血吸虫及肺吸虫中间宿主拟钉螺的研究Ⅰ.云南省拟钉螺一新种:景洪拟钉螺(腹足纲:觿螺科)

五十年代后期在湄公河流域发现可感染人的湄公血吸虫病,其病原湄公血吸虫 Schistosma mekongi的中间宿主被证明为开放拟钉螺 Tricula aperta (Temcharoen,1971)。湄公河的上游是流贯云南省的澜沧江,我们从1981年开始进行调查,在西双版纳发现有血吸虫和肺吸虫寄生的拟钉螺,经鉴定隶属拟钉螺属 Tricula一新种。     

血吸虫疫苗研究进展

血吸虫疫苗研究进展许家喜（北京大学化学与分子工程学院,北京１００８７１）关键词血吸虫疫苗血吸虫病的防治在当今世界上仍是一个有待解决的严重问题,迄今已发现１９种血吸虫能侵犯人体,其中对人类健康有威胁的有曼氏、日本、埃及、湄公与间插５种血吸虫。据世界卫生...     

两种品系小鼠对日本血吸虫感染及肿节风处理反应的比较

本实验对BALB/c近交鼠及昆明小鼠感染日本血吸虫及肿节风处理后的反应,对血吸虫的生物学特性及宿主的若干反应作了比较研究,区分了它们充作日本血吸虫终末宿主的特点。认为,在缺乏更适宜的近交鼠的情况下,昆明小鼠不失为一种较好的日本血吸虫感染的动物模型。 .     

中国大陆五个地区日本血吸虫人工感染恒河猴的研究

本文报告了具有分布区代表性的中国大陆5地日本血吸虫人工感染恒河猴的实验结果。在相同宿主、相同感染度和相同感染期的条件下,恒河猴感染云南、广西两地日本血吸虫后的平均虫卵开放前期、两性虫体体长及性腺发育以及肝组织中单个虫卵引起增生期肉芽肿的平均体积与感染安徽、湖北、四川三地虫体的有所不同。这表明恒河猴宿主机体对感染前两地虫体的应答情况与对感染后三地的有异,并提示中国大陆境内日本血吸虫可能存在不同的品系。     

黄牛与水牛感染日本血吸虫的比较研究

本文报告了15头黄牛和14头水牛感染日本血吸虫后的虫卵开放前期、虫体回收率、成虫体长及性腺发育状况、肝组织中虫卵肉芽肿大小和虫卵周围何博礼现象等比较结果,表明黄牛较水牛对日本血吸虫更为易感。根据耕牛在日本血吸虫病中的传播特点和流行病学意义以及人兽共患寄生虫病的概念,建议将这类动物终末宿主称为交替宿主(alternative host)以取代过去沿用和内涵狭溢的“贮存宿主或保虫宿主(reservoir host)”的名称。     

日本血吸虫非编码小RNA研究进展

非编码小RNA是一类通过调节基因的表达从而影响生命活动的小分子,主要包括微小RNA、内源性小干扰RNA、Piwi蛋白相互作用的RNA及竞争性内源RNA。研究发现日本血吸虫感染动物后,宿主和虫体的非编码小RNA的表达水平均发生了改变。宿主源的非编码小RNA主要为微小RNA,其中miR-454和miR-203与日本血吸虫病发生发展有关,miR-223和miR-451与日本血吸虫自身生长发育有关;日本血吸虫非编码小RNA包括微小RNA、内源性小干扰RNA,这些非编码小RNA在日本血吸虫的生长、发育、性成熟及产卵中发挥着重要作用,如sjalet-7、sja-bantam,而且像sja-miR-3479和sja-miR-0001还可以诊断日本血吸虫病。就日本血吸虫非编码小RNA的研究进展进行综述,为日本血吸虫病的防治提供参考。     

