The role of bacterial biofilm in persistent infections and control strategies

Bacterial biofilms can be viewed as a specific type of persistent bacterial infection. After initial invasion, microbes can attach to living and non-living surfaces, such as prosthetics and indwelling medical devices, and form a biofilm composed of extracellular polysaccharides, proteins, and other components. In hosts, bioffim formation may trigger drug resistance and inflammation, resulting in persistent infections. The clinical aspects of biofilm formation and leading strategies for hiofilm inhihitors will be discussed in this mini-review.

Consensus by Chinese Expert Panel on Chlamydia trachomatis-Resistant and Chlamydia trachomatis-Persistent Infection

Chlamydia trachomatis （Ct） genital infection is the most common sexually transmitted disease （STD） in China and the US. The morbidity of Ct genital infection in China has increased from 32.48/100,000 in 2008 to 37.18/100,000 in 2015.[1] The major areas of Ct infections are concentrated in the Zhujiang Delta, Changjiang Delta, Minjiang Area, and West China. In these areas, the highest incidence of Ct infection reaches 615.99/100,000 citizens. In the US, there are 1,441,789 reported Ct, which include 627.2 females and 278.4 males per 100,000 population. It is now the most prevalent STD, with its rate increasing to 22% in males and 6% in females.[2] Ct genital infection can cause epididymitis, prostatitis, cervicitis, annexitis, infertility, and atopic pregnancy, which have been identified as the major public health problems.

Analysis of therapeutic effect of cervical radiofrequency ablation on persistent HR-HPV infection

Background:To investigate the therapeutic effect of cervical radiofrequency ablation on high risk-HPV persistent infection.Methods:One hundred patients with persistent high risk-HPV infection diagnosed in our hospital from April 2019 to February 2020 were selected.Those in the same period were randomly selected by SPSS19.0 software machine according to the ratio of 1:1,and divided into the treatment group(BBT-RF-A radiofrequency group)and the observation group(recombinant human interferon suppository group)with 50 cases in each group.The negative conversion rate of high risk-HPV between the 2 groups was compared at the 6th and 12th months after treatment,and the types of persistent HR-HPV infection in Changle were studied.Results:The negative conversion rates of HR-HPV in the treatment group were 60%(35/50)and 82%(41/50)at 6 and 12 months after treatment,respectively,while the negative conversion rates of high risk-HPV in the observation group were 30%(15/50)and 44%(22/50)at 6 and 12 months after treatment,respectively.The negative conversion rates in the treatment group were significantly higher than those in the observation group(P<0.05).Studying the main types of high risk-HPV persistent infection has guiding value for HPV vaccine injection in Changle.Conclusion:Self-clotting cutter radiofrequency ablation has a good effect on the negative conversion rate of high risk-HPV persistent infection.These results suggest that the main types of single persistent cervical HR-HPV infection are 16,52 and 58,not including the 18 types.

The Identification of Three Sizes of Core Proteins during the Establishment of Persistent Hepatitis C Virus Infection in vitro

Similar to Hepatitis C virus (HCV) infection in humans, HCVcc infection can also result in persistent and chronic infection. The core protein is a variable protein and exists in several sizes. Some sizes of core proteins have been reported to be related to chronic HCV infection. To study the possible role of the core protein in persistent HCV infection, a persistent HCVcc infection was established, and the expression of the core protein was analysed over the course of the infection. The results show that there are three sizes of core proteins (p24, p21 and p19) expressed during the establishment of persistent HCVcc infection. Of these, the p21 core protein is the mature form of the HCV core protein. The p24 core protein is the phosphorylated form of p21. The p19 core protein appears to be a functional by-product generated during the course of infection. These three core proteins are all localized in the cytoplasm and can be encapsidated into the HCV virion. The appearance of the p19 and p24 core proteins might be related to acute HCVcc infection and chronic infection respectively and may play an important role in the pathology of a HCV infection.

STUDY OF PERSISTENT VIRAL INFECTION IN AN ANIMAL MODEL OF VIRAL MYOCARDITIS BY PCR

Objective To study the role of persistent viral infection in the mechanism of viral myocarditis. Methods A mice model of CVB3m viral myocarditis wes made and the viral RNA in mice myocardium and whole bind sample wes tested by using polymerase chain reaction (PCR ) technique. The pathological changes in mice myocardium were determined. Results De day 3, the viral gene in whole bind and myocardium wes found, which portly became negative on day 8, but the change of myocardial anthology borne obvious. Although the bind specimens wers tested negatively on day 12, the viral gene in mice myocardium remained positive within 120d. Conclusion This study indicates that persistent viral infection plays a role in the pathogenesis of viral myocarditis.

