Table of Content

28 February 1996, Volume 14 Issue 1

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STUDIES ON THE DYNAMIC CHANGES OF CIRCULATING ANTIGEN IN SCHISTOSOMA JAPONICUM INFECTION AND ITS MECHANISM

Lou Wenxian; Zhang Enying; Yu Anzhou; Xu Donghong Yang Shijing; Shen Dakang; Zhu Xuming; Xue Chunliang

1996, 14(1):  5-10. 

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AIM: To observe the dynamic changes of circulating antigen in Schistosoma japonicum infection and its mechenism. METHOD: After fusion of B lymphocytes from mice infected with S.japonicum and mouse myeloma cell(SP2/0 strain), McAbs against different schistosomal antigenic epitopes were combined as probes to detect sera from schistosomiasis cases, splenic blood and peripheral blood of advanced schistosomiasis cases, portal vein blood and peripheral blood of rabbits and mice infected with S.japonicum. RESULTS: Nine monoclonal antibodies against schistosome antigen were detected by IFA. When these McAbs against different antigenic epitopes were used, in combination the sensitivity of antigen detection could be raised by 4- 8 times. established on the basis of compounded McAbs. When sandwich ELISA and dot-ELISA were used for detection of chronic schistosomiasis, the sensitivity was 74% and 84.2%, the specificity was 96.1% and 95.7%, respectively. The circulating antigen level were significantly higher in portal vein blood and splenic blood than in peripheral blood. CONCLUSION: McAbs against different schistosomal antigens used in combination in sandwich ELIAS could enhance the sensitivity of antigen detection. Not only circulating antigen but also immune complex of schistosomes were detected by dot-ELISA, so it might interfere with judgement of curative effect.

PROTECTION OF THE RESIDENTS FROM SCHISTOSOME INFECTION USING ORAL ARTEMETHER IN MOUNTAINOUS ENDEMIC AREA

Xiao Shuhua ; Wang Jialong ; Wang Cunzhi; Yang Zhong ; Chu Bo; Yang Hui ; Liu Yuhua ; Zheng Jiang ; Chen Minggang

1996, 14(1):  11-14. 

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AIM: To study the preventive effect of oral artemether (Art) in a schistosomiasis endemic area of mountainous type. METHOD:Three villages of Eryuan County, Dali City, Yunnan Province were selected as the pilot of the study where the infection rate of the snail was 8.7% with a mean density of infected snail of 0.2219/0.11 m.2 and the infection rate of the residents was 16.4%. Residents aged 4-60 in the pilot were selected for study and allocated randomly to Art group and the control group. One month before the performance of prevention with Art, stool examination was carried out in all residents and praziquantel was given orally to the egg-negative residents and egg-positive residents at a single dose of 40 mg/kg and 50 mg/kg, respectively. In Art group, the first dose of 6mg/kg was given to the residents in the late May, i. e., about 15 days after contacting with infested water, followed by repeated dosing every 15 days for 3 times. Placebo(starch) was given to the residents in the control group at the same time as in Art group. The efficacy was evaluated by stool examination 25- 32 days after the last medication. RESULTS: In Art group 13 out of 307 residents examined revealed stool positive with an infection rate of 4.2%, while in the control group 46 out of 306 residents examined showed stool positive with an infection rate of 15%. Meantime, the egg per gram of feces (EPG) determined with the Kato-Katz method was 49.8±28.6 in the cont ro l group and 2818±1017 in A rt group. The differences in infect ion rates and EPG ( s) between the two groups were statistically significant. Furthermore, 4 cases of acute schistosomiasis were seen in the control group, but none was found in Art group. CONCLUSION: In schistosomiasis endemic area of mountainous type, oral Art exhibited a promising preventive effect on both reducing infection rate and controlling acute schistosomiasis.

