[Polymorphism analysis of Plasmodium falciparum histidine-rich protein II and III].

OBJECTIVE: To analyze the polymorphism of Plasmodium falciparum histidine-rich protein (PfHRP) II and III. METHODS: Genomic DNA was isolated from blood samples of 20 patients infected with Plasmodium falciparum in Yunnan Province. Blood samples were tested by microscopy and RDTs. The Pfhrp2 and Pfhrp3 gene fragments were amplified by PCR and sequenced. The sequencing results were analyzed and compared using the bioinformatics software. RESULTS: 20 patients infected with Plasmodium falciparum tested by microscopy and RDTs. PCR showed that the Pfhrp2 gene was with 389~986 bp, and Pfhrp3 gene with 329-640 bp. All PfH-IRP II sequences started with type 1 repeat (AHHAHHVAD) and ended with the type 12 repeat (AHHAAAHHEAATH). The number of type 7 (AHHAAD), type 2 (AHHAHHAAD) and type 6 (AHHATD) within PfHRP II was more than the other types of repeats, as well as type 16 (AHHAAN) and type 17 (AHHDG) for PfHRP III. Type 11 repeat (AHN) was not found from the PfHRP II and PfHRP III sequences. CONCLUSION: There is an extensive diversity in Pfhrp2 and Pfhrp3 fragments in the individuals infected with P. falciparum in Yunnan. Some types of repeats are shared by PfHRP II and PfHRP III.

[Changes of IFN-gamma, IL-4 and T cells in Schistosoma japonicum-infected mice after praziquantel treatment].

OBJECTIVE: To investigate the serum levels of IFN-gamma and IL-4, and the dynamic changes of IFN-gamma-specific and IL-4-specific lymphocytes in mice with Schistosoma japonicum infection after treatment by praziquantel. METHODS: Ninety BALB/c mice were randomly divided into three groups (n = 30) named as infection group, treatment group and control group. The mice in treatment group and infection group were infected with (25 +/- 2) S. japonicum cercariae through the abdominal skin. At 6 weeks post-infection, the mice in treatment group were administered orally with praziquantel [300 mg/(kg x d)] for 3 d. At 4, 6, 8 and 12 weeks post-treatment, the mice were weighed, and serum samples were collected. Serum levels of IFN-gamma and IL-4 were measured by ELISA. At the same time, the spleens were aseptically removed to prepare cell suspension, and the counts of IFN-gamma and IL-4 specific lymphocytes were examined by ELISPOT after stimulation of Schistosoma japonicum soluble egg antigen (SEA). RESULTS: From 4 to 12 weeks after praziquantel treatment, the body weight of mice in treatment group were significantly heavier than that of infection group (P < 0.05), but no significant difference was found between treatment group and control group (P < 0.05). At 4 weeks posttreatment, there was no significant difference in serum levels of IFN-gamma and IL-4 between treatment group and infection group (P > 0.05). At 6, 8, and 12 weeks after treatment, the serum levels of IFN-gamma (0.038 +/- 0.013, 0.028 +/- 0.001, and 0.027 +/- 0.007) and IL-4(0.051 +/- 0.020, 0.045 +/- 0.019, and 0.043 +/- 0.016) in treatment group were significantly lower than that of infection group (IFN-gamma: 0.057 +/- 0.004, 0.060 +/- 0.023, and 0.052 +/- 0.017; IL-4: 0.150 +/- 0.014, 0.148 +/- 0.014, and 0.123 +/- 0.017) (P < 0.05). Serum IFN-gamma and IL-4 levels in treatment group and infection group were significantly higher than that of control group (P < 0.05). ELISPOT results showed that at 4, 6 weeks post-treatment, there was no significant difference in the number of IFN-gamma-specific lymphocytes between treatment group and infection group (P > 0.05). While at 8 and 12 weeks after treatment, the IFN-gamma-specific lymphocytes in treatment group (39.9 +/- 22.8 and 38.5 +/- 6.2) were significantly less than that of infection group (141.9 +/- 39.3 and 106.8 +/- 28.6) (P < 0.05). At 4-week post-treatment, the IL-4-specific lymphocytes in treatment group were much more than that of infection group (175.6 +/- 62.3) (P < 0.05), and then began to decline. At 8 and 12 weeks after treatment, the IL-4-specific lymphocytes (111.3 +/- 14.3 and 113.0 +/- 44.2) in treatment group were significantly less than that of infection group (220.3 +/- 107.1 and 208.1 +/- 17.2) (P < 0.05). The IFN-gamma-specific and IL-4-specific lymphocytes in treatment group and infection group were significantly more than that of control group (P < 0.05). CONCLUSION: After praziquantel treatment, the serum levels of IFN-gamma and IL-4 in mice with S. japonicum infection decrease, and the number of IFN-gamma and IL-4 specific lymphocytes reduces.

