Localization of enteroviral antigen in myocardium and other tissues from patients with heart muscle disease by an improved immunohistochemical technique

Bioinformatics and immunoinformatics approach to develop potent multi-peptide vaccine for coxsackievirus B3 capable of eliciting cellular and humoral immune response

Coxsackievirus B3 (CVB3) is a viral pathogen of various human disorders with no effective preventative interventions. Herein, we aimed to design a chimeric vaccine construct for CVB3 using reverse vaccinology and immunoinformatics approaches by screening the whole viral polyprotein sequence. Firstly, screening and mapping of viral polyprotein to predict 21 immunodominant epitopes (B-cell, CD8+ and CD4+ T-cell epitopes), fused with an adjuvant (Resuscitation-promoting factor), appropriate linkers, HIV-TAT peptide, Pan DR epitope, and 6His-tag to assemble a multi-epitope vaccine construct. The chimeric construct is predicted as probable antigen, non-allergen, stable, possess encouraging physicochemical features, and indicates a broader population coverage (98 %). The tertiary structure of the constructed vaccine was predicted and refined, and its interaction with the Toll-like receptor 4 (TLR4) was investigated through molecular docking and dynamics simulation. Computational cloning of the construct was carried out in pET28a (+) plasmid to guarantee the higher expression of the vaccine protein. Lastly, in silico immune simulation foreseen that humoral and cellular immune responses would be elicited in response to the administration of such a potent chimeric construct. Thus, the design constructed could vaccinate against CVB3 infection and various CVB serotypes. However, further in vitro/in vivo research must assess its safety and effectiveness.

Designing a multi-epitope vaccine against coxsackievirus B based on immunoinformatics approaches

Coxsackievirus B (CVB) is one of the major viral pathogens of human myocarditis and cardiomyopathy without any effective preventive measures; therefore, it is necessary to develop a safe and efficacious vaccine against CVB. Immunoinformatics methods are both economical and convenient as in-silico simulations can shorten the development time. Herein, we design a novel multi-epitope vaccine for the prevention of CVB by using immunoinformatics methods. With the help of advanced immunoinformatics approaches, we predicted different B-cell, cytotoxic T lymphocyte (CTL), and helper T lymphocyte (HTL) epitopes, respectively. Subsequently, we constructed the multi-epitope vaccine by fusing all conserved epitopes with appropriate linkers and adjuvants. The final vaccine was found to be antigenic, non-allergenic, and stable. The 3D structure of the vaccine was then predicted, refined, and evaluated. Molecular docking and dynamics simulation were performed to reveal the interactions between the vaccine with the immune receptors MHC-I, MHC-II, TLR3, and TLR4. Finally, to ensure the complete expression of the vaccine protein, the sequence of the designed vaccine was optimized and further performed in-silico cloning. In conclusion, the molecule designed in this study could be considered a potential vaccine against CVB infection and needed further experiments to evaluate its safety and efficacy.

Immunohistochemical diagnosis of human infectious diseases: a review

BACKGROUND

Immunohistochemistry (IHC) using monoclonal and polyclonal antibodies is a useful diagnostic method for detecting pathogen antigens in fixed tissues, complementing the direct diagnosis of infectious diseases by PCR and culture on fresh tissues. It was first implemented in a seminal publication by Albert Coons in 1941.

MAIN BODY

Of 14,198 publications retrieved from the PubMed, Google, Google Scholar and Science Direct databases up to December 2021, 230 were selected for a review of IHC techniques, protocols and results. The methodological evolutions of IHC and its application to the diagnosis of infectious diseases, more specifically lice-borne diseases, sexually transmitted diseases and skin infections, were critically examined. A total of 59 different pathogens have been detected once in 22 different tissues and organs; and yet non-cultured, fastidious and intracellular pathogens accounted for the vast majority of pathogens detected by IHC. Auto-IHC, incorporating patient serum as the primary antibody, applied to diseased heart valves surgically collected from blood culture-negative endocarditis patients, detected unidentified Gram-positive cocci and microorganisms which were subsequently identified as Coxiella burnetii, Bartonella quintana, Bartonella henselae and Tropheryma whipplei. The application of IHC to ancient tissues dated between the ends of the Ptolemaic period to over 70 years ago, have also contributed to paleomicrobiology diagnoses.