血吸虫病感染特征及其免疫病理机制的研究进展

血吸虫病是由血吸虫病裂体吸虫属血吸虫引起的一种寄生虫病,分布范围广,广泛分布在热带及亚热带的贫困偏远地区,其在公共卫生方面的重要性仅次于疟疾,该病已经造成了大量的残疾和死亡。据世界卫生组织(WHO)血吸虫病专家委员会1984年统计,全球感染血吸虫人口已达2亿。血吸虫种类繁多,寄生于人体的有6类,其中埃及血吸虫、曼氏血吸虫和日本血吸虫是主要的致病种类。血吸虫卵是血吸虫病的主要致病因子,寄生于宿主组织中的虫卵使宿主发生免疫病理反应,导致泌尿生殖系统(埃及血吸虫)炎症和梗阻性疾病、肠道疾病、肝脾炎症和肝纤维化(曼氏血吸虫和日本血吸虫)的发生。没有得到有效控制的早期血吸虫病发展到晚期,可引起包括上消化道出血、肝性脑病(日本血吸虫和曼氏血吸虫)、膀胱鳞状细胞癌(埃及血吸虫)和不孕不育症在内的严重并发症,主要对血吸虫病流行病学、临床表现、临床分期、并发症、致病机制及其免疫病理机制作一综述。     

曼氏血吸虫中间宿主——藁杆双脐螺

藁杆双脐螺(Biotaphafaria straminea)是曼氏血吸虫中间宿主。曼氏血吸虫(Shistosoma mansoni)是寄生在人体内的血吸虫,生活史与日本血吸虫生活史大体相似,成虫交配产卵,卵随大便、偶从小便排出体外,在水中孵出毛蚴,毛蚴入双脐螺体内,发育成母胞蚴、子胞蚴,尾蚴,然后到终末宿主(人)。曼氏血吸虫与日本血吸虫在终末宿主体内的移行径路极为相似,常能数次通过肝毛细血管、肺及大循环,最后定     

单性感染及复性感染日本血吸虫发育的研究

1.单性感染之雌性日本血吸虫平均不超过5.35±0.07毫米,只为复性感染中成熟雌虫长度之1/3左右,且其生殖器官始终呈童雏状态。单性感染之雄虫能发育成熟,贮精囊内也有活动精子,但其大小与成熟合抱之雄虫平均相差3.05毫米左右。 2.宿主性别之不同对于血液中的雄性血吸虫有比较显著的影晌。在雄性宿主体内单性雄虫比雌性宿主体内之单性雄虫发育快。宿主性别之不同对于单性雌虫之影响则不甚明显,雌性宿主体内发育之雌虫仅略大于在雄性宿主体内之单性雌虫。 3.血液中合抱成熟之雌虫及雄虫的分泌物质不能促使未合抱之雄虫发育正常。未合抱之雄虫似略大于单性感染之雄虫,但是显著小于合抱雄虫。 4.合抱成熟之雌虫及雄虫的分泌物质对于未合抱之雌虫完全没有促使发育的作用。相反地,有一定的抑制作用而使未合抱之雌虫显著地小于单性感染之雌虫,二者之生殖器官皆停留于雏形状态。 5.复性感染中每对雌雄成虫之抱合是永久性的。每一条雄虫只能促使一条雌虫发育成熟而不再转换抱合其余未成熟之雌虫。 6.鉴于雌雄合抱对于日本血吸虫正常发育的必要性,故就生物进化之观点讨论了日本血吸虫雌雄异体的原始性。     

日本血吸虫在离体培养中的产卵和虫卵发育过程的研究

1.本文证明日本血吸虫卵在适合的条件下,在离体培养中亦能发育至成熟,并孵出毛蚴,而并不一定需要经过一个宿主组织内发育阶段。日本血吸虫卵在离体培养中自产出到完全发育成熟所需的时间最少为12—13天。 2.日本血吸虫卵在离体培养中发育至成熟的必需条件为:培养液中必需有血清及红血细胞的存在,其中尤以红血细胞的存在更为重要。 3.本文应用相比差显微镜初步但较系统地观察和描写了血吸虫卵细胞的分裂发育过程。证明血吸虫卵细胞的分裂过程亦属不等裂的类型,与其它吸虫卵细胞分裂发育的过程类似。为了便于统计,本文把血吸虫卵的发育过程分为以下四个时期:1)单细胞期。2)细胞分裂期。3)胚胎发育期。4)毛蚴成熟期。本文并对发育各期的出现时间及增减趋势进行了初步观察。 4.本文证明凡是在宿主体内曾经合抱过的发育成熟的血吸虫雌虫,不论它在离体培养时是否处于合抱状态,雌虫均能产卵。其所产出的虫卵数量的多少与所用培养液的种类及雌虫在培养液中的存活时间有关。同时亦证明了血吸虫在离体培养的环境中不仅能将其子宫中已形成的虫卵排出,而且还有新的虫卵的形成。其产卵数量和培养时间有关,其产卵高峰期为培养后的第2—7天。     

