Molecular Characterization of Coxsackievirus B1 Strains Isolated from Patients with Hand Foot and Mouth Disease in Yunnan,Southwest China

Coxsackievirus(CV)B belongs to the species Enterovirus B,genus Enterovirus of the family Picornaviridae.Enterovirus B(EV-B)includes 63 serotypes:CVB1-6;CVA9;echoviruses E1-7,9,11-21,24-27,and 29-33;EV-B69,EV-B 73-75,EV-B77-88,EV-B 93,EV-B 97-101,EV-B 106-107.

Coxsackievirus B_(3m)与T-2毒素对小鼠脂质过氧化物代谢的影响

目的探讨Ｔ－２毒素与ＣｏｘｓａｃｋｉｅｖｉｒｕｓＢ３ｍ的双重作用对小鼠肝脏脂质过氧化物的影响。方法实验采用析因设计，ＢＡＬＢ／Ｃ小鼠随机分成４组，Ｉ正常对照组；Ⅱ病毒组；ⅢＴ－２毒素组；Ⅳ病毒＋毒素组。病毒组常规腹腔接种０．１ｍｌ内含１０００ＴＣＩＤ５０的１６４０营养液；毒素组隔日按１．０ｍｇ／ｋｇ体重Ｔ－２毒素灌胃，直至实验结束；病毒＋毒素组先Ｔ－２灌胃，３周后腹腔接种同稀释度病毒。各组鼠于病毒接种后第７天，１４天，２１天，３０天，５０天分批处死测定肝脏脂质过氧化物（ＬＰＯ）含量。结果显示病毒和Ｔ－２毒素均可非常明显（Ｐ＜０．０１）引起小鼠肝脏ＬＰＯ含量升高。两者双重作用更为明显，但两者之间没有交互作用。结论ＣｏｘｓａｃｋｉｅｖｉｒｕｓＢ３ｍ和Ｔ－２毒素作用于生物体可导致机体脂质过氧化损伤。

Molecular Epidemiology of Coxsackievirus B1-5 Associated with HFMD in Fujian Province, China, 2011-2016

Hand,foot and mouth disease(HFMD)is a common infectious disease that usually affects children less than 5 years of age.HFMD is caused by human enteroviruses(HEVs).HEVs,members of the Enterovirus genus of the Picornaviridae(small RNA virus)family.

Coxsackievirus B3 Infection Triggers Autophagy through 3 Pathways of Endoplasmic Reticulum Stress

Objective Autophagy is a highly conserved intracellular degradation pathway. Many picornaviruses induce autophagy to benefit viral replication, but an understanding of how autophagy occurs remains incomplete. In this study, we explored whether coxsackievirus B3(CVB3) infection induced autophagy through endoplasmic reticulum(ER) stress. Methods In CVB3-infected HeLa cells, the specific molecules of ER stress and autophagy were detected using Western blotting, reverse transcription polymerase chain reaction(RT-PCR), and confocal microscopy. Then PKR-like ER protein kinase(PERK) inhibitor, inositol-requiring protein-1(IRE1) inhibitor, or activating transcription factor-6(ATF6) inhibitor worked on CVB3-infected cells, their effect on autophagy was assessed by Western blotting for detecting microtubule-associated protein light chain 3(LC3). Results CVB3 infection induced ER stress, and ER stress sensors PERK/eIF2α, IRE1/XBP1, and ATF6 were activated. CVB3 infection increased the accumulation of green fluorescent protein(GFP)-LC3 punctuation and induced the conversion from LC3-Ⅰ to phosphatidylethanolamine-conjugated LC3-1(LC3-Ⅱ). CVB3 infection still decreased the expression of mammalian target of rapamycin(mTOR) and p-mTOR. Inhibition of PERK, IRE1, or ATF6 significantly decreased the ratio of LC3-Ⅱ to LC3-Ⅰ in CVB3-infected HeLa cells. Conclusion CVB3 infection induced autophagy through ER stress in HeL a cells, and PERK, IRE1, and ATF6 a pathways participated in the regulation of autophagy. Our data suggested that ER stress may inhibit mTOR signaling pathway to induce autophagy during CVB3 infection.