Regulation of microRNA by hepatitis B virus infection and their possible association with control of innate immunity

Hepatitis B virus(HBV)chronically infects more than350 million people worldwide.HBV causes acute and chronic hepatitis,and is one of the major causes of cirrhosis and hepatocellular carcinoma.There exist complex interactions between HBV and the immune system including adaptive and innate immunity.Tolllike receptors(TLRs)and TLR-signaling pathways are important parts of the innate immune response in HBV infections.It is well known that TLR-ligands could suppress HBV replication and that TLRs play important roles in anti-viral defense.Previous immunological studies demonstrated that HBV e antigen(HBeAg)is more efficient at eliciting T-cell tolerance,including production of specific cytokines IL-2 and interferon gamma,than HBV core antigen.HBeAg downregulates cytokine production in hepatocytes by the inhibition of MAPK or NF-κB activation through the interaction with receptor-interacting serine/threonine protein kinase.MicroRNAs(miRNAs)are also able to regulate various biological processes such as the innate immune response.When the expressions of approximately 1000 miRNAs were compared between human hepatoma cells HepG2 and HepG2.2.15,which could produce HBV virion that infects chimpanzees,using real-time RT-PCR,we observed several different expression levels in miRNAs related to TLRs.Although we and others have shown that HBV modulates the host immune response,several of the miRNAs seem to be involved in the TLR signaling pathways.The possibility that alteration of these miRNAs during HBV infection might play a critical role in innate immunity against HBV infection should be considered.This article is intended to comprehensively review the association between HBV and innate immunity,and to discuss the role of miRNAs in the innate immune response to HBV infection.

Occult hepatitis B virus infection:A complex entity with relevant clinical implications

Occult hepatitis B virus(HBV) infection is a world-wide entity,following the geographical distribution of detectable hepatitis B.This entity is defined as the persistence of viral genomes in the liver tissue and in some instances also in the serum,associated to negative HBV surface antigen serology.The molecular basis of the occult infection is related to the life cycle of HBV,which produces a covalently closed circular DNA that persists in the cell nuclei as an episome,and serves as a template for gene transcription.The mechanism responsible for the HBsAg negative status in occult HBV carriers is a strong suppression of viral replication,probably due to the host’s immune response,co-infection with other infectious agents and epigenetic factors.There is emerging evidence of the potential clinical relevance of occult HBV infection,since this could be involved in occult HBV transmission through orthotopic liver transplant and blood transfusion,reactivation of HBV infection during immunosuppression,impairing chronic liver disease outcome and acting as a risk factor for hepatocellular carcinoma.Therefore it is important to bear in mind this entity in cryptogenetic liver diseases,hepatitis C virus/ HIV infected patients and immunosupressed individuals.It is also necessary to increase our knowledge in this fascinating field to define better strategies to diagnose and treat this infection.

E Sequence Analysis of Persistently Infected Mutant Japanese Encephalitis Virus Strains

Summary： A persistent infection model was established after human hepatoma cells infected by Japanese encephalitis viruses were subcultured for several times. Viral titers of mutant viruses in persistently infected cells were examined by plaque methods using BHK cells. Nucleotides of the E coding region of two wild and two mutant viruses were amplified by RT-PCR. PCR products were sequenced by ABI-PRSM^TM310 sequencing system. Compared to JaGAr-01 wild strains, four amino acids were replaced （E61Tyr→Asp, E219His→Tyr, E384Val→Glu, E418Pro→Ala） in the E sequence of JaGAr-01 persistently-infected mutant strains. Eleven amino acid replacement （E51Arg →Ser, E61Tyr→Asp, E83Lys→Glu, E123Ser→Arg, E209Arg→Lys, E227Pro→Ser, E276Asp→er, E290Arg→Lys, E387Lys→Arg, E418Leu→Pro, E454Arg→Gly） was also noted when we compared the E sequence between persistently infected Nakayama and its wild strains. A lot of similarities of amino acid sequence between mutant strains JaGAr-01 and Nakayama were also noted. It was concluded that geno-variation existed in E region of mutant viruses and the mutant protein encoded by E region, especially the mutation of E61 （Tyr→Asp） may contribute to the maintenance of the persistent infection of Japanese encephalitis virus.

