Hybridomas producing monoclonal antibodies (McAb) directed against Trichomonas vaginalis have been produced by fusing NSI myeloma cells with spleen cells of BALB/c mice immunized with Trichomonas vaginalis.IFA technique was used to test the binding activity of four McAbs produced.The McAb belonged to the IgG subtypes IgGl(2A2,2A4 McAb),IgG3 (2H9 McAb) and IgG 2b (2A12 McAb).Three McAbs,designated 2A2,2A4,2A12,reacted with a surface membrane component of live Trichomonas vaginalis.One (2A12) of them produced com-plement-dependent cytolysis of the parasites.Others (2A2.2A4) produced complement-independent cytotoxicity of the parasites.2H9 McAb which reacted with the nucleus of the organisms did not agglutinate the parasites.The four McAbs which did not have cross reaction with some protozoa of Zoomastigophorea species were specific antibodies against Trichomonas vaginalis.(Figs.1-3)

Objective To study the effect of artemether (Art) on total antioxidant capacity (T-AOC) in adult Schistosoma japonicum. Methods In vitro, the T-AOC was determined in five-week old worms incubated without or with Art and/or hemin for 24 h, and the worms were continuously incubated for 96 h, then worm survival was assessed. In vivo, T-AOC was determined in worms freshly recovered from mice 6 - 24 h after treatment with Art 300 mg/kg. Results Throughout 96 h incubation no worms were killed by 50 μmol/L Art or 50 μmol/L hemin alone, but approximatdy 80% of them were killed by Art plus hemin. Addition of reduced glutathione and vitamin E could significantly block the cidal action of the combined treatment. No effect on T-AOC was seen in the worms exposed to Art or heroin alone for 24 h, but the combined treatment led to a pronounced T-AOC reduction in female worms in vitro. Such a drug effect on female worms was demonstrated in vivo. After female worms were exposed to Art for 6 - 24 h in vivo, their T-AOC was significantly reduced by 40% - 64%. However, no drug effect on male worms' T-AOC was observed in vivo and in vitro exposed to Art plus hemin. Conclusion Art-induced T-AOC reduction in female worms may sensitize them to lethal damages of endogenous and exogenous oxygen radicals.

[Objective] To determine the effect of Schistosoma japonicum infection on the testoterone level in the sera from male C57BL/6 mice. [Methods] Radioimmunoassay was used to examine testosterone levels in sera of 9 male mice experimentally infected with Schistosoma japonicum. [Results] The serum testosterone levels reduced significantly in all experimentally infected animals 45 days after infection, as compared with the uninfected controls. [Conclusion] Infection with Schistosoma japonicum decreases testosterone levels in the mouse host.

[Objective] To evaluate the diagnostic value of the recombinant antigen of 39 amino acid repeats encoded by a kinesin-like gene of Leishmania changasi (rK39) in serodiagnosis of visceral leishmaniasis (VL). [Methods] In Kashi, Xinjiang, 13 VL patients with splenomegaly and bone marrow aspirate culture positive were subjected to dipstick assay. A drop of whole blood or serum from patient was placed at the absorbing pad at the bottom of the dipstick.Flooding of the bottom protein with buffer allows serum proteins to migrate upwards, producing the positive band and Western blot analysis of rK39 subsequently performed with the sera collected. [Results] The end-point titers of antirK39 antibodies of these sera were determined by ELISA and found to fall within the range of 10-2 to 10-4, which were consistent with the intensity of their reaction with rK39 in dipstick assay. The positive sera could also recognize the specific rK39 band as analyzed by Western blot analysis. [Conclusion] The rK39 dipstick assay is more rapid, specific, sensitive and less invasive than the conventional methods of diagnosis for VL in the areas of low endemicity.

[Objectice] To study the relationship between the livestock trade and schistosomiasis transmission and to provide an evidence for making a strategy of schistosomiasis control in mountainous areas. [Methods] A retrospective survey and analysis was conducted to investigate the prevalence of schistosomiasis in both humans and livestock (cattle, horses, mules, donkeys and pigs), and the number and migration of livestock in Weishan County, Yunnan Province in 1980～ 1991. [Results] A positive correlation was found between the infection rate of residents and the numbers of livestock migration (R=0. 9151, P＜0.01). During 1980 to 1991 the infection rate was increased gradually along with the development of livestock husbandry, especially, from the economic reforms since 1984. In 1984 there was positive correlation in the infection rate both human and livestock (R=0. 8458, P＜0.05). The results show that the infection rates of livestock on sale including cattle, horses, mules, donkeys and pigs are 9.54%, 29.39%, 16.38%, 14.47%, 25.73% and 11.11%, respectively. [Conclusion] The infection rate of human and livestock arises by parallel. The high frequency of livestock trade resulted in serious spreading of the infection source of schistosomiasis. The migration of the infected livestock might be an important factor in transmitting schistosomiasis.

[Objective] To obtain the genetic information on Necator americanus and to search for the purpose genes.[Methods] Mrna was isolated from the third stage larvae of Necator americanus maintained in hamsters.Double strand Cdna was synthesized and ligated to ΛzapⅡ vector to construct the Cdna library.Expresed se-quence tages (ESTs) were obtained by single pass sequencing of randomly isolated Cdna clones from the es-tablished library.[Results] A Cdna librazy of N.americanus was successfully constructed with high recombi-nant efficiency.The titer of unamplified library was 1×107.The insert size was about 750～3000bp.Of 11 ESTs obtained from the library,7 have a significant homology with certain functional genes.[Conclunsion]A high quality and high representative Cdna library of N.americanus was constructed at the first time and ome functional genes were identified from the library by ESTs.