CONCLUSION

IHC plays an important role in diagnostic of infectious diseases in tissue samples. Paleo-auto-IHC derived from auto-IHC, is under development for detecting non-identified pathogens from ancient specimens.

An Albumin-Binding Domain Peptide Confers Enhanced Immunoprotection Against Viral Myocarditis by CVB3 VP1 Vaccine

Coxsackievirus B3 (CVB3)-induced viral myocarditis is a common clinical cardiovascular disease without effective available vaccine. In this study, we tried to potentiate the immunoprotection efficacy of our previous CVB3-specific VP1 protein vaccine by introducing a streptococcal protein G-derived, draining lymph nodes (dLNs)-targeting albumin-binding domain (ABD) peptide. We found that compared with the original VP1 vaccine, ABD-fused VP1 (ABD-VP1) vaccine gained the new ability to efficiently bind murine albumin both in vitro and in vivo, possessed a much longer serum half-life in serum and exhibited more abundance in the dLNs after immunization. Accordingly, ABD-VP1 immunization not only significantly facilitated the enrichment and maturation of dendritic cells (DCs), induced higher percentages of IFN-γ+ CD8 + cells in the dLNs, but also robustly promoted VP1-induced T cell proliferation and cytotoxic T lymphocyte (CTL) responses in the spleens. More importantly, ABD-VP1 also elicited higher percentages of protective CD44hi CD62Lhi memory T cells in dLNs and spleens. Consequently, obvious protective effect against viral myocarditis was conferred by ABD-VP1 vaccine compared to the VP1 vaccine, reflected by the less body weight loss, improved cardiac function, alleviated cardiac histomorphological changes and an increased 28-day survival rate. Our results indicated that the ABD might be a promising immune-enhancing regime for vaccine design and development.

Steatosis induced CCL5 contributes to early-stage liver fibrosis in nonalcoholic fatty liver disease progress

The rapidly increasing prevalence of nonalcoholic fatty liver disease (NAFLD) has become one of the major public health threats in China and worldwide. However, during the development of NAFLD, the key mechanism underlying the progression of related fibrosis remains unclear, which greatly impedes the development of optimal NAFLD therapy. In the current study, we were endeavored to characterize a proinflammatory cytokine, CCL5, as a major contributor for fibrosis in NAFLD. The results showed that CCL5 was highly expressed in fatty liver and NASH patients. In NAFLD rats induced by 8-week-HFD, CCL5 and its receptor, CCR5, were significantly up-regulated and liver fibrosis exclusively occurred in this group. In addition, we showed that hepatocytes are the major source contributing to this CCL5 elevation. Interestingly, a CCL5 inhibitor Met-CCL5, significantly decreased liver fibrosis but not hepatic steatosis. Using a cell model of hepatic steatosis, we found that the conditioned medium of lipid-overloaded hepatocytes (Fa2N-4 cells) which produced excessive CCL5 stimulated the profibrotic activities of hepatic stellate cells (LX-2) as manifested by increased migration rate, proliferation and collagen production of LX-2 cells. CCL5 knockdown in Fa2N-4 cells, Met-CCL5 or CCR5 antibody treatment on LX-2 cells all significantly inhibited the conditioned medium of FFA-treated Fa2N-4 cells to exert stimulatory effects on LX-2 cells. Consistently, the conditioned medium of Fa2N-4 cells with CCL5 over-expression significantly enhanced migration rate, cell proliferation and collagen production of LX-2 cells. All these results support that CCL5 produced by steatotic hepatocytes plays an essential role in fibrotic signaling machinery of NAFLD. In addition, we were able to identify C/EBP-β as the up-stream regulator of CCL5 gene transcription in hepatocytes treated with free fatty acid (FFA). Our data strongly supported that CCL5 plays a pivotal regulatory role in hepatic fibrosis during NAFLD, which constitutes a novel and exciting observation that may call for potential future development of specific CCL5-targeted NAFLD therapy.