A novel real-time RT-PCR with TaqM an-MGB probes and its application in detecting BVDV infections in dairy farms

A real-time RT-PCR assay using Taq Man-MGB probes was developed to detect and type the bovine viral diarrhea virus（BVDV） in cattle.Universal primers and Taq Man-MGB probes were designed from the 5′-untranslated region of known pestiviral sequences.Prior to optimizing the assay, c RNAs were transcribed in vitro from the BVDV 1 and BVDV 2 RTPCR products to make standard curves.The detection limit of the assay was 1.72×102 copies for BVDV 1 and 2.14×102copies for BVDV 2.The specificity of the assay evaluated on several BVDV strains including bovine herpesvirus 1（BHV 1）, foot and mouth disease virus（FMDV） and several classical swine fever virus（CSFV） strains showed specific detection of the positive virus over 40 cycles.The assay was highly reproducible with the coefficient of variance ranging from 1.04 to 1.33% for BVDV 1 and from 0.83 to 1.48% for BVDV 2, respectively.Using this method, we tested a total of 2 327 cattle from three dairy farms for the presence of BVDV persistently infected（PI） animals.In this assay, each RT-PCR template contained a mixture of ten samples from different animals.The occurrence rate of PI cattle in three farms ranging from 0.9 to 2.54% could represent partly the PI rates in cattle farm in China.In conclusion, using our real-time PCR assay, we could effectively detect and type BVDV and identify PI cattle in a rapid and cost-effective manner.

Incidence of persistent and high-risk human papillomavirus infection and associated factors among HIV-positive women in China, 2015-2016

Background:Persistent human papillomavirus(HPV)infection is the necessary factor for cervical cancer.Human immunodeficiency virus(HIV)-positive women are a high-risk population for cervical cancer,but little is known about persistent HPV infection among HIV-positive women in China.We aimed to investigate the persistence and incidence of infection with high-risk HPV(hrHPV)and associated factors among HIV-positive women in China.Method:Using a prospective observational study design,we collected data from 670 HIV-positive women in five counties of three provinces through interviews,medical record reviews,health examination,and laboratory tests at a baseline survey in 2015 and a follow-up survey in 2016.We tested HIVpositive women for hrHPV infection using the Cobas 4800 HPV test,and analyzed factors associated with persistence and new incidence of hrHPV infection using logistic regression.Results:After an average of 15 months at follow-up,the persistence and new incidence rates of hrHPV infection were 38.0%(46/121,95%CI:29.2%-46.8%)and 8.3%(35/420,95%CI:5.7%-11.1%),respectively.HIV-positive women in Yunnan and Guangxi were more likely to have persistent hrHPV infections than those in Xinjiang(aOR=3.18,95%CI:1.00-10.14,p=0.05;aOR=6.38,95%CI:2.29-17.77,p<0.001).Migrant women had a higher rate of new hrHPV incidence than local women(aOR=4.48,95%CI:1.65-12.15,p=0.003).HIV-positive women from Xinjiang were 6.5 times more likely to be newly infected with hrHPV than those from Yunnan(95%CI:2.40-17.60,p<0.001).HIV-positive women with HBV infection had a higher risk of being infected with hrHPV than those without HBV infection(aOR=3.48,95%CI:1.13-10.71,p=0.029).Conclusions:The persistence and new incidence rates of hrHPV infection among HIV-positive women were high and varied significantly between regions.HBV infection and being among the migrant population were associated with new hrHPV infection.

Correlations among Persistent Viral Infection,Heart Function and Chinese Medicine Syndromes in Dilated Cardiomyopathy Patients

Objective：To investigate the correlations among persistent viral infection,heart function and Chinese medicine（CM） difined-syndromes in patients with dilated cardiomyopathy（DCM）.Methods：Fifty patients with DCM in the First Affiliated Hospital of Zhejiang Chinese Medical University from October 2009 to December 2011 were selected as the research subjects,and 30 healthy people were simultaneously selected as the normal control group to detect persistent viral infections after admission.The CM syndrome type and grade of heart function were then evaluated.The expression level of Coxsackie adenovirus receptor（CAR） was detected using the flow cytometry（FCM） technique,coxsackie virus RNA（CVB-RNA） using reverse transcription polymerase chain reaction（RTPCR）,and the plasma brain natriuretic peptide（BNP） level with a Triage meter plus diagnosis instrument.Finally,the parameters such as left ventricular end diastolic diameter（LVEDd） and left ventricular ejection fraction（LVEF） were measured by ultrasonic cardiogram.Person correlation analysis was used for measured data,Spearman correlation analysis for rating data,and the Chi-square test for numerical data.Results：CVB-RNA was positive in 22 patients（44%） with DCM,while only 6 cases（20%） were CVB-RNA-positive in the normal control group,with a significant difference between the two groups（P〈0.01）.The expression level of CAR was significantly elevated in the DCM group compared with the normal control group（P〈0.01）.In CVB-RNA-positive patients（22 cases）,the expression level of CAR was significantly higher than in CVB-RNA-negative patients（28 cases;P〈0.01）.In the DCM patients,there was a positive correlation between the CAR expression and the BNP level（r=0.34,P〈0.05）,while no significant difference was found between the CAR expression and the LVEF and LVEDd（r=-0.32,0.30,P〉0.05）.There was no clear correlation between virus infection and the CM syndrome types in DCM patients（r=-0.22,P〉0.05）.According to the sequence of syndrome types：phlegm → qi deficiency → blood stasis → hydroretention with asthenic yang（from low to high）,a positive correlation was existed between the BNP levels and CM syndrome types（r=0.139,P〈0.05）.Conclusion：The expression of CAR on the surface of white cells could be used to detect persistent viral infection.The expression level of CAR and heart function in DCM patients were highly correlated.The expression level of BNP may serve as an objective index for differentiating CM syndromes for patients with DCM.