Molecular phylogenetic position of Schistosoma sinensium in the genus Schistosoma

The status of Schistosoma sinensium (samples from Thailand and from Sichuan, China) relative to other species of the genus Schistosoma was investigated using DNA sequences from the mitochondrial cytochrome c oxidase subunit 1 (CO1) gene (partial) and the nuclear ribosomal DNA second internal transcribed spacer 2 (ITS2). Trees inferred from these sequences place S. sinensium as sister to the S. japonicum group and suggest a basal position in the clade utilizing snails of the family Pomatiopsidae. The sequence differences between specimens of S. sinensium from China and Thailand are at least as great as between S. malayensis and S. mekongi. Schistosoma sinensium is probably best regarded as a species complex.     

Schistosoma malayensis n. sp.: a Schistosoma japonicum-complex schistosome from Peninsular Malaysia

Schistosoma malayensis n. sp., a member of the Schistosoma japonicum complex is described from Rattus muelleri in Peninsular Malaysia and 2 strains are characterized. The only morphological differences noted among adults from natural hosts were that S. malayensis are in general smaller than S. mekongi and S. japonicum. But these differences may be the result of host-induced variations and therefore are of little taxonomic value. To minimize the effects of host-induced variations, adult worms recovered from laboratory mice with similar worm burdens at 50-56 days postinfection were compared. These comparisons revealed only minor morphometric differences among these 3 species. Schistosoma malayensis eggs from naturally and experimentally infected hosts are most similar to those of S. mekongi, with eggs of both species being, in general, smaller than those of S. japonicum. The egg index for S. malayensis is usually higher than for S. japonicum and lower than for S. mekongi. Differences were noted in the developmental rates in mice for 2 isolates of S. malayensis, S. mekongi, and S. japonicum (Philippine strain), but relatively large differences observed between isolates of S. malayensis indicate that, in this case, the developmental rate is not a useful taxonomic character. Schistosoma malayensis is erected principally on the basis of differences, reported elsewhere, in the life histories and in the electrophoretic migration patterns of isoenzymes of adult worms as compared to S. mekongi and S. japonicum. These comparisons indicate that S. malayensis is more closely related to S. mekongi than to S. japonicum.     

Schistosoma mekongi and Schistosoma japonicum: Differences in the distribution of eggs in the viscera of mice

The difference in the distribution of Schistosoma eggs in the viscera has not been clearly elucidated in the two closely related species Schistosoma japonicum and Schistosoma mekongi. In this study, we quantitatively compared the distribution of eggs in mice infected with the two species. In S. mekongi-infected mice, 56.6% to 69.4% of total eggs were found in the distal small intestine 9 to 15 weeks after infection, while in S. japonicum-infected mice, 48.8% to 71.8% of eggs were found in the proximal small intestine during the same period. There were significantly more eggs in the liver in mice infected with S. japonicum than in those infected with S. mekongi. The number of adult worms recovered did not differ between the two species during the study period. The total number of eggs laid in the tissues also did not differ between the two species at 12 to 15 weeks postinfection, but in the earlier period the total number of eggs was significantly fewer in S. mekongi-infected than in S. japonicum-infected mice, suggesting the delayed maturation of the former compared with the latter. These results clearly show that S. japonicum and S. mekongi exhibit different oviposition behavior in their hosts.     

Schistosoma mansoni, S. haematobium, and S. japonicum: identification of genus- and species-specific antigenic egg glycoproteins

Immunoreactive egg glycoproteins of Schistosoma mansoni, S. haematobium, and S. japonicum which are genus- and species-specific, or react with sera of patients infected with other parasites, have been identified. Egg proteins were labeled with Iodine-125, and the concanavalin A-binding glycoproteins were immunoprecipitated with sera of patients infected with one of four species of Schistosoma or Trichinella spiralis, Taenia solium, Echinococcus granulosus, Entamoeba histolytica, or Wuchereria bancrofti. These immunoprecipitates were analyzed by two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Despite the strikingly different patterns of glycoproteins of the African species, the antibody immune responses of patients infected with S. mansoni and S. haematobium were found to be so similar that differentiation could not be established. In contrast, sera of patients infected with S. japonicum, S. mekongi, or parasites not of the genus Schistosoma, immunoprecipitated fewer of the major S. mansoni or S. haematobium glycoproteins. Likewise, antibody immune responses of patients infected with the Oriental schistosomes (S. japonicum and S. mekongi) could not be differentiated. Only a few quantitative differences were noted between our S. mansoni egg glycoprotein extract and a standardized soluble egg antigen extract. This study provides an explanation for the extensive cross-reactivity observed in diagnostic assays which utilize various fractions of schistosomal egg extracts as the antigen.     

