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.

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.

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.

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.

Exosomal let-7a-5p derived from human umbilical cord mesenchymal stem cells alleviates coxsackievirus B3-induced cardiomyocyte ferroptosis via the SMAD2/ZFP36 signal axis

Viral myocarditis(VMC)is one of the most common acquired heart diseases in children and teenagers.However,its pathogenesis is still unclear,and effective treatments are lacking.This study aimed to investigate the regulatory pathway by which exosomes alleviate ferroptosis in cardiomyocytes(CMCs)induced by coxsackievirus B3(CVB3).CVB3 was utilized for inducing the VMC mouse model and cellular model.Cardiac echocardiography,left ventricular ejection fraction(LVEF),and left ventricular fractional shortening(LVFS)were implemented to assess the cardiac function.In CVB3-induced VMC mice,cardiac insufficiency was observed,as well as the altered levels of ferroptosis-related indicators(glutathione) peroxidase 4(GPX4),glutathione(GSH),and malondialdehyde(MDA).However,exosomes derived from human umbilical cord mesenchymal stem cells(hucMSCs-exo)could restore the changes caused by CVB3 stimulation.Let-7a-5p was enriched in hucMSCs-exo,and the inhibitory ffect of hucMSCs-exoa-ie-pmimo on CVB3-induced ferroptosis was higher than that of hucMSCs-exommie N(NC:negative control).Mothers against decapentaplegic homolog 2(SMAD2)increased in the VMC group,while the expression of zinc-finger protein 36(ZFP36)decreased.Let-7a-5p was confirmed to interact with SMAD2 messenger RNA(mRNA),and the SMAD2 protein interacted directly with the ZFP36 protein.Silencing SMAD2 and overexpressing ZFP36 inhibited the expression of ferroptosis-related indicators.Meanwhile,the levels of GPX4,solute carrier family 7,member 11(SLC7A11),and GSH were lower in the SMAD2 overexpression plasmid(oe-SMAD2)+let-7a-5p mimic group than in the oe-NC+let-7a-5p mimic group,while those of MDA,reactive oxygen species(ROS),and Fe^(2+)increased.In conclusion,these data showed that ferroptosis could be regulated by mediating SMAD2 expression.Exo-let-7a-5p derived from hucMSCs could mediate SMAD2 to promote the expression of ZFP36,which further inhibited the ferroptosis of CMCs to alleviate CVB3-induced VMC.

Coxsackievirus B3 HFMD animal models in Syrian hamster and rhesus monkey

Coxsackievirus B3(CVB3)is the pathogen causing hand,foot and mouth disease(HFMD),which manifests across a spectrum of clinical severity from mild to severe.However,CVB3-infected mouse models mainly demonstrate viral myocarditis and pancreatitis,failing to replicate human HFMD symptoms.Although several enteroviruses have been evaluated in Syrian hamsters and rhesus monkeys,there is no comprehensive data on CVB3.In this study,we have first tested the susceptibility of Syrian hamsters to CVB3 infection via different routes.The results showed that Syrian hamsters were successfully infected with CVB3 by intraperitoneal injection or nasal drip,leading to nasopharyngeal colonization,acute severe pathological injury,and typical HFMD symptoms.Notably,the nasal drip group exhibited a longer viral excretion cycle and more severe pathological damage.In the subsequent study,rhesus monkeys infected with CVB3 through nasal drips also presented signs of HFMD symptoms,viral excretion,serum antibody conversion,viral nucleic acids and antigens,and the specific organ damages,particularly in the heart.Surprisingly,there were no significant differences in myocardial enzyme levels,and the clinical symptoms resembled those often associated with common,mild infections.In summary,the study successfully developed severe Syrian hamsters and mild rhesus monkey models for CVB3-induced HFMD.These models could serve as a basis for understanding the disease pathogenesis,conducting pre-trial prevention and evaluation,and implementing post-exposure intervention.

Long noncoding RNA 1392 regulates MDA5 by interaction with ELAVL1 to inhibit coxsackievirus B5 infection