SEQUENCING OF TWO STRUCTURAL GENES ENCODING SPECIFIC PROTEINS IN ES ANTIGEN FROM TRICHINELLA SPIRALIS AND CONSTRUCTION OF RECOMBINANT PLASMIDS

Yan Yuhe, Xu Weiguang, Chen Hui, Ma Zengquan, Li Chunhua, Zhang Hongquan, Zhu Yuanxiao, Lu Jingliang

1996, 14(1):  15-19. 

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AIM: To identify and clone structural genes encoding ES antigen from T.spiralis for preparing gene recombinant antigen of T.spiralis. METHOD: RT PCR technique was used to gain the target genes. After sequencing and restriction enzyme digestion, the genes were respectively cloned into the fusion expression vectors pEX31C, pEX31B and another expression vector pBV220 by using recombinant DNA techniques. Their expression level in E.coli was evaluated and the specificity of the expression products was also identified. RESULTS: Two structural genes encoding the specific proteins in ES antigen were obtained (0.7 kb and 0.95 kb). Compared with those reported previously, the sequences exhibited some differences. Three recombinant plasmids were constructed. It was shown that the corresponding recombinant proteins were expressed in E.coli containing the plasmids by SDS-PAGE electrophoresis. All the recombinant proteins could be recognized by sera from swine infected with T.spiralis, but the specificity of non-fusion protein was stronger than that of fusion protein. The expression level of the fusion protein was higher than that of the non-fusion protein, and the molecular weight of the expression proteins was in negative correlation with the expression level under the same condition. CONCLUSION: Three recombinant proteins expressed in E.coli are candidate antigenic proteins for preparing gene recombinant antigen of T.spiralis.

CHARACTERISTICS OF POLYMORPHISM OF CIRCUMSPOROZOITE PROTEIN GENE OF PLASMODIUM VIVAX OF DIFFERENT GEOGRAPHICAL STRAINS

HUANG Tian-Yi, Victoria H Mann, CHENG Qin, HUANG Ya-Ming, Allan Saul

1996, 14(1):  20-25. 

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AIM: To explore the polymorphism of circumsporozoite protein (CSP) genes of different geographic strains of Plasmodium vivax and its significance. METHOD: PCR amplification and electrophoresis excised purification was used to obtain the studied DNA fragments. Dye primer cycle sequencing was used to sequence the CSP genes. A schematic diagram method was employed to compare and analyse the sequence deviation. RESULTS: All obtained CSP gene sequences of the 15 isolates from China, Philippines and Solomon Islands are P.vivax type-I in which some geographic deviations have been found. Six Chinese isolates were similar to NK isolate and one of them, C-2, was identical to NK isolate and remarkably distinct from all other type-I isolates. CONCLUSION: Based on the sequence deviation at amino acid level of CSP genes from different parts in the world and on Qarit's and Mann's grouping, all of type-I isolates published so far can be categorized into 2 families including 6 groups. The grouped sequence characteristics might be used to develop a rapid and practical method for the detection and identification of different geographic strains which could be of significance in malaria epidemiology and control, and be useful in the research of biology, taxonomy and phylogenetic of this parasite.

RELATIONSHIP BETWEEN GEOGRAPHICAL DISTRIBUTION OF SANDFLIES AND LANDSCAPE FEATURES IN XINJIANG UYGUR AUTONOMOUS REGION OF CHINA

GUAN Li-Ren, CHAI Jun-Jie, YANG Li-Pu

1996, 14(1):  26-32. 