Coxsackievirus A6 was the most common enterovirus serotype causing hand,foot,and mouth disease in Shiyan City,central China

BACKGROUND Hand,foot,and mouth disease(HFMD)has become one of the most common infectious diseases in China.Before 2016,the primary causal serotypes were enterovirus A71(EV-A71)and coxsackievirus A16(CV-A16).Following the introduction of EV-A71 vaccines in China since 2016,the situation could change.CV-A6 has recently replaced EV-A71 and CV-A16 in some areas of China.However,the epidemiological characteristics of central China remain unknown.AIM To investigate the clinical symptoms and pathogen spectrum of HFMD in Shiyan City,central China,in recent years.METHODS The epidemiological,clinical,and laboratory data from HFMD cases reported to the Shiyan Center for Disease Control and Prevention between January 2016 and December 2020 were analyzed.196 throat swab specimens were collected from hospitalized HFMD patients between January 2018 and December 2020.To detect and genotype enteroviruses,real-time reverse transcription-polymerase chain reaction and sequencing of the 5'-untranslated region were used.In Shiyan,168 laboratory-confirmed HFMD cases were studied using a logistic regression model to determine the effect of predominant enterovirus serotypes.Based on the logistic regression model,the least absolute shrinkage and selection operator model was used to analyze the correlation between CV-A6 infection and various clinical characteristics in HFMD patients in Shiyan.RESULTS From 2016 to 2020,35840 HFMD cases were reported in Shiyan.The number of cases decreased by 48.4%from 2016 to 2017.Approximately 1.58-fold increases were found in 2018 and 2019 when compared to the previous year,respectively.In 2020,a decrease of about 85.5%was reported when compared to 2019.The most common serotypes shifted from EV-A71 and CV-A16(about 60%-80%in 2016 and 2018)to others(more than 80.0%in 2017,2019,and 2020).EV-A71 lost its dominance in 2017 in Shiyan.Among 196 confirmed HFMD cases,85.7%tested positive for enterovirus,with CV-A6 being the most common serotype(121/168,72.0%).The positive rates for CV-A16 and CVA10 were 4.8%and 3.0%,respectively.There was no EV-A71 discovered.Infection with CV-A6 was linked to fever,myocardial damage,increased creatine kinase MB isoenzyme,and lactate dehydrogenase levels.CONCLUSION CV-A6 was the most common enterovirus serotype in Shiyan City,replacing EV-A71 and CV-A16 as the HFMD pathogen.Developing vaccines against CV-A6 or multiple pathogens,as well as rising CV-A6 surveillance,will help prevent HFMD in central China.

Murine model of acute myocarditis and cerebral cortical neuron edema induced by coxsackievirus B4

Globally, coxsackievirus B4 （CV-B4） has been continuously isolated and evidence suggests an association with the development of pancreatitis and type I diabetes. In addition, CV-B4 is also associated with myocarditis and severe central nervous system （CNS） complications, which remain poorly studied and understood. In the present study, we established an institute for Cancer Research （ICR） mouse model of CV-B4 infection and examined whether CV-B4 infection resulted in a predisposition to myocarditis and CNS infection. We found high survival in both the treatment and control group, with no significant differences in clinical outcomes observed. However, pathological lesions were evident in both brain and heart tissue of the CV-B4-infected mice. in addition, high viral loads were found in the neural and cardiac tissues as early as 2 days post infection. Expressions of IFN-y and IL-6 in sera were significantly higher in CV-B4-infected mice compared to uninfected negative controls, suggesting the involvement of these cytokines in the development of histopathological lesions. Our murine model successfully reproduced the acute myocarditis and cerebral cortical neuron edema induced by CV-B4, and may be useful for the evaluation of vaccine candidates and potential antivirals against CV-B4 infection.