Long noncoding RNAs(lncRNAs)modulate many aspects of biological and pathological processes.Recent studies have shown that host lncRNAs participate in the antiviral immune response,but functional lncRNAs in coxsackievirus B5(CVB5)infection remain unknown.Here,we identified a novel cytoplasmic lncRNA,LINC1392,which was highly inducible in CVB5 infected RD cells in a time-and dose-dependent manner,and also can be induced by the viral RNA and IFN-β.Further investigation showed that LINC1392 promoted several important interferon-stimulated genes(ISGs)expression,including IFIT1,IFIT2,and IFITM3 by activating MDA5,thereby inhibiting the replication of CVB5 in vitro.Mechanistically,LINC1392 bound to ELAV like RNA binding protein 1(ELAVL1)and blocked ELAVL1 interaction with MDA5.Functional study revealed that the 245–835 nt locus of LINC1392 exerted the antiviral effect and was also an important site for ELAVL1 binding.In mice,LINC1392 could inhibit CVB5 replication and alleviated the histopathological lesions of intestinal and brain tissues induced by viral infection.Our findings collectively reveal that the novel LINC1392 acts as a positive regulator in the IFN-I signaling pathway against CVB5 infection.Elucidating the underlying mechanisms on how lncRNA regulats the host innate immunity response towards CVB5 infection will lay the foundation for antiviral drug research.

抗柯萨奇病毒B型药物的研究进展

柯萨奇病毒B型(Coxsackieviruses B,CVB)是一种微小、无包膜的单正链RNA病毒,属于小核糖核酸病毒科(Picornaviridae)肠道病毒属(Enterovirus),主要经消化道传播。CVB感染可以引起多种疾病,如手足口病、腹泻、急性心肌炎、无菌性脑膜炎、骨髓炎及出疹性疾病等。此外,CVB感染也是Ⅰ型糖尿病的诱发因素,严重威胁人们健康。目前,越来越多的天然和人工合成化合物以及单克隆抗体等已经被用于CVB感染的治疗,但是高效抗CVB药物仍然缺乏。本文对抗CVB病毒的药物进行综述,以期为CVB的预防、治疗和药物研发提供思路和依据。

Pathogenesis of coxsackievirus B3-induced myocarditis： role of macrophage migration inhibitory factor

Background Macrophage migration inhibitory factor （MIF） is an upstream regulator in immune and inflammatory responses.However,its role in viral myocarditis remains unknown.In this study,we investigated the role of the MIF in coxsackievirus B3 （CVB3）-induced myocarditis.Methods Mice were randomized into two groups receiving either Eagle＇s minimal essential medium （EMEM,control group） or virus solution （infected group）.Subsets of mice in the infected group were sacrificed on days 3,7,14 and 28 after inoculation.Expression of MIF was detected using an enzyme-linked immunosorbent assay （ELISA）,reverse transcription polymerase chain reaction and immunohistochemistry.A neutralizing antibody （Ab） to MIF was injected intraperitoneally from day 0 to 7 after inoculation.Disease severity was estimated by histopathology of the heart and by the heart weight to body weight ratio,and the interleukin-1β （IL-1β） and tumor necrosis factor α （TNF-α） in the myocardium were measured by ELISA on day 14.Results The serum MIF concentration and expression levels of myocardial MIF mRNA and protein were significantly elevated in mice on days 7 and 14 post-infection.The survival rate was markedly higher and disease severity was obviously less in mice treated with anti-MIF Ab.Furthermore,MIF blockade significantly decreased the IL-1β and TNF-α in the myocarditic heart.Conclusion These results demonstrate that MIF is an important naturally occurring inflammatory cytokine in CVB3-induced myocarditis,and anti-MIF Ab may lessen the inflammatory response.

MicroRNA-324-3p Plays A Protective Role Against Coxsackievirus B3-Induced Viral Myocarditis

Viral myocarditis(VM) is an inflammatory disease of the myocardium associated with heart failure, which is caused by common viral infections. A majority of the infections are initiated by coxsackievirus B3(CVB3). Micro RNAs(mi RNAs)have a major role in various biological processes, including gene expression, cell growth, proliferation, and apoptosis, as well as viral infection and antiviral immune responses. Although, mi RNAs have been found to regulate viral infections,their role in CVB3 infection remains poorly understood. In the previous study, mi RNA microarray results showed that mi R-324-3 p expression levels were significantly increased when cells and mice were infected with CVB3. It was also found that miR-324-3p downregulated TRIM27 and decreased CVB3 replication in vitro and in vivo. In vitro, analysis of downstream signaling of TRIM27 revealed that, miR-324-3p inhibited CVB3 infection, and reduced cytopathic effect and viral plaque formation by reducing the expression of TRIM27. In vivo, miR-324-3p decreased the expression of TRIM27,reduced cardiac viral replication and load, thereby strongly attenuating cardiac injury and inflammation. Taken together,this study suggests that miR-324-3p targets TRIM27 to inhibit CVB3 replication and viral load, thereby reducing the cardiac injury associated with VM.

