Potential zoonotic pathogens hosted by endangered bonobos

Few publications, often limited to one specific pathogen, have studied bonobos (Pan paniscus), our closest living relatives, as possible reservoirs of certain human infectious agents. Here, 91 stool samples from semicaptive bonobos and bonobos reintroduced in the wild, in the Democratic Republic of the Congo, were screened for different infectious agents: viruses, bacteria and parasites. We showed the presence of potentially zoonotic viral, bacterial or parasitic agents in stool samples, sometimes coinfecting the same individuals. A high prevalence of Human mastadenoviruses (HAdV-C, HAdV-B, HAdV-E) was observed. Encephalomyocarditis viruses were identified in semicaptive bonobos, although identified genotypes were different from those identified in the previous fatal myocarditis epidemic at the same site in 2009. Non-pallidum Treponema spp. including symbiotic T. succinifaciens, T. berlinense and several potential new species with unknown pathogenicity were identified. We detected DNA of non-tuberculosis Mycobacterium spp., Acinetobacter spp., Salmonella spp. as well as pathogenic Leptospira interrogans. Zoonotic parasites such as Taenia solium and Strongyloides stercoralis were predominantly present in wild bonobos, while Giardia lamblia was found only in bonobos in contact with humans, suggesting a possible exchange. One third of bonobos carried Oesophagostomum spp., particularly zoonotic O. stephanostomum and O. bifurcum-like species, as well as other uncharacterized Nematoda. Trypanosoma theileri has been identified in semicaptive bonobos. Pathogens typically known to be transmitted sexually were not identified. We present here the results of a reasonably-sized screening study detecting DNA/RNA sequence evidence of potentially pathogenic viruses and microorganisms in bonobo based on a noninvasive sampling method (feces) and focused PCR diagnostics.

Molecular characterization of encephalomyocarditis virus strains isolated from an African elephant and rats in a French zoo

In November 2013, a fatal encephalomyocarditis virus (EMCV) case in a captive African elephant (Loxodonta africana) occurred at the Réserve Africaine de Sigean, a zoo in the south of France. Here we report the molecular characterization of the EMCV strains isolated from samples collected from the dead elephant and from 3 rats (Rattus rattus) captured in the zoo at the same time. The EMCV infection was confirmed by reverse-transcription real-time PCR (RT-rtPCR) and genome sequencing. Complete genome sequencing and sequence alignment indicated that the elephant's EMCV strain was 98.1-99.9% identical to the rat EMCV isolates at the nucleotide sequence level. Phylogenetic analysis of the ORF, P1, VP1, and 3D sequences revealed that the elephant and rat strains clustered into lineage A of the EMCV 1 group. To our knowledge, molecular characterization of EMCV in France and Europe has not been reported previously in a captive elephant. The full genome analyses of EMCV isolated from an elephant and rats in the same outbreak emphasizes the role of rodents in EMCV introduction and circulation in zoos.

Mastomys natalensis is a possible natural rodent reservoir for encephalomyocarditis virus

Encephalomyocarditis virus (EMCV) infects a wide range of hosts and can cause encephalitis, myocarditis, reproductive disorders and diabetes mellitus in selected mammalian species. As for humans, EMCV infection seems to occur by the contact with animals and can cause febrile illnesses in some infected patients. Here we isolated EMCV strain ZM12/14 from a natal multimammate mouse (Mastomys natalensis: M. natalensis) in Zambia. Pairwise sequence similarity of the ZM12/14 P1 region consisting of antigenic capsid proteins showed the highest similarity of nucleotide (80.7 %) and amino acid (96.2%) sequence with EMCV serotype 1 (EMCV-1). Phylogenetic analysis revealed that ZM12/14 clustered into EMCV-1 at the P1 and P3 regions but segregated from known EMCV strains at the P2 region, suggesting a unique evolutionary history. Reverse transcription PCR (RT-PCR) screening and neutralizing antibody assays for EMCV were performed using collected tissues and serum from various rodents (n=179) captured in different areas in Zambia. We detected the EMCV genome in 19 M. natalensis (19/179=10.6 %) and neutralizing antibody for EMCV in 33 M. natalensis (33/179=18.4 %). However, we did not detect either the genome or neutralizing antibody in other rodent species. High neutralizing antibody litres (≧320) were observed in both RT-PCR-negative and -positive animals. Inoculation of ZM12/14 caused asymptomatic persistent infection in BALB/c mice with high antibody titres and high viral loads in some organs, consistent with the above epidemiological results. This study is the first report of the isolation of EMCV in Zambia, suggesting that M. natalensis may play a role as a natural reservoir of infection.

[Isolation, identification and full-length genome sequence analysis of encephalomyocarditis virus from local aardvarks]

Encephalomyocarditis virus (EMCV) is a natural epidemic zoonotic pathogen. However, no reports have been published regarding the isolation, identification and full-length genome of EMCV from a local aardvark population. In present study, an EMCV isolate HNXX13 was isolated from aardvarks named Huainan-pig in Henan Province. The systematic identification, full-length genome sequencing and molecular characteristic analysis of the isolate HNXX13 were conducted. The result showed that the isolate was spherical with a diameter of 24-30 nm, neither heat- nor acid-resistant, sensitive to trypsin, insensitive to chloroform, not protected by bivalent cationic, and the specific fluorescence was observed in the cytoplasm of BHK-21 cells infected with the isolate by using indirect fluorescence assay. The full-length genome of EMCV HNXX13 generated a 7 725bp sequence (GenBank: F771002), with 81.0%-99.9% nucleotide identity to reference strains from different animals, and 99.5% with a Chinese reference strain isolated earlier from a commercial pig herd. The phylogenetic tree based on the full-length genome and ORF sequences identified that all EMCV strains were divided into three groups G1, G2 and G3, and strain HNXX13 belonging to the G1 group with other Chinese reference strains. The result also identified that this EMCV infection could cause severe clinical signs in a local aardvark population, and enriches the molecular epidemiological data of EMCV in China. Regional differences exist in EMCV genome and transmission is limited within a certain area. However, the cross-infection and transmission of EMCV between aardvark and mice appears most likely. Mutations have occurred in some amino acids of EMCV strain HNXX13 during the transmission in local aardvark herd and these mutations might make the virus easier to infect the aardvark.