Coxsackievirus B heart infections and their putative contribution to sudden unexpected death: An 8-year review of patients and victims in the coastal region of Tunisia

Coxsackieviruses B (CV B) are known as the most common viral cause of human heart infections. Cardiac inflammations contribute to sudden unexpected death (SUD) significantly. The diagnosis remains difficult with the traditional diagnostic tests and must be substantially improved. This has prompted health professionals to seek new diagnostic procedures which may provide important clues regarding underlying etiology. The present study is based on patients with infectious heart diseases and SUD victims with no relevant pathologies. They were investigated for possible CV-B infection. Patients with coronary artery diseases and unnatural road and domestic accident victims served as controls. The samples were studied for CV-B applying PCR. Histopathology for inflammatory markers, immunohistochemistry (IHC) for immune inflammatory cells and the enteroviral VP1-capsid protein were performed. Overall, 102 patients and 87 SUD victims were studied. As controls, 100 patients and 54 SUD unnatural accident victims were enrolled. CV-B were detected in 28 patients and 15 SUD victims. The control group samples were completely virus negative. Compared to controls, IHC revealed a significant presence of T and B lymphocytes within the myocardium. Furthermore, enteroviral VP1-capsid protein were detected from samples by IHC. Applying a comprehensive combination of methods, our results demonstrate the involvement of CV-B in cases of heart infection suggesting they play a significant role in SUD. Our results emphasize the importance of opting for a combination of methods.

Properties of Two Enterovirus Antibodies that are Utilized in Diabetes Research

Human enteroviruses (EVs) comprise >100 different types. Research suggests a non-chance association between EV infections and type 1 diabetes. Immunohistochemical studies with the anti-EV antibody 5D-8.1 have shown that the EV capsid antigen is present in pancreatic islet cells of diabetic subjects. When it was noticed that 5D-8.1 may cross-react with human proteins, doubt was casted on the significance of the above histopathologic findings. To address this issue, properties of EV antibodies 5D-8.1 and 9D5 have been investigated using peptide microarrays, peptide substitution scanning, immunofluorescence of EV-infected cells, EV neutralization assays, bioinformatics analysis. Evidence indicates that the two antibodies bind to distinct non-neutralizing linear epitopes in VP1 and are specific for a vast spectrum of EV types (not for other human viruses). However, their epitopes may align with a few human proteins at low expected values. When tested by immunofluorescence, high concentrations of 5D-8.1 yelded faint cytoplasmic staining in uninfected cells. At reduced concentrations, both antibodies produced dotted staining only in the cytoplasm of infected cells and recognized both acute and persistent EV infection. Thus, the two monoclonals represent distinct and independent probes for hunting EVs in tissues of patients with diabetes or other endocrine conditions.

Postmortem diagnosis of infectious heart diseases: A mystifying cause of Sudden Infant Death

Sudden infant death (SID) is an unresolved problem of high relevance and previous studies have indicated a role of viral heart infections. The diagnosis remains difficult in clinical practice using routine diagnostic tests and must be substantially improved. A prospective study based on post-mortem samples from SID victims whose heart disease was not clinically recognized was conducted for 4 years in a Tunisian University Hospital. Pediatric cases of unnatural death served as controls. Both SID victims and controls were investigated for possible coxsackievirus-B (CV-B) infection in heart tissue. During the study period, 39 cases with a male predominance (77%) were reported. There was no positive family history of coronary artery disease among the victims. In 35 cases (90%), low birth weight and/or critical development period were reported. All SID victims had complained of mild fever and insomnia for a few days preceding death, which required infectious laboratory investigations marked with an elevated white blood cell count (WBC) and C-reactive protein (CRP). The cardiac biomarkers were also elevated. The histopathological investigations of the heart tissue samples revealed signs of myocardial and pericardial inflammation. Enterovirus was detected by immunohistochemistry (IHC) and PCR from myocardial samples from 6 cases (15.3%) having myocarditis and 3 cases (7.7%) having perimyocarditis. The current study is of great interest and is aimed at urging health professionals to adopt systematically long intensive heart care in infants with underlying vulnerability as well as new diagnostic approaches including histopathology complemented with IHC and molecular pathology.

