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Objective:To analyze the changes in biological characteristics including infectivity, growth and pathogenicity of Chlamydia muridarum ( Cm) after serial passage in vitro in special conditions in order to provide reference for screening attenuated live vaccines and virulence-related genes. Methods:Wild-type Cm strain (G0) was cultured for several passages using conventional cell culture method under alternate unassisted and assisted culture conditions. Then, the 28th generation (G28) of Cm was selected and compared with the parental G0 strain in terms of centrifugation dependence, attaching ability, intracellular growth curve, plaque size and fallopian tube lesions after genital tract infection in a mouse model. Results:Compared with the parental G0 strain, the G28 strain showed significantly decreased dependence on centrifugation during cell infection ( P<0.05) and increased attachment capacity to cells ( P<0.05). No significant differences were observed in the growth curves 32 h after cell infection or in the plaque sizes between the parental G0 and G28 strains. In the in vivo virulence test, fallopian tube lesions were observed in 87.5% of G0-infected mice and 37.5% of G28-infected mice ( P<0.05). Conclusions:Compared with the parental G0 strain, the G28 strain showed significantly enhanced in vitro infection ability, but decreased in vivo pathogenicity, which brought hope for further identification of virulence genes, isolation of attenuated strains with single genotype and development of live attenuated Chlamydia vaccines.
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Objective To explore the factors what may influence the formation of tophi by high frequency ultrasound.Methods The gouty patients who were experiencing an acute attack and were clinically diagnosed with gouty arthritis were divided into two groups:the tophi group (44 cases) and the no tophi group (101 cases) group,clinical data and ultrasound features of joints were collected.The differences of ultrasound features and clinical characteristics between the two groups were analyzed.Results ① Ultrasound features showed that synovitis (x2=8.479,P=0.004) and effusion (x2=9.740,P=0.002) of the first metatarsophalangeal joint (MTP1) were most frequently observed in the no tophi group;bone erosion of MTP1 (x2=9.593,P=0.003),double contour (DC) sign (x2=14.069,P=0.000) and bone erosion (x2=5.870,P=0.020) of ankle joint,DC sign of knee joint (x2=8.224,P=0.006) were most frequently observed in the tophi group.Hyperechoic aggregates of MTP1 (x2=9.649,P=0.003) were most frequently observed in no tophi group.(②) Logistic regression analysis showed that MTP1 was the first attacked joint [OR=9.725,95％CI(2.765,34.209),P=0.000],the multiple joints involved [OR=1.908,95％CI (1.190,3.057),P=0.007] and bone erosion of MTP1 [OR=4.339,95％CI(1.300,14.490),P=0.017] were the main risks of the formation of tophi.Synovitis of MTP1 often presented in no tophi patients [OR=0.108,95％CI(0.026,0.441),P=0.002].Conclusion High frequency ultrasound combine with clinical data is of great value for evaluating the development and treatment of gout.