Evaluation of Reverse Transcription Loop-Mediated Isothermal Amplification assays for Rapid Detection of Human Enterovirus 71 and Coxsackievirus A16 in Clinical Samples

A sensitive reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for human enterovirus 71 (EV71) and Coxsackievirus A16 (CVA16) infection was further evaluated. The one step reaction was performed in a single tube at 65?C for 45 min for EV71 and 35 min for CVA16. The detection limits of RT-LAMP assays for both EV71 and CVA16 were 0.1 of a 50% tissue culture infective dose (TCID50) per reaction, based on 10—Fold dilutions of a titrated EV71 or CVA16 strain. The specific assay showed there were no cross-reactions with Coxsackievirus A (CVA) viruses (CVA 2, 4, 5, 7, 9, 10, 14, and 25), Coxsackievirus B (CVB) viruses (CVB 1, 2, 3, 4, and 5) or ECHO viruses (ECHO 3, 6, 11, and 19). In parallel with commercial quantitative real-time polymerase chain reaction (qRT-PCR) diagnostic kits for EV71 and CVA16, the RT-LAMP assay was evaluated with 515 clinical specimens, the results showed the RT-LAMP assay and the qRT-PCR assay were in complete agreement for 513/515 (99.6%) of the specimens. Two samples with discrepant results from two methods were further verified by nested reverse transcription polymerase chain reaction (nRT-PCR) assay and sequencing to be true positives for CVA16. In conclusion, RT-LAMP assay is demonstrated to be a sensitive and specific assay and have a great potential for the rapid and visual screening of EV71 and CVA16 in China, especially in those resource-limited hospitals and rural clinics of provincial and municipal regions.

Bioinformatic Analysis of Non-VP1 Capsid Protein of Coxsackievirus A6

This study bioinformatically analyzed the non-VP1 capsid proteins（VP2-VP4） of Coxasckievirus A6（CVA6）, with an attempt to predict their basic physicochemical properties, structural/functional features and linear B cell eiptopes. The online tools Sub Loc, Target P and the others from Ex PASy Bioinformatics Resource Portal, and SWISS-MODEL（an online protein structure modeling server）, were utilized to analyze the amino acid（AA） sequences of VP2-VP4 proteins of CVA6. Our results showed that the VP proteins of CVA6 were all of hydrophilic nature, contained phosphorylation and glycosylation sites and harbored no signal peptide sequences and acetylation sites. Except VP3, the other proteins did not have transmembrane helix structure and nuclear localization signal sequences. Random coils were the major conformation of the secondary structure of the capsid proteins. Analysis of the linear B cell epitopes by employing Bepipred showed that the average antigenic indices（AI） of individual VP proteins were all greater than 0 and the average AI of VP4 was substantially higher than that of VP2 and VP3. The VP proteins all contained a number of potential B cell epitopes and some eiptopes were located at the internal side of the viral capsid or were buried. We successfully predicted the fundamental physicochemical properties, structural/functional features and the linear B cell eiptopes and found that different VP proteins share some common features and each has its unique attributes. These findings will help us understand the pathogenicity of CVA6 and develop related vaccines and immunodiagnostic reagents.

Replication Kinetics of Coxsackievirus A16 in Human Rhabdomyosarcoma Cells

Coxsackievirus A16(CVA16),together with enterovirus type 71(EV71),is responsible for most cases of hand,foot and mouth disease(HFMD) worldwide.Recent findings suggest that the recombination between CVA16 and EV71,and the co-circulation of these two viruses may have contributed to the increase of HFMD cases in China over the past few years.It is therefore important to further understand the virology,epidemiology,virus-host interactions and host pathogenesis of CVA16.In this study,we describe the viral kinetics of CVA16 in human rhabdomyosarcoma(RD) cells by analyzing the cytopathic effect(CPE),viral RNA replication,viral protein expression,viral RNA package and viral particle secretion in RD cells.We show that CVA16 appears to first attach,uncoat and enter into the host cell after adsorption for 1 h.Later on,CVA16 undergoes rapid replication from 3 to 6 h at MOI 1 and until 9 h at MOI 0.1.At MOI 0.1,CVA16 initiates a secondary infection as the virions were secreted before 9 h p.i.CPE was observed after 12 h p.i.,and viral antigen was first detected at 6 h p.i.at MOI 1 and at 9 h p.i.at MOI 0.1.Thus,our study provides important information for further investigation of CVA16 in order to better understand and ultimately control infections with this virus.