Establishment of a panel of in-house polyclonal antibodies for the diagnosis of enterovirus infections

The aim of this study was to establish a reliable method of virus detection for the diagnosis of critical enterovirus infections such as acute infective encephalitis, encephalomyelitis and myocarditis. Because histopathological and immunohistochemical analyses of paraffin-embedded tissues play an important role in recognizing infectious agents in tissue samples, six in-house polyclonal antibodies raised against three representative enteroviruses using an indirect immunofluorescence assay and immunohistochemistry were examined. This panel of polyclonal antibodies recognized three serotypes of enterovirus. Two of the polyclonal antibodies were raised against denatured virus particles from enterovirus A71, one was raised against the recombinant VP1 protein of coxsackievirus B3, and the other for poliovirus type 1 were raised against denatured virus particles, the recombinant VP1 protein and peptide 2C. Western blot analysis revealed that each of these antibodies recognized the corresponding viral antigen and none cross-reacted with non-enteroviruses within the family Picornaviridae. However, all cross-reacted to some extent with the antigens derived from other serotypes of enterovirus. Indirect immunofluorescence assay and immunohistochemistry revealed that the virus capsid and non-structural proteins were localized in the cytoplasm of affected culture cells, and skeletal muscles and neurons in neonatal mice experimentally-infected with human enterovirus. The antibodies also recognized antigens derived from recent clinical isolates of enterovirus A71, coxsackievirus B3 and poliovirus. In addition, immunohistochemistry revealed that representative antibodies tested showed the same recognition pattern according to each serotype. Thus, the panel of in-house anti-enterovirus polyclonal antibodies described herein will be an important tool for the screening and pathological diagnosis for enterovirus infections, and may be useful for the classification of different enterovirus serotypes, including coxsackieviruses A and B, echoviruses, enterovirus A71 and poliovirus.

Coxsackievirus B detection in cases of myocarditis, myopericarditis, pericarditis and dilated cardiomyopathy in hospitalized patients

Coxsackieviruses B (CV-B) are known as the most common viral cause of human heart infections. The aim of the present study was to assess the potential role of CV-B in the etiology of infectious heart disease in hospitalized patients. The present study is based on blood, pericardial fluid and heart biopsies from 102 patients and 100 control subjects. All of the samples were examined for the detection of specific enteroviral genome using the reverse transcription polymerase chain reaction (RT-PCR) and sequence analysis. Immunohistochemical investigations for the detection of the enteroviral capsid protein, VP1, from the biopsies were performed. The samples were cultured on confluent KB monolayer cell line for possible virus isolation. The epidemiological data were also collected. CV-B was detected in 28 of the 102 patients. The sequence analysis demonstrated that 27 strains were identical to CV-B3 and only one strain was identical to CV-B1. Furthermore, VP1 in the heart biopsies was detected in enterovirus-positive cases, as revealed by RT-PCR. Pericarditis infection was more frequent than myocarditis (P<0.05) or myopericarditis (P=0.05). The epidemiological data demonstrate that CV-B heart infections occur mainly during autumn and winter, and young male adults are more susceptible than adolescents or adults (P<0.5). The present findings demonstrate a higher prevalence of viral heart infections, suggesting that CV-B may significantly contribute to heart infections.

Sudden unexpected death related to enterovirus myocarditis: histopathology, immunohistochemistry and molecular pathology diagnosis at post-mortem

BACKGROUND

Viral myocarditis is a major cause of sudden unexpected death in children and young adults. Until recently, coxsackievirus B3 (CVB3) has been the most commonly implicated virus in myocarditis. At present, no standard diagnosis is generally accepted due to the insensitivity of traditional diagnostic tests. This has prompted health professionals to seek new diagnostic approaches, which resulted in the emergence of new molecular pathological tests and a more detailed immunohistochemical and histopathological analysis. When supplemented with immunohistochemistry and molecular pathology, conventional histopathology may provide important clues regarding myocarditis underlying etiology.

METHODS

This study is based on post-mortem samples from sudden unexpected death victims and controls who were investigated prospectively. Immunohistochemical investigations for the detection of the enteroviral capsid protein VP1 and the characterization and quantification of myocardial inflammatory reactions as well as molecular pathological methods for enteroviral genome detection were performed.

RESULTS

Overall, 48 sudden unexpected death victims were enrolled. As for controls, 37 cases of unnatural traffic accident victims were studied. Enterovirus was detected in 6 sudden unexpected death cases (12.5 %). The control samples were completely enterovirus negative. Furthermore, the enteroviral capsid protein VP1 in the myocardium was detected in enterovirus-positive cases revealed by means of reverse transcriptase-polymerase chain reaction (RT-PCR). Unlike control samples, immunohistochemical investigations showed a significant presence of T and B lymphocytes in sudden unexpected death victims.

CONCLUSIONS

Our findings demonstrate clearly a higher prevalence of viral myocarditis in cases of sudden unexpected death compared to control subjects, suggesting that coxsackie B enterovirus may contribute to myocarditis pathogenesis significantly.