Clinical significance of human papilloma virus infection in the cervical lesions

Cervical lesions have been regarded as the common and frequently occurring diseases in China.Recently,the morbidity and youth tendency of cervical cancer have gradually increased.Cervical cancer,related with human papilloma virus(HPV)infection,has been one of the severest diseases threatening health and life of women,and is an infectious disease.The universality of HPV infection in the reproductive tract should not be ignored.The well-known risk factors of HPV infection in cervical lesions consist of high-risk sexual behaviors,immunosuppression,age,contraceptive methods,the concurrent infection of other sexually transmitted diseases,etc.The variation of cervical lesions induced by HPV infection is involved in the continuous pathological process,including the subclinical,latent,and persistent infection of high risk(HR)-HPV,chronic cervicitis with abnormal results of cytological examination,cervical intraepithelial neoplasia(CIN),and cervical cancer.The outcome of patients with HPV infection is influenced by many factors,such as HPV subtype dominance,persistent HPV infection,HPV loading dose,and multiple HPV infection.Controlling HR-HPV persistent infection should be an important strategy for reducing cervical lesions.

Endodontic bacteria from primary and persistent endodontic lesions in Chinese patients as identified by cloning and 16S ribosomal DNA gene sequencing

Background Few literatures pertain to the 16S ribosomal DNA （16S rDNA） analysis of bacteria contributing to primary and persistent endodontic lesions, with no information available for the Chinese population. As such, we investigated endodontic bacteria associated with primary and persistent endodontic lesions in adult Chinese patients living in Beijing, China using 16S rDNA gene sequencing techniques. Methods Endodontic microbial samples were obtained from fourteen adult Chinese patients and subjected to DNA extraction. Pllymerase chain reaction （PCR） products were cloned and 100 clones from each generated library were randomly selected. Purified plasmid DNA with 16S rDNA gene inserts was sequenced, and the sequences were searched against GenBank databases using the BLASTN algorithm. Only significant identification with the highest-scored BLAST result and 99% minimum similarity was considered for phylotyping. Results More than 150 taxa were obtained. Primary endodontic infection was mainly associated with Burkholderia cepacia, Actinomyces, Aranicola spp. and Streptococcus sanguinis, whilst Burkholderia cepacia was predominant in the persistent endodontic infections. Conclusion There is a difference in the species profile associated with endodontic infections of Chinese patients living in Beijing in comparison to other geographical or ethnic reports.

A Delayed HIV Infection Model with the Homeostatic Proliferation of CD4^(+)T Cells

In this paper,we investigate a delayed HIV infection model that considers the homeostatic prolif-eration of CD4^(+)T cells.The existence and stability of uninfected equilibrium and infected equilibria(smaller and larger ones)are studied by analyzing the characteristic equation of the system.The intracellular delay does not affect the stability of uninfected equilibrium,but it can change the stability of larger positive equilibrium and Hopf bifurcation appears inducing stable limit cycles.Furthermore,direction and stability of Hopf bifur-cation are well investigated by using the central manifold theorem and the normal form theory.The numerical simulation results show that the stability region of larger positive equilibrium becomes smaller as the increase of time delay.Moreover,when the maximum homeostatic growth rate is very small,the larger positive equilibrium is always stable.On the contrary,when the rate of supply of T cells is very small,the larger positive equilibrium is always unstable.

Genes and regulatory networks involved in persistence of Mycobacterium tuberculosis

The causative agent of tuberculosis,Mycobacterium tuberculosis,is one of the most successful of human pathogens.It can evade the host immune response and establish a persistent infection or enter a dormant state within the host which can be reactivated if the host becomes immuno-compromised.Both of these features are major obstacles to tuberculosis eradication.Dormancy and reactivation of M.tuberculosis are tightly coordinated dynamic processes involving numerous genes and their products.Molecular mechanisms underlying M.tuberculosis persistence may provide an opportunity for the discovery of effective drug targets for tuberculosis control.Here,we review the genes required for M.tuberculosis persistence and propose a regulatory network for the action of these genes using text mining.This should provide fresh insights into the persistence mechanisms of M.tuberculosis and suggest candidates for new drug targets and immune intervention.