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AIM: To explore the geographical distribution of sandfly and its relation to natural landscape in Xinjiang Uygur Autonomous Region. METHOD: A number of survey of sandfly distribution pattern besed on entomological geography and landscape features had been performed. RESULTS: There exist one or two representative species of sandflies in a definite locality with specific geographical and landscape features. In the mountainous zone with brown calcareous soil, Phlebotomus chinensis longiductus was generally the predominant species; in stony desert places with brown desert soil adjacent to mountains, Ph.alexandri (69.7% - 100% ) was the major species; in old oasis covered with moistened/yellow oasis soil, Ph.chinensis longiductus was the chief species; in desert covered with desert-forest soil and sparsely distributed with plant of Populus diversifolia, Ph.majorwui had a high proportion ( 60.9% - 77.6% ) , followed by Sergentomyia minutus sinkiangensis; in desert densely distributed with plant of Haloxylon sp. (Half- stuck aeolian sandy soil), Ph. andrejevi amounted to 85.2% - 97.9%; in areas with vegetation of Reaumuria soongarich mixed with Tamarix sp. (gray desert soil), Ph. mongolensis (67.3% - 84.4% ) was the chief species; in the solonchak desert below sea level with sparsely grown vegetation of Alhagi sparsifolia, only S.arpaklensis was detected. CONCLUSION: The existence of different predominant species of sandflies in areas of varied landscape features indicates the necessity of characteristic habitat for a definite sandfly species to grow and develop, and the importance of coincidence in environmental factors and sandfly eco ogy is evident.

OBSERVATION ON THE KINETIC CHANGES OF SPECIFIC HELPER T CELL SUBSETS OF MICE AFTER INFECTION WITH TRICHINELLA SPIRALIS

Lan Yan; Jiang Hongjie; Bian Yinghua

1996, 14(1):  33-36. 

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AIM: To explore the cellular immunoregulation in Trichinella spiralis infected C57BL/6J mice. METHOD: IL-2 and IL-6 levels induced by in vitro Trichinella antigen and ConA stimulated splenocytes from lightly and heavily infected C57BL/6J mice were determined by using the dependent cell line HT2 and 7TD1, IgG level was deterined by ELISA, and CD4⁺ and CD8⁺ levels were determined by flow cytometry. RESULTS: The production of IL-2 was predominant in the early phase after infection, while the production of IL-6 was mainly in the later phase. The levels of IL-2 and IL-6 secreted were higher in the heavily infected group than in the lightly infected group. IgG first appeared on d7 after infection and reached its peak through d28 to d35. From d14 to d21 the CD4⁺ T cells showed a decrease and then increased; while the CD8⁺ T cells increased gradually throughout the period after infection. CONCLUSION: The sustained increase in IL-6 4weeks after infection might play an important role in the acquired immunity of trichinosis. The coincidence of the increase in IL-2 and CD8⁺ suggests that the cytokines of Th1 might promote the activation of CD8⁺ T cells.

PRESENT STATUS OF THE SENSITIVITY OF PLASMODIUM FALCIPARUM  TO ANTIMALARIALS IN CHINA

Liu Dequan, Liu Ruijun, Zhang Chunyong, Cai Xianzheng, Tang Xian, Yang Pinfang, Dong Ying

1996, 14(1):  37-41. 

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AIM: To assess the sensitivity of Plasmodium falciparum to antimalarials. METHOD: WHO standard in vitro microtest was used. RESULTS: Except for the absence of resistance to mefloquine and quinine, the resistance rate of the parasite to chloroquine, amodiaquine and piperaquine was 84.6%, 86.1% and 38.0% respectively. Plasmodium falciparum in 8 3% of the cases showed resistance to pyronaridine. CONCLUSION: Among the antimalarials tested in Hainan and Yunnan, high resistance of P.falciparum to chloroquine, amodiaquine and piperaquine was found. The sensitivity of P.falciparum in a few cases to pyronaridine and artemisinin and its derivatives was decreased. Cross resistance between some of the antimalarials has been evidenced.

 STUDIES ON THE SIMILARITY AND CLASSIFICATION OF GAMASID MITE COMMUNITIES ON SMALL MAMMALS IN THE WEST OF YUNNAN PROVINCE

Guo Xianguo, Ye Binghui, Gu Yiming, Chen Yuanmin

1996, 14(1):  42-45. 