Malic dehydrogenase patterns in different strains of Schistosoma japonicum and subspecies of Oncomelania hupensis.

Malic dehydrogenase (MDH) of the Formosan Philippine and Indonesian Strains of Schistosoma japonicum and 3 subspecies of snails, Oncomelania hupensis formosana, O. h. quadrasi, and O. h. lindoensis were identified by disc electrophoresis with 10.5% acrylamide gel columns using tris-malic buffer. Male worm extracts of S. japonicum demonstrated 3, 2, and 2 clear MDH patterns and female worm extracts showed patterns of 2, 1 and 1 for the Formosan, Philippine and Indonesian strains of the parasite, respectively. MDH patterns were the same for all 3 subspecies of snails; one major and one minor band being found in all.     

Schistosoma mekongi: a prominent neutrophil chemotactic activity of egg antigen with reference to that of Schistosoma japonicum

Schistosoma mekongi causes granulomatous lesions around eggs deposited in the liver with neutrophil-rich inflammatory reactions in the early stage of the egg laying. To define the aspects of the typical pathogenesis of S. mekongi infection, we determined the difference between soluble egg antigen (SEA) from S. mekongi and S. japonicum with a focus on chemotactic factors for neutrophils or eosinophils. Mean volume and protein amount of S. mekongi eggs was 71 and 58% of those of Schistosoma japonicum eggs, respectively. Neutrophil chemotactic activity of S. mekongi SEA was about two times higher than that of S. japonicum. In contrast, eosinophil chemotactic activity of S. mekongi SEA was about half of that of S. japonicum SEA. Molecular analysis revealed that S. mekongi SEA contains higher molecular-weight components with a lower level of glycosylation, and this is likely to be related to the intense neutrophil chemotactic activity in comparison with S. japonicum SEA. The prominent chemotactic reactivity for neutrophils is likely to be involved in the typical pathogenesis of mekongi schistosomiasis.     

Transplantation of Schistosoma japonicum daughter sporocysts in Oncomelania hupensis

Schistosoma japonicum daughter sporocysts obtained from infected Oncomelania hupensis hupensis were successfully transplanted to parasite-free O. hupensis hupensis. Survival and infection rates of recipient snails were 80% and 75% respectively. Intramolluscan development of transplanted daughter sporocysts in recipient snails appears to proceed in a similar manner as those reported for transplanted S. mansoni and S. haematobium in their respective snail intermediate hosts. Complete colonization of the digestive gland of recipient snails by sporocysts was observed 80 days after transplantation. Cercarial production during a 10-day observation from recipient snails was characterized by periods of high and low and irregular daily emissions. The average daily cercarial production was 150 per snail. Cercariae produced by recipient snails were infective to mice. Of those cercariae exposed to mice, approximately 30% developed to adult schistosomes. These results have definitive utility in the maintenance of S. japonicum in the laboratory.     

洞庭湖外睾吸虫新种及其生活史

本文报告洞庭湖区鲶鱼肠道寄生的洞庭湖外睾吸虫Exorchis dongtinghuensis sp.nov(新种)及其全程生活史,其第一中间宿主为湖北钉螺Oncomelania hupensis;第二中间宿主为鲤鱼、鲫鱼和金鱼;终宿主为鲶鱼Parasilurus asotus。作者对各期宿主作了人工感染试验和现场自然感染调查。对其发育过程作了观察比较。     

The pig as a host for Schistosoma mekongi in Laos.

A survey of helminths in domestic pigs was conducted in Khong District, Laos, to elucidate if these domestic animals could act as definitive hosts for Schistosoma mekongi and to obtain a general overview of their helminthological infection status. Fecal samples were collected from 98 pigs. Twelve pigs (12.2%) were found to excrete S. mekongi eggs. Infection was confirmed by detection of S. mekongi eggs in tissues of liver, rectum, and cecum of 2 pigs. A total of 75.8% of the pigs was infected with 1 or more helminth species. This study showed that pigs may act as a definitive host for S. mekongi.