Evaluation of immunohistochemistry and in situ hybridization methods for the detection of enteroviruses using infected cell culture samples

BACKGROUND

Enterovirus infections are frequent in all age groups. In addition to acute infections, they have been connected to chronic diseases such as cardiomyopathies and type 1 diabetes. Based on this there is an increasing need for the reliable detection of enteroviruses in different kinds of tissue samples.

OBJECTIVES

The aim of this study was to set up a test panel which can detect a wide range of different enteroviruses in paraffin-embedded samples and fresh frozen samples using immunohistochemical and in situ hybridization methods.

STUDY DESIGN

A panel of nine enterovirus antibodies was optimized for the detection of different enterovirus types in both paraffin-embedded and frozen cell culture samples. In addition, an oligonucleotide probe detecting all human enteroviruses was evaluated for ISH in formalin-fixed paraffin-embedded cell culture samples.

RESULTS

Most antibodies worked well in both sample types. Some antibodies detected only one of the tested serotypes, whereas others detected several serotypes. ISH was able to detect all tested enterovirus types.

CONCLUSIONS

This test panel makes it possible to detect a wide range of different enterovirus types in both formalin-fixed paraffin-embedded and frozen samples. The same methods can also be applied for tissue sections, but may need further optimization for each tissue type.

5' terminal deletions in the genome of a coxsackievirus B2 strain occurred naturally in human heart

Enteroviruses can induce human myocarditis, which can be modeled in mice inoculated with group B coxsackieviruses (CVB) and in which CVB evolve to produce defective, terminally deleted genomes. The 5' non-translated region (NTR) was enzymatically amplified from heart tissue of a fatal case of enterovirus-associated myocarditis in Japan in 2002. While no intact 5' viral genomic termini were detected, 5' terminal deletions ranged in size from 22 to 36 nucleotides. Sequence of the 5' third of this viral genome is of a modern strain, closely related to CVB2 strains isolated in Japan in 2002. A CVB3 chimera containing the 5' NTR with a 22 nt deletion produced progeny virus upon transfection of HeLa cells. When the 5' 22 nucleotide deletion was repaired, the virus induced myocarditis in mice and replicated like wild type virus in murine heart cells. This is the first report of these naturally-occurring defective enteroviral genomes in human myocarditis.

Persistent viral infection in primary Sjogren's syndrome: review and perspectives

Exocrine gland pathology in primary Sjogren's syndrome is characterized by destruction of acinar epithelial cells and chronic lymphocytic infiltrates surrounding ductal epithelial cells. These cells seem to be activated, as it is inferred by their immunophenotype. The cause of this activation and the chronic inflammatory response that targets epithelial cells remain unknown. Here, we will review the evidence pointing to a persistent viral infection as a probable cause of primary Sjogren's syndrome and discuss potential directions for future research.

Histopathologic, immunohistochemical, and polymerase chain reaction assays in the study of cases with fatal sporadic myocarditis

Paraffin tissue blocks from 27 cases with sporadic myocarditis were collected during a 12-year period at a single medical examiner's office. Blocks were studied by using histopathology; immunohistochemistry for viruses (adenovirus, enterovirus, influenza A and B, and human herpes types 4 and 5), bacteria (Neisseria meningitidis, Ehrlichia sp, spotted fever group Rickettsia) and parasites (Toxoplasma gondii and Trypanosoma cruzi); and polymerase chain reaction (PCR)/RT-PCR for adenovirus and enterovirus. We identified enterovirus in 5 (18.5%) cases and Sarcocystis in a 36-year-old woman who had focal inflammation and myocyte necrosis. Immunohistochemical evidence of enteroviruses was found in the myocytes of 2 patients less than 6 months old who had diffuse mononuclear myocardial inflammation, interstitial pneumonitis; one also had encephalitis. In these 2 patients, the presence of enterovirus was confirmed by RT-PCR targeting the 5' nontranslated region and was serotyped as coxsackievirus B2 by sequencing the VP1 capsid region. In another 3 cases (ages 12, 47, and 54), enterovirus was detected by the 5' nontranslated region region; VP1 sequencing identified these as echoviruses 6, 13, and 7, respectively. Accurately identifying an infectious agent is the foundation for clinical and public health interventions. Despite using multiple diagnostic methods, an organism could only be detected in a small proportion of sporadic myocarditis cases.