Antiviral Effects of Aqueous Extract from Spatholobus suberectus Dunn.against Coxsackievirus B3 in Mice

Objective： To investigate the antiviral effects of the aqueous extract of Spatholobus suberectus Dunn. （A.E.）, a Chinese medicinal herb, against coxsackievirus B3 （CVB3）. Methods： The antiviral effects of A.E. against CVB3 in vitro （primarily cultured myocardial cells） and in vivo （BALB/c mice） were determined. Serum pharmacological method was also adopted by in vitro experiments. The effects of A.E. inhibiting the CVB3 mRNA expression were compared by RT-PCR in mice in vivo. Results： A.E. exhibited obvious antiviral effects in vivo, and serum samples obtained from the rats with oral administration of A.E. （10 μg/mL, 5 μg/mL） reduced the virus titers in the infected myocardial cells （3.00±0.70, 3.55±0.52, P〈0.01）. Meanwhile, the viral myocarditis induced by CVB3 was inhibited significantly by A.E., and the 15-day mortality was reduced to 40% and 45% （P〈0.01） in mice treated with A.E. at doses of 50 mg/kg and 100 mg/kg, respectively, while the 30-day mortality was decreased to 45% and 50%, respectively （P〈0.01）. Moreover, the mRNA expression of Coxsackie virus B3 was significantly inhibited by A.E. Conclusion： Aqueous extract of Spatho/obus suberectus Dunn. （A.E.） has inhibitory effect on CVB3 both in vitro and in vivo.

Expression Profile and Function Analysis of Long Non-coding RNAs in the Infection of Coxsackievirus B3

The roles of lnc RNAs in the infection of enteroviruses have been barely demonstrated. In this study, we used coxsackievirus B3(CVB3), a typical enterovirus, as a model to investigate the expression profiles and functional roles of lnc RNAs in enterovirus infection. We profiled lnc RNAs and m RNA expression in CVB3-infected He La cells by lnc RNA-m RNA integrated microarrays. As a result, 700 differentially expressed lnc RNAs(431 up-regulated and 269 down-regulated) and665 differentially expressed m RNAs(299 up-regulated and 366 down-regulated) were identified in CVB3 infection. Then we performed lnc RNA-m RNA integrated pathway analysis to identify potential functional impacts of the differentially expressed m RNAs, in which lnc RNA-m RNA correlation network was built. According to lnc RNA-m RNA correlation, we found that XLOC-001188, an lnc RNA down-regulated in CVB3 infection, was negatively correlated with NFAT5 m RNA,an anti-CVB3 gene reported previously. This interaction was supported by q PCR detection following si RNA-mediated knockdown of XLOC-001188, which showed an increase of NFAT5 m RNA and a reduction of CVB3 genomic RNA. In addition, we observed that four most significantly altered lnc RNAs, SNHG11, RP11-145 F16.2, RP11-1023 L17.1 and RP11-1021 N1.2 share several common correlated genes critical for CVB3 infection, such as BRE and IRF2 BP1. In all, our studies reveal the alteration of lnc RNA expression in CVB3 infection and its potential influence on CVB3 replication,providing useful information for future studies of enterovirus infection.

Stress Granule Formation is One of the Early Antiviral Mechanisms for Host Cells Against Coxsackievirus B Infection

Stress granules(SGs) are intracellular granules formed when cellular translation is blocked and have been reported to be involved in a variety of viral infections. Our previous studies revealed that SGs are involved in the coxsackievirus B(CVB)infection process, but the role of SGs in CVB infection has not been fully explored. In this study, we found that CVB type 3(CVB3) could induce SG formation in the early phase of infection. Results showed that levels of CVB3 RNA and protein were significantly inhibited during the early stage of CVB3 infection by the elevated formation of SGs, while viral RNA and protein synthesis were significantly promoted when SG formation was blocked. Our findings suggest that SG formation is one of the early antiviral mechanisms for host cells against CVB infection.