Development of a TaqMan-based real-time reverse transcription polymerase chain reaction assay for the detection of encephalomyocarditis virus

Encephalomyocarditis virus (EMCV) is one of the major zoonosis pathogens and can cause acute myocarditis in young pigs or reproductive failure in sows. In this study, a TaqMan-based real-time reverse transcription polymerase chain reaction (RT-PCR) assay targeting 3D gene of EMCV was developed and their sensitivities and specificities were investigated. The results indicated that the standard curve had a wide dynamic range (10(1)-10(6) copies/μL) with a linear correlation (R(2)) of 0.996 between the cycle threshold (Ct) value and template concentration. The real-time RT-PCR assay is highly sensitive and able to detect 1.4×10(2) copies/μL of EMCV RNA, as no cross-reaction was observed with other viruses. These data suggested that the real-time RT-PCR assay developed in this study will be suitable for future surveillance and specific diagnosis of EMCV-infection.

Rapid detection of encephalomyocarditis virus by one-step reverse transcription loop-mediated isothermal amplification method

The encephalomyocarditis virus (EMCV) can cause acute myocarditis in young pigs or reproductive failure in sows. In this study, a reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay was developed to detect EMCV RNA. The RT-LAMP assay was highly sensitive and able to detect 2.2 × 10(-5)ng of EMCV RNA, as no cross-reaction was observed with other viruses. The RT-LAMP assay was conducted in isothermal (62 °C) conditions within 50 min. The amplified products of EMCV could be detected as ladder-like bands using agarose gel electrophoresis. This is the first report to demonstrate the application of a one-step RT-LAMP assay for the detection of EMCV. The sensitive, specific and rapid RT-LAMP assay developed in this study can be applied widely in clinical diagnosis and field surveillance of EMCV.

Effects of Tacrolimus (FK506) on Encephalomyocarditic Virus-Induced Diabetes in Mice

The effects of tacrolimus on insulin-dependent diabetes mellitus (IDDM) induced by the D-variant of encephalomyocarditis virus (D-EMCV) have been investigated. Male BALB/c mice were treated with tacrolimus before viral inoculation, and then were inoculated with 10 plaque forming units (PFU) of DEMCV. The mice continued to be treated with tacrolimus until the animals were sacrificed. D-EMCV-infected mice, which were treated with saline as controls, showed abnormal glucose tolerance test (GTT) values, whereas all infected mice with tacrolimus pretreatment were normal on 7 days-post inoculation (DPI). Histological observations revealed that non-treated tacrolimus D-EMCV-infected mice and which developed diabetes showed severe insulitis in their islets of Langerhans. On the other hand, D-EMCV-infected mice treated with tacrolimus were normal. In D-EMCV-infected mice, viruses in the pancreata were detected at the same level regardless of treatment with tacrolimus or saline. Expressions of TNF-alpha and IFN-gamma mRNA in spleens of tacrolimus-treated D-EMCV-infected mice were lower than that of non-treated tacrolimus DEMCV-infected mice on 7 DPI. The results suggest that tacrolimus suppresses expressions of TNF-alpha and IFN-gamma mRNAs to prevent the onset of D-EMCV-induced IDDM.

Isolation, molecular characterization, and phylogenetic analysis of porcine encephalomyocarditis virus strain HB10 in China

Encephalomyocarditis virus (EMCV) can cause myocarditis, respiratory failure, reproductive failure, and mortality in pregnant sows, fetuses, and ablactating piglets. Diseases caused by EMCV currently affect the swine industry worldwide. A virus was isolated from organs of dead piglets that presented with acute myocarditis in northern China. The production of a specific cytopathic effect on susceptible cells and the results of hemagglutination inhibition (HI) assay, PCR, electron microscopy (EM), and sequencing indicated that the pathogen was EMCV; the strain was named HB10. Other pathogenic agents causing myocarditis and death were excluded as possible pathogenic agents. Phylogenetic analyses of the capsid coding region and the VP3/VP1 genes using the neighbour-joining method revealed that EMCV isolates cluster into two groups (groups 1 and 2) with two sub-clusters within group 1 (group 1a and b). HB10 belongs to group 1a, along with strains CBNU, GX0601, BJC3, NJ08, and BEL-2887A/91. Five strains isolated from Sus scrofa belong to group 2. The results of this and previous studies indicate that HB10 and other EMCV strains cause myocarditis of pigs in China.

Pathogenicity and molecular analysis of an encephalomyocarditis virus isolate from mideastern China

Encephalomyocarditis virus (EMCV) can infect many host species and cause acute myocarditis and sudden death in preweaned piglets. In this study, an EMCV strain (NJ08) was isolated from newborn pigs with clinical signs on a pig farm in mideastern China. It was identified by indirect immunofluorescence assay and reverse-transcription polymerase chain reaction. Experiments showed that the isolate could cause severe clinical symptoms and pathological changes in mice but no obvious clinical and pathological changes in commercial piglets. Complete genomic sequencing showed that the NJ08 strain was 78.3% to 100% identical with other isolates in regions coding for various proteins. Phylogenetic analysis showed that the NJ08 isolate belonged to subgroup Ia. This study confirmed that an EMCV isolate from pigs could be fatal to mice and provided new epidemiologic data on EMCV in China.

[Sequencing and analysis of the complete genome of encephalomyocarditis virus strain GXLC isolated from swine]

The complete genome of encephalomyocarditis virus (EMCV)strain GXLC isolated from swine was sequenced and analyzed. Five overlapped gene fragments covering the entire open reading frame (ORF) were amplified by RT-PCR, and the 3'-untranslated region (UTR) and 5'-UTR were amplified by the 3'-rapid amplification of cDNA ends (RACE) and 5'-RACE method, respectively. The genome sequences of strain GXLC were obtained by assembling the sequences of RT-PCR-generated cDNA fragments. The length of the complete genome was 7 725 nucleotides (nt). The homology comparison and phylogenetic analysis of the nucleotide and deduced amino acid sequences between strain GXLC and other EMCV strains available in GenBank were performed. The results showed that the complete genome identity between GXLC strain and the strains from China, i.e. GX0601, GX0602, BJC3 and HB1 and the strains from other countries, i.e. CBNU, K3, K11, TEL-2887A, EMCV-R and PV21 was over 99%. The phylogenetic trees based on the complete genome, the structural protein or the non-structural protein gene sequences revealed that the tree topology was similar. All the EMCV strains could be divided into two groups: group I and group II, and group I could be subdivided into subgroup Ia and subgroup Ib. The strains from swine belonged to subgroup Ia or Ib, and the strains from mice belonged to subgroup Ia, while the strains from Sus scro fa belonged to group II. Strain GXLC, together with other EMCV isolates from China, belonged to subgroup Ia.