Development of O-antigen gene cluster-specific PCRs for rapid typing six epidemic serogroups of Leptospira in China.

BACKGROUND: Leptospira is the causative agent of leptospirosis. The O-antigen is the distal part of the lipopolysaccharide, which is a key component of outer membrane of Gram-negative bacteria and confers serological specificity. The epidemiology and clinical characteristics of leptospirosis are relative to the serology based taxonomic unit. Identification of Leptospira strains by serotyping is laborious and has several drawbacks. RESULTS: In this study, the O-antigen gene clusters of four epidemic Leptospira serogroups (serogroup Canicola, Autumnalis, Grippotyphosa and Hebdomadis) in China were sequenced and all genes were predicted in silico. Adding published sequences of two serogroups, Icterohaemorrhagiae (strain Lai and Fiocruz L1-130) and Sejroe (strain JB197 and L550), we identified six O-antigen-specific genes for six epidemic serogroups in China. PCR assays using these genes were developed and tested on 75 reference strains and 40 clinical isolates. CONCLUSION: The results show that the PCR-based assays can be reliable and alternative means for rapid typing of these six serogroups of Leptospira.

[Observation on dynamic changes of SEA specific antibody in sera of BALB/c mice infected with Schistosoma japonicum].

OBJECTIVE: To investigate the dynamic changes of SEA-induced specific IgG, IgM in sera of BALB/c mice infected with Schistosoma japonicum in 18 weeks. METHODS: After mice were infected with S. japonicum cercarial for 2 weeks, the sera were collected from 2 to 18 weeks post-infection. The serum levels of SEA-specific IgG and IgM antibodies were measured respectively by ELISA, and the different fractions of IgG and IgM antibodies were identified by the Western blotting method. RESULTS: The ELISA results showed that the serum levels of SEA-specific IgG increased 5, 6, 9, 11 week, after the infection, and SEA-specific IgM increased obviously 5, 9 weeks after the infection. The Western blotting results showed that 140, 180 kDa molecules were recognized by IgG antibodies in the mouse sera 4 weeks after the infection. The specific IgG antibodies of 43, 50 kDa antigens appeared 5 weeks after the infection. 60-130 kDa fractions were recognized by IgG in the sera 6 weeks post-infection, and 38, 73 kDa proteins were recognized by IgG in the sera 9 weeks post-infection. The IgG antibodies of 26, 32, 35, 80 kDa molecules appeared 11 weeks post-infection and reacted strongly 12 weeks post-infection. The IgM antibodies of 100, 140, 180 kDa molecules appeared 3 weeks after the infection, and 73 kDa protein was recognized by sera 6 weeks after the infection, but the reaction became strong 9 weeks after the infection. The 38, 43, 50 kDa proteins induced IgM antibodies in 9-week-infection sera and the reaction became stronger 9 weeks after the infection. CONCLUSIONS: There is a dynamic change in the levels of specific IgG and IgM antibodies induced by S. japonica SEA and the appearance of the antibodies is related to different infection stages. The 43, 50, 10, 140, 180 kDa antigens might have the potential value of early immunodiagnosis. The 73 kDa antigen shows high diagnostic value in both acute and chronic schistosomiasis. The 28, 32, 35, 38, 80 kDa antigens are not only the diagnostic molecules for chronic schistosomiasis, but they may also have therapeutic effects, and in addition, they may be the candidate vaccines of the disease.