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

Abstract

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.

Functional Consequences of RNA 5′-Terminal Deletions on Coxsackievirus B3 RNA Replication and Ribonucleoprotein Complex Formation

“…In this report, we demonstrate that transfected RNAs harboring 5=-terminal sequence deletions are able to direct the synthesis of viral proteins, but not genomic RNAs, in human and murine cardiomyocytes. Moreover, we show that the binding of cellular and viral replication factors to viral RNA is conserved despite genomic deletions but that the impaired RNA synthesis as- (30)(31)(32). However, these recent findings showed for the first time the existence of TD CVB genomic-RNA populations in a patient suffering from chronic cardiomyopathy.…”

“…pCVB3-TD7, pCVB3-TD30, and pCVB3-TD49 are variants of pCVB3-28 in which 5=-terminal deletions of 7, 30, and 49 nucleotides, respectively, were engineered into the pCVB3-28 genome with a ribozyme to ensure cleavage at the authentic 5=-terminal nucleotide of each genome (32). pCVB3-TD21 contains the 5=-terminal sequence of a virus detected in the heart in a fatal human case of CVB2 infection engineered into pCVB3-28 as described above but with a ribozyme designed to ensure cleavage at the 22nd nucleotide to generate a deletion of 21 nucleotides relative to wild-type RNA (30).…”

How RNA viruses maintain their genome integrity

“…It was found that there was a correlation between the presence of complete or truncated termini, and acute versus persistent infection, respectively (Kim et al, 2005). More recent work has detected the presence of terminally deleted genomes in human tissue collected from a fatal case of myocarditis, suggesting that there is significance for terminal deletions in the context of a human infection (Chapman et al, 2008).…”

Quantitative Genomic and Antigenomic Enterovirus RNA Detection in Explanted Heart Tissue Samples from Patients with End-Stage Idiopathic Dilated Cardiomyopathy

“…However, the viral molecular mechanisms involved in the progression of acute myocarditis to chronic myocarditis and subsequently to IDCM are currently poorly understood. In 2008, Chapman et al (7) reported for the first time the isolation from human heart tissue of a CVB2 strain with genomic 5=-terminal deletions (TD). These mutations induced significant slowing of viral replication and a lowering of virus titer in cell culture models where an absence of classical cytopathic effects was associated with an abnormal positive-to negative-strand viral RNA ratio close to 1 rather than the high positive-to negative-strand ratios normally seen in wild-type virus infected cells (11).…”

“…The threshold of viral RNA detection was found repeatedly to be 30 copies per well for both wild-type and TD EV RNA transcripts for both positive-and negative-strand RNAs. This sensitivity of detection, is crucial because TD mutants replicate slowly and to low titers (7,10,11). This will be important for future work and may explain past inability to detect RNA despite viral capsid protein VP1 detection (1).…”