Quilty effect has the features of lymphoid neogenesis and shares CXCL13-CXCR5 pathway with recurrent acute cardiac rejections

Quilty effect (QE) is a frequent, yet enigmatic feature of cardiac allograft, since it is apparently devoid of clinical significance, though its association with acute (A) rejection (R) is strongly suspected. It was observed in 126/379 biopsies from 22 patients during the first posttransplant year. Most grade (G)2R biopsies displayed a concomitant QE. The following features typical of QE were identified: (a) focal angiogenesis and lymphangiogenesis associated with bFGF, VEGF-C and VEGF-A expression, (b) marked infiltrate of CD4(+)T and CD20(+)B followed by CD8(+)T lymphocytes arranged around PNAd(+)HEV-like vessels. Most QE appear as distinct B-T-cell-specific areas with lymphoid follicles sometimes endowed with germinal center-like structures containing VCAM-1(+)CD21(+)FDC and CD68(+)macrophages, which frequently expressed CXCL13. These cells were also found in mantle-like zones, where small lymphocytes expressed CXCR5, otherwise in the whole area of not clustered lymphoid aggregates. CXCL13 was also expressed, in association with CD20(+)B lymphocyte recruitment, in G2R biopsies obtained from patients with recurrent AR. QE has features of a tertiary lymphoid tissue suggesting an attempt, by the heart allograft, to mount a local response to a persistent alloantigen stimulation resulting in aberrant CXCL13 production, as also occurs in recurrent AR. CXCL13-CXCR5 emerge as a common molecular pathway for QE and recurrent episodes of AR.

Endomyocardial infiltration by B and NK cells foreshadows the recurrence of cardiac allograft rejection

Heart allograft outcome is unpredictable and acute rejection episodes still occur despite the improvement of immunosuppressive regimens. We therefore investigated whether the immunopathological profile of endomyocardial biopsies might underlie the variations in the clinical course of a graft. Biopsies from transplanted patients were analysed by histology, immunohistochemistry (associated with digital image analysis), confocal and electron microscopy to determine the type and the functional state of leukocytes infiltrating the myocardium, together with their ultrastructural features and those of the graft itself. In comparison with biopsies with grade 0R or grade 1R rejection, those from patients with grade 2R rejection displayed significant infiltration of macrophages, T lymphocytes, and CD83+ and DC-SIGN+ dendritic cells. Fifty-seven per cent were invaded by CD20+B lymphocytes, most of which expressed CD69 activation marker and cooperated in interleukin-12 production, and by CD69+CD94+NK cells expressing interferon-gamma. Ultrastructural signs of myocyte degeneration and microvessel rupture by NK cells were frequent. These patients developed recurrent episodes of acute allograft rejection. Endomyocardial B and NK infiltrates are involved in the dynamics of allograft rejection and are associated with a high risk of its recurrence. Immunopathological assessment of endomyocardial biopsies may thus serve to forecast the probable outcome of a heart allograft.

Autoimmunity and Coxsackievirus Infection in Primary Sjögren's Syndrome

Exocrine gland epithelial cells are the target of autoimmune pathology in primary Sjögren's syndrome (pSS). Their activated phenotype has incited the notion that they are infected by a virus. We recently presented evidence that coxsackieviruses may persistently infect the salivary glands of pSS patients. We hypothesize that coxsackieviruses may play a permissive role for the perpetuation and possibly the induction of autoimmune disease in pSS.

Fulminant myocarditis demonstrating uncommon morphology--a report of two autopsy cases

Two autopsy cases of fulminant myocarditis demonstrating uncommon morphology were studied. Subjects included two male patients: a 42-year-old (case 1) and a 39-year-old (case 2). Both cases had fever, chest or epigastric pain, electrocardiographic abnormalities, prominent elevation of serum glutamic oxaloacetic transaminase, glutamic pyruvic transaminase, lactic dehydrogenase and creatine phosphokinase. They were treated with intra-aortic balloon pumping and percutaneous cardiopulmonary support, and they died at 3 days and 4 days after admission (total course of 10 days and 9 days), respectively. Case 1 showed focal necrosis, severe myocardial dystrophic calcification positive for Kossa stain, inflammatory edema, lymphocyte and macrophage infiltration and extravasation of erythrocytes. Case 2 showed acute inflammation and severe myocardial necrosis with neutrophilic abscess, lymphocyte and macrophage infiltration, cell debris and purulent exudate. Calcified, degenerative and necrotic cardiac myocytes and macrophages were reacted with anti-Enterovirus antibody (clone 5-D8/1), which recognizes an epitope on the VP1 peptide of most Coxsackievirus, echovirus, poliovirus and enterovirus strains. Therefore, the present two cases may be compatible with fulminant enterovirus-associated myocarditis. Using reverse transcriptase-semi-nested polymerase chain reaction, picornaviral RNA was detected in the amplified products extracted from the paraffin-embedded myocardial sample of case 1 but not in case 2.

