Direct antiviral effect of cycloferon (10-carboxymethyl-9-acridanone) against adenovirus type 6 in vitro.

Adenoviruses represent a broad group of human pathogens that currently have no specific and safe drugs for treatment. We demonstrated direct (non IFN-mediated) antiviral activity of cycloferon (10-carboxymethyl-9-acridanone, CMA), a potent interferon inducer, against adenovirus type 6 (Ad6) in Hep-2 cells. Virus production and details of morphogenesis were studied by ELISA with antibodies to the Ad6 hexon protein, and transmission electron microscopy, respectively. Immunoenzyme assay revealed that CMA does not inhibit viral protein synthesis but instead strongly reduces the ability of the virus to generate infectious progeny virus in a dose dependent manner. Ultrastructural study shows that CMA alters the structure of intranuclear virus-specific inclusions. We suggest that CMA suppresses the late stages of viral cycle in the infected cell.

Isolation and characterization of adenovirus 5 from the brain of an infant with fatal cerebral edema.

This report describes a fatal case of cerebral edema caused by adenovirus in a previously healthy 18-month-old infant who developed skin rash, pulmonary congestion, and fever and who died 6 days later. Adenovirus hexon gene sequences were detected in brain tissue and brain tissue cultures. The virus was typed as adenovirus 5.

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. Genomic 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.

Antibodies to glutamic acid decarboxylase and P2-C peptides in sera from coxsackie virus B4-infected mice and IDDM patients.

The possible role of amino acid sequence and epitope homologies between a protein P2-C of Coxsackie virus B4 and human GAD in the development of host-specific immune response in insulin-dependent diabetes mellitus (IDDM) (molecular mimicry) was investigated. Peptide antibodies to the P2-C protein, GAD65, and GAD67 were raised to analyze their immunoreactivity by enzyme-linked immunosorbent assay and immunoblotting with GAD purified from the brain and pancreas of mice that develop hyperglycemia after the infection. Additionally, antibody reactivity to these peptide antigens was assessed in sera from the virus-infected mice and IDDM patients. All three peptide antisera reacted very strongly with homologous peptides; P2-C antiserum cross-reacted with GAD65 as efficiently as GAD65 antiserum with P2-C, but no cross-reaction was detected between P2-C and GAD67 although cross-reaction between the two GADs was quite pronounced. P2-C antiserum immunocomplexed with GAD65 from mouse brain or pancreas, whereas GAD65 and GAD67 antisera both immunocomplexed with the two GADs from these sources. Most of the sera from virus-infected mice were reactive to brain and pancreas GAD65 and also to P2-C peptide, whereas some reacted to GAD65 and a few to GAD67 peptides. A number of IDDM sera reacted with mouse GAD65 and also with P2-C and GAD65 peptides, whereas only a few reacted with GAD67 peptide. The immunoreactivity of the mouse and IDDM sera to P2-C and GAD65 peptides was blocked by pre-adsorption with mouse GAD. The results suggest that molecular mimicry may play a role in the pathogenesis of the disease.

Coxsackievirus B4 alters pancreatic glutamate decarboxylase expression in mice soon after infection.

The 64,000-M(r) (64K) islet autoantigen, which is considered to be a target protein of beta cell destruction in insulin-dependent diabetes mellitus (IDDM), has recently been identified as the enzyme glutamic acid decarboxylase (GAD). We reported a two- to three-fold increased expression of the antigen in islets of diabetes-susceptible mice following infection with a diabetogenic strain of Coxsackievirus B4 (CB4) at 72-h postinfection (p.i.), a time point of active virus replication in the islets. Most of the infected animals subsequently developed 64K autoantibodies and hyperglycemia. Since the infection increases 64K expression, we have analysed immunoreactive GAD expression with a panel of peptide antisera and two widely-used polyclonal antisera against GAD, and measured GAD activity in the brain, pancreas and islets of these mice. Two isoforms, GAD65 and GAD67, are detected in these tissues from non-infected mice. Both GADs are also present in the infected mice brain at 72 h p.i.; however, their islets contain about three-fold more GAD65, and essentially no detectable GAD67. GAD activity is significantly higher in the brain compared with whole pancreas or islets, and islet GAD activity is higher than pancreas GAD activity. The infection significantly reduces islet GAD activity, but not brain GAD activity. CB4-induced abnormalities in islet GAD expression may play a role in virus-induced diabetes.

