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,...

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Insulin-dependent (type 1) diabetes mellitus (T1D) onset is mediated by individual human genetics as well as undefined environmental influences such as viral infections. The group B coxsackieviruses (CVB) are commonly named as putative T1D-inducing agents. We studied CVB replication in nonobese diabetic (NOD) mice to assess how infection by diverse CVB strains affected T1D incidence in a model of human T1D. Inoculation of 4-or 8-week-old NOD mice with any of nine different CVB strains significantly reduced the incidence of T1D by 2-to 10-fold over a 10-month period relative to T1D incidences in mock-infected control mice. Greater protection was conferred by more-pathogenic CVB strains relative to less-virulent or avirulent strains. Two CVB3 strains were employed to further explore the relationship of CVB virulence phenotypes to T1D onset and incidence: a pathogenic strain (CVB3/M) and a nonvirulent strain (CVB3/GA). CVB3/M replicated to four-to fivefold-higher titers than CVB3/GA in the pancreas and induced widespread pancreatitis, whereas CVB3/GA induced no pancreatitis. Apoptotic nuclei were detected by TUNEL (terminal deoxynucleotidyltransferase-mediated dUTP-biotin nick end labeling) assay in CVB3/M-infected pancreata but not in CVB3/GA-infected pancreata. In situ hybridization detected CVB3 RNA in acinar tissue but not in pancreatic islets. Although islets demonstrated inflammatory infiltrates in CVB3-protected mice, insulin remained detectable by immunohistochemistry in these islets but not in those from diabetic mice. Enzyme-linked immunosorbent assay-based examination of murine sera for immunoglobulin G1 (IgG1) and IgG2a immunoreactivity against diabetic autoantigens insulin and HSP60 revealed no statistically significant relationship between CVB3-protected mice or diabetic mice and specific autoimmunity. However, when pooled sera from CVB3/M-protected mice were used to probe a Western blot of pancreatic proteins, numerous proteins were detected, whereas only one band was detected by sera from CVB3/GA-protected mice. No proteins were detected by sera from diabetic or normal mice. Cumulatively, these data do not support the hypothesis that CVB are causative agents of T1D. To the contrary, CVB infections provide significant protection from T1D onset in NOD mice. Possible mechanisms by which this virus-induced protection may occur are discussed.The group B coxsackieviruses (CVB; family Picornaviridae, genus Enterovirus, species group B coxsackievirus; six serotypes, CVB1 to -6) are among the best studied of human enteroviruses (102). The CVB genome is a single strand of positive sense RNA 7,400 nucleotides in length that encodes 11 proteins in a single open reading frame (89). The CVB have been associated with diverse human diseases, among the more serious of which are myocarditis, pancreatitis, and aseptic meningitis. The CVB have been soundly implicated as causes of human myocarditis (1, 26, 42, 60-62, 73, 74, 108, 109) and pancreatitis (2,41,54,58,66,107) and, furthermore, cause these diseases readily i...

The group B coxsackieviruses (CVB) induce experimental pancreatitis and myocarditis in mice and are established agents of human myocarditis, especially in children. We tested the hypothesis that the development of CVB-induced myocarditis is linked to CVB-induced pancreatitis by studying the replication of different CVB strains in mice. Eight of nine genotypically different type 3 CVB (CVB3) strains induced acute pancreatitis in mice; of these, three viruses also induced acute myocarditis. One CVB3 strain was avirulent for both organs. Myocarditis was not observed in the absence of pancreatitis. The results obtained by inoculation of mice with strains of other CVB serotypes were consistent with these data. Infectious virus titers were measured in serum, pancreas, and heart as a function of time after inoculation of mice with three CVB3 strains. Each strain was representative of one of the three viral virulence phenotypes: avirulent, pancreovirulent only, and cardiovirulent. All strains replicated well and persisted in the pancreas through 8 days post-inoculation, but the cardiovirulent CVB3 strain tended to replicate to higher titer earlier and persist longer in sera, pancreatic, and cardiac tissues than the noncardiovirulent strains. Replication of the CVB3 strains were studied in two human pancreatic tumor lines and in primary human endothelial cell cultures derived from cardiac artery. Cardiovirulent strains, both individually and as a group, tended to replicate to titers as high as, or higher than, noncardiovirulent strains did in cell culture. The data are consistent with the possibility of an etiologic link between CVB-induced pancreatic and heart disease.

Group B coxsackieviruses (CVB) are believed to trigger some cases of human type 1 diabetes (T1D), although the mechanism by which this may occur has not been shown. We demonstrated previously that inoculation of young nonobese diabetic (NOD) mice with any of several different CVB strains reduced T1D incidence. We also observed no evidence of CVB replication within islets of young NOD mice, suggesting no role for CVB in T1D induction in the NOD mouse model. The failure to observe CVB replication within islets of young NOD mice has been proposed to be due to interferon expression by insulin-producing beta cells or lack of expression of the CVB receptor CAR. We found that CAR protein is detectable within islets of young and older NOD mice and that a CVB3 strain, which expresses murine IL-4, can replicate in islets. Mice inoculated with the IL-4 expressing CVB3 chimeric strain were better protected from T1D onset than were mock-infected control mice despite intraislet viral replication. Having demonstrated that CVB can replicate in healthy islets of young NOD mice when the intraislet environment is suitably altered, we asked whether islets in old prediabetic mice were resistant to CVB infection. Unlike young mice in which insulitis is not yet apparent, older NOD mice demonstrate severe insulitis in all islets. Inoculating older prediabetic mice with different pathogenic CVB strains caused accelerated T1D onset relative to control mice, a phenomenon that was preceded by detection of virus within islets. Together, the results suggest a model for resolving conflicting data regarding the role of CVB in human T1D etiology.