Nested polymerase chain reaction for high-sensitivity detection of enteroviral RNA in biological samples

A method based on nested polymerase chain reaction was developed for the detection of enteroviral genomes in biological samples. By taking advantage of the conserved 5' noncoding region of the enteroviral RNA, two sets of primers were utilized, enabling the detection either of a broad range of enteroviruses or of group B coxsackieviruses only. The sensitivity of the method is close to the detection of single molecules of viral RNA in as much as 1 mg of tissue sample. A preliminary study showed the usefulness of this technique for the analysis of endomyocardial biopsy samples from patients with idiopathic dilated cardiomyopathy and myocarditis.

Cytolytic cross-reactive antibodies directed against the cardiac membrane and viral proteins in coxsackievirus B3 and B4 myocarditis. Characterization and pathogenetic relevance

BACKGROUND

Coxsackievirus B3 and B4 (CVB) myocarditis was assessed by a more than twofold change in titer of the microneutralization tests against enteroviruses within 3 weeks in all patients, by an endomyocardial biopsy indicative of active myocarditis in eight cases, and by pericardial effusion and acute cardiomegaly in two patients. In all endomyocardial biopsies, immunoglobulin binding to the sarcolemma and to the interstitial tissue was demonstrated irrespective of an infiltrate being at the same focus or not. IgG binding was found in nine, IgM and IgA in seven, C3 in C1q in three, and C5b9 in three of 10 patients. In addition, circulating antimyolemmal antibodies (AMLAs) were demonstrated regularly.

METHODS AND RESULTS

In this study, for the first time adult human myocytes isolated from atrial appendages during open-heart surgery were used as antigen in the indirect immunofluorescence test: nine of 10 sera of patients with CVB myocarditis demonstrated AMLAs of the homologous type in titers of 1:40-1:320, whereas eight of 10 reacted with rat myocytes (heterologous type) only. Circulating AMLAs fixed complement component C4 in the majority of cases. During the in vitro assay of antibody-mediated cytolysis with vital heart cells, fixation of components C3, C4 to the myolemma in all, of C1q in seven, and of the C3b9 complex in eight of 10 sera was demonstrated after addition of a fresh complement source, indicating the potential of a complement-mediated cytolysis being operative. In vitro cardiocytolysis of isolated adult rat heart cells is present in the untreated sera of patients with enteroviral myocarditis and is abolished after adsorption of sera with CVB and with isolated rat heart cells. This indicates functional cross-reactivity of the antimembrane antibodies. To analyze further the cross-reactive epitopes, sodium dodecyl sulfate gel electrophoresis of human and rat sarcolemma and consecutive immunoblots were performed. Cross-reactivity between viral (CVB) and sarcolemmal epitopes could be demonstrated to bands of 220 kd in 10%, 110 kd in 50%, 48 kd in 40%, 35 kd in 40%, and 31 and 28 kd in 30% each. Cardiospecific non-cross-reactive epitopes for antisarcolemmal antibodies or AMLAs were membrane proteins of 90 kd and 78 kd in 50%, 72 kd in 90%, 67 kd in 40%, and 45 kd in 50%. Virus-specific antibody binding sites for sera included proteins of 33 and 34 kd.

CONCLUSIONS

Western blot analysis of sera incubated with cardiac membranes or enteroviral proteins demonstrated that the antibodies are directed to defined epitopes of the sarcolemma. Some antibodies were cross-reactive to enteroviral proteins, indicating that enteroviral infection may be the etiological trigger of an autoreactive myocarditis. The cytolytic property of the patients' sera in vitro suggests in addition that humoral autoreactivity and antigenic mimicry are major pathogenetic principles operative in human enteroviral myocarditis and its sequelae.

