[Experimental study on determination of viability of Schistosoma japonicum cercariae by staining].

OBJECTIVE: To determine the viability of Schistosoma japonicum cercariae by staining. METHODS: Schistosoma japonicum cercariae were stained by 0.4% trypan blue, 0.5% methylene blue-eosin-borax (M.E.B), 0.5% eosin, 0.5% methylene blue and 0.05% neutral red, respectively, for 5 min, then they were observed under a stereoscopic microscope. RESULTS: The dead cercariae were stained in the trypan blue, M.E.B, eosin and neutral red, but unstained in the methylene blue. The vital cercariae were unstained in all the five kinds of dyes. CONCLUSION: The staining methods by using 0.4% trypan blue, 0.5%M.E.B, 0.5% eosin and 0.05% neutral red can be used to determine the viability of S. japonicum cercariae.

[Preliminary studies on effect of polysaccharides from Tegillarca granosa as an adjuvant on DNA vaccine against Schistosoma japonicum infection].

OBJECTIVE: To discuss the effect of polysaccharides from Tegillarca granosa as an adjuvant on pcDNA3.1-Sj26GST vaccine against Schistosoma japonicum infection. METHODS: Sixty SPF BALB/c mice were divided into four groups randomly (15 mice each group), including a control group, a polysaccharides group, a vaccine group, and a vaccine plus polysaccharides group. In the 0, 2th and 4th week of the experiment, the mice in the above four groups were immunized for 3 times with 100 µl PBS, 100 µg polysaccharides from Tegillarca granosa, 100 µg Sj26GST vaccine, and 100 µg Sj26GST vaccine plus equivalent polysaccharides, respectively. Two weeks after the last immunization, all the mice were infected with 40 ± 1 Schistosoma japonicum cercariae through the skin of the abdomen. After the infection for 6 weeks, all the mice were sacrificed, and their serums, livers and the adult worm of Schistosoma japonicum in them were collected, the specific sera IgG antibodies were detected by ELISA, and the worm reduction rates and egg reduction rates in the liver were calculated. RESULTS: Six weeks after the infection, the IgG antibody levels of the mice in the vaccine group and the vaccine plus polysaccharides group were 18.26 ± 0.42 mg/ml and 20.21 ± 0.89 mg/ml respectively, the difference between them were statistically significant, and both of the IgG levels of the above groups were significantly higher than those in the control (both P < 0.05). The worm reduction rate and egg reduction rate in the vaccine group were 28.60% and 35.84%, respectively, and the rates in the vaccine plus polysaccharides group were 38.04% and 49.74%, respectively, the differences between the worm reduction rates and egg reduction rates were both statistically significant (both P < 0.05). Meanwhile, the two rates in the two above groups were all significantly higher than those in the control group (all P < 0.01). CONCLUSION: Polysaccharides from Tegillarca granosa using as an adjuvant can increase the protection effect of pcDNA3.1-Sj26GST vaccine against Schistosoma japonicum infection.

[Preliminary studies on protective immunity induced by recombinant protein of Schistosoma japonicum P14 gene and its mechanism against schistosome infection in mice].

