Studies on Murine Retrovirus-Related Sequences in the Schistosome. DNA

从日本血吸虫成虫和曼氏血吸虫成虫提取的DNA经Southern杂交证实，存在与小鼠嗜生性和嗜异性逆转录病毒env基因同源的序列。在日本血吸虫成虫和曼氏血吸虫虫卵的DNA中也检测到了与亲水性小鼠白血病病毒Gag区和Pol区以及与小鼠脑池内A颗粒和内源性C型逆转录病毒同源的DNA序列。该反应在抗体与逆转录病毒粒子吸附后被完全抑制。日本血吸虫和巴氏血吸虫的反应性抗原定位于雄性成虫的亚节层和成虫的卵黄腺。对两种寄生虫提取的蛋白质进行免疫印迹分析。抗Bv2gp70抗血清…More与来自血吸虫和血吸虫的这些蛋白发生反应，并且不同性别和物种的条带不同。与来自毛细管虫的克隆SmE15 DNA杂交，在来自Bmansoni成虫的DNA中没有信号，表明这些序列在成虫中缺失。用分别从曼氏血吸虫雌成虫和雄性成虫中克隆的1.3kb和2.2kb的探针SmF25和SmM51与曼氏血吸虫毛滴虫DNA进行杂交实验，未发现与曼氏血吸虫毛滴虫DNA相关的信号。在日本血吸虫成虫DNA、日本血吸虫卵和曼氏血吸虫DGGS中检测到小鼠L Alu序列(B1)、小鼠2型Alu序列(B2)和小鼠小卫星mo-2序列等寄主基因组中的重复序列。几乎所有上述序列在曼氏血吸虫成虫DNA中都不存在。使用mo-2序列的血吸虫DNA指纹彼此难以区分，与它们的小鼠宿主相似。此外，血吸虫DNA中的mo-2序列发生了高甲基化，其量是可变的。这些事实表明，宿主相关序列确实存在于血吸虫中，mo-2重复序列可能存在于染色体外。利用逆转录病毒Gag区的引物进行聚合酶链式反应，在日本血吸虫雄性成虫和曼氏血吸虫卵的DNA中扩增出与Gag相关的序列。较少

Southern hybriaizdtion of the DNA extracted from adults of Schistosoma japonicum and S. mansoni demonstrated the presence of sequences homologous to the env gene of mouse ecotropic and xenotropic retroviruses. DNA sequences homologous to the gag and pol regions of the ecotropic murine leukemia virus, and to the mouse intracisternal A particle and endogenous type C retrovirus were also detected in the DNA of S. japonicum adults and S. mansoni eggs.Antibodies against the retrovirus envelope glycoprotein (gp70) of mouse xenotropic retrovirus, BALB virus 2 (Bv2) reacted with the adult worms of S. japonicum and S. mansoni. This reaction was completely inhibited after adsorption of the antibodies with virions of retrovirus. The reactive schistosome antigen was located in the subsegumental layer of adult male fluke and in the vitelline gland of the adult female of S. japonicum and S. Bmasoni. Proteins extracted from both parasites were examined by immunoblot analysis. Anti-Bv2 gp70 antiserem … More reacted with those proteins from both schistosomes and the band patterns were different among sexes and species.Hybridization with a clone SmE15 DNA from S. Bmasoni miracidia as a probe showed no signal in the DNAs from S. Bmansoni adults, indicating these sequences deleted in adults. Hybridization experiments using the probes SmF25 and SmM51 which are 1.3 and 2.2kb fragments cloned from s. mansoni adult females and males respectively, demonstrated no signal to DNA from S. mansoni miracidia. These data suggested the existence of stagespecific DNA sequences in S. mansoni.Repetitive sequences in the host genome such as mouse type l Alu sequence (Bl), mouse type 2 Alu sequence (B2) and mo-2 sequence, a mouse minisatellite, were detected in the DNAs from adults and eggs of S. japonicum and dggs of S. mansoni. Almost all of the sequences described above were absent in the DNAs of S. mansoni adults. The DNA fingerprints of schistosomes, using the mo-2 sequence, were indistinguishable from each other and resembled those of their murine hosts. Morever, the mo-2 sequence was hypermethylated in the DNAs of schistosomes and its amount was variable in them. These facts indicate that host-related sequence are actually present in schistosomes and that the mo-2 repetitive sequence exists probably in extra-chromosome.Polymerase chain reaction using the primer sets of gag region of retrovirus revealed the amplification of gag -related sequences in the DNAs of S. japonicum male adults and S. mansoni eggs. Less