Lack of 64,000-M(r) islet autoantigen overexpression and antibody development following coxsackievirus B4 infection in diabetes-resistant mice.

Congenic B10.BR/SgSnJ H-2kTlaa mice were infected with a diabetogenic strain of coxsackievirus CB4 to correlate abnormalities of sugar metabolism with virus replication in islets, 64,000-M(r) (64K) islet autoantigen expression, 64K antibody development, and pancreas histopathology in early and late infection. Plaque assay was used to measure virus replication, whereas immunoprecipitation of the mouse islet extracts with 64K antibody-positive and -negative human sera measured autoantigen expression and antibody development. The infected mice exhibited blood glucose values below that of the noninfected control animals at 72 h postinfection, this subnormal blood glucose persisted at 6 wk postinfection and later. A baseline expression of the autoantigen was detected in the noninfected mice; however, the infected animals did not overexpress the protein at 72 h postinfection or develop 64K antibodies after infection. Limited virus replication was detected in the islets at 72 h postinfection but not later. Acinar necrosis, but not islet loss due to mononuclear cell infiltration, was evident in the infected mice. The congenic mice did not develop hyperglycemia and appear to be diabetes-resistant, their beta cells were largely preserved. This may be due to limited virus replication in their islets or their failure to overexpress the autoantigen and develop 64K antibodies following the infection. Diabetes-susceptible mice, on the contrary, support active virus replication in their islets, overexpress the autoantigen at 72 h postinfection, and develop 64K antibodies and hyperglycemia following such infection (Gerling et al., 1988, 1991).

Coxsackievirus B4 infection alters thymic, splenic, and peripheral lymphocyte repertoire preceding onset of hyperglycemia in mice.

Diabetogenic Coxsackievirus B4 infection may trigger autoimmune islet loss in diabetes-susceptible mice, resulting in hyperglycemia in nearly 90% of the animals at 6-8 weeks postinfection (p.i.). To ascertain whether changes in lymphocyte repertoire following infection could predispose these animals to diabetes, alterations in their thymic, splenic, and peripheral lymphocytes were analyzed. Additionally, lymphocyte changes were correlated with the virus load in these tissues and with lymphocyte migration to the inflammatory pancreas. Splenic B lymphocytes more than doubled at 72 hr p.i. and then continuously decreased by 16% of the noninfected controls at 8 weeks p.i. T lymphocytes (CD4+ + CD8+) decreased by about 50% at 72 hr and then increased to the control level by 8 weeks p.i.; CD8+ subset continuously decreased by 40% of the control at 8 weeks, resulting in a 67% increase in CD4+/CD8+ ratio. Macrophages and CD5+ B subset increased at 72 hr and then dipped by 93% and 84%, respectively, at 8 weeks. In contrast, peripheral B lymphocytes increased by 74% and T lymphocytes decreased by 11% at 8 weeks p.i. Macrophages increased by twofold at 72 hr and then dipped slightly (6%) at 8 weeks, whereas CD5+ B subset increased by 245%. Most prominent thymic T lymphocyte alteration was reflected by about 150% increase in CD4- CD8- cells at 8 weeks p.i. The peak viremia occurred at 72 hr p.i., with highest and lowest virus in the spleen and thymus, respectively. The thymus cleared virus by 3 days, the other tissues by 7 days. Insulitis and acinar necrosis followed infection; infiltrating lymphocytes were mostly CD4+. Virus-induced abnormal lymphocyte maturation may contribute to the development of insulitis and hyperglycemia.

Coxsackievirus B4-induced development of antibodies to 64,000-Mr islet autoantigen and hyperglycemia in mice.