Analysis of the expression of coxsackievirus and adenovirus receptor in five colon cancer cell lines

AIM： To investigate the expression of coxsackievirus and adenovirus receptor （CAR） and adenovirus-mediated reporter gene transfer in five human colon cancer cell lines.METHODS： Expression of CAR-specific mRNA and protein was analyzed by reverse transcriptase polymerase chain reaction and Western blotting, respectively. Adenovirusbased gene delivery was evaluated by infection of cells with adenoviral vector carrying the green fluorescent protein （GFP） gene.RESULTS： All the colon cancer cell lines examined （HT29, LS180, SW480, SW948 and SWlll6） expressed CAR full-length mRNA and an alternatively-spliced variant that lacks the transmembrane coding exon. All cell lines were detected as CAR-positive by Western blot analysis. Further, all cells we examined were efficiently infected with adenoviral vector-GFP.CONCLUSION： The data indicated that the five colon cancer cell lines tested expressed adenovirus primary receptor and could be efficiently infected by adenoviral vectors. Therefore, these cell lines will be useful for adenovirus-based gene transfer and research.

Coxsackievirus B3-induced apoptosis and Caspase-3

Cell death can be classified into two categories: apoptosis and necrosis. Apoptotic pathway can beeither caspase-dependent or caspase-independent. Caspase-independent cytopathic effect (CPE) has beendescribed. In order to evaluate the pattern of HeLa cell death induced by Coxsackievirus B3 (CVB3)and whether apoptosis involves caspase activation, we co-cultivated HeLa cells with CVB3 and detectedthe cytopathic changes, the alteration of mRNA and protein expression of caspase-3 gene plus caspase-3activity, as well as analyzing DNA fragmentation before and after caspase-3 activity inhibition. Accordingto the results, we propose that CVB3 may induce apoptosis and necrosis in HeLa cells, the latter appearingmuch earlier. Caspase-3 is activated at the levels of both transcription and translation, and procaspase-3 isproteolytically cleaved, thus leading to the continuous increasing of both caspase-3 precursor protein and itssubunit. However, besides CPE, apoptosis induced by CVB3 is not a direct consequence of the activationof caspase-3, or caspase-3 is not the only effector molecule in apoptotic cell death, for caspase-3 inhibitorcan not decrease DNA fragmentation. Some other biochemical mechanisms may participate in the process,whose role weakens the effect of inhibiting caspase-3 activity.

Molecular Characterisation of Two Coxsackievirus B6 Strains from the Tibet Autonomous Region of China

Enteroviruses (EVs) are members of the genus Enteroviruswithin the orderPicornavirales, family Picornaviridae, and consist of 12 species, including EV-A, EV-B, EV-C, and EV-D, which are associated with human infections. Coxsackievirus B6 (CV-B6)belongs to the species EV-B, which currently consists of 63 serotypes, including echovirus (serotypes 1–7,9, 11–21, 24–27, 29–33), coxsackievirus group A (CVA9), coxsackievirus group B (CV-B, serotypes 1–6),the newly identified EVs (serotypes EV-B69, B73–75,B77–88, B93, B97–98, B100–101, B106–107, and B110–113), and the simian enterovirus SA5.

Coxsackievirus B infection presenting as a hemorrhagic pericardial effusion causing tamponade

The coxsackievirus is well known for its vastly differing clinical presentations.Patients with coxsackievirus usually present with a viral prodrome which can then progress to the cardiac symptoms of chest pain and/or palpitations.Most patients improve quickly with simply supportive care and nonsteroidal anti-inflammatory medications.