Stimulation of picornavirus replication by the poly(A) tail in a cell-free extract is largely independent of the poly(A) binding protein (PABP)

Picornavirus infectivity is dependent on the RNA poly(A) tail, which binds the poly(A) binding protein (PABP). PABP was reported to stimulate viral translation and RNA synthesis. Here, we studied encephalomyocarditis virus (EMCV) and poliovirus (PV) genome expression in Krebs-2 and HeLa cell-free extracts that were drastically depleted of PABP (96%-99%). Although PABP depletion markedly diminished EMCV and PV internal ribosome entry site (IRES)-mediated translation of a polyadenylated luciferase mRNA, it displayed either no (EMCV) or slight (PV) deleterious effect on the translation of the full-length viral RNAs. Moreover, PABP-depleted extracts were fully competent in supporting EMCV and PV RNA replication and virus assembly. In contrast, removing the poly(A) tail from EMCV RNA dramatically reduced RNA synthesis and virus yields in cell-free reactions. The advantage conferred by the poly(A) tail to EMCV synthesis was more pronounced in untreated than in nuclease-treated extract, indicating that endogenous cellular mRNAs compete with the viral RNA for a component(s) of the RNA replication machinery. These results suggest that the poly(A) tail functions in picornavirus replication largely independent of PABP.

Partitioning and inactivation of viruses by the caprylic acid precipitation followed by a terminal pasteurization in the manufacturing process of horse immunoglobulins

Caprylic acid (octanoic acid), has been used for over 50 years as a stabilizer of human albumin during pasteurization. In addition caprylic acid is of great interest, by providing the advantage of purifying mammalian immunoglobulins and clearing viruses infectivity in a single step. Exploiting these two properties, we sequentially used the caprylic acid precipitation and the pasteurization to purify horse hyperimmune globulins used in the manufacturing of Sérocytol. To evaluate the effectiveness of the process for the removal/inactivation of viruses, spiking studies were carried out for each dedicated step. Bovine viral diarrhoea virus (BVDV), pseudorabies virus (PRV), encephalomyocarditis virus (EMCV) and minute virus of mice (MVM) were used for the virological validation. Our data show that the treatment with caprylic acid 5% (v/v) can effectively be used as well to purify or to ensure viral safety of immunoglobulins. Caprylic acid precipitation was very efficient in removing and/or inactivating enveloped viruses (PRV, BVDV) and moderately efficient against non-enveloped viruses (MVM, ECMV). However the combination with the pasteurization ensured an efficient protection against both enveloped and non-enveloped viruses. So that viruses surviving to the caprylic acid precipitation will be neutralized by pasteurization. Significant log reduction were achieved > or =9 log(10) for enveloped viruses and 4 log(10) for non-enveloped viruses, providing the evidence of a margin of viral safety achieved by our manufacturing process. Its a simple and non-expensive manufacturing process of immunoglobulins easily validated that we have adapted to a large production scale with a programmable operating system.

Assessment of viral inactivation during pH 3.3 pepsin digestion and caprylic acid treatment of antivenoms

Antivenoms are manufactured by the fractionation of animal plasma which may possibly be contaminated by infectious agents pathogenic to humans. This study was carried out to determine whether pre-existing antivenom production steps, as carried out by EgyVac in Egypt, may reduce viral risks. Two typical manufacturing steps were studied by performing down-scaled viral inactivation experiments: (a) a pH 3.3 pepsin digestion of diluted plasma at 30 degrees C for 1h, and (b) a caprylic acid treatment of a purified F(ab')2 fragment fraction at 18 degrees C for 1h. Three lipid-enveloped (LE) viruses [bovine viral diarrhoea virus (BVDV), pseudorabies virus (PRV), and vesicular stomatitis virus (VSV)] and one non-lipid-enveloped (NLE) virus [encephalomyocarditis virus (EMC)] were used as models. Kinetics of inactivation was determined by taking samples at 3 time-points during the treatments. The pH 3.3 pepsin digestion resulted in complete clearance of PRV (>7.0 log(10)) and in almost complete reduction of VSV (>4.5 but < or =6.4 log(10)), and in a limited inactivation of BVDV (1.7 log(10)). EMC inactivation was > or =2.5 but < or =5.7 log(10). The caprylic acid treatment resulted in complete inactivation of the 3 LE viruses tested: BVDV (>6.6 log(10)), PRV (>6.6 log(10)), and VSV (>7.0 log(10)). For EMC no significant reduction was obtained (0.7 log(10)). Cumulative reduction was >13.6, >11.5, >8.3 and > or =2.5 for PRV, VSV, BVDV and EMC, respectively. Therefore the current manufacturing processes of at least some animal antisera already include production steps that can ensure robust viral inactivation of LE viruses and moderate inactivation of a NLE virus.

Genomic analysis of two porcine encephalomyocarditis virus strains isolated in China

Two strains of encephalomyocarditis virus (EMCV), designated BJC3 and HB1, were isolated from an aborted fetus and the heart tissue of a dead piglet that had pericardial fluid, respectively. The complete genomic sequences of the two viruses were determined and analyzed. The size of the genomes of BJC3 and HB1 were 7746 and 7735 nucleotides, respectively, including poly(A) tails. Comparative analysis with the genomic sequences of other EMCV strains showed that BJC3 and HB1 shared higher identity (92.5-99.6%) with BEL-2887A/91, EMCV-R and PV21, but lower identity (83.3-84.6%) with EMC-B, EMC-D and D variants, and only 81.0% with Mengo virus. Two amino acid mutations in the leader protein of the two viruses and one amino acid substitution in VP1 of BJC3 were found in comparison to other EMCV strains Phylogenetic analysis based on the amino acid sequences of the entire ORF revealed that the two Chinese isolates BJC3 and HB1 clustered together with the strains BEL-2887/91, EMCV-R and PV21, which belong to the same genetic subgroup as EMCV-30. Our results provide genomic information for EMCV isolated in China.

Serological survey of encephalomyocarditis virus infection in pigs in France

Samples of serum from 76 gilts, 1440 sows, 1473 piglets and 3093 finishing pigs from 96 farrow-to-finish herds were tested for antibodies to encephalomyocarditis virus (EMCV) in microtitre serum neutralisation tests employing two strains of virus, one associated with myocarditis and the other with reproductive failure. The total seroprevalence of EMCV infection was 2.48 per cent. There was no significant difference between the seroprevalence of the reproductive failure strain (1.6 per cent) and the myocardial strain (1.85 per cent). The seroprevalence was higher in the gilts (6.57 per cent) and sows (5.13 per cent) than in the piglets (1 per cent) and finishing pigs (1.84 per cent), and the highest titres were observed in the sows (1:540) and finishing pigs (1:640). In the gilts, the difference in seroprevalence between the reproductive failure strain (3.95 per cent) and the myocardial strain (5.33 per cent) was wider than in the other groups.