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AIM: To illustrate the similarity, transitional tendency and classification of gamasid mite communities on nine dominant species of small mammals in the west of Yunnan Province. METHOD: Fuzzy clustering analysis. RESULTS: The similarity among the gamasid mite communities on Rattus flavipectus, Rattus norvegicus and Mus musculus was prominent. These gamasid mite communities tended to be the type of house rats. The gemasid mite communities on Muscaroli, Apodemus chevrieri and Eothenomys miletus were proved to be the type of field rats. The gamasid mite communities on Rattus nitidus, Crocidura attenuata and Suncus murinus were the type of transitionals, being intermediate between the types of house rats and field rats in the fuzzy clustering phenogram. The whole fuzzy clustering process showed a tendency from the type of house rats to the type of field rats. CONCLUSION: The types of gamasid mite communities mainly depend upon the habitat preference of the corresponding hosts, smallmammals. Under the similar habitat circumstances, the closer the hosts in taxonomy are, the more similar the gamasid mite communities on them will be.

A CONDITIONAL LOGISTIC MULTI REGRESSION ANALYSIS ON SOCIOECONOMIC FACTORS AFFECTING MALARIA TRANSMISSION

Gu Zhengcheng, Si Youzhong, Tang Linhua, Wu Kaichen, Deng Da, Luo Peiwen, Cai Xianzheng, Zhen Linhai, Chen Jifeng, Sheng Huifeng

1996, 14(1):  46-49. 

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AIM: To understand the socioeconomic and human behavior factors affecting malaria transmission in minority areas of Hainan Province. METHOD: The methods used for analyzing single and multiple factors were chi square test and conditional logistic multi regression analysis. RESULTS: The results of the two methods were coincident. Three important factors related to the local malaria transmission were selected. CONCLUSION: Staying overnight in the mountain, having knowledge of malaria prevention and using bed net were three significant factors closely associated with malaria transmission. Hence, more attention should be paid to these risk factors in formulating the malaria control programme.

T CELL IMMUNE RESPONSE IN LYMPHATIC FILARIASIS ──ANALYSIS OF PARASITE ANTIGEN INDUCED IL-2 AND IFN-γ PRODUCTION

Chen Zhilin, Shen Yiping, Chen Shuzhen, Zhang Yaojuan, Guan Xiaohong, You Lifen, Yang Weiping, Wang Zengxian

1996, 14(1):  50-53. 

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AIM: To investigate the mechanism of T cell immune response in lymphatic filariasis. METHOD: IL-2 and IFN-γ production in peripheral blood mononuclear cells (PBMC) were examined in vitro from 31 patients with microfilaremia, 32 amicrofilaremic individuals living in bancroftian filariasis endemic area of Anhui Province and 32 controls living in non endemic area. The jirds infected with B.malayi were also examined for IL-2 and IFN-γ production in spleen cells. RESULTS: In each group of human subjects, the production of IL-2 or IFN-γ in response to PHA and ConA did not differ significantly. When B. malayi adult antigen (BmA) -induced IL-2 o -r IFN-γ production was examined, the amicrofilaremic individuals generated significantly more cytokines than did the patients with microfilaremia. In jirds, the results were similar to those in humans. CONCLUSION: These results suggest that there exists T cell hyporesponsiveness to BmA in patients with microfilaremia from bancroftian filariasis endemic area and in jirds  ith microfilaremia of B.malayi.

STUDIES ON CELLULAR IMMUNITY OF MICE INFECTED WITH TOXOPLASMA GONDII AT EARLY STAGE

Wu Shaoting, Lu Fangli, Shi Youen

1996, 14(1):  54-57. 

