[Reactive epitope analysis of agB subunit antigens of Echinococcus granulosus by using synthetic peptides].

OBJECTIVE: To analyze reactive epitope of three subunit antigens AgB1, AgB2 and AgB4 of Echinococcus granulosus by using synthetic peptides. METHODS: Five synthetic peptides, KK36, RK30, B4-1, B4-2, and B4-3, derived from the sequences of AgB1, AgB2, and AgB4 subunit of E. granulosus, and the three recombinant subunits were used for the detection of serum antibodies by ELISA. A panel of 209 serum samples from patients with cystic echinococcosis (115), alveolar echinococcosis (54), cysticercosis (22), and healthy persons (18) was used in the study. The diagnostic efficiency of the recombinant subunits and peptides for serum detection was estimated and compared using receiver-operating characteristics (ROC) curve. RESULTS: The sensitivity and specificity of peptides KK36 and RK30 in patients with cystic echinococcosis were 89.2% and 62.5%, 85.0% and 59.4%, respectively. Their diagnostic efficiency (84.8% and 80.4%) was similar to AgB1 and AgB2 antigen (84.5% and 81.2%). The ROC curves of peptides KK36 and RK30 were well fitted by that of recombinant subunit AgB1 and AgB2. For the three peptides derived from AgB4 subunit, serum detection indicated that the diagnostic efficiency of B4-1, B4-2 and B4-3 were 49.4%, 57.9%, and 77.4%, respectively. Peptides B4-3 showed best reactivity and B4-2 also showed certain reactivity to the sera from patients with cystic echinococcosis. CONCLUSION: Peptides KK36 and RK30 contain the reactive epitope region of AgB1 and AgB2 subunits. B4-2 and B4-3 contain partial region of the reactive epitope of AgB4. The epitope region of AgB4 may be in the central and back part.

[A newly identified endemic area of visceral leishmaniasis in Minfeng county of South Xinjiang I. epidemiological survey].

OBJECTIVE: To investigate the epidemiological status of visceral leishmaniasis in Minfeng county, a newly identified endemic area in south Xinjiang, China. METHODS: Based on a hint of possible existence of patients, a retrospective survey was carried out house by house in Andier Township of the county to find cases with suspected signs/symptoms of the disease in the past 20 years including those died. Meanwhile, a survey on current status was conducted, including physical examination(liver and spleen palpation) to those under 15 years-old, leishmanin skin test and rk39 immunochromatographic strip test for part of the residents. RESULTS: The investigation covered 313 local residents and revealed no case with present illness but 60 cases with a history of suspected signs/symptoms including 13 deaths, traced back as visceral leishmaniasis. Leishmanin skin test was performed in 171 people with a positive rate of 99.4% and 28 out of 29 suspected cases showed positive (96.6%). rk39 immunochromatographic strip test was conducted in 197 people with a positive rate of 10.2% (20/197) and 19.4% (6/31) in those with a history of suspected signs/symptoms. CONCLUSION: The epidemiological investigation indicates that the Andier Township of Minfeng County is an endemic area of visceral leishmaniasis.

[A newly identified endemic area of visceral leishmaniasis in Minfeng county of south Xinjiang II. Investigation on phlebotomine vectors].

OBJECTIVE: To investigate the transmitting phlebotomine sandfly in Minfeng County, a newly-identified endemic area of visceral leishmaniasis in the south of Talim Pendi of Xinjiang. METHODS: Sandflies were collected using routine methods in and around the Yatonggusi village of Andier Township. The sandflies were identified to get their composition. Sandfly density was calculated following an observation at a given spot and time-period, and their appearance was recorded at night-time and day-time. Sandflies were dissected to analyze the gonotrophic cycle and to find infection of promastigotes. RESULTS: Phlebotomus wui was identified as the transmitting vector of visceral leishmaniasis in Andier Township, which occupied 99.2% of the sandflies collected. The first and second ten-day period of June was the first peak of its seasonal distribution. Analysis of the gonotrophic cycle revealed that Ph. wui was an exophilic species and appeared nocturnally for feeding with preference to human blood. Natural infection with promastigotes was found in 2 sandflies. CONCLUSION: Phlebotomus wui is the transmitting vector for visceral leishmaniasis in the newly found endemic area of south Xinjiang.

[Preparation of specific antibodies against recombinant Eml8 antigen and detection of the circulating antigen].

OBJECTIVE: To prepare specific antibodies against the recombinant Eml8 antigen (ReEml8), establish a sandwich ELISA and detect the Eml8 circulating antigen in patients' sera. METHODS: Rabbits and BALB/c mice were immunized with the ReEml8 antigen, which was purified by affinity method for preparation of the specific poly-clonal and monoclonal antibodies. A sandwich ELISA was established by the specific antibodies. RESULTS: By immunizing with the ReEml8 antigen, high antibody level was reached with a serum dilution of 1: 204 800 and above in the immunized rabbits. After double selection by ELISA using the ReEml8 antigen and block ELISA using both AE-positive and negative control sera, 14 positive cell clones were obtained with an inhibition rate of more than 50%. Those mono-and poly-clonal antibodies were matched freely in sandwich ELISA tests for detecting the ReEml8 antigen. A combination of monoclonal antibody No.9 and polyclonal antibody showed the best result. The sensitivity to detect ReEml8 antigen was at 3 ng/ml. Six of 11 AE sera were positive when tested with the sandwich ELISA system. CONCLUSION: Highly specific polyclonal and monoclonal antibodies have been prepared, and a sensitive sandwich ELISA established. Preliminary result is suggested that a detectable level of Eml8 circulating antigen is present in AE patients' sera.