Relevance of inflammatory cell infiltrates for complete atrioventricular block in experimental murine myocarditis

BACKGROUND

There are few systemic pathologic studies on myocarditis. This study aimed to clarify the pathologic characteristics of murine myocarditis.

METHODS

We recorded serial electrocardiograms in experimental viral myocarditis in mice and then examined their cardiac pathology. After taking baseline electrocardiograms, we inoculated the mice intraperitoneally with the encephalomyocarditis virus. Electrocardiograms were serially recorded until 220 days after the virus inoculation.

RESULTS

Serial electrocardiograms revealed ectopic beats, low voltage of the QRS complex, and the appearance of complete atrioventricular (AV) block. Corresponding myocardial lesions were found in the hearts of mice with these ectopic beats. Mononuclear cell infiltrations into the His bundle were most frequently found in mice with complete AV block.

CONCLUSIONS

Inflammatory change with cellular infiltrations was the most common pathologic finding in mice with complete AV block. In clinical settings, anti-inflammatory therapy might be recommended for patients with myocarditis complicated with conduction disturbances.

Genetic variability of encephalomyocarditis virus (EMCV) isolates

In order to evaluate the variability of encephalomyocarditis virus (EMCV), field isolates originating from different European regions and inducing different clinical pictures in pigs have been molecularly characterised. The regions targeted were the poly(C) tract, a part of the 5'-UTR (360 nucleotides), the Leader gene (201 nucleotides), the complete capsid coding region (2502 nucleotides), the 2A gene (403 nucleotides), the end of the 3D polymerase gene (305 nucleotides) and the 3'-UTR (123 nucleotides). Analyses have also been performed on a virulent field isolate, which had been subjected to serial passages in vivo and in vitro resulting, in the case of the in vitro passaged virus, in attenuation, as demonstrated by animal experiments. The present study shows that different clinical pictures, such as acute fatal myocarditis or reproductive failure, may not only be caused by EMCV isolates which are genetically diverse but also by the same isolate. Thus no correlation could be demonstrated between genotype and clinical disease. However, the European isolate which showed the highest genetic divergence also gave rise to a more complex clinical picture. Despite EMCV having been isolated from cases of acute fatal myocarditis in pigs in certain areas of the world for many years, clinical disease, including a variety of clinical pictures and pathogenicity, has only been recognised in Europe since 1986 and thus it can be considered an emerging disease in this region. These findings, associated with the reported phenotype changes of the virus under environmental changes (passages), along with its wide distribution among vertebrate species (including higher primates), shows the validity of considering EMCV as a potential pathogen for recipients in xenotransplantation.

Pathogenesis of encephalomyocarditis experimental infection in young piglets: a potential animal model to study viral myocarditis

The pathogenesis of encephalomyocarditis (EMC) due to the EMC virus (EMCV) was studied in 24 piglets oro-nasally infected with the field isolate B279/95. Two pigs were kept as negative controls and were euthanised at hour 0. The remaining 24 were euthanised every 6 h up to 78-h post infection (hpi). Virus isolation, histological examination and EMCV immunodetection were performed on the spleen, intestine, pancreas, liver, kidneys, heart, lungs, lymph nodes, tonsils and brain. EMCV was isolated at 6-hpi from the intestine and lymph nodes and at 12-hpi from the heart. From 6 to 12-hpi, scattered degenerate myocardiocytes were immunolabelled. Subsequently, myocarditis developed and progressively worsened. Immunopositive reaction in tonsil macrophages, observed in the early stage of infection (6-hpi), suggests that tonsils are the portal of entry, and by mean of wandering macrophages the EMC virus is then distributed through the body. Afterwards, EMCV-B279/95 replicates intensively in the cytoplasm of myocardiocytes and the acute myocarditis is strictly related to the tropism of these cells. Four pigs died spontaneously. In three animals no post mortem lesions or virus were isolated/detected, although all of them showed mild myocarditis. The experimental infection with EMCV B279/95 indicates: (i) the experimental protocol mimics the individual variability observed in natural disease, (ii) tonsils are the portal of entry of infection and the heart is the target organ, (iii) EMCV provides a valuable animal model for comparative studies on progressive viral myocarditis.

Pathogenesis of experimental encephalomyocarditis: a histopathological, immunohistochemical and virological study in rats

Rats (n=40) aged 8 weeks were infected, either by oronasal inoculation or by contact, with one of two different myocardial strains of encephalomyocarditis virus (EMCV), namely, the Greek strain 424/90 and the Belgian strain B279/95. The animals were killed at 11-62 days post-infection (dpi) and samples of brain, heart, pancreas, kidney, Peyer's patches, spleen, lung and thymus were processed for virological, histopathological and immunohistochemical evaluation. This experimental infection was inapparent, but virus was isolated from faeces and several organs of all animals. The main histopathological changes were focal interstitial pancreatitis, degeneration and necrosis of pancreatic acinar cells, depletion of thymus and Peyer's patches, and interstitial pneumonia. EMCV antigen was detected in the cytoplasm of cardiac muscle cells, pancreatic acinar cells and hepatic epithelial cells, and in macrophages of the spleen, lung and thymus. In the heart (the target organ of EMCV in pigs), the presence of EMCV in cardiac muscle cells without lesions lends support to the hypothesis that the rat is a natural reservoir host species of EMCV. The persistence of virus in the macrophages of the thymus may represent a mechanism of perpetuation and reactivation, under immunosuppressive conditions, of the infection.

The occurrence of encephalomyocarditis virus (EMCV) in European pigs from 1990 to 2001

The occurrence of encephalomyocarditis virus (EMCV) among domestic pigs and wild boar in several European countries is described and discussed. From 1990 to 2001 clinical outbreaks were analysed and serum samples, partly from existing screening programmes, were tested for antibodies against EMCV. Most clinical EMCV outbreaks were reported in Belgium (320), followed by Italy (110), Greece (15) and Cyprus (6). The outbreaks appeared to be clustered in 'endemic areas' with an increase in outbreaks during the autumn and winter months. The within-herd seroprevalence measured in clinically affected pig farms varied considerably among farms (2-87%), with age (0-84%) and by country. Data from farms with no clinical disease showed that subclinical infection with EMCV was found both within (seroprevalence 6-62%) and outside (up to 17 %) the endemic areas of the clinically affected countries as well as in the non-clinically affected countries Austria and France (3-5.4%). Among wild boar, the seroprevalence varied between 0.6 and 10.8%, and a study in Belgium found a prevalence of virus infection of 3.3%.

