Molecular phenotypes of human parvovirus B19 in patients with myocarditis

Abstract

AIM:To investigate molecular phenotypes of myocardial B19V-infection to determine the role of B19V in myocarditis and dilated cardiomyopathy (DCM). METHODS:Endomyocardial biopsies (EMBs) from 498 B19V-positive patients with myocarditis and DCM were analyzed using molecular methods and functional experiments. EMBs were obtained from the University Hospitals of Greifswald and Tuebingen and additionally from 36 German cardiology centers. Control tissues were obtained at autopsy from 34 victims of accidents, crime or suicide. Identification of mononuclear cell infiltrates in EMBs was performed using immunohistological staining. Anti-B19V-IgM and anti-B19V-IgG were analyzed by enzyme-linked immunosorbent assay (ELISA). B19V viral loads were determined using in-house quantitative real-time polymerase chain reaction (PCR). For B19V-genotyping a new B19V-genotype-specific restriction fragment length polymorphism (RFLP)-PCR was established. B19V-genotyping was verified by direct DNAsequencing and sequences were aligned using BLAST and BioEdit software. B19V P6-promoter and HHV6-U94-transactivator constructs were generated for cell culture experiments. Transfection experiments were conducted using human endothelial cells 1. Luciferase reporter assays were performed to determine B19V-replication activity. Statistical analysis and graphical representation were calculated using SPSS and Prism5 software. RESULTS:The prevalence of B19V was significantly more likely to be associated with inflammatory cardiomyopathy (iCMP) compared to uninflamed DCM (59.6% vs 35.3%) (P < 0.0001). The detection of B19V-mRNA replication intermediates proved that replication of B19V was present. RFLP-PCR assays showed that B19V-genotype 1 (57.4%) and B19V-genotype 2 (36.7%) were the most prevalent viral genotypes. B19V-genotype 2 was observed more frequently in EMBs with iCMP (65.0%) compared to DCM (35%) (P = 0.049). Although there was no significant difference in gender-specific B19V-loads, women were more frequently infected with B19V-genotype 2 (44.6%) than men (36.0%) (P = 0.0448 samples and was associated with higher B19V viral load compared to B19V-monoinfected tissue (P = 0.0012). The most frequent coinfecting virus was human herpes virus 6 (HHV6, 16.5%). B19V-coinfection with HHV6 showed higher B19V-loads compared to B19V-monoinfected EMBs (P = 0.0033), suggesting that HHV6 had transactivated B19V. In vitro experiments confirmed a 2.4-fold increased B19V P6-promoter activity by the HHV6 U94-transactivator. CONCLUSION:The finding of significantly increased B19V loads in patients with histologically proven cardiac inflammation suggests a crucial role of B19V-genotypes and reactivation of B19V-infection by HHV6-coinfection in B19V-associated iCMP. Our findings suggest that B19V-infection of the human heart can be a causative event for the development of an endothelial cell-mediated inflammatory disease and that this is related to both viral load and genotype.© 2014 Baishideng Publishing Group Co., Limited. All rights reserved.Key wor...

Clinical presentation and diagnosis of myocarditis

“…Recently, parvovirus B19 replication intermediates were found in human acute myocarditis with high viral load but not in DCM; co-infection with other cardiotropic viruses was observed more frequently with HHV6 31. Co-infected patients had higher viral parvovirus B19 load compared with monoinfected patients, suggesting that HHV6 had transactivated parvovirus B19 31.…”

“…Recently, parvovirus B19 replication intermediates were found in human acute myocarditis with high viral load but not in DCM; co-infection with other cardiotropic viruses was observed more frequently with HHV6 31. Co-infected patients had higher viral parvovirus B19 load compared with monoinfected patients, suggesting that HHV6 had transactivated parvovirus B19 31. These researchers suggest that parvovirus B19 infection of the human heart may cause the development of an endothelial cell-mediated inflammatory disease and that this is related to both viral load and genotype, in brief that parvovirus B19 infection may be pathogenic only in a subset of patients with myocarditis 10 31…”

Therapeutic implications of a combined diagnostic workup including endomyocardial biopsy in an all‐comer population of patients with heart failure: a retrospective analysis

“…Viral DNA in EMB specimens can also be found in the myocardium of patients with no myocarditis or DCM . Therefore, the presence of viral replication in EMB specimens is required for the diagnosis of viral myocarditis . The final EMB diagnosis was a combined assessment by the pathologist based on histological and immunohistochemical findings, as well as those of the mRNA expression analysis by PCR.…”

Telbivudine in chronic lymphocytic myocarditis and human parvovirus B19 transcriptional activity

“…Recent findings further indicate that a subgroup of myocarditis patients characterized by transcriptionally active cardiotropic B19V have an altered cardiac gene expression compared with control patients and myocarditis patients with latent B19V, suggesting that probably active replicating B19V with detectable viral RNA is related to myocarditis. 16 Besides the extent of the viral load 17,18 and the replicative status/transcriptional activity of B19V, 16 other studies further suggest that the relevance of B19V in myocarditis and DCM depends on the presence of other cardiotropic viruses. 17 The unclarity about the pathogenic role of B19V in myocarditis and DCM, partly due to the absence of experimental in vivo models, has hampered the search for potential B19V-targeted therapies.…”

“…16 Besides the extent of the viral load 17,18 and the replicative status/transcriptional activity of B19V, 16 other studies further suggest that the relevance of B19V in myocarditis and DCM depends on the presence of other cardiotropic viruses. 17 The unclarity about the pathogenic role of B19V in myocarditis and DCM, partly due to the absence of experimental in vivo models, has hampered the search for potential B19V-targeted therapies. 19 Nevertheless, there is evidence from cell culture experiments showing that B19V modulates inflammatory signalling and apoptosis in endothelial cells 20 and that its capsid protein VP1 damages circulating angiogenic cells, 21 resulting in dysfunctional endogenous vascular repair.…”