Demonstration of Coxsackie virus RNA in formalin-fixed tissue sections from childhood myocarditis cases by in situ hybridization and the polymerase chain reaction

This is a combined study using in situ hybridization and the polymerase chain reaction to investigate the presence of Coxsackie virus RNA in formalin-fixed tissue from cases of childhood myocarditis. Of the ten cases studied, two were positive by both methods. The virus RNA was predominantly located in areas showing an inflammatory cell infiltrate and myofibre necrosis. These findings suggest that direct lytic infection of myocytes by virus is responsible for myocarditis in these cases, rather than an autoimmune process, which has been suggested previously. The findings in one case, where the virus showed a marked sub-endocardial distribution, may have implications for the aetiology of endocardial fibroelastosis by confirming a viral tropism for this location. The techniques used in this study are easily repeatable and can be directly applied to look for viruses in a number of other diseases where a viral aetiology is suspected.

Evidence of perforin-mediated cardiac myocyte injury in acute murine myocarditis caused by Coxsackie virus B3

We have recently demonstrated that killer cells expressing a cytolytic factor, perforin, infiltrate the hearts of mice with acute viral myocarditis and may play an important role in the mechanism of myocardial damage. To clarify the mechanism of in vivo cardiac myocyte injury mediated by perforin, we investigated the release of perforin molecules from killer cells by immunoelectron microscopy and examined the circular lesions formed by perforin on the membrane of cardiac myocytes. We found that there was massive release of perforin molecules from the killer cells directly onto the surface of the cardiac myocytes. Furthermore, electron microscopy of ultrathin ventricular sections treated with trypsin revealed numerous circular lesions with the characteristics of perforin pores, in the membranes of cardiac myocytes. These findings provide the first direct evidence that killer cells injure cardiac myocytes by releasing perforin and may play a critical role in the myocardial damage occurring in acute viral myocarditis.

[Acute severe coxsackie virus B myocarditis of pseudonecrotic form. Apropos of 2 cases]

This study reports two cases of acute severe Coxsackie virus B4 myocarditis in which the immediate clinical signs suggested the acute phase of myocardial infarction, apparently antero-lateral in the first case in a context of cardiogenic shock and infero-lateral in the second case, in the context of acute pulmonary edema. Both cases were characterized by the severity of the initial signs. Numerous other cases of acute Coxsackie virus B myocarditis, simulating myocardial infarction, have been reported in the literature and these contexts deserve to be recognized earlier as they call for specific treatment. The immediate outcome was favorable in both cases but required massive cardiological intensive care in the first patient. Long term follow-up was excellent.

Studies of virus-induced myocardial injury in mice: value of the scid mutation on different genetic backgrounds and combined with other mutations

The mechanism of cardiac muscle damage in virus-induced myocarditis remains to be fully understood. In particular, a direct role for viral replication has been obscured by evidence of immune-mediated injury. The combined use of severe combined immunodeficient (scid) and doubly mutant scid/beige mice of different genetic backgrounds has provided a unique opportunity to study the consequences of viral proliferation apart from the influence of immunologic responses. In these immunodeficient animals, inoculation with coxsackievirus B3 caused severe myocardial injury, indicating a profound and direct pathogenic potential of viral infection. These studies, in turn, serve to illustrate the value of the scid mutation in experimental biology, as defined among different genetic backgrounds and combined with other mutations.

Expression of intercellular adhesion molecule-1 in murine hearts with acute myocarditis caused by coxsackievirus B3