Evaluation of virus decontamination techniques for porcine embryos produced in vitro

The objective of this study was to explore approaches to decontaminate embryos either contaminated naturally or under experimental conditions with different viruses. Embryos were obtained from in vitro maturation and fertilisation of porcine oocytes. After 7 days of development, morula and blastocyst stages were exposed for 1 h to the following viruses: encephalomyocarditis virus (EMCV), porcine circovirus type 2 (PCV2), porcine parvovirus (PPV), porcine reproductive and respiratory syndrome virus (PRRSV), and bovine viral diarrhea virus (BVDV) at an infectivity of 100 TCID50/mL. Embryos samples were treated with different washing procedures, which all included the following standard washing solutions: PBS+0.4% BSA (five times for 10 s), Hank's+0.25% trypsin (two times for 60-90 or 120-150 s, or one time of 5 min), Hank's+0.1 mg/mL DNase 1+20 U/mL RNase One (one time of 30 min) and PBS+0.4% BSA again (five times for 10s). Two new approaches were used to improve trypsin treatment, 0.1% hyaluronidase (one time for 5 min) instead of trypsin and a pre-incubation with oviductal cells. Therefore, in the first experiment, oocytes received standard maturation treatments and in the second, they were also co-incubated with oviductal cells for the last 3 h of maturation. The effectiveness of the different washing techniques in removing viruses was evaluated by polymerase chain reaction (PCR) analysis. In the first experiment, trypsin treatment did not eliminate PRRSV, PPV, PCV, and EMCV from contaminated embryos. Surprisingly, treatment with hyaluronidase eliminated all tested viruses. In the second experiment, all viruses tested were removed from the oocytes following the different enzymatic treatments. In conclusion, in vitro embryo decontamination was more effective following exposure to oviductal secretions and hyaluronidase eliminated more virions than trypsin in washing techniques.

Encephalomyocarditis in Monkeys

This paper presents the results of studies of a spontaneous viral infection in monkeys--encephalomyocarditis caused by encephalomyocarditis virus. The infection first detected in the Sukhumi Breeding Center in 1974 was observed in the Adler Breeding Center since 2001. The characteristics of the virus are described and principles of diagnostic by the results of pathologic studies are presented.

Transplanting encephalomyocarditis virus-infected porcine islet cells reverses diabetes in recipient mice but also transmits the virus

Previous studies demonstrated that porcine encephalomyocarditis virus (EMCV) caused acute and persistent infection in the myocardium, central nervous system, and spleen of non-human primates (cynomolgus macaques); and it productively infected primary human cardiomyocytes, suggesting that the virus may pose a risk in pig-to-human transplantation. Recently, transplantation of myocardial and pancreatic tissues from acutely infected pigs transmitted the virus to recipient mice, resulting in acute fatal EMCV disease. Here, we examined whether porcine islet cells (PICs), which are under clinical trial for treatment of type I diabetes in humans, are susceptible to porcine EMCV, and whether EMCV-infected PICs could function in vivo to reverse diabetes. PICs were infected with EMCV in vitro for 5 h, and resulting insulin production compared with that produced by uninfected PICs. Subsequently, infected PICs were transplanted intra-abdominally or under the kidney capsule of C57BL/6 mice, and both virus transmission and PIC function analyzed. PICs were highly susceptible to porcine EMCV, resulting in a 1500-fold increase in production of infectious virus within 5 h of inoculation and cytolysis that destroyed up to 50% of cells within 96 h. However, as long as they were viable, infected PICs produced insulin at levels comparable with uninfected PICs. Intra-abdominal transplantation of 2000 PICs, infected with one plaque forming unit (pfu) per cell of porcine EMCV, into C57BL/6 mice transmitted the virus resulting in acute fatal EMCV disease characterized by hind limb paresis and paralysis and acute respiratory distress in 40% of recipient mice. More importantly, transplantation of 2500 EMCV-infected PICs under the kidney capsule of diabetic C57BL/6 mice (glucose level > or =350 mg/dl) reversed diabetes in 83% of recipient mice (glucose level < or =170 mg/dl); however these mice succumbed to acute EMCV disease transmitted by the xenograft 5 days after transplantation. EMCV infection does not appear to affect insulin production by PICs, but infected xenografts can transmit the virus to recipient animals, resulting in severe disease.

Removal of small non-enveloped viruses by nanofiltration

BACKGROUND AND OBJECTIVES

Nanofiltration is one of the most effective virus reduction methods in the manufacturing process of plasma products. However, it is difficult to remove small viruses from high molecular weight protein preparations like immunoglobulin G or factor VIII complex by nanofiltration, because the size of the protein is similar to that of viruses. In order to separate the viruses from these proteins by nanofiltration, it is necessary to change the size of either one. In this study, we report that such non-enveloped viruses as human parvovirus B19 (B19), human encephalomyocarditis virus (EMC) or porcine parvovirus (PPV) aggregate in the presence of certain kinds of amino acids and could be easily removed by nanofiltration.

MATERIALS AND METHODS

0.3 M Glycine (or other amino acid) solution spiked with viruses was subjected to dead-end single filtration with a 35-nm pore-size filter. Virus removal by nanofiltration was either evaluated by PCR or by infectivity assay.

RESULTS

B19 in a 0.3 M glycine solution was reduced to 1:10(7.5) (7.5-log) by nanofiltration with a 35-nm pore-sized filter, whereas in PBS it was not reduced. Similarly, B19 was also reduced when suspended in other amino acids solutions. This effect was also confirmed with the other small non-enveloped viruses EMC or PPV. When 5% globulin or 5% albumin was added to a 0.3 M glycine solution, the removal rate was decreased.

CONCLUSIONS

These data suggest that viruses in the presence of certain kinds of amino acids could be aggregated and effectively removed by a filter that has a pore size larger than the size of the viruses.

Attenuation of virus-induced myocardial injury by inhibition of the angiotensin II type 1 receptor signal and decreased nuclear factor-kappa B activation in knockout mice

OBJECTIVES

This study examined the role of angiotensin II (Ang-II) in a murine model of viral myocarditis.

BACKGROUND

Ang-II plays an important role in the pathophysiology of various cardiovascular disorders. However, the role of Ang-II in inflammatory heart diseases is not known.

METHODS

Four-week-old wild-type (WT) and Ang-II type 1 receptor (AT(1)R) knockout (KO) mice were inoculated with the encephalomyocarditis virus (EMCV). Survival, histopathology, expression of proinflammatory cytokines, and activity of nuclear factor-kappa B (NF-kB) in the heart were examined.