Diabetogenic Coxsackievirus B4 infection produces a diabetes syndrome in susceptible mice resembling insulin-dependent diabetes mellitus. We reported a two- to threefold increased expression of a 64,000-Mr (64 K) islet autoantigen in the infected mice preceding the development of hyperglycemia, suggesting a possible role of the virus in autoimmunity. To assess if the virus could be a trigger of autoimmunity, 64 K autoantibody development was correlated with hyperglycemia and virus replication in islets during early and late infection. Additionally, the effects of blood removal from these mice on the incidence of hyperglycemia and antibody production were evaluated. Noninfected control mice were essentially 64 K antibody negative, the infected consistently positive. Approximately 30% of the animals developed antibodies by 72 h postinfection (p.i.) and 90% by 4-6 wk p.i. Virus-induced hyperglycemia appeared bimodal: hyperglycemia in 50% of the mice by 1 wk p.i., which decreased to 30% by 3 wk and then increased to 80-100% by 6 wk p.i. Infectious virus was abundant in the islets at 72 h but undetectable later. Hyperglycemia seen at 6 wk decreased dramatically (67-73%) if the mice were bled once between 72 h and 2 wk p.i. Only 50-60% of the mice bled once were 64 K positive compared to 90% positive nonbled mice. Coxsackievirus may initiate or enhance the autoimmune response.

Pancreatic D-cell disorder in coxsackievirus B4-induced diabetic mice.

Pancreatic D-cell disorder was analyzed in Coxsackievirus B4-induced diabetic mice employing molecular hybridization with a radiolabelled probe to quantitate somatostatin mRNA, and specific immunoprecipitation to measure somatostatin synthesis and its release. Many infected mice showed blood glucose lower than noninfected control animals at 72 h postinfection and 85% became hyperglycemic at 6-8 weeks postinfection. Pancreatic somatostatin decreased by 24% and 43% at 72 h and 6 weeks postinfection, respectively, while somatostatin release in islets from the infected mice increased by 2-fold or more. Residual islet somatostatin content after release was initially higher than control at 72 h and then declined at 6 weeks. Islet cellular RNA content decreased by 35% at 6 weeks, somatostatin mRNA content decreased by approximately 45% at 72 h and 6 weeks postinfection. D-cell disorder - somatostatin mRNA supply, synthesis, and release - is clearly evident in this model, which could be of significance in type I diabetes.

Detection of enteroviruses using subgenomic probes of Coxsackie virus B4 by hybridization.

The objective of this research was to develop group- and type-specific probes for the detection of enteroviruses. Coxsackie virus B4 RNA was cloned, and a series of subgenomic clones were generated. Six of these clones, containing sequences from the 3' end or the 5' end of the genome, were tested for their ability to detect these viruses in a small number of infected cells employing nucleic acid hybridization technique and total cytoplasmic RNA from a panel of 11 serotypes of enteroviruses. The RNA from cells infected with Coxsackie B viruses gave characteristic and positive hybridization signals. Coxsackie B-specific probes and a control Echo 9 probe detected Coxsackie A9 and Echo 3 weakly. As little as 0.5 microgram of the RNA--which contained 10-20 ng of poly(A)-containing, virus-specific, hybridizable RNA--was sufficient to successfully conduct the assay, suggesting high sensitivity of these probes. Probes that are 3' end-specific appear to be group specific, while those that are 5' end-specific appear to be type specific among the serotypes tested.

Effect of coxsackievirus B4 infection in mice on expression of 64,000-Mr autoantigen and glucose sensitivity of islets before development of hyperglycemia.

Diabetogenic strains of Coxsackievirus B4 (CB4) produce a diabetes syndrome in susceptible mice that resembles insulin-dependent diabetes mellitus. To assess the possible role of autoimmunity, the expression of a 64,000-Mr islet antigen in SJL/J and CD1 mice infected with a diabetogenic strain of CB4 was monitored in early and late infection. Additionally, virus-induced abnormalities in glucose metabolism were correlated with several changes in purified islets to assess beta-cell physiology. Over 80% of the mice exhibited subnormal blood glucose at 72 h postinfection (p.i.) and were hyperglycemic at 6 and 8 wk p.i. Islet yield in infected mice decreased by 29-47% at 72 h and 6 wk p.i. compared to noninfected mice. Insulin release stimulated by 16.7 mM glucose increased greater than twofold at 72 h p.i. but declined at 6 wk well below the level of noninfected mice. Likewise, residual islet insulin content after release also increased at 72 h and then declined. Total protein synthesis in the islets decreased by 30% at 72 h and by 60% at 6 wk p.i. Although the synthesis of five proteins of heterogeneous molecular weights, including tubulin, was severely depressed in the infected islets at 72 h p.i. compared with control islets or islets at 6 wk p.i., synthesis of the 64,000-Mr component and another protein of 36,000 Mr increased by two- to threefold. It is possible that CB4 infection may initiate or enhance an autoimmune reaction by increased expression of the 64,000-Mr antigen.

