[Anti-schistosomiasis effect induced by full length DNA vaccine coding paramyosin of Schistosoma japonicum in C57BL/6 mice].

OBJECTIVE: To observe the anti-schistosomiasis effect in mice immunized with Sjc97 DNA vaccine. METHODS: C57BL/6 mice were vaccinated intramuscularly with the Sjc97 DNA twice at an interval of 3 weeks, and challenged with 30 +/- 2 cercariae of Schistosoma japonicum three weeks after immunization. Mice in blank plasmid vector control and infection control groups were also infected with same number of cercariae. The mice were sacrificed 7 weeks after challenge infection. The size of single egg granulomas in livers was measured with micrometer. The level of hyaluronic acid (HA) and laminin (LN) in sera of the mice was determined by ELISA. PCR-ELISA was used to examine the expression of TGF-beta1 mRNA in liver. RESULTS: The mean hepatic egg granuloma diameters of the three groups, the Sjc97 DNA, blank plasmid vector and infection control, were 183.75 +/- 42.36 microns, 303.12 +/- 37.36 microns and 304.38 +/- 53.23 microns, respectively. The hepatic granuloma was significantly smaller in the Sjc97 DNA group than that in control. The level of HA and LN in sera of Sjc97 DNA vaccinated mice was markedly lower than those in the two control groups (P < 0.01). The amount of TGF-beta1 mRNA isolated from the livers of mice in Sjc97 DNA group decreased significantly. CONCLUSION: The results showed that Sjc97 DNA vaccine may act as an effective inhibitor against formation of egg granuloma and reduce immunopathological damage caused by Schistosoma japonicum in the host.

[Immunological characteristics induced in mice by nucleic acid vaccine harboring the gene encoding GAPDH in Schistosoma japonicum].

OBJECTIVE: To study the immunological characteristics induced in C57BL/6 mice by nucleic acid vaccine harboring the gene encoding glyceraldehyde-3-phosphate dehydrogenase (GAPDH) of Schistosoma japonicum. METHODS: The gene encoding GAPDH of S. japonicum from screening of cDNA library was amplified using universal primer T3 promoter and T7 promoter, the PCR product was cloned into the T-A vector pT-Adv. GAPDH-pT-Adv and eukaryotic expression vector pcDNA3 were digested by restriction endonucleases Hind III and Xho I, and the nucleic acid vaccine harboring the gene encoding GAPDH was then constructed by ligating the digested products. C57BL/6 mice were immunized using the purified pcDNA3-SjGAPDH. The expression of GAPDH in local muscle in mice was examined by immunofluorescence assay. The specific characteristics induced by pcDNA3-SjGAPDH were analyzed using SDS-PAGE, Western blotting, and ELISA respectively. RESULTS: Light green fluorescence was observed in local muscle cell under the fluoroscope 24 and 48 hours after immunization, which indicated the expression of GAPDH. The recombinant plasmid induced specific anti-GAPDH IgG, predominantly IgG2a, IgG2b and IgG3. Cytokines IFN-gamma, IL-2 but IL-4 were detected in C57BL/6 mice vaccinated with the vaccine. CONCLUSION: The DNA vaccine, pcDNA3-SjGAPDH induces Th1 type immune response in mice.

[Schistosoma japonicum: screening of cDNA library with sera from self-cured water buffaloes (Bos buffelus)].

OBJECTIVE: To understand and identify the molecules related to the self-cure of Schistosoma japonicum infection in water buffaloes. METHODS: The S. japonicum adult worm cDNA library was immunologically screened with the sera of self-cured water buffaloes. The positive clones were identified, cloned, sequenced and analysed with software. RESULTS: Three genes encoding antigens relevant to sera antibodies in water buffaloes were cloned and sequenced. These antigens included paramyosin (Sj97), GST, carbonyl reductase-like 20-beta-hydroxysteroid dehydrogenase(CR/20-beta-HSD). CONCLUSION: Sera from self-cured S. japonicum infected water buffaloes can be used to screen adult worm cDNA library for vaccine development.

[Screening of cDNA library of Schistosoma japonicum with sera from rabbits vaccinated with ultraviolet-attenuated schistosomula].

OBJECTIVE: To search new potential schistosomiasis vaccine by screening cDNA library with sera of rabbits vaccinated with attenuated larvae. METHODS: Schistosoma japonicum (Sj) adult worm cDNA library was screened with sera of rabbits vaccinated with ultraviolet-attenuated schistosomula and by sera of infected rabbits, and the inserts of positive clones were amplified and sequenced. RESULTS: Six kinds of Sj genes were obtained after three rounds of screening. Among the genes were glyceraldehyde 3-phosphate dehydrogenase (GAPDH), serine protease inhibitors (serpin), mitochondrion coding region, part of myosin heavy chain gene and two new genes, respectively. CONCLUSION: Screening cDNA library with sera of animals vaccinated with attenuated larvae is an effective way to search new vaccine candidates for schistosomiasis.

[Preliminary observation on specific antibody level and reduction of ovulation induced by recombinant Schistosoma japonicum 26 kDa GST antigen in water buffaloes].

OBJECTIVE: To observe the specific antibody level and reduction of egg-laying induced by a recombinant Schistosoma japonicum 26 kDa GST antigen (rSjc26 GST) in water buffaloes. METHODS: 20 water buffaloes were randomly divided into two groups, the vaccination group and control group, with 10 buffaloes each. The subjects in vaccination group were immunized with rSjc26 GST antigen while the control received adjuvant only. After challenged with S. japonicum cercariae, the anti-rSjc26 GST antibody level and the numbers of eggs and miracidia in stool were detected. RESULTS: The anti-rSjc26 GST antibody appeared 1 month after immunization with rSjc26 GST antigen and maintained a high level for 12 months. Numbers of eggs (EPG) and miracidia (MPG) in vaccination group were significantly lower than those in control group during the period of day 50 to day 90 post-challenge. However, EPG and MPG tended to decrease starting from day 100 post challenge in both groups. The difference of EPG and MPG between the two groups diminished progressively, and both groups showed zero egg count from day 330 on post challenge. CONCLUSION: The specific anti-rSjc26 GST antibody was detected in vaccinated water buffaloes and maintained a high level for 12 months. The vaccination showed a significant effect to the reduction of ovulation in the first three months after S. japonicum cercariae challenge.