RESULTS

The 14-day survival was significantly increased in KO compared with WT mice. Histopathologic scores for myocardial necrosis (0.86 +/- 0.69 vs. 2.44 +/- 0.88, p < 0.01) and cellular infiltration (0.86 +/- 0.38 vs. 2.33 +/- 0.50, p < 0.01) were lower in KO than in WT mice. The expression of tumor necrosis factor-alpha (TNF-alpha) was increased 43.2-fold, that of interleukin-1-beta (IL-1-beta) 45.8-fold, and the activity of NF-kB 2.24-fold by EMCV inoculation in WT mice (each p < 0.01), but not in KO mice (5.9-fold, 6.3-fold, and 1.12-fold, respectively, each p = NS). The AT(1)R blocker also significantly attenuated the expression of proinflammatory cytokines and the activation of NF-kB in virus-inoculated WT mice. Intravenous Ang-II injection enhanced the activation of NF-kB (2.28-fold, p < 0.01) and increased the expression of TNF-alpha (2.31-fold, p < 0.01) and IL-1-beta (2.45-fold, p < 0.01) in heart tissue of WT but not KO mice.

CONCLUSIONS

These results indicate that the AT(1)R signal is obligatory for the development of virus-induced myocardial injury through the proinflammatory action of Ang-II via the NF-kB/cytokine pathway.

Transmission of porcine encephalomyocarditis virus (EMCV) to mice by transplanting EMCV-infected pig tissues

We recently demonstrated that pigs infected with porcine encephalomyocarditis virus (EMCV) develop a persistent infection (up to 90 days post-infection (PI)) in the heart and brain that is accompanied by virus-induced pathologic changes, and that EMCV productively infects human cardiomyocytes in vitro, suggesting that EMCV may pose a risk to humans following transplantation of pig tissues to humans (Brewer et al. J Virol 2001; 75: 11621-11629). In this report, we demonstrate that intra-abdominal of myocardial or pancreatic sections from acutely-EMCV infected pigs (2 days PI) in either non-mutant C57BL/6 or C57BL/6-RAG-1-/- mice that lack B or T lymphocytes, resulted in transmission of the virus and acute fatal disease in all mice. In recipient RAG-1-/- mice, fatal EMCV disease occurred within 2 days post-transplantation, and it was accompanied by high virus titers in brain, heart, liver, spleen, kidneys and skeletal muscle, whereas in non-mutant C57BL/6 mice, disease occurred 5 to 6 days post-transplantation and was accompanied by lower virus titers. Transplantation of myocardial or pancreatic tissues from chronically EMCV-infected pigs (21 and 50 days PI) did not induce clinical disease, but resulted in detection of EMCV RNA in the brain of recipient RAG-1-/- mice, no viral RNA was detected in non-mutant C57BL/6 mice. Intra-abdominal transplantation of uninfected porcine myocardial tissues into RAG-1-/- mice followed by intramuscular inoculation with EMCV induced acute clinical disease but did not result in transmission of virus to the xenograft. These results show that EMCV can be efficiently transmitted from pig myocardial and pancreatic tissues to mice, providing a model of pig-to-human viral xenozoonosis that can be used to develop and test prophylactic and therapeutic measures against such infection.

Pathogenesis of encephalomyocarditis virus (EMCV) infection in piglets during the viraemia phase: a histopathological, immunohistochemical and virological study

Six piglets aged 20 days were inoculated oranasally with 5 ml of a suspension (10(6) TCID(50)/ml) of a Greek myocardial strain of encephalomyocarditis virus (EMCV). The animals either died (n=2) or were killed for examination on days 1,2 or 3 post-inoculation (pi). EMCV was isolated from virtually all organs examined (heart, tonsils, palatine glands, pancreas, spleen, small intestine and mesenteric lymph nodes). Histopathologically, interstitial myocarditis, necrosis of cardiac muscle cells and Purkinje fibres, and necrotizing tonsillitis were detected in all inoculated piglets. Focal interstitial pancreatitis, necrosis of pancreatic acinar cells and Langerhans islet cells, and necrosis of germinal centre lymphocytes of the lymph nodes and Peyer's patches were detected in two piglets that died or were killed on day 3 pi. Immunohistochemically, viral antigen was detected in epithelial cells of all organs examined, including the tonsils, palatine glands, pancreatic interlobular ducts and small intestine. This suggests that EMCV is epitheliotropic, in addition to its known myocardial tropism. The frequent presence of intracytoplasmic EMCV in macrophages of the tonsils and spleen supports the hypothesis that macrophages play a role in viral replication and dissemination in the body.

Detection of encephalomyocarditis virus in clinical samples by immunomagnetic separation and one-step RT-PCR

A method of immunomagnetic separation and one-step reverse transcription-polymerase chain reaction (RT-PCR) was developed for the detection of Encephalomyocarditis virus (EMCV). EMCV was captured from sample on magnetic beads with homologous monoclonal antibody and then heat denatured. The heated beads were used directly in one-step RT-PCR reaction to amplify a 285-bp PCR fragment at the 3' end of the genomic region that encodes the viral polymerase. This method detected as little as 3.5 TCID(50) of EMCV from infected cell culture. It was shown with this method that the sensitivity of RT-PCR increased when applied for the detection of EMCV added to fecal extract. Using this protocol EMCV was detected from heart homogenate samples containing less than 100 TCID(50)/ml. The amplified product was sequenced to ensure specificity. The immunomagnetic-RT/PCR procedure described here should be useful for the rapid, specific and sensitive detection of EMCV in clinical samples. This technique is rapid, reliable and can be readily adapted to detect EMCV from other clinical samples.

Nucleotide sequence and construction of an infectious cDNA clone of an EMCV strain isolated from aborted swine fetus

A full-length cDNA clone of an Encephalomyocarditis virus (EMCV) strain (2887A) isolated from aborted swine fetus was constructed and sequenced. Sequence comparison showed more than 99% nucleotide and amino acid sequence identity with two other EMCV strains, EMCV-PV21 and -R. However, the 2887A genomic sequence showed only about 84% nucleotide identity and 96% amino acid identity with EMCV-B, -D and -PV2 variants. RNA synthesized by in vitro transcription of this cDNA clone was infectious upon transfection of BHK21 cells, as shown by cytopathic effects and identification by neutralization test, and by propagation of the virus released into the culture media. The transcript RNA led to the production of infectious particles despite the presence of two nongenomic nucleotide residues at the 5' end, the short poly(C) tract (C(10)TCTC(3)TC(10)), the short poly(A) tail (7A), and the presence of six nongenomic nucleotides at the 3' end. The rescued virus was also found to be highly pathogenic for mice by intra-peritoneal inoculation producing a fatal disease indistinguishable from that of wild-type virus. An important finding concerning the molecular basis of infectivity was that the in vitro synthesized EMCV RNA transcript is infectious, although it contains a very short poly(A). The availability of the infectious cDNA clone of the reproductive failure strain of EMCV should prove to be useful for studying the molecular basis of the pathogenicity of EMCV in pig.