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AIM: To study the immune response of mice infected with Toxoplasma gondii. METHOD: Lymphocyte transformation test, determination of natural killer cell (NK) activity, tumor necrosis factor(TNF) and specific IgG antibody in serum. RESULTS: In the early stage after mice were infected with Toxoplasma gondii, the spleen lymphocyte response and NK actitity enhanced, and the quantity of TNF in serum increased but the level of IgG in serum remained unchanged. CONCLUSION: In the immune response of mice infected with  Toxoplasma gondii, the cellular immunity was more effective than the humoral immunity in the early stage in addition to their synergetic actions.

 EXPERIMENTAL RESEARCH AND ELECTRON MICROSCOPY ON THE KILLING EFFECT OF USNIC ACID ON TOXOPLASMA GONDII TACHYZOITE IN VITRO

Wu Jie1, Cheng Yianbin1, Yang Shaoyi2

1996, 14(1):  58-62. 

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 AIM: To study the anti Toxoplasma effect of usnic acid in vitroand its mechanism . METHOD: After usnic acid (final concentration 5-50 μg/ml) was added into the ascites of experimentally infected mice for 30 min-4 h, the effect was observed under light microscope and transmission electron microscope. Spiramycin was used as control. In addition, mice were inoculated with the drug treated tachyzoites. RESULTS: Under the action of 10 μg/ml usnic acid for 30 min, the rhoptries lysed and the daughter cell membrane and membranate structures of tachyzo ites appeared broken. The tachyzoites treated by 50 μg/ml usnic acid for 4 h could not be recovered in the inoculated mice. The toxop lasmacidal effect of spiramycin was inferior to that of usnic acid at the same concentration. CONCLUSION: Usnic acid could kill Toxoplasma gondii tachyzoites in vitro. The penetration and multiplication of the tachyzoites could be inhibited by usnic acid. The toxoplasmacidal activity of the drug has positive correlation with the concentration and the time of action of usnic acid. The toxoplasmacidal effect of usnic acid was proved to be more remarkable than that of spiramycin.

AN EPIDEMIOLOGICAL SURVEY OF INTESTINAL ACARIASIS

Li Chaopin, Wang Kexia, Xu Guangxu, Li Lin, Wang Jian, Li Zhongdong

1996, 14(1):  63-65. 

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AIM: To make an epidemiological survey of infestinal acariasis in Huainan area, Anhui Province. METHOD: Case history, stool examination (saturated saline flotation method), and blood examination (differential leukocyte count). RESULTS: Stool examination of 3 312 subjects showed that 218 were mite positive, the detection rate being 6.6%. For mites thus detected, 7 species had been found, i.e., Acarus siro, Tyrophagus putrescentiae, Dermatophagoides farinae, D.pteronyssinus, Carpoglyphus domesticus, Glycyphagus domesticus, and Tarsonemus granarius. 30 out of the 218 intestinal acariasis cases further examined for eosinophilia had an average count of 0.17×10⁹/L(0.32- 0.78×10⁹/L). The main clinical symptoms were abdominal pain, diarrhea, and pyohemofecia. CONCLUSION: For personnel working at their specific vocation, the need for reinforcement of knowledge of prevention should be stressed.

STUDIES ON RELATIONSHIP BETWEEN DEMODEX INFESTATION AND ROSACEA

Sun Xiuqin, Wang Jiawei, Lin Shufang, Zhao Suyun

1996, 14(1):  66-71. 

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AIM: To further understand the relationship between rosacea (brandy nose) and Demodex infestation and prepare specific drug. METHOD: P.folliculorum and D.brevis were detected using cellophane tape applied on the face and nasolabial groove of 120 patients. RESULTS:Patients having acne or having the past history of acne accounted for 91.7% in 120 patients. The more intensely the face was affected, the more seriously the rosacea became aggrevated. Patients suffered from rosacea for more than 10 years had more rhinophyma. The numbers of D.folliculorum and D.brevis detected on the face and the nose were 3 821 and 413, respectively. “Fumandi” ointment was used to treat the rosacea, the effective rate was 98.0%. CONCLUSION: Demodex infestation is an important cause resulting in rosacea.