EFFECT OF COXSACKIEVIRUS B3 ON ION CHANNEL CURRENTS IN RAT VENTRICULAR MYOCYTES

To investigate the effects of coxsackievirus B 3(CVB 3) on ion channel currents in rat ventricular myocytes. Methods.Rat hearts were isolated with collagenase to acquire single ventricular myocytes, L type voltage dependent calcium channel(VDCC)current (I Ca ),Na + current (I Na ), outward potassium current (I out ), inwardly rectifying potassium current(I KI ) were recorded using whole cell patch clamp techniques. ResultsCVB 3 infection increased I Ca and I out , while decreased I KI ; but it had no obvious effect on I Na . Conclusion.The effects of CVB 3 on I Ca 、 I out 、 I KI may be one of the mechanisms of myocytes damage and the occurrence of abnormal electroactivities induced by CVB 3 infection.

The effects of coxsackievirus B3 infection on induction of ICAM-1 in cardiac myocytes and on Iymphocyte-myocyte adhesion

objective:To observe the effects of coxsackievirus B3(CoxB3) infection on-induction of intercellu lar adhesion molecule-1 (ICAM-1) in cardiac myocytes and on lymphocyte-myocyte adhesion. Metkods: ICAM 1 expression on cultured neonatal rat cardiac myocytes infected by CoxB3 was determined through enzyme linked immunosorbent assay (ELISA) analysis. Lymphocyte-myocyte adhesion was observed with adherence assay and monoclonal antibodies to adhesion molecule inhibition. Results:ICAM-1 expression on cardiac my ocytes was markedly induced after exposure to CoxB3 100 or 200 TCID50/ml infectious dose for 24~48 h (P<0. 05). Adhesion of rat activated lymphocytes to myocytes was stimulated by CoxB3 infection,and the effects of CoxB3 infection on adherence was significantly inhibited by anti-lymphocyte function antigen-1 (LFA-12)monoclonal antibodies (inhibition rate 40. 6% and 26. 45 % respectively). Couclusion:CoxB3 infec tion promotes lymphocyte-myocyte adhesion through inducing ICAAM-1 expression on cardiac myocytes.

STUDY ON PERSISTENT INFECTION OF COXSACKIEVIRUSGROUP B IN MURINE MODEL OF CHRONICVIRAL MYOCARDITIS

Objective To investigate the dynamic change of coxsackievirus B3 (CVB3) in murine model ofchronic myocarditis and revel the molecular mechanism of the persistent infection of the tirus.Methods Strand - specific RT- PCR(ssRT- PCR), quantitative RT- PCR (qRT - PCR) and multiplexRT- PCR(mRT- PCR). Results The positive strand of CVB3 RNA existed in heart tissue up to 3 monthsalthough its amount decreased by 103～4 folds from acute to chronic phase. The negative strand RNA for virusreplication kept its amount on la moleculars per gram heart tissue. Some conserved areas of virus RNA 5’NTRand 3’NTR were lost in chronic phase. Conclusion The virus kept replication during the whole phase ofmyocarditis and speeded down on chronic period in the status of persistent infection. That may be due to theterminal lose of CVB RNA.

Evaluation of Antibodies Induced by the Injection of Single Capsid Protein or Purified Virus Particle of Coxsackievirus B3 in Mice

Four capsid proteins (VP1, VP2, VP3, and VP4) of coxsackievirus B3 (CVB3) were expressed as recombinant proteins in an Escherichia coli expression system and used as antigens for subunit vaccines against CVB3 in ICR mice. Antigens were expressed as thioredoxin-histidine (TrxHis)-tagged protein and purified before immunization. Although all VPs other than VP4 induced anti-CVB3 specific antibodies in mice (detected by ELISA and western blotting), they did not neutralize the infectious CVB3 in a virus neutralization assay. Meanwhile, 2 virus strains were purified from CVB3 virus stock on the basis of their plaque size on HeLa cells. ICR mice were infected with the 2 purified virus strains (S-strain and L-strain) and unpurified virus stock (wild type) to analyze the difference in antibody responses against infections of purified and unpurified virus strains. The reactivity of antisera against each virus strain was tested by ELISA, and the results showed that the inoculation of purified virus strain induced a strong antibody response against the inoculated strain. As a result, the antibody response against wild-type and other virus strains was suppressed. These results suggest using unpurified virus stock as an antigen is advantageous for inducing a broad antibody response in inoculated animals.