Reduction of cardiac endothelin-1 by angiotensin II type 1 receptor antagonist in viral myocarditis of mice

Renin angiotensin system contributes to activation of circulating endothelin in congestive heart failure. To investigate the effects of angiotensin II receptor antagonist and angiotensin converting enzyme inhibitors (ACEI) on the levels of endothelin-1 (ET-1), we administered orally angiotensin II type 1 receptor (AT1) antagonist, L-158,809 (ATA) (6, 1.2 and 0.12 mg/kg/day), enalapril (1 mg/kg/day) and captopril (7.5 mg/kg/day) for 14 days to mice with viral myocarditis, beginning 7 days after encephalomyocarditis virus (500 pfu/mouse) inoculation. Plasma ET-1, cardiac ET-1, heart weight (HW) and HW/ body weight (BW) ratio were examined and compared with infected untreated mice. Moreover, the HW (mg) and HW/BW (x 10(-3)) ratio were significantly (P<0.05) reduced in mice treated with ATA and ACEIs in comparison with infected control. ACEIs and higher dosed of ATA reduced myofiber hypertrophy. Both of plasma and cardiac ET-1 proteins were significantly elevated in infected control compared with uninfected normal mice. Plasma ET-1 was significantly (P<0.01) reduced in mice with three different concentrations of ATA but were not decreased in mice with captopril or enalapril compared with infected control. The expression of endothelin-1 mRNA was significantly reduced in mice with ATA in comparison with infected untreated mice by competitive RT-PCR. ATA reduced ET-1 protein and mRNA in the myocardium of mice with myocarditis, improving congestive heart failure and myofiber hypertrophy. We suggest the effect of ATA on the reduction of endothelin has a different pathway from angiotensin converting inhibitor and that ATA seems to be a useful agents for congestive heart failure due to viral myocarditis.

Persistence of encephalomyocarditis virus (EMCV) infection in piglets

Six piglets that had survived experimental infection with encephalomyocarditis virus (EMCV) were treated with dexamethasone for a period of 5 days. The virus had not been detected in excretions of putative carriers for a period of 13-20 days before the treatment. All piglets showed a rise in cardiac isoenzyme (CK-MB) activity, from the first day of treatment, suggesting myocardial damage. Antibody titres against EMCV remained stable or slightly decreased during treatment. EMCV was isolated from blood, nasal and faecal samples from all piglets on days 2 and 3 after initiation of treatment and from various tissues of three piglets. Four contact piglets, that were housed together with the dexamethasone-treated piglets, became infected, indicating that EMCV was shed by treated piglets. It is suggested that recovered pigs may play an important role in the dissemination of EMCV.

Apoptosis in congestive heart failure induced by viral myocarditis in mice

It has recently been speculated that progressive deterioration of left ventricular function in chronic heart failure is due to the ongoing loss of viable cardiac myocytes. However, as there is little direct evidence of significant apoptosis contributing to the pathogenesis in cardiac myocytes in vivo, the significance of apoptosis in heart failure remains to be clarified. We investigated the role of apoptosis in heart failure induced by encephalomyocarditis virus myocarditis. DBA/2 mice were inoculated with the virus (day 0), then killed, and their hearts were extracted 3 to 28 days later. Internucleosomal DNA fragmentation, chromatin binding dye staining, and in situ terminal transferase deoxyuridine triphosphate (dUTP) end-labeling were used to detect apoptosis. Internucleosomal DNA fragmentation (DNA ladder) was clearly demonstrated on days 5 to 14 in the virus-infected hearts when myocardial necrosis and infiltration of mononuclear cells were prominent in the hearts. Apoptotic cells demonstrated morphological changes typical of apoptosis (condensation of chromatin and nuclear fragmentation). Both Fas antigen and Fas ligand immunoreactivity were detected in the infiltrating mononuclear cells. The in situ terminal transferase dUTP end-labeling method demonstrated condensed nuclei of infiltrating mononuclear cells on day 7. However, nuclei of cardiac myocytes surrounded by the cellular infiltration were absent. The main source of apoptotic cells in the heart in mice with viral myocarditis appeared to be the infiltrating mononuclear cells.

Phylogenetic analysis of European encephalomyocarditis viruses: comparison of two genomic regions

The phylogenetic relationships of encephalomyocarditis (EMC) viruses isolated from pigs and rodents in Europe were determined by comparison of nucleotide sequences from two different regions of the virus genome, the VP3/VP1 gene junction (part of the capsid-coding region) and part of the 3D polymerase-coding region. Thirty-five European EMC viruses could be divided into two genetic groups, one which contained viruses from Greece isolated between 1986 and 1997 and from Belgium in 1991 and the other which contained viruses from Italy (1986-1996), Cyprus (1994-1995), France (1995) and Belgium (1995-1996).

Epidemiologic, pathogenic and molecular analysis of recent encephalomyocarditis outbreaks in Belgium

In 1991 EMCV was isolated for the first time in Belgium from the offspring of a sow with reproductive failure. From August 1995 until December 1996, EMCV was diagnosed in 154 Belgian pig holdings in association with myocardial failure and sudden death in fatteners and suckling piglets or with reproductive failure in sows. To clarify some epidemiological aspects 3 EMCV isolates characteristic for the different clinical pictures and outbreaks were studied. Field observations and animal experiments indicated that the pathogenicity induced by each isolate is specific for one age category and that the spread of the virus is limited. The presented data also suggest that rodents may play a role in the transmission of EMCV but that pig-to-pig transmission is at least as important. Molecular analysis of two separate regions on the genomes of the respective EMCV isolates showed that the 1995-96 EMCV epizootic in Belgium was due to a new virus introduction. Furthermore, the VP1 coding gene is proposed as a marker of virulence.

Virus reduction in the preparation of intravenous immune globulin: in vitro experiments

BACKGROUND

While immune globulins for intravenous administration (IGIV) have an excellent record with respect to virus safety, concern regarding these preparations has been raised by reports of transmission of hepatitis C virus (HCV) to patients treated with IGIV and the presence of genetic material for HCV in IGIV preparations.

STUDY DESIGN AND METHODS

This in vitro study evaluated the effectiveness of several manufacturing steps, including ethanol precipitation and pasteurization, in reducing HIV and model viruses including encephalomyocarditis (EMC) virus, pseudorabies virus (PRV), bovine viral diarrhea virus (BVDV), Sindbis virus, vaccinia virus, and vesicular stomatitis virus (VSV), as well as HCV RNA, in IGIV.

