ApoB-containing lipoproteins promote infectivity of chlamydial species in human hepatoma cell line

AIM:To evaluate the direct binding of two main chlamydial biovars(C.trachomatis and C.pneumoniae) to plasma lipoproteins and its effect on chlamydial infection rate in human hepatoma cell line(HepG2 cells). METHODS:Murine plasma lipoproteins were fractionated and isolated using fast-performance liquid chromatography(FPLC),spotted on nitrocellulose membrane and incubated with chlamydial suspensions. Direct binding of chlamydial particles to lipoprotein fractions has been studied using lipopolysaccharide-specific antibodies in immuno-dot blot binding assay and immunoprecipitation analysis.Immunostaining protocol as well as flow cytometry analysis have been employed to study the infectivity rate of chlamydial species in HepG2 cells. RESULTS:Elementary bodies of both C.trachomatis and C.pneumoniae bind ApoB-containing fractions of plasma lipoproteins.That binding becomes stronger when heat-denatured FPLC fractions are used, suggesting a primary role of apolipoproteins in interaction between chlamydial particle and lipoprotein. Both chlamydial biovars efficiently propagate in human hepatoma cell line-HepG2 cells even in serum free conditions forming late-stage inclusion bodies and releasing extracellular elementary bodies.Preincubation of C.trachomatis and C.pneumoniae with native ApoB-containing lipoproteins enhances the rate of chlamydial infection in HepG2 cells.CONCLUSION:A productive infection caused by C. trachomatis and C.pneumoniae may take place in human-derived hepatocytes revealing hepatic cells as possible target in chlamydial infection.Obtained results may suggest the participation of lipoprotein receptors in the mechanism of attachment and/or entry of chlamydial particles into target cells.

Preparation and analysis of immunocompetence of recombinant fusion protein of the immunodominant region in chlamydial protease-like activity factor from Chlamydophila pneumoniae and its application in serodiagnosis

To clone the gene coding the immunodominant region in the chlamydial protease-like activity factor （CPAF） from Chlaroydophila pneumoniae, to analyze immunoeoropetenee of the expressed protein, and to evaluate its value in serodiagnosis, the CPAF immunodominant region gene was amplified, ligated into a pGEX6p-2 vector, and then the expressed recombinant protein was purified with glutathione Stransferase （GST） agarose gel FF after renaturation, then identified by SDS-PAGE and Western blot. A new indirect ELISA was developed with the purified protein as coating antigen. The immunogenicity of the recombinant protein was evaluated by immunization to New Zealand rabbits, and its immunoreactivity was analyzed by reacting with anti-C, pneumoniae antibody. 300 clinical sera samples were respectively detected by mieroimmunofluorescenee （MIF） as reference method and the indirect ELISA, and the difference between the two methods was analyzed. Cross-reactivity against Chlamydia trachomatis was investigated with the indirect ELISA to detect anti-C, trachomatis positive antisera. The results indicated that a 51.3 kDa recombinant protein was obtained. Western blot assay proved that the recombinant protein could merely specifically react with human anti- C. pneurnoniae antisera. The titers of the specific IgG antibodies in the immunized New Zealand rabbits were above 1 ： 16 000. Anti- C. pneumoniae IgG positive and negative reference sera were detected with the indirect ELISA, and the concordance rate of negative and positive results were both 100% （40/40）. The sensitivity and specificity of the indirect ELISA in comparison with MIF were 93.8% （45/48） and 100% （252/252） separately by detecting 300 clinical sera samples, and the concordance rate between the two methods was 99.0%. No cross reaction against C. trachomatis was found with the indirect ELISA to detect anti-C, trachomatis positive antisera. In conclusion, the prepared recombinant protein of the CPAF immunodominant region shows excellent immunocompetence and can be used to develop a new indirect ELISA as a method to detect anti-C, pneumoniae antibody for diagnosis of C. pneumoniae infection.

Progress of Study on Chlamydial Pathogenesis

Chlamydia, a human pathogen that mediates chronic, persistent and repeated infection progress, is capable of inflicting permanent scar formation. A typical reticular body is found in persistent infections. Chlamydial Hsp 60, interferon(IFN) -gamma and other cytokines function in the course of repeated infection. Immunopathological factors mediate chronic infection.

