Pathogenesis of chronic myocarditis in mice infected with coxsackie B3 viruses.

Infection of 300 mice of the Swiss race with Coxsackie B3 viruses gave rise to chronic myocarditis and endocarditis. The virus was cultured from the heart muscle 9 days post infection. Between days 18 and 108 post infection, virtually all mice showed evidence of an active inflammatory process in the myocardium, and in one half there was proliferation of endothelial cells, and infitration and fibrosis in the endocardium. Immunomorphologic studies demonstrated the precence of antiheart antibodies in the blood serum, and Coxsackie B3 antigen and immunoglobulin deposits in the myocardium and endocardium. Highest levels of antivirus antibodies were observed 18 days post infection.     

Myocarditis induced by coxsackie B3 virus in mature mice.

Forty female mice during breast-feeding were infected intraperitoneally with coxackie B3 virus. Gross and microscopic examination of the hearts of the mice 7, 20, 44 and 120 days after infection revealed myocarditis typical of the acute stage of the disease, not reported previously, and gradually increasing intensity of immunologic changes in the chronic stage.     

Electron microscopic studies on BHK 21 cells infected with rift valley fever virus

Summary Electron microscopic studies on BHK 21 cells infected with Rift Valley Fever virus (RVFV) are reported. Entry of virus particles into the cell up to 20 hours after inoculation is demonstrated. No envelope derived from the cell membrane is present on virus particles inside or outside the cell. The particle has a diameter of approximately 94 m, a core diameter of approximately 77 m and a capsid-like outermost layer of width 9 m. Between core and capsid is an electron-translucent area of width 8 m. Myelin figures are abundant and progeny particles are usually found in association with cisternae of the endoplasmic reticulum. The appearance of peculiar rod-shaped structures in the cytoplasmic matrix suggests some transformation of the elements of the endoplasmic reticulum. Characteristic granular nuclear inclusions are present.     

Spherical aggregates of coxsackie B4 virus particles in mouse pancreas.

A high titer culture of Coxsackie B4 virus was used to induce pancreatitis in newborn mice. In animals sacrificed 1 or 2 days after intraperitoneal inoculation, we observed cytonecrosis consistent with picornaviral infection as well as necrosis indicative of pancreatitis. In addition, we observed aggregates of particles which seem to be Coxsackie B4 virus particles, some arranged in the typical picornaviral crystalloid lattice formation and others arranged into spherical masses approximately 102 nm in diameter. Depending upon the depth and orientation of section through the spherical aggregates, the particles were arranged into two patterns which were readily distinguishable. When the plane of section was through the center of the sphere, 10 particles circularly arranged around a dense particle core were observed. When the sphere was cut tangentially, the particles were arranged in a zig-zag pattern so that there were two concentric layers of at least 6 particles per layer, with no central core. Both crystalloid and spherical aggregates were observed free within acinocyte cytoplasm, and within autophagic vacuoles, cytosegresomes, and fine granular bodies of acinocytes, and within phagocytic vacuoles of macrophages. We conclude that the spherical aggregates represent a distinct crystalloid form of Coxsackie B4 virus during its replicative cycle, which may eventually develop into the more typical picornaviral crystalloid lattice configuration and that the spherical aggregates are located in foci of viral synthesis. Marked pathogenicity of Coxsackie B4 virus in the newborn mouse pancreas should be considered a factor in the observations noted.     

Electron microscopic studies of bovine viral diarrhea virus in tissues of diseased calves and in cell cultures

Summary Pathomorfological studies by electron microscopy (EM) were carried out on the intestines and lymphoid tissues, the buffy coat cells and cultured lymphocytes from calves suffering from mucosal disease (MD). This led to the detection of particles, 45–55 nm in diameter, within characteristic vesicular structures. As these findings coincided with the isolation of bovine viral diarrhea virus (BVDV) from the same tissues and demonstration of BVDV-antigen by immunocytochemical techniques in corresponding samples, the particles were tentatively identified as the BVDV.A detailed study ofin vitro infected bovine cell cultures corroborated this supposition and contributed to a conjectural evaluation of the viral morphogenesis. It revealed a difference from the morphogenesis of most other togaviruses, as the presumed virions were assembled within smooth-membraned vesicles, formed during the infection. Thus, in the material examined, a budding process was not involved in the development of BVDV.With 11 Figures     

Tumour necrosis factor alfa and glucose levels in sera of mice infected with coxsackie B4 and A7 viruses.

Cytokines have been suggested to play an important role in the pathogenesis of type I diabetes mellitus through their direct and indirect effects on the pancreatic islet cells. We studied the time course of tumour necrosis factor alpha (TNF-alpha) and glucose levels in the sera of mice infected with coxsackie B4 and A7 viruses. Two correlating peaks of TNF-alpha and glucose were found. These results suggest the involvement of TNF-alpha in the damage of the insulin producing cells and thus an immunity-related inflammatory process.     

Clinicopathological study of coxsackie B viral myocarditis

Autopsy cases of myocarditis caused by Coxsackie viruses in two infants, aged 5 years and 10 months and 12 years, and two adults, aged 24 years and 45 years, were presented. Of the four cases, three revealed a rise in serum neutralization titer to Cox B,4 virus and one to both Cox B2 and Cox B4 viruses. Compared with the adult cases, the 2 infant cases showed less inflammatory response with relatively prominent hypertrophy in the heart. Both of the adult cases revealed intensive inflammatory reaction. Extensive inflammatory cell infiltration remained in one of the adult cases though the case survived about 4 years after manifestation of the infection, suggesting possible involvement of immunological factors.     

