecific reactors, and 260 (29%) were seropositive. Most of the titers (81%) were low, ie, from 1:64 to 1:128, but a few (2%) were high, ie, 1:1024 or greater.     

弓形虫主要表面抗原的研究进展

弓形虫(Toxoplasma gondii)是一种呈世界性分布的机会性致病原虫,它的宿主范围非常广泛,感染包括人在内的190多种哺乳动物和鸟类。弓形虫的表面是与宿主细胞最先接触的部分,其表面抗原(SAG,Surface antigen)在虫体对宿主细胞的吸附、信号传导、入侵等过程中以及弓形虫的各个发育阶段中发挥着重要作用。本文主要对近年来国内外对弓形虫表面抗原的研究进展作一综述。