Purification and characterization of a strain of coxsackievirus B4 of human origin that induces diabetes in mice.

A diabetogenic strain of coxsackievirus B4 of human origin has been purified to study its biochemistry and diabetogenicity. Tissue culture cells infected with the virus contain two distinct types of particles--virions and membrane-bound virions (MBV). MBVs are lighter (p = 1.29) than virions (p = 1.34), and they contain relatively more protein than RNA. Virons contain four capsid proteins, VPI-4, of various molecular weights: VP1, 37,500; VP2, 36,000; VP3, 26,000; and VP4, 5,500. MBVs contain three of these proteins and several additional proteins of molecular weights 45,000 to greater than 92,500, possibly of host or viral origin. The RNA in each type of particle is a 35S molecule; T1 oligonucleotide fingerprint profiles suggest minor differences in the two RNAs. Hybridization experiments show a great deal of sequence homology between the RNA of the diabetogenic strain and the RNA of prototype CB4, which does not induce overt diabetes. MBVs are 10-70 times less infective than virions, yet they are more pathogenic in mice and induce significantly higher glucose intolerance (hyperglycemia). The hyperglycemic response appears to be lower in mice infected with both types of particles than in mice infected with MBVs alone. Thus, the two subpopulations of virions present in the diabetogenic strain differ biochemically and in their ability to induce diabetes.

Insulin mRNA content in pancreatic beta cells of coxsackievirus B4-induced diabetic mice.

Molecular hybridization was used to measure poly(A)-containing mRNA and insulin mRNA, and to evaluate viral persistence, in pancreatic beta cells of coxsackievirus B4-induced diabetic mice. Cellular RNA was hybridized with [3H]poly(U) to measure poly(A)-containing total mRNA, 32P-labeled preproinsulin I and II probes to measure insulin mRNA, and a 32P-labeled virus-specific probe to evaluate persistence. The infected mice (80-90%) showed subnormal blood glucose at 72 h postinfection and were hyperglycemic at 6 and 8 weeks. Poly(A)-containing total mRNA decreased by about 26% at 72 h and 6 weeks and by 49% at 8 weeks, while preproinsulin I mRNA by 30% and preproinsulin II by 46% at 8 weeks postinfection compared to control. Viral sequences were abundant at 72 h and in fair amounts later. It appears that persistent viral infection produces a pathological state, which impairs beta cell function to reduce insulin mRNA and consequently insulin synthesis apparently leading to hyperglycemia.

Protein kinase in nondiabetogenic coxsackievirus B4.

Alkali-dissociated, purified preparations of prototype coxsackievirus B4 release a protein kinase that catalyzes the incorporation of gamma-phosphate from 32P-labeled ATP into three virus capsid proteins (VP1, VP3, VP4), several additional proteins of the particle, and exogenous acceptor proteins. Using protamine sulfate as an acceptor protein, we detected nearly 20-fold more enzyme activity in membrane-bound virions (MBV) than in virions of the virus. The activity in the MBV is cyclic nucleotide-independent, divalent cation-dependent, and has a pH optimum of 8.0. Phosphoserine is labeled with 32P. The enzyme activity sediments at about 5S and is separated into at least two peaks of heterogeneous proteins by ion-exchange chromatography. The patterns of phosphorylation by these enzyme peaks are somewhat similar. Coxsackievirus-associated protein kinase appears to be located internally in the virus and may be host-cell-coded. The enzyme appears to be lacking in a variant of the virus that produced diabetes in mice.

Functional alterations in pancreatic beta cells as a factor in virus-induced hyperglycemia in mice.

Alterations in the functional capacity of pancreatic beta cells appear to contribute to coxsackievirus B4-induced, long-term hyperglycemia in mice. Mice infected with prototype B4 or its diabetogenic E2 variant were monitored for abnormalities in sugar metabolism (by the glucose tolerance test), for total protein and insulin synthesis in intact beta cells, for alterations in beta cell proteins, and for virus replication. The infected mice were hypoglycemic at 72 h postinfection and hyperglycemic at 6 weeks. At 8 weeks postinfection, few of the prototype- but most of the E2-infected mice remained hyperglycemic. Total protein and synthesis of immunoprecipitable insulin decreased during early infection. At 8 weeks postinfection, insulin synthesis in the prototype-infected mice increased almost to the level of control mice. Although insulin synthesis increased likewise in the E2-infected mice, it remained well below the control level. Two-dimensional gel electrophoresis revealed the disappearance of many cellular proteins in beta cells from E2-infected mice but of very few in cells from prototype-infected mice at 72 h postinfection. Many of the disappearing proteins reappeared gradually in the E2-infected group. Infectious virus was recovered from the infected beta cells only at 72 h postinfection. Functional impairment in these cells appears to be a factor in virus-induced hyperglycemia.