Complete nucleotide sequence of a strain of coxsackie B4 virus of human origin that induces diabetes in mice and its comparison with nondiabetogenic coxsackie B4 JBV strain

The E2 strain of coxsackie B4 virus (CB4), which is of human origin, can induce a diabetes-like syndrome in mice. The cDNA of the genome of the E2 strain was cloned and sequenced. The E2 viral genome was found to comprise 7,396 bases, which appear to encode a polyprotein of 2,183 amino acids with an overall similarity of 94.91% to nondiabetogenic CB4 prototype JBV strain. The E2 genome is organized like other enteroviruses. It has a 5′ noncoding region of 744 nucleotides, a single long open translational reading frame starting at nucleotide 745 and extending to nucleotide 7293, a 3′ noncoding region of 100 nucleotides, and a poly (A) tract. Ge-nomic sequence comparison of the E2 and JBV strains showed 1,369 nucleotide substitutions in the genome of the E2 strain, most of which are single and silent. There were 111 resultant amino acid changes arising from some of these substitutions, including 82 amino acid changes in the noncapsid proteins, and 29 amino acid changes in the capsid proteins VP1, VP2, VP3, and VP4, which showed 11, 13, 4, and 1 substitution(s), respectively. Noncapsid protein P2-C showed eight amino acid substitutions. On the basis of the sequence comparison of E2 and JBV strains of CB4, we suggest that some of the amino acid changes in the capsid and noncapsid proteins of the E2 strain may be involved in the determination of its diabetogenicity. © 1994 Wiley-Liss, Inc.     

Myocarditis in mice infected with Coxsackie virus B3.

Perimyocarditis in the heart of BALB/c mice infected with Coxsackie virus group B type 3 (CB3) was studied to determine whether it is limited to the right perimyocardium and to show whether or not perimyocarditis or myocardial lesions are produced in both left and right ventricles. CB3 was recovered from the heart on days from 2 to 13 after inoculation, but thereafter no virus was isolated from any part of the heart. Histopathologically, from days 1 to 4, hyaline or granular degeneration and necrosis of the muscle fibres with or without calcium deposits and an inflammatory mononuclear cell infiltration was limited to the right perimyocardium. On days 6 to 18, however, degeneration and necrosis of the muscle fibres and an inflammatory mononuclear cell infiltration were found not only in the right perimyocardium, but also in both left and right ventricular wall, the left perimyocardium, both right and left endomyocardium and the septum. In the right ventricular lesions, the incidence and intensity of the histopathological changes in the perimyocardium were greater than those in the muscular layer or septum. In contrast, in left ventricular lesions, the incidence and intensity of the histopathological changes in the muscular layers were greater than those in the peri- and endo--cardium. It is inferred, therefore, that the right perimyocardium and left ventricular wall are more susceptible to CB3 infection than right ventricular wall or left peri- and endocardium. It is concluded that CB3 can produce not only right-sided perimyocarditis, but also both right and left ventricular lesions and endocardial or septal changes in the mouse heart.     

Characterization of anti-heart antibodies in mice after infection with coxsackie B3 virus

Coxsackie virus B3 (CVB3) infection results in a marked inflammatory response and the production of autoantibodies to cardiac antigens, with cardiac myosin heavy chain documented to be the most immunogenic antigen. The present study investigated the temporal appearance of anti-heart antibodies in mice after mock infection or infection with an attenuated variant of CVB3 or wildtype CVB3 by SDS-PAGE and Western blotting. Further characterization of the autoantigens was carried out using 2D electrophoresis followed by Western blotting. Mice infected with wildtype CVB3 demonstrated high levels of IgG anti-heart antibodies, reacting predominantly with myosin heavy chain but also with numerous other myocardial proteins. Significant increases in anti-myosin heavy chain, anti-actin, and anti-tropomyosin antibodies were seen in wildtype-infected mice as early as day 7 postinfection compared to those mice that were mock infected or infected with attenuated virus. Characterization of other antigens revealed novel reactivities against myosin subfragments, heat shock proteins, and desmin and its subfragments.     

Ultrastructural lesions of the myocardial cell in Coxsackie B4 virus infected mice

Summary This study describes aspects of the specific changes which occur in the myocardial cells of Coxsackie B₄ virus infected suckling mice. These changes consisted of cellular shedding, membrane-vesicle complex formation, disappearance of Golgi body, nuclear shrinkage and densification of chromatin and an increase in ribosomal population. These changes are in addition to the nonspecific changes which probably result as a nonspecific cellular response to injury.

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Ultrastrukturelle Veränderungen an Muskelfasern des Myokards nach Infektion von Mäusen mit Coxsackie B₄-Virus

Zusammenfassung Beschreibung der elektronenoptischen Befunde in Herzmuskelfasern nach Infektion von Mäusesäuglingen mit Coxsackie B₄-Virus. Die Veränderungen bestehen im wesentlichen in einer Lockerung des Zellgefüges, Bildung von Komplexen aus membranösen Bläschen, Reduktion der Golgi-Körper, Kernschrumpfungen, Verdichtungen des Kernchromatins und Zunahme der Ribosomen. Zu diesen spezifischen Veränderungen kommen noch unspezifische Veränderungen, die bei jeder Zellschädigung beobachtet werden.

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Supported by grants from the U.S. Public Health Service, the Rudolph Matas Memorial Fund for the Kate Prewitt Hess Laboratory and the Rowell A. Billups Fund for Research in Heart Disease.