Enteroviruses as agents of emerging infectious diseases

Although the enteroviruses as a group are ubiquitous and not normally considered as "emerging pathogens," the many different serotypes circulate at different frequencies in any given year and the prevalence of a given serotype may fluctuate wildly from year to year. As a result, several enterovirus serotypes have been associated with the emergence of specific diseases (for example, pandemic acute hemorrhagic conjunctivitis) and specific serotypes have emerged to cause outbreaks of major public health concern. Enterovirus 71 is a recognized cause of epidemic severe central nervous system disease in Southeast Asia. Acute hemorrhagic conjunctivitis was a newly described disease in the 1970s associated with emergence of enterovirus 70 and coxsackievirus A24 variant. In addition, the impending eradication of poliovirus and some of the challenges currently faced by the eradication program present the possibility that poliomyelitis could emerge in the posteradication era. These links between enterovirus infections and emerging diseases are reviewed.

Unexpected hazard of illegal immigration: Outbreak of viral myocarditis exacerbated by confinement and deprivation in a shipboard cargo container

We present a group of 18 illegal immigrant stowaways who arrived in a shipboard cargo container suffering from gastroenteritis, dehydration, and malnutrition and showing evidence of viral myocarditis in 3 of 4 fatalities. Our investigation included an evaluation of the 2-week ocean voyage, analysis of medical records and laboratory results of the survivors, autopsies on the decedents, and viral studies on their heart tissue. Of 3 stowaways who died shipboard, 2 showed lymphocytic myocarditis and 1 could not be evaluated histologically due to decomposition. A fourth stowaway died 4 months after arrival with dilated cardiomyopathy and lymphocytic myocarditis. Reverse-transcriptase polymerase chain reaction and nucleotide sequencing of viral isolates from the decedents' heart tissues demonstrated Coxsackie virus B3 genome. We believe that these cases represent an outbreak of viral myocarditis, exacerbated by acute dehydration and malnutrition, due to confinement within the shipping container. Our evidence indicates that close confinement promoted the spread of the virus, and nutritional deprivation increased the stowaways' vulnerability. Furthermore, our observations support the conclusion, based on experimental studies, that nutritionally induced oxidative stress increased the virulence of the etiologic viral agent. In summary, these cases represent a potential infectious disease hazard of illegal immigration.

Herpes simplex virus type 1 infection associated with atrial myxoma

Some findings suggest an infectious factor in cardiac myxoma and certain histopathological features indicate herpes simplex virus type 1 (HSV-1) infection. We hypothesized that HSV-1 may be involved in the pathogenesis of cardiac myxoma. Paraffin-embedded tissue samples from 17 patients with atrial myxoma were investigated for HSV-1 antigen by immunohistochemistry and viral genomic DNA by nested polymerase chain reaction. The histogenesis and oncogenesis of atrial myxoma were assessed by the expression of calretinin, Ki67, and p53 protein, respectively. Autopsy myocardial samples, including endocardium from 12 patients who died by accident or other conditions, were used for comparison. HSV-1 antigen was detected in atrial myxoma from 12 of 17 patients: 8 of these 12 samples were positive also for HSV-1 DNA. No HSV-1 antigen or DNA was found in tissue from the comparison group. Antigens of HSV-2, varicella-zoster virus, Epstein-Barr virus, and cytomegalovirus were not found in atrial myxoma. Calretinin was found in myxoma cells of all 17 cases but Ki67 was present only in smooth muscle cells or infiltrating cells in some cases. p53 was not detectable in any myxoma. Most infiltrating cells were cytotoxic T lymphocytes. These data suggest that HSV-1 infection is associated with some cases of sporadic atrial myxoma and that these may result from a chronic inflammatory lesion of endocardium.