RESULTS

Ethanol precipitation carried out after pasteurization resulted in virus reductions (log10) of >3.97 for HIV, 1.95 for EMC virus, >5.39 for PRV, and 3.52 for BVDV. Pasteurization inactivated EMC virus by 4.52 log10 and resulted in a log10 reduction of >6.54 for HIV, >5.39 for PRV, >6.64 for BVDV, >7.78 for Sindbis virus, >5.84 for vaccinia virus, and >6.99 for VSV. All viruses except EMC virus were reduced below the limit of detection within 6 hours of the beginning of pasteurization. Cohn processing of Fraction II + III paste and the 4.5-percent alcohol precipitation step prior to pasteurization provided additional virus removal. Studies using the polymerase chain reaction technique found that HCV RNA was detectable in the starting fraction of Cohn Fraction II paste, but not in the final IGIV preparation.

CONCLUSION

These findings strongly support the viral safety of IGIV prepared by this method and show a significant added measure of virus safety associated with pasteurization of this preparation.

Identification of encephalomyocarditis virus in clinical samples by reverse transcription-PCR followed by genetic typing using sequence analysis

The objective of the present study was to gain a better understanding of the epidemiology of encephalomyocarditis virus (EMCV) infections in pigs by applying molecular techniques. The diagnostic potential of a reverse transcription-PCR (RT-PCR) targeting 286 nucleotides at the 3' end of the gene which encodes the viral polymerase was assessed with experimental and field samples. In addition, the use of the amplified sequences for an epidemiological study was evaluated. The heart was clearly shown to be the most suitable organ. The detection limit was determined to be 1 viral particle in 100 mg of heart tissue. The sensitivity and specificity of the assay on the basis of the results obtained in this study were 94 and 100%, respectively. Phylogenetic analysis of the amplified sequences classified EMCVs in two distinct lineages. Group A consists of the reference strain ATCC 129B, all isolates collected between 1991 and 1994 in Belgium in association with reproductive failure, and all Greek isolates. All Belgian isolates collected since the first isolation of EMCV in relation to myocardial failure in fatteners in Belgium group together with the isolates from Cyprus (1996 and 1997), Italy (1986 to 1996), and France (1995) in group B irrespective of their pathogenicity. The analyzed part of the 3D gene differed by 13.0% between Groups A and B. In contrast to the sequence homogeneity of the Belgian isolates collected between 1991 and 1994, molecular diversity, which ranged between 0 and 2%, was observed among the Belgian isolates collected in 1995 and 1996. Among all Greek isolates the diversity ranged between 1 and 8%. However, this diversity does not seem to reflect geographical links between the outbreaks. A RT-PCR for the rapid and specific diagnosis of EMCV in a variety of clinical samples followed by nucleotide sequence analysis proved to be valuable for molecular epidemiological studies.

Molecular analysis of encephalomyocarditis viruses isolated from pigs and rodents in Italy

Partial nucleotide sequences of encephalomyocarditis (EMC) viruses isolated from five, apparently independent, outbreaks of fatal myocarditis in pigs in Italy were compared with three EMC viruses isolated from wild rodents from a different geographic region in the same country. These viruses were also compared with EMC viruses isolated from pigs in other European countries and three historical strains. All the Italian EMC viruses were closely related (> 94.6% nucleotide identity), but were distinct from viruses occurring in Belgium in 1991 (< 80.5% nucleotide identity), Greece in 1990 (< 83.3% nucleotide identity) and the three older viruses (< 82.9% nucleotide identity). An EMC virus isolated from pigs in the Netherlands in 1988, was closely related to the Italian viruses (95.3-99.3% nucleotide identity). It is suggested that pigs may play a role in the movement of EMC viruses between different geographic regions.

RNase L inhibitor (RLI) antisense constructions block partially the down regulation of the 2-5A/RNase L pathway in encephalomyocarditis-virus-(EMCV)-infected cells

The interferon-(IFN)-inducible 2',5'-oligoadenylate (2-5A)/endoribonuclease L (RNase L) pathway plays a major role in the antiviral and antiproliferative effects of IFN. The 2-5A/RNase L pathway appears to be regulated by the cell-growth status or viral infection. Viruses, and picornaviruses in particular, have evolved strategies to escape the 2-5A/RNase L-pathway-associated antiviral activity. We have recently cloned a cDNA coding for RLI, a RNase-L-specific protein inhibitor. Its regulated expression by viral infection could provide a new strategy to modulate the 2-5A/RNase L pathway. Since RNase L had been shown to be down regulated upon encephalomyocarditis (EMCV) infection, we stably transfected HeLa cells with a RLI antisense cDNA expressing vector. Four independent clones named VAS1, VAS2, VAS3 and VAS4 and one clone transfected with the empty vector (VV) as control, were analyzed. The level of RLI was decreased by 20% for VAS1, 25% for VAS2, 75% for VAS3 and 50% for VAS4. The inactivation of RNase L observed during EMCV infection was decreased in these clones as compared to control HeLa cells. Here again the results vary between the four clones. The maximum inhibition of RNase L (90%) was observed in control cells and in VAS1 while 48% inhibition was observed in VAS4 and 25% in VAS3. The reversal in RNase L inhibition thus reflects closely the resulting RLI level, in keeping with a major role of RLI in EMCV-induced down regulation of 2-5A-binding activity of RNase L. Moreover, cells expressing a low level of RLI (VAS3 and VAS 4) are partially resistant to EMCV infection.

Comparative study of the pathogenic properties of a Belgian and a Greek encephalomyocarditis virus (EMCV) isolate for sows in gestation

Thirteen conventional sows were inoculated between 61 and 92 days of gestation with a Belgium or a Greek EMCV isolate to investigate the difference in pathogenicity of both strains for sows in gestation. The Belgian EMCV strain was isolated from the offspring of a sow with productive failure and without myocardial lesions. The Greek strain was isolated from a 3-month-old pig with prominent myocardial lesions. The present study demonstrates a transplacental virus transmission with fetal death following an infection of the sows in gestation with both isolates. The fetal pathogenicity was more severe with the Greek strain than with the Belgian isolate. No myocardial lesions were noticed.

Rapid diagnosis of encephalomyocarditis virus infections in pigs using a reverse transcription-polymerase chain reaction

Encephalomyocarditis virus (EMCV) is widespread and the economic losses caused by an EMCV outbreak in pig holdings and the similarity between a foot-and-mouth disease virus (FMDV) and an EMCV infection in young piglets stress the need for a rapid, specific and broad diagnostic assay. An alternative to the time-consuming seroneutralisation assay, currently used for the characterisation of EