Objective To analyze the difference among antigens of Angiostrongylus cantonensis in different developmental stages and identify dominant diagnostic antigen for angiostrongyliasis. Methods Antigens of A.cantonensis in different developmental stages were analyzed by SDS-PAGE and immunoblot. Results The protein bands of all developmental stages were similar on SDS-PAGE. The Mr 40 000 , 50 000 , 66 000 and 80 000 antigens reacted not only with the sera of rats infected by A.cantonensis but also with the sera of normal rats. The Mr 104 000 antigen could be discerned by sera of rats infected with A.cantonensis for 2 weeks. The Mr 32 000 antigen could be recognized by sera of rats 2 weeks after infection, and the reaction became stronger with the infection continued. Conclusion The Mr 40 000 , 50 000 , 66 000 and 80 000 antigens might result in the unspecific reaction in the immunodiagnosis of angiostrongyliasis using the crude antigen of A.cantonensis. The Mr 104 000 of larva, Mr 33 000 of adult females and Mr 32 000 of the worms might be used as candidate antigens in early diagnosis and epidemiological survey of angiostrongyliasis.

Objective To investigate the popularity and distribution of Paragonimus westermani in Nankun Mountain,Northern suburban of Guangzhou.Methods 2012 snails and 63 crabs were picked from creeks.Three feces samples of wild cats in epidemic area and two feces samples of domestic cats inoculated with P.westermani metacercariae were collected.The cercariae,metacercariae and eggs of P.westermani were detected.P.westermani-positive cats were identified by detection,in which adults of Paragonimus were checked.P.westermani eggs artificially inoculated were also anatomized.Results Infection ratio in snails was 0.15‰(3/2000),while infection ratio of P.westermani metacercariae in crab was 100%(59/59),with an intensity of infection of 2~516 metacercariae per crab,and 2~10 matacercariae per gram crab.Snails and crabs were identified to be Semisulcospira libertina type and Sinopotamon pinheense type,respectively.P.westermani eggs were also found in two feces samples from wild cats,with an infection ratio of 66.66%(2/3).Eleven adults of P.westermani were found in two domestic cats inoculated with P.westermani.Conclusion Nankun Mountain in northern suburban of Guangzhou as an ultra-high infectious focus of P.westermani(Grade I) is reported for the first time.In view of the fact that P.westermani is one of the major disease paragonimus and the infectious focus Nankun Mountain nature reserve is an 4 A scenic spot and popular summer resort,tourists can become infected by P.westermani by drinking water from streams,springs and ponds.More attention should be paid to prevent human infection with P.westermani in Nankun Mountain.

OBJECTIVETo analyze the diagnostic value of larval excretory-secretory antigen in Angiostrongylus cantonensis (LESA) infection.

METHODSA.cantonensis larvae harvested from mice brain were cultured in vitro. The LESA and the adult worm antigens of A.cantonensis (AWA) were collected and analyzed using SDS-PAGE and Western blotting. Two ELISA systems were established using the two antigens (LESA-ELISA and AWA-ELISA) to detect the serum spectra from different sources.

RESULTSSDS-PAGE and Western blotting displayed fewer protein and antigen bands for LESA than for the adult antigen. Two distinct bands of LESA (with relative molecular masses of 40 000 and 26 000) showed reactivity with the sera from patients with A. cantonensis infection. The serum levels of IgG and IgM antibodies to LESA increased at the beginning of infection in mice, reaching the peak on day 5 after infection and decreased on day 10. Compared with AWA-ELISA, LESA-ELISA showed a lower seropositive ratio in suspected patients with A.cantonensis, with also a lower cross-positive ratio in patients with schistosomiasis and clonorchis sinensis.

CONCLUSIONLESA possesses fewer antigen reaction bands than AWA. Although with a slightly lower positive ratio than AWA, LESA has a higher specificity for detecting serum antibodies in suspected cases of A.cantonensis infection, and therefore shows a potential for the diagnosis of angiostrongyliasis especially in the early stage and in current infection.

Angiostrongylus cantonensis ; immunology ; Animals ; Antigens, Helminth ; immunology ; Enzyme-Linked Immunosorbent Assay ; Humans ; Larva ; immunology ; Mice ; Mice, Inbred BALB C ; Rats ; Rats, Sprague-Dawley ; Strongylida Infections ; diagnosis ; parasitology