OBJECTIVE: To explore the immune protective effect of the basic calponin-like protein (SjP14) in mice response to the infection of Schistosoma japonicum. METHODS: The recombinant plasmid pET28a(+)-SjP14 was built, and transferred into E. coli BL21 cell line. After induced, by isopropyl-beta-D-thiogalactoside (IPTG), the target protein was purified, and then analyzed by SDS-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blotting, respectively. Thirty female BALB/c mice (six-week age) were randomly divided into three groups (n = 10 for each), including A group (rSjP14 experimental), B group (adjuvant control), and C group (saline control). The mice in the A group were subcutaneously injected with 100 microg rSjP14 vaccine for three times at 2-week interval. After the final immunization, the mice were infected by cercariae of S. japonicum. The B or C groups experienced subcutaneous injections of adjuvant or saline, respectively, except for cercaria infection. The levels of sera IgG, IL-4 and IFN-gamma were detected by ELISA before immunizing, 6 weeks after immunizing, and 6 weeks after the infection, respectively. The reduction rates of worms or eggs were also calculated at the 6th week after the infection. RESULTS: The SjP14 protein was about 38 kDa and was recognized successfully by polyclonal antibody of SjP14. The level of serum IgG in the A group at the 6th week after the infection of cercariae was significant increased [ (25.52 +/- 1.91) microg/ml] compared with that in the B [ (18.65 +/- 3.16) microg/ml] and C [(22.44 +/- 2.83) mcirog/ml] groups (P < 0.05); the level of serum IFN-gamma [(171.30 +/- 70.12) ng/L] was also increased, compared with that in the B [(136.89 +/- 37.62) ng/L] and C [(153.64 +/- 43.44) ng/L] groups (P < 0.05). However, the level of serum IL-4 [(112.05 +/- 15.02) ng/L] in A group was significant decreased at the 6th week after the infection, compared with that in the C group [(102.82 +/- 27.46) ng/L] (P < 0.05). The reduction rates of worms and eggs in the A group were 29.2% and 41.3%, respectively, after the infection, which had statistically significant differences compared with those of the C group (P < 0.05). CONCLUSION: SjP14 has a protective immunity against S. japonicum infection in mice.

[Killing effect of exogenous NO on cercariae of Schistosoma japonicum in vitro].

OBJECTIVE: To explore the killing effects of exogenous NO on the cercariae of Schistosoma japonicum in vitro and the blocking effects of NO inhibitors. METHODS: The cercariae of S. japonicum were collected from naturally infected snails, and then formulated into a 1000 cercariae/ml suspension with RPMI 1640 medium. The relationship between the killing effects and doses of exogenous NO on cercariae were investigated through the suspension with different concentrations of NO generating agents (SNP) and negative control (without SNP). On the other hand, the blocking effects were also investigated through the suspensions being added 2.00 mmol/L SNP and four different NO inhibitors, Hb, FeSO4, L-cyst, L-arg and their combination. Additionally, the appropriate positive(2.00 mmol/L SNP) and negative controls (without NO generating agent) were used. RESULTS: The mortality rates of cercariae were (8.3 +/- 1.1)%, (6.26 +/- 2.3)%, and (9.3 +/- 1.0)% in the SNP 0.06, 0.1 and 0.2 mmol/L groups, respectively, and there were no statistically significant differences between the blank control group and the above-mentioned three groups, respectively (P > 0.05). The mortality rates of cercariae were(23.5 +/- 3.9)%, (46.0 +/- 1.1)%, and (59.4 +/- 0.5)% in the SNP 0.50, 1.00 and 2 mmol/L groups, respectively, and there were statistically significant differences between the blank control group and the above-mentioned groups, respectively (P < 0.05). The mortality rates of cercariae were (30.1 +/- 1.2)%, (45.1 +/- 1.4)%, (31.1 +/- 1.3)%, (34.2 +/- 3.1)%, (47.8 +/- 2.0)%, (49.1 +/- 0.6)%, and (44.2 +/- 0.1)% in the 2.00 mmol/L SNP suspensions which were added of Hb, FeSO4, L-cyst, L-arg, FeSO4+L-cyst, FeSO4+L-arg, FeSO4+L-arg+L-cyst, respectively. Compared with the 2.00 mmol/L SNP suspension, the mortality rates of the above-mentioned groups declined, and there were statistically significant differences (P < 0.05). CONCLUSION: There are killing effects of exogenous NO on the cercariae of S. japonicum in vitro, and four different NO inhibitors, Hb, FeSO4, L-cyst, L-arg and their combinations have some different degrees of blocking effects.

[Reform and practice on the experiment teaching of medical parasitology].

A new model of education is investigated to meet the new idea of experiment teaching in university. Therefore the establishment of experiment teaching model of medical parasitology needs to be correspondently reformed. A variety of new management measures are taken to raise the efficiency of experiment teaching in training the students in the College.