Epidemiology of Genital Chlamydial Infection in China in 2019

Objective:Genital chlamydial infection is a globally common sexually transmitted infection caused by Chlamydia trachomatis.This study aimed to describe the epidemiological characteristics of the disease reported in China in 2019.Methods:Genital chlamydial infection cases were identified in 105 national sexually transmitted disease surveillance sites from the National Notifiable Infectious Disease Reporting System,which covers 31 provinces,autonomous regions,and municipalities in Chinese mainland.Data were collected and used to calculate the overall incidence,and the incidences per surveillance site,province,sex,and age group.Results:In 2019,there were 50,874 new cases of genital chlamydial infection reported in China,corresponding to an incidence of 55.32 cases per 100,000 population,and comprising a 9.98%increase from 2018(50.30 cases per 100,000 population).The highest incidences of genital chlamydial infection occurred in Zhejiang,Guangdong province,Guangxi autonomous region,and Hainan province(average 137.49-233.37 cases per 100,000 population).The incidence of genital chlamydial infection was much higher in females than males,with a female-to-male ratio of 3.09(84.55 per 100,000 population vs 27.35 per 100,000 population).The highest incidence of genital chlamydial infection was reported in the 20-24-year age group(184.70 cases per 100,000 population),followed by the 25-29-year age group(180.79 cases per 100,000)and 30-34-year age group(151.53 cases per 100,000 population).The highest proportion(68.30%)of genital chlamydial infection was reported from general hospitals,followed by maternal and child health hospitals(25.59%).Conclusion:The incidence rate of genital chlamydial infection in 2019 has an increase trend from 2018 and be a common sexually transmitted infection in China.The incidence is much higher in females than in males.Sexually active young adults are the highest risk population.There is substantial geographic diversity in incidence,with the highest incidence occurring in the southeast coastal areas with a developed economy.Epidemic of genital chlamydial infection in China should be concerned,and its surveillance needs to be improved.

Type 1 T-cell responses in chlamydial lung infections are associated with local MIP-1a response

Chemokines and their receptors are important mediators of leukocyte trafficking and recruitment and sometimes work as modulators of T-cell responses during infections and inflammation.Modulating the biological activity of chemokines has been found to influence the course of diseases.However,little is known about the role of chemokine responses during chlamydial lung infections.We therefore analyzed the dynamics of multiple chemokines,which are frequently associated with type 1(Th1)T cell immune responses,and their receptors for their expression in the lungs during Chlamydia muridarum(Cm)infections.We also examined the relationship between chemokine responses and the development of Th1 responses as well as the clearance of infection.Our results showed that in parallel with the high levels of gamma interferon(IFN-c)and IL-12 production in the lungs and draining lymph nodes,and the expansion of IFN-c-producing CD4 and CD81 T cells,the production of the cell-related chemokines RANTES,IFN-c-inducible protein-10(IP-10)and macrophage inflammatory protein-1a(MIP-1a)and their receptor CCR1 was elevated in the lung tissues after infection.Interestingly,in a later phase of infection,the expression of RANTES and IP-10 remained elevated but the expression of MIP-1a and CCR1 decreased to a low level,which suggests a closer association with the pattern of Th1 cytokine responses in the process of infection.These results suggest a close association between the MIP-1a response and the Th1-type T-cell responses in chlamydial lung infections .

RAPID DIAGNOSIS AND TREATMENT OF CHLAMYDIAL CONJUNCTIVITIS

During December 1989 to December 1992, conjunctival specimens from 63 patients with severe trachoma and 30 with acute follicular conjunctivitis at the eye clinic of Tong Ren Hospital in Beijing, were tested by using direct immunofluorescent technique and amplified enzyme-inked immunoassay (Micro Trak and IDEIA) for chlamydial antigenicity. Trachoma accounted for 97.6% while acute follicular conjunctivitis accounted for 2.4% of the positive cases. Micro Trak and IDEIA tests proved advantageous over the culture method for the detection of Chlamydia trachomatis. In our study, Ofloxacin eye ointment has been proved to be an alterative drug for severe trachoma with better curative effectiveness.

实时荧光定量PCR技术检测肺炎衣原体的诊断价值

目的探讨实时荧光定量PCR技术检测肺炎衣原体的诊断价值。方法对呼吸道感染的186例患者的痰液分别采用实时荧光定量PCR技术和基因测序检测,以评价实时荧光定量PCR技术检测肺炎衣原体感染的准确性。结果实时荧光定量PCR检测肺炎衣原体的灵敏度为100.0%,特异度为93.1%,阳性预期值为80.8%,阴性预期值为100.0%,准确率为94.6%。结论实时荧光定量PCR技术检测肺炎衣原体具有较高的可靠性,适用于临床快速诊断肺炎衣原体感染的相关疾病。

Screenning of Chlamydia trachomatis Infection among Women Attending Outpatient Clinic of Infertility

Objective: The goal of this study was to determine the prevalence of C. trachomatis in women diagnosed with infertility attending the Outpatient Clinic of Infertility from Botucatu Medical School, UNESP, Brazil. Patients and Methods: This molecular study enrolled a total of 112 women. Among these patients, 62 presented primary infertility while 50 presented secondary infertility. The criteria for eligibility included women who were: reproductive-aged;no prior report of seroconversion for HIV;no antibiotic or vaginal cream used in the preceding 30 days;and abstinence from sexual intercourse for 72 hours before the visit. The women were submitted to a gynecological examination and cervical samples were collected with an endocervical cytobrush for molecular analysis of C. trachomatis. Results: The prevalence of chlamydial infection was 8% with similar prevalence between primary (8.1%) and secondary (8.0%) infertility. Conclusion: Considering the asymptomatic nature of chlamydial infection and its association with tubal factor infertility, there is a pressing need to incorporate the screening of C. trachomatis infection as part of the routine investigation for infertility. The early diagnostic by screening can minimize complications and reduce Public Health costs with Assisted Reproductive Technology.