Membrane-bound virions of coxsackievirus B4: cellular localization, analysis of the genomic RNA, genome-linked protein, and effect on host macromolecular synthesis.

Hela cells infected with several group B coxsackieviruses contain, in addition to standard virions, a population of virus-specific ribonucleoprotein particles which we (5) designated membrane-bound virions (MBV). MBVs differ from standard virions in buoyant density, yield, appearance, protein composition and infectivity. Here we present several new features of MBVs of coxsackievirus B4. The MBVs are lighter (rho about 1.30) and are localized in rough membranes, intermixed with virions. They contain 35S virion RNA covalently linked with a small protein, VPg. The VPg contain two proteins of different charge. MBV VPg is considerably smaller than the 5300-dalton virion VPg. MBV RNA is homologous to the base sequence present in B4 virus double-stranded RNA. The T1 oligonucleotide fingerprint of MBV RNA is distinguishable from that of virion RNA by one oligonucleotide. Several oligonucleotides of virion RNA appear to occur in submolar quantities in MBV RNA. MBVs are 75 to greater than 200 times less infective; they inhibit host cell macromolecular synthesis less efficiently than virions. In coinfected cells, the extent of inhibition of host synthesis is less severe than in cells infected with virions alone, which suggest interference by MBV particles.

Differences in sequence content of nuclear and cytoplasmic polyribosomal RNA from adenovirus-infected cells.

RNA molecules from nuclear and cytoplasmic polyribosomes of adenovirus-infected HeLa cells were compared by hybridization to analyse the sequence content. Nuclear polyribosomes were released by exposure of intact detergent-washed nuclei to poly(U) and purified. Cytoplasmic polyribosomes were also purified from the same cells. To show that nuclear polyribosomes contain ribosomes linked by mRNA, polyribosomes were labelled with methionine and uridine in the presence of actinomycin D in adenovirus-infected cells. Purified nuclear polyribosomes were treated with EDTA under conditions which dissociate polyribosomes into ribosomes and subunits with a simultaneous release of mRNA, and sedimented. The treatment dissociated these polyribosomes, releasing the mRNA from them. Radiolabelled total RNA from each polyribosome population was fractionated in sucrose gradients into several pools or hybridized to intact adenovirus DNA to select virus-specific RNA. Sucrose-gradient-fractionated pool-3 RNA (about 28S) and virus-specific RNA were then hybridized to fragments of adenovirus DNA cleaved by restriction endonucleases SmaI, HindIII and EcoRI by the Southern-blot technique and by filter hybridization. The results showed that nuclear RNA contained sequences, from about 0 to 18 map units, which were essentially absent from cytoplasmic RNA. Furthermore, the amount of virus-specific RNA for a particular sequence was also different in the two populations.

RNA and protein synthesis and kinetics of processing and release of insulin in cultures of mouse pancreatic beta cells.

Monolayer cultures of mouse pancreatic beta cells were used to study protein composition, the extent and nature of RNA and protein synthesis, and the kinetics of insulin precursors synthesis, precursor processing, and the release of nascent insulin. The cells synthesized both RNA and proteins actively, but the amounts synthesized declined with the age of the culture. The size and spectrum of proteins synthesized in cells soon after isolation and after maintenance in culture were very similar. At least 15 proteins (mol. wt. 66,000 to less than 14,000) were synthesized, including insulin precursors and insulin. Radioactive labeling and chase experiments revealed the synthesis of insulin precursors and insulin continuously. Radioactivity present in the precursors decreased rapidly during the early times of chase. This reduction in radioactivity was partly due to the processing of insulin precursors into insulin and partly due to the release of proinsulin into the medium along with newly synthesized insulin. The residual labeled precursors turned over at a slower rate. It appears that the processing of insulin precursors is two-phase-initially rapid and then slow and prolonged, which could have resulted from two populations of precursors with different half-lives.