PROTECTIVE ROLE OF SOPHOCARPINE IN COXSACKIEVIRUS B3 INFECTION IN CULTURED RAT CARDIOMYOCYTES

Objective To observe the anti-CVB3 （ Coxsackievirus B3 ） effect of sophocarpine （SC） extracted from Sophora flavescens, a traditional Chinese herb in vitro. Methods Cardiomyocytes from the neonatal rat were cultured to establish the viral myocarditis model The cells were divided into four groups： infected group （ infected by CVB3 ） , SC treated group （ added SC 100 μg/mL after viral infection ）, SC control group （ added SC 100 μg/mL only）, and normal control group. The cytopathic effect （CPE） and the beating frequency of the myocardial cells were observed and the LDH levels in the supernatant were measured at day 2,3, and 5. The cultured myocytes were added different concentrations of SC （ 12. 5 -400 μg/mL ） after infection with CVB3, the CPE was observed and the concentrations of LDH were measured and compared at day 2, 3, and 5. Results In the SC treated group （ 100 μg/mL ） , the cytopathic effect was lighter and the LDH level was lower than the infected group. SC in a concentration of 12. 5 - 300 μg/mL could relieve the CPE and lower the LDH level, while in a higher concentration （400 μ/m ） , it exacerbated the CPE caused by the virus, and the LDH levels were higher than the infected cells. Conclusion SC in certain concentration could protect the cultured rat cardiomyocytes from CVB3 infection.

ROLE OF COXSACKIEVIRUS AND ADENOVIRUS RECEPTOR (CAR)IN CARDIOTOXICITY INFECTED BY COXSACKIEVIRUS B3

Objective To explore the role of coxsackievirus and adenovirus receptor（CAR） in cardiotoxicity infected by coxsackieviras B3. Methods A toxic cellular model was established in vitro by adding myocarditic coxsackievirus B3 （CVB3m） into the culture of neonatal mouse cardiomyocytes. 48 h later, the cardiomyocytes were divided into control, CVB3m, and CAR antibody ＋ CVB3m groups. CVB3m-mediated myocytopathic effect of above three groups was observed after further culturing for 48h. At the same time, the cardiomyocytes＇ viability of above three groups was assessed by MTT assay. Results The degree of cytopathic effect（CPE） of CAR antibody ＋ CVB3m group was significantly lower than CVB3m group （ P 〈 0. 01 ） and there was a significant increase in cell viability in CAR antibody ＋ CVB3m group compared with CVB3m group（ P 〈 0. 01 ）. No significant difference was found between CAR antibody ＋ CVB3m group and control group. Conclusion CAR antibody possesses a protective effect on CVB3m infected cardiomyoctyes, which indicates that CAR may play an important role in mediating cardiotoxicity infected by CVB3m.

Baicalein suppresses Coxsackievirus B3 replication by inhibiting caspase-1 and viral protease 2A

Myocarditis is an inflammatory disease of the cardiac muscle and one of the primary causes of dilated cardiomyopathy.Group B coxsackievirus(CVB)is one of the leading causative pathogens of viral myocarditis,which primarily affects children and young adults.Due to the lack of vaccines,the development of antiviral medicines is crucial to controlling CVB infection and the progression of myocarditis.In this study,we investigated the antiviral effect of baicalein,a flavonoid extracted from Scutellaria baicaleinsis.Our results demonstrated that baicalein treatment significantly reduced cytopathic effect and increased cell viability in CVB3-infected cells.In addition,significant reductions in viral protein 3D,viral RNA,and viral particles were observed in CVB3-infected cells treated with baicalein.We found that baicalein exerted its inhibitory effect in the early stages of CVB3 infection.Baicalein also suppressed viral replication in the myocardium and effectively alleviated myocarditis induced by CVB3 infection.Our study revealed that baicalein exerts its antiviral effect by inhibiting the activity of caspase-1 and viral protease 2A.Taken together,our findings demonstrate that baicalein has antiviral activity against CVB3 infection and may serve as a potential therapeutic option for the myocarditis caused by enterovirus infection.