Development of A Neonatal Mouse Model for Coxsackievirus B1 Antiviral Evaluation

Coxsackievirus B1(CVB1) is a leading causative agent of severe infectious diseases in humans and has been reported to be associated with outbreaks of aseptic meningitis, myocarditis, and the development of chronic diseases such as type 1 diabetes mellitus(T1DM). There is no approved vaccine or effective antiviral therapy to treat CBV1 infection. And animal models to assess the effects of antiviral agents and vaccine remain limited. In this study, we established a neonatal mouse model of CVB1 using a clinically isolated strain to characterize the pathological manifestations of virus infection and to promote the development of vaccines and antiviral drugs against CVB1. One-day-old BALB/c mice were susceptible to CVB1 infection by intraperitoneal injection. Mice challenged with CVB1 at a low dose [10 median tissue culture infective dose(TCID_(50))] exhibited a series of clinical symptoms, such as inactivity, emaciation, limb weakness, hair thinning,hunching and even death. Pathological examination and tissue viral load analysis showed that positive signals of CVB1 were detected in the heart, spinal cord, limb muscle and kidney without pathological damage. Particularly, CVB1 had a strong tropism towards the pancreas, causing severe cellular necrosis with inflammatory infiltration, and was spread by viraemia. Notably, the monoclonal antibody(mAb) 6H5 and antisera elicited from CVB1-vaccinated mice effectively protected the mice from CVB1 infection in the mouse model. In summary, the established neonatal mouse model is an effective tool for evaluating the efficacy of CVB1 antiviral reagents and vaccines.

The effect of astragalus membranaceus in combination with taurine on coxsackievirus B3 murine myocarditis

Objective To evaluate the effect of astragalus membranaceus (AM) in combination with taurine on coxasckievirus B3 (CVB3) murine myocarditis. Methods One hundred and sixty mice were infected with CVB3 and equally divided into four groups: normal saline (NS) treated group, AM treated group, taurine treated group and AM combined with taurine treated group. The treatment were carried out from day 1 to 7 after infection. Ten mice were extracted from each group for observing mortality within day 21 postinfection, the rests were killed and the hearts were removed on day 8 (n=15) and 21 (all survival mice), respectively. Electrocardiograph (ECG) of each mouse was analysed before infection and repeated on the day of being killed. CVB3 RNA in murine myocardium was detected by in situ hybridization and myocardial lesions were observed by light microscope. Results Mortality was lower in drug treated groups than that in NS treated group, and it was the lowest in AM combined with taurine treated group, but all the differences were not significant (P>0.05). All drug treatments reduced the incidence of abnormal ECG changes in the acute phase of infection (P<0.05, vs NS treated group), but AM combined with taurine was the most effective in reducing the incidence of abnormal ECG (P<0.05, vs other groups). AM inhibited viral replication in myocardium at the early and late stage of murine myocarditis effectively and AM combined with taurine enhanced the effect of anti virus. All drugs decreased myocardial damage (P<0.05, vs control group), and the effect of AM combined with taurine was most significant (P<0.05). Conculsion The AM combined with taurine on CVB3 murine myocarditis is more effective than that of AM or taurine.

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.

柯萨奇病毒B组3型VP1基因真核表达重组质粒的构建及免疫效果

目的构建柯萨奇病毒B组 3型 (CoxsackievirusesgroupB3,CVB3)VP1基因的真核表达重组质粒pcDNA3/VP1,并观察它对小鼠的免疫保护作用。方法从CVB3感染细胞中扩增出VP1片段 ,构建真核表达重组质粒 pcDNA3/VP1,经大量扩增纯化后 ,肌内注射免疫BALB/c小鼠 ,每次免疫后的第 6天 ,断尾取血检测CVB3中和抗体 ;3次免疫后用致死量 (10 0 0TCID50 )的CVB3感染小鼠 ,观察 pcDNA/VP1对小鼠的免疫保护作用。 结果pcDNA3/VP1重组质粒免疫小鼠后 ,能诱导机体产生中和抗体 ,各次免疫后抗体滴度分别为 <1∶5 ,1∶5 .7和1∶34.8;用致死量CVB3感染小鼠 ,pcDNA3/VP1重组质粒免疫组、pcDNA3质粒对照组及生理盐水对照组生存率分别为 30 %、2 0 %及 15 % ,3组小鼠生存率无明显差异 (P >0 .0 5 )。结论 pcDNA3/VP1重组质粒在小鼠体内能够表达并能诱导机体产生中和抗体 ,抗体滴度随免疫次数增加 。

柯萨奇B_(3m)病毒感染Balb/c鼠接种浓度的研究

通过柯萨奇Ｂ３ｍ病毒（ＣＶＢ３ｍ）接种Ｂａｌｂ／ｃ鼠浓度的研究，探索其与ＣＶＢ３ｍ的ＬＤ５０、血清抗体、病毒分离和脏器病理变化之间的关系，以获得产生明确病毒标志的最合适病毒接种浓度来筛选抗病毒性心肌炎药物。结果表明：有规律的病毒标志为小鼠的死亡率、中和抗体水平和病毒血症，腹腔接种１ＬＤ５０可使小鼠于第５天血清中和抗体效价≥１∶１６０～１∶３２０，并有病毒血症，第９天病毒血症消失，小鼠开始死亡。表明此接种浓度可出现有利于药物筛选的病毒标志。