A cell-mediated autoimmune mechanism has been strongly implicated in the pathogenesis of viral myocarditis. Using a murine model of myocarditis caused by coxsackievirus B3 (CVB3), we previously reported that the heart is infiltrated first by natural killer cells, which express a cytolytic factor, perforin, and then by activated T cells. This action may play an important role in the pathogenesis of the observed myocardial cell damage. Cell-cell contact and adhesion is required in immune responses, and intercellular adhesion molecule-1 (ICAM-1), which is a ligand for lymphocyte function-associated antigen-1 (LFA-1), plays an important role in this process. To investigate the essential role of the ICAM-1/LFA-1 pathway in the cell-mediated cytotoxicity involved in viral myocarditis, we examined by immunofluorescence the expression of ICAM-1 in murine hearts with acute myocarditis caused by CVB3. We also evaluated the induction of ICAM-1 in cultured cardiac myocytes treated with cytokines by immunofluorescence and Northern blot hybridization. Furthermore, we analyzed the effects of in vivo administration of anti-ICAM-1 mAbs on the inflammation associated with acute viral myocarditis. We found that CVB3-induced murine acute myocarditis resulted in enhanced expression of ICAM-1 in myocardial cells. The expression of ICAM-1 in myocardial cells could be induced in vitro by IFN-gamma and TNF-alpha, which were shown to be synthesized by the infiltrating cells. In vivo treatment with F(ab')2 fragments of an anti-ICAM-1 mAb significantly reduced the myocardial inflammation induced by CVB3. These data strongly suggest that the expression of ICAM-1 in myocardial cells plays a critical role in the cell-mediated cytotoxicity involved in acute viral myocarditis.

Myocardial fibrin deposition in experimental viral myocarditis that progresses to dilated cardiomyopathy

Myocardial fibrosis is a characteristic late feature in cases of viral myocarditis that progress to dilated cardiomyopathy. However, the pathogenesis of the myocardial fibrosis in such cases is unknown. Prior studies have shown that in healing wounds and tumor stroma generation, interstitial fibrin deposition precedes the development of fibrosis. Therefore, interstitial fibrin deposition in the myocardium was investigated in a murine model of myocarditis in which dilated cardiomyopathy develops. Inbred male C3H/He mice inoculated with coxsackievirus B3 were killed 0, 3, 7, 14, 21, 30, and 60 days after infection. Paraffin sections of hearts were stained with hematoxylin-eosin, Masson's trichrome stain, and antibodies to fibrinogen/fibrin by use of an immunoperoxidase technique. Pretreatment of all mice with anticoagulants and antifibrinolytics 5 minutes before death was used to prevent artifactual fibrin deposition and fibrinolysis during tissue manipulation. Tissue fixation in formalin supplemented with acetic acid served to extract non-cross-linked fibrin, fibrinogen, and fibrinogen and fibrin degradation products, thus ensuring that clotted and cross-linked fibrin was the major immunoreactant. Myocardial fibrin deposition and fibrosis were each quantitated by computer-assisted image analysis. Myocardial fibrin deposition first appeared on day 3, was maximal on day 14, and disappeared by day 30. Conversely, myocardial fibrosis was not detectable until day 14 and was maximal at day 60. Thus, as in healing wounds and developing tumor stroma, fibrin deposition preceded fibrosis in this murine model of myocarditis that progresses to dilated cardiomyopathy.

Antigenic analysis of coxsackievirus B3 with monoclonal antibodies

All the 16 mouse monoclonal antibodies (McAbs) raised against Nancy strain of coxsackievirus B3, CoxB3(N), were type 3-specific. The reactivity of CoxB3(N) to this McAb panel during the serial passages showed a variation. Three field isolates of CoxB3, all neutralizable with the reference Anti-CoxB3 hyperimmune serum, were checked for the reactivities with the McAb panel. The isolates from the patients in Fujiang reacted with 12 McAbs and variably with the remaining four McAbs. On the basis of the reactivities with different virus strains, the McAbs were found to fall into four groups possibly corresponding to at least four epitopes. A considerable antigenic variation of CoxB3 was thus suggested.

[Lyme carditis]

Lyme borreliosis, a systemic disease, described as a new nosological unit as late as in 1976, has called for special attention in particular during the past few years. The author concentrated his attention on affection of the heart, and based on analysis of many publications in the world literature, he submits a review on Lyme carditis which comprises the clinical picture, diagnostic possibilities and treatment. In the conclusion he indicates possible ways how to investigate the disease the course and prognosis of which are the subject of open discussion.

Electrophysiological and pathological observations on experimental coxsackie B-3 viral myocarditis in mice

Electrophysiological action of right ventricular myocardium examined by standard intracellular microelectrode technique and real-time microcomputer data processor system and histological and ultrastructural changes of myocardium in BALB/c mice infected with coxsackie B-3 virus from 3 days to 9 months were observed. It was found that electrophysiologic parameters of action potential changed very quickly at the early stage (3 days to 1 month) of the disease. Those abnormalities became most apparent by the 5-30th day, and 7 patterns of abnormal action potential occurred frequently within the same period. These changes were basically parallel to the myocardial lesions. At the late stage (3-9 months) the electrophysiological parameters were nearly normal, while the myocardial lesions decreased gradually. However, the abnormal patterns of action potential were still detected, even though they were improved gradually. The results suggest that myocardial damages caused by viral infection may lead to changes of cardiac electric action, which may be one of the factors in arrhythmias in the episode of viral myocarditis.

Enhancement of coxsackievirus B3 myocarditis in mice by lobenzarit disodium through inhibition of splenic pan T cells

OBJECTIVE

The aim was to test the efficacy of the immune system modulator lobenzarit disodium in the treatment of coxsackievirus B3 myocarditis.

METHODS

Two week old C3H/He mice were inoculated with 10(3) plaque forming units of coxsackievirus B3. Lobenzarit disodium, 25 mg.kg-1.d-1, was given subcutaneously daily on days 0-14 (experiment I; group 2) and days 14-28 (experiment II; group 4). Both treated groups were compared to infected controls for each experiment (groups 1 and 3). For the analysis of splenic lymphocyte subsets, additional mice in untreated and treated groups were killed on d 7, and the percentages of Thy 1.2 (CD3), L3T4 (CD4), Ly 2 (CD8) subsets were analysed by laser flow cytometry (experiment III).

RESULTS

In experiment I, the survival rate in the lobenzarit treated group was significantly lower than in the controls (2/11 v 8/11). Cellular infiltration and myocardial necrosis in the lobenzarit group were more severe. Myocardial virus titres and serum neutralising antibody titres did not differ significantly between the two groups. In experiment II, the survival rate (7/9 v 13/13) and cardiac pathology between the two groups did not differ significantly. In experiment III, the percentage of the Thy 1.2 subset (CD3) in the treated group was significantly lower (p < 0.05) than in the control group, at 36.0(SD 2.9)% v 42.8(5.8)%.

CONCLUSIONS

Lobenzarit disodium decreased splenic pan T cells and aggravated both clinical course and cardiac pathology in acute murine coxsackievirus B3 myocarditis.

[Virus and dilated cardiomyopathies]

Dilated cardiomyopathy is so called when an etiological investigation is negative and no cause can be found for ventricular dilatation-hypokinesia. Current research points to genetic, immunological and infectious factors, often associated, and the passage of subclinical viral myocarditis to chronic disease. There is a lot of evidence in favour of this hypothesis. In the experimental model, the relationship between viral myocarditis and dilated cardiomyopathy has been demonstrated with, as cofactors, a genetic predisposition and an immunitary deficiency leading to an auto-immune subacute myocarditis. In the clinical setting, the enterovirus with a high cardiac tropism seems to play an epidemiological role in the genesis of dilated cardiomyopathy. The concentrations of neutralising anti-coxsackie B virus antibodies is higher in subjects with dilated cardiomyopathy than in a control population. The frequency of lymphocytic infiltration, a marker of dysimmunitary myocarditis, is variable from study to study but the presence of sequences of enterovirus genome in the myocardium could explain slow replication of the virus progressively destroying the myocytes. Techniques of molecular hybridization with or without prior genic amplification by the "Polymerase Chain Reaction" have demonstrated such sequences of specific enterovirus genome but discordant results require further studies.

T lymphocyte responses in CVB3-induced murine myocarditis

Three monoclonal antibodies (mAB) to group A streptococcus M5 serotype (mAB 36.2.2, 49.8.9 and 54.2.8) cross-reactivity bind to various heart antigens (including myosin, tropomyosin and vimentin) and neutralize a myocarditic variant of coxsackievirus B-3 (Nancy) (CVB3). The existence of shared antigenic epitopes between the two distinct infectious agents and the heart implies that antigenic mimicry may form the foundation of the autoimmune response. Plaque purified variants of CVB3 were isolated with these streptococcal mAB. The wild-type virus (H3) and the virus variants made with mABs 36.2.2 (H3-36) and 54.2.8 (H3-54) caused significant myocarditis in Balb/c (H-2d) mice, but not in CBA (H-2k) animals. The virus variant made with mAB 49.8.9 (H3-49) caused myocarditis in CBA, but not in Balb/c mice. No significant differences in virus concentrations in the heart were detected with any of the virus variants. Cytolytic activity of mesenteric lymph node cells generally correlated to the severity of myocarditis in the infected animals. Using overlapping synthetic peptides of the CVB3 VP1 protein, mAB 49.8.9 was shown to bind preferentially peptides 6, 8, 11, and 12. T lymphocytes from H3 infected mice proliferated to VP1 peptides 1, 3, 9, 13, 14, and 21. To determine whether immunity to specific peptides could affect CVB3 pathogenicity, Balb/c mice were immunized with VP1 peptides 1, 3, 6, 13, 14 and 21 in complete Freund's adjuvant (CFA) then infected with 5 x 10(4) PFU CVB3 14 days later. Pre-immunization of animals with (a) peptide 1 resulted in a significant decrease in virus titers in the heart, (b) peptides 3, 13 and 21 increased animal mortality and lymphocyte mediated cytotoxicity to uninfected cardiocyte targets, and (c) peptides 3 and 21 resulted in significant increases in myocarditis compared to animals given virus without pre-immunization.

[Antibodies to pathogens of Lyme's disease in patients with myocarditis and dilated cardiomyopathy]

The paper presents the information on the involvement of the cardiovascular system in the patients with Lyme's disease as well as the results of serological investigation in patients with myocarditis and dilatation cardiomyopathy for the presence of antibodies to the causative agent of Lyme's disease with the aid of enzyme immunoassay. Out of 71 sera 3 specimens had the values of optical density higher than the upper normal limits. Based on the investigation conducted and the analysis of the clinical picture, the authors suspected a Borrelia origin of these cardiac involvements. However, to verify the diagnosis morphological examination of endomyocardiac biopsy specimens was found to be mandatory.

Cytomegalovirus associated inflammatory heart muscle disease

Cytomegaloviruses(CMV) belong to a group of cardiotropic DNA-viruses with well-documented but sporadic cardiac involvement. By in situ hybridization with a biotinylated cDNA probe CMV-DNA was analysed in 2 different series of patients(1982-1988; 1989-1991) in the endomyocardial biopsy specimens of 35 patients with active myocarditis as defined by the Dallas criteria, and of 35 patients with acute perimyocarditis (pericardial effusion and cardiomegaly or segmental wall motion abnormality and/or an endomyocardial biopsy positive for active myocarditis) were analysed. 51% of patients with active myocarditis, 65% positive findings were observed in patients with perimyocarditis when all positive signals in the myocardium were taken into account. Since in interstitial cells and the vascular endothelium HCMV-DNA was also detected in controls we conclude that only HCMV-DNA in the nuclei are specific for HCMV-associated myocarditis. The incidence of positive signals in the myocytes was lower: 14% of all myocarditis patients and 8.5% of all pericarditis patients demonstrated this pattern. The results from in situ hybridization were compared to circulating anti-CMV antibodies from by an ELISA. As possible predisposing immunologic factors or associated alterations of effector functions we found a shift from normal to reduced natural killer cell activity and a marginal increase in B- and activated T-cells in the peripheral blood.

Pneumonia, myocarditis and reactive arthritis due to Chlamydia pneumoniae

A 37 year old HLA B27 negative man developed erythema nodosum, pneumonia, myocarditis and oligoarthritis due to Chlamydia pneumoniae. He recovered completely over a four month period. This is the first clinical description of reactive arthritis caused by C. pneumoniae.