[Objective] To answer the following questions:① For Oncomelania snails collected two years apart from the same locality,has there been genetic divergence?②How much experimental error has there been in studying subsets of these populations? ③As this is an unstable population,what has the net effect been on Hardy-Weinberg equilibrium(Hwe)?[Methods] Allozymes were studied using horizontal starch gel electrophoresis.Data collected from numbers of experiments were conapiled.Data from each collection were divided into two equal subsets based on chronology of the experiments.Thirty-four loci were studied using 72 to 180 snails per subset.[Results] The mean number of alleles per locus ranged frcra 1.5～1.9.With each consecutive subset,the 96 polymorphic loci dropped from 38.2 to 17.6.The mean heterozygosity was very low:0.033 to 0.049 and not significantly different from Hardy-Weinberg expectations.Ten loci and 11 alleles exclusive to the first group were eliminated from the overall study reducing the number of polymorphic loci from 19 to 10.There were significant departures from Hwe at five loci having a substantial number of individuals for each allele.Nei's and Wright's D were 0.003±0.001 and 0.054±0.006 respectively.[Conclusion] ①There were significant errors seen primarily in the results scored' in the earliest experiments.②These earlier errors involving scoring difficult to resolve loci,and interpretation of rare alleles that were not found in later experiment had no significant effect on overall genetic distance.③The use of Wright's D for closely related populations is explained.Results with Nei's D indicated no significant difference among the four subunits; Wright's D yielded significant difference between the collections made two years apart,attributed to the annual flooding of the Yangtze River mixing snails from different localities.④ Major polymorphic loci were not in Hwe as predicted using the unstable population model.⑤One must study 25 or more individuals to find relatively rate alleles and study population genetics.

[Objective] To study the synergic effect of praziquantel (PZQ) and host acquired immunity on Clonorchis sinensis. [Methods] Acquired immunity to C. sinensis was induced by immunization with crude adult worm antigen (AW Ag) and excretory-secretory antigen (ES Ag) or infection with C. sinensis metacercariae. The effect was assessed by the worm reduction rate compared with the control groups after challenge infection with 50 metacercariae and treated orally with a subcurative dose of praziquantel (50 mg/kg). Significant test was performed by analysis of variance (ANOVA) and Nparl way Kruskal-Wallis test. All calculations were performed by PC-SAS system. [Results] 1. PZQ was more effective against C. sinensis larvae than against adult worms in the control (P＜0. 001), ES Ag (P＜0.01) or crude AW Ag immunization group (P＜0. 001). 2. As compared with the control, the worm reduction rate after challenge infection was significantly higher (P＜0. 001) in ES Ag immunized group (35.60%) and metacercaria infection group (97.5 % ) and less in crude AW Ag group (23.4 %). The PZQ efficacy was significantly enhanced in ES Ag immunized group. [Conclusion] The efficacy of PZQ against C. sinensis could be synergically enhanced in rats by inducing host acquired immunity.

[Objective] To evaluate the infectivity of Cryptosporidium parvum oocysts in NMRI suckling mouse.[Methods] Four-day- old SPF NMRI suckling mice were inoculated with different amounts of oocysts by oral gavage.On clay 7 after inoculation, suckling mice were sacrificed, and a suspension was prepared by homogenizing the intestinal tract from pylorus to anus. A mouse was considered infected when oocysts were found in smears of the intestinal content suspension stained with carbo lfuchsin solution. The infectivity of oocysts was evaluated as measured by the percentage of infected mice in each group. [Results] Mice receiving 1 500 or 2 000 oocysts were all infected. The percentages of infected mice were 88, 74, 51 and 28 respectively after ingestion of 1 000, 500, 250 and 100 oocysts. The percentage of infected mice was 9.5 % after ingesting as few as 50 oocysts. [Conclusion] This model is convenient for evaluation of the infectivity of C. parvum oocysts.

Objective To clone and sequence variant-specific surface antigen gene from Giardia lamblia isolate SUCH/89/BTMRI/2(C2) derived from human in China. Methods Total genomic DNA of G.lamblia was extracted and a full-length variant-specific surface antigen gene fragment was amplified by pelymerase chain reaction (PCR). The PCR product was cloned into pMD19-T simple-vector, transformed into an Escherichia coli JM109 strain and then sequenced. The sequence analysis for cloned fragment was finished by Vector NTI 9.0 software for the homology of Giardia variantspecific surface antigen gene to that of sequences publishend in GenBank. Results The full-length variant-specific surface antigen gone fragment from G. lamblia was found to be 2 142 bp, encoding a 713 amino acid polypeptide and contained a single open reading frame (ORF). The deduced polypeptide sequence was rich in cysteine (11.8 mol%), most of which occurred with in 29 copies of the 4-amino acid CXXC motif, one GGCY-tetrapeptide motifs and three NXS consensus N-linked glycosylation sites. This polypeptide was also rich in threonine (10.2 mol%), glycine (12.1 mol%) and alanine (10.1 mol%). Like other previously identified VSPs, it contained a highly conserved hydropbebic Cterminal region. The homology of G. lamblia SUCH/89/BTMRI/2(C2) variant-specific surface antigen gene to that of sequence (TSA417) published in GenBank was 99% both at the nueleotide and the amino acid levels. Conclusion The full length variant-specific surface antigen gene from the isolate of G. lamblia has the common characteristics with other previously identified VSPs.