Detection of enterovirus capsid protein VP1 in myocardium from cases of myocarditis or dilated cardiomyopathy by immunohistochemistry: further evidence of enterovirus persistence in myocytes

The association of enteroviruses with myocardial disease has been investigated extensively by molecular biological techniques to detect viral RNA, but remains controversial. This retrospective study investigated the involvement of enterovirus in myocarditis or dilated cardiomyopathy (DCM) by detection of viral antigens in myocardial samples from a new patient series using an optimized immunohistochemical technique. Formalin-fixed, paraffin-embedded biopsy, autopsy or explanted myocardial tissue samples were obtained from 136 subjects. These comprised histologically proven cases of acute fatal myocarditis (n=10), DCM (n=89, including 10 patients with healing/borderline myocarditis) and a comparison group of samples from 37 unused donor hearts and cases with other conditions. A monoclonal antibody 5-D8/1 directed against a conserved, non-conformational epitope in capsid protein VP1 was employed for broad detection of different enterovirus serotypes. Investigations were performed blindly. Histological sections from 7 of 10 fatal myocarditis cases, 47 of 89 patients (52.8%) with DCM were positive for the viral capsid protein VP1 by immunohistochemical staining. Consecutive sections of positive samples were negative when the antibody was omitted or replaced with subclass- and concentration-matched normal mouse IgG. In contrast, only 3 of 37 samples (8.1%) in the comparison group were positive (Yates corrected chi(2)=19.99, P<0.001: odds ratio =12.68). VP1 staining was distributed in individual or grouped myofibers and localized in the cytoplasm of myocytes. In some cases, VP1 was detected in only a few myofibers within an entire section. These results provide further evidence of enterovirus involvement in a high proportion of DCM cases and demonstrate that VP1 is present in disease stages from acute myocarditis, healing myocarditis to end-stage DCM requiring cardiac transplantation, indicating translation of viral protein during persistent enterovirus infection.

Antigen retrieval techniques: current perspectives

Development of the antigen retrieval (AR) technique, a simple method of boiling archival paraffin-embedded tissue sections in water to enhance the signal of immunohistochemistry (IHC), was the fruit of pioneering efforts guided by the philosophy of rendering IHC applicable to routine formalin-fixed, paraffin-embedded tissues for wide application of IHC in research and clinical pathology. On the basis of thousands of articles and many reviews, a book has recently been published that summarizes basic principles for practice and further development of the AR technique. Major topics with respect to several critical issues, such as the definition, application, technical principles, and further studies of the AR technique, are highlighted in this article. In particular, a further application of the heat-induced retrieval approach for sufficient extraction of nucleic acids in addition to proteins, and standardization of routine IHC based on the AR technique in terms of a test battery approach, are also addressed. Furthermore, understanding the mechanism of the AR technique may shed light on facilitating the development of molecular morphology.

Nitric oxide and Coxsackievirus B3 myocarditis: differential expression of inducible nitric oxide synthase in mouse heart after infection with virulent or attenuated virus

Increased expression of inducible nitric oxide synthase (iNOS) has been found in inflammatory myocardial disease and increased production of nitric oxide (NO) has both an inhibitory effect on virus replication and a cytotoxic effect on host cells. To investigate the relationship between severity of enteroviral myocarditis and iNOS expression, a characterised murine model was infected with either cardiovirulent or an attenuated Coxsackievirus B3 and myocardial samples were collected on Day 7. The ability of these viruses to induce NOS expression was compared by measurement of iNOS enzyme activity and localisation of iNOS protein or peroxynitrite, a product of excessive NO production. In accordance with previous reports, high expression of iNOS was detected in mice infected with the cardiovirulent virus. The iNOS protein was located mainly in infiltrating macrophages in and around foci of necrotic myofibres where viral genomic RNA was detected. In contrast, the level of iNOS expression was significantly lower in mice infected with the attenuated virus. This correlates with fewer and smaller myocarditic lesions and less infiltrating cells in the heart. iNOS was not detected in mock-infected mice by the above assays. These findings suggest that one mechanism of attenuation may be associated with the reduced ability of the variant to induce NOS expression in the heart. This also confirms a cytotoxic role for NO in the pathogenesis of Coxsackievirus B3-induced myocarditis.