Adult human enteroviral heart disease is often associated with the detection of enteroviral RNA in cardiac muscle tissue in the absence of infectious virus. Passage of coxsackievirus B3 (CVB3) in adult murine cardiomyocytes produced CVB3 that was noncytolytic in HeLa cells. Detectable but noncytopathic CVB3 was also isolated from hearts of mice inoculated with CVB3. Sequence analysis revealed five classes of CVB3 genomes with 5 termini containing 7, 12, 17, 30, and 49 nucleotide deletions. Structural changes (assayed by chemical modification) in cloned, terminally deleted 5-nontranslated regions were confined to the cloverleaf domain and localized within the region of the deletion, leaving key functional elements of the RNA intact. Transfection of CVB3 cDNA clones with the 5-terminal deletions into HeLa cells generated noncytolytic virus (CVB3/TD) which was neutralized by anti-CVB3 serum. Encapsidated negative-strand viral RNA was detected using CsCl-purified CVB3/TD virions, although no negative-strand virion RNA was detected in similarly treated parental CVB3 virions. The viral protein VPg was detected on CVB3/TD virion RNA molecules which terminate in 5 CG or 5 AG. Detection of viral RNA in mouse hearts from 1 week to over 5 months postinoculation with CVB3/TD demonstrated that CVB3/TD virus strains replicate and persist in vivo. These studies describe a naturally occurring genomic alteration to an enteroviral genome associated with long-term viral persistence.The six serotypes of the group B coxsackieviruses (CVB1-6) are enteroviruses (Picornaviridae, species HEV-B) (53). The CVB genome is a single-stranded RNA molecule, 7,400 nucleotides (nt) in length, that is encapsidated within an icosahedral shell (74). The 11 viral proteins (83) are encoded by a single open reading frame which is flanked on the 5Ј and 3Ј termini by nontranslated regions (NTRs) (20). The CVB induce numerous human illnesses, including inflammatory heart disease, pancreatitis, and aseptic meningitis and may also trigger the onset of type 1 diabetes (5,31,72,81,82). The CVB were recognized as causes of human heart disease shortly after their description early in the 1950s (26, 27) and remain the enteroviruses most commonly associated with human cardiomyopathies on the grounds of isolation and serology (5,6,34,62,88). Meta-analysis shows an association between enteroviruses and myocarditis in 23% of cases (7), although this association is more variable in cases of dilated cardiomyopathy, a serious disease that often leads to a failing heart (61). Mouse models of CVB-induced pancreatitis (94, 110), myocarditis (45,52,110), myositis (104, 105), and rapid-onset type 1 diabetes (31) which facilitate the study of these diseases have been developed.Enterovirus infections are generally considered to be acute events, with symptoms and virus titers peaking within a few days postinoculation (p.i.) and with virus being cleared by the adaptive immune response (17). However, enterovirus infections can persist under conditions of immunodeficiency (48,51,...

Group B coxsackieviruses (CVB) cause numerous diseases, including myocarditis, pancreatitis, aseptic meningitis and possibly type 1 diabetes. To date, infectious cDNA copies of CVB type 3 (CVB3) genomes have all been derived from pathogenic virus strains. An infectious cDNA copy of the well-characterized, non-pathogenic CVB3 strain GA genome was cloned in order to facilitate mapping of the CVB genes that influence expression of a virulence phenotype. Comparison of the sequence of the parental CVB3/GA population, derived by direct RT-PCR-mediated sequence analysis, to that of the infectious CVB3/GA progeny genome demonstrated that an authentic copy was cloned; numerous differences were observed in coding and non-coding sequences relative to other CVB3 strains. Progeny CVB3/GA replicated similarly to the parental strain in three different cell cultures and was avirulent when inoculated into mice, causing neither pancreatitis nor myocarditis. Inoculation of mice with CVB3/GA protected mice completely against myocarditis and pancreatitis induced by cardiovirulent CVB3 challenge. The secondary structure predicted for the CVB3/GA domain II, a region within the 5′ non-translated region that is implicated as a key site affecting the expression of a cardiovirulent phenotype, differs from those predicted for cardiovirulent and pancreovirulent CVB3 strains. This is the first report characterizing a cloned CVB3 genome from an avirulent strain.