Quantitative Microbial Risk Assessment of / 生物医学与环境科学（英文）

We aimed to assess the risks of

Dynamic changes of myeloid-derived suppressor cells and regulatory T cells in livers of mice infected with Echinococcus granulosus / 中国血吸虫病防治杂志

Objective To investigate the dynamics changes of the myeloid-derived suppressor cells (MDSCs) and regulatory T (Treg) cells in mice infected with Echinococcus granulosus and explore the possible biological significance. Methods Thirty female BALB/c mice of 6 weeks old were randomly divided into the infection and control groups, of 15 mice in each group. Mice in the infection group were intraperitoneally injected with 2 000 E. granulosus protoscoleces, while those in the control group were injected with the same volume of physiological saline. Mouse liver white blood cells were harvested 3 (early stage), 6 (medium stage) and 12 months (late stage) post-infection, and the proportions of MDSCs, their subpopulations (M-MDSCs and PMN-MDSCs) and Treg cells were assessed by flow cytometry. Results The proportions of MDSCs were (1.61 ± 0.36)%, (5.68 ± 0.69)% and (16.18 ± 0.69)% in mouse liver white blood cells in the infection group 3, 6 and 12 months post-infection with E. granulosus, and (2.19 ± 0.42)%, (0.99 ± 0.07) % and (4.18 ± 0.84)% in the control group, and there were significant differences in the proportion of the MDSCs in mouse liver white blood cells between the infection and control groups 6 and 12 months post-infection (P < 0.01). The proportions of M-MDSCs were (0.69 ± 0.27)%, (5.30 ± 0.72)% and (10.75 ± 0.29)% in mouse liver white blood cells in the infection group 3, 6 and 12 months post-infection, and (0.42 ± 0.24)%, (0.69 ± 0.02)% and (2.12 ± 0.13)% in the control group, and there were significant differences in the proportion of the M-MDSCs in the mouse liver white blood cells between the infection and control groups 6 and 12 months post-infection (P < 0.01). The proportions of PMN-MDSCs were (0.93 ± 0.23)%, (0.32 ± 0.02)% and (5.14 ± 1.03)% in mouse liver white blood cells in the infection group 3, 6 and 12 months post-infection, and (1.77 ± 0.26)%, (0.28 ± 0.05)% and (1.99 ± 0.90)% in the control group, and there were significant differences in the proportion of PMN-MDSCs in mouse liver white blood cells between the infection and control groups 3 and 12 months post-infection (P < 0.05). The proportions of Treg cells were (3.35 ± 0.14)%, (6.24 ± 0.38)% and (3.41 ± 0.07)% in mouse liver white blood cells in the infection group 3, 6 and 12 months post-infection, and (3.48 ± 0.46)%, (3.65 ± 0.45)% and (3.12 ± 0.12)% in the control group, and there were significant differences in the proportion of Treg cells in mouse liver white blood cells between the infection and control groups 6 and 12 months post-infection (P < 0.01). Conclusions The percentages of both MDSCs and Treg cells increase in mouse liver white blood cells 6 and 12 months post-infection with E. granulosus, and a more remarkable increase is seen in the percentage of MDSCs, which is mainly found in M-MDSCs. These findings suggest that M-MDSCs may play a major immunosuppressive role in the medium and late stages of E. granulosus infection in mice.

Comparison of efficiency of Kato-Katz technique and PCR assay for detecting Clonorchis sinensis infection / 中国血吸虫病防治杂志

Objective To compare the performance of modified Kato-Katz thick smear method (KK method) and PCR assay in field detection of Clonorchis sinensis in human fecal samples, which provides insight into the selection of tools for detecting C. sinensis. Methods Based on the epidemiological investigation of human C. sinensis infections in Tengxian County of Guangxi Zhuang Autonomous Region in 2016, a total of 133 fecal samples were randomly selected and stored at -20 ℃. All fecal samples were detected for C. sinensis infection using KK method and PCR assay, and the detection rate was compared between the two techniques. In addition, Kappa test was used to evaluate the consistency between the two methods. Results Among all fecal samples, the overall detection rate of C. sinensis was 77.44% (103/133), and the detection rate was significantly higher by PCR assay (70.68%, 93/133) than by KK method (57.14%, 76/133) (χ2 = 26.15, P < 0.01). There were 88.16% (67/76) of the microscopy-positive fecal samples positive for PCR assay, and 47.37% (27/57) of the microscopy-negative fecal samples positive for PCR assay. The detection rate of C. sinensis by PCR assay (94.74%, 18/19) was higher in fecal samples with EPG of > 1 000 than in samples with EPG of < 1 000 (85.96%, 49/57) (χ2 = 1.05, P = 0.436). The consistency of the detection rate of C. sinensis was moderate between the KK method and PCR assay (Kappa = 0.73). Conclusions The detection rate of C. sinensis by PCR assay is significantly higher than by KK method. In low-endemic areas of C. sinensis infections, the combination of KK method and PCR assay is suggested, so as to improve the detection rate.

Comparison of efficiency of Kato-Katz technique and PCR assay for detecting Clonorchis sinensis infection / 中国血吸虫病防治杂志

Objective To compare the performance of modified Kato-Katz thick smear method (KK method) and PCR assay in field detection of Clonorchis sinensis in human fecal samples, which provides insight into the selection of tools for detecting C. sinensis. Methods Based on the epidemiological investigation of human C. sinensis infections in Tengxian County of Guangxi Zhuang Autonomous Region in 2016, a total of 133 fecal samples were randomly selected and stored at -20 ℃. All fecal samples were detected for C. sinensis infection using KK method and PCR assay, and the detection rate was compared between the two techniques. In addition, Kappa test was used to evaluate the consistency between the two methods. Results Among all fecal samples, the overall detection rate of C. sinensis was 77.44% (103/133), and the detection rate was significantly higher by PCR assay (70.68%, 93/133) than by KK method (57.14%, 76/133) (χ2 = 26.15, P < 0.01). There were 88.16% (67/76) of the microscopy-positive fecal samples positive for PCR assay, and 47.37% (27/57) of the microscopy-negative fecal samples positive for PCR assay. The detection rate of C. sinensis by PCR assay (94.74%, 18/19) was higher in fecal samples with EPG of > 1 000 than in samples with EPG of < 1 000 (85.96%, 49/57) (χ2 = 1.05, P = 0.436). The consistency of the detection rate of C. sinensis was moderate between the KK method and PCR assay (Kappa = 0.73). Conclusions The detection rate of C. sinensis by PCR assay is significantly higher than by KK method. In low-endemic areas of C. sinensis infections, the combination of KK method and PCR assay is suggested, so as to improve the detection rate.

Dynamic changes of myeloid-derived suppressor cells and regulatory T cells in livers of mice infected with Echinococcus granulosus / 中国血吸虫病防治杂志

Objective To investigate the dynamics changes of the myeloid-derived suppressor cells (MDSCs) and regulatory T (Treg) cells in mice infected with Echinococcus granulosus and explore the possible biological significance. Methods Thirty female BALB/c mice of 6 weeks old were randomly divided into the infection and control groups, of 15 mice in each group. Mice in the infection group were intraperitoneally injected with 2 000 E. granulosus protoscoleces, while those in the control group were injected with the same volume of physiological saline. Mouse liver white blood cells were harvested 3 (early stage), 6 (medium stage) and 12 months (late stage) post-infection, and the proportions of MDSCs, their subpopulations (M-MDSCs and PMN-MDSCs) and Treg cells were assessed by flow cytometry. Results The proportions of MDSCs were (1.61 ± 0.36)%, (5.68 ± 0.69)% and (16.18 ± 0.69)% in mouse liver white blood cells in the infection group 3, 6 and 12 months post-infection with E. granulosus, and (2.19 ± 0.42)%, (0.99 ± 0.07) % and (4.18 ± 0.84)% in the control group, and there were significant differences in the proportion of the MDSCs in mouse liver white blood cells between the infection and control groups 6 and 12 months post-infection (P < 0.01). The proportions of M-MDSCs were (0.69 ± 0.27)%, (5.30 ± 0.72)% and (10.75 ± 0.29)% in mouse liver white blood cells in the infection group 3, 6 and 12 months post-infection, and (0.42 ± 0.24)%, (0.69 ± 0.02)% and (2.12 ± 0.13)% in the control group, and there were significant differences in the proportion of the M-MDSCs in the mouse liver white blood cells between the infection and control groups 6 and 12 months post-infection (P < 0.01). The proportions of PMN-MDSCs were (0.93 ± 0.23)%, (0.32 ± 0.02)% and (5.14 ± 1.03)% in mouse liver white blood cells in the infection group 3, 6 and 12 months post-infection, and (1.77 ± 0.26)%, (0.28 ± 0.05)% and (1.99 ± 0.90)% in the control group, and there were significant differences in the proportion of PMN-MDSCs in mouse liver white blood cells between the infection and control groups 3 and 12 months post-infection (P < 0.05). The proportions of Treg cells were (3.35 ± 0.14)%, (6.24 ± 0.38)% and (3.41 ± 0.07)% in mouse liver white blood cells in the infection group 3, 6 and 12 months post-infection, and (3.48 ± 0.46)%, (3.65 ± 0.45)% and (3.12 ± 0.12)% in the control group, and there were significant differences in the proportion of Treg cells in mouse liver white blood cells between the infection and control groups 6 and 12 months post-infection (P < 0.01). Conclusions The percentages of both MDSCs and Treg cells increase in mouse liver white blood cells 6 and 12 months post-infection with E. granulosus, and a more remarkable increase is seen in the percentage of MDSCs, which is mainly found in M-MDSCs. These findings suggest that M-MDSCs may play a major immunosuppressive role in the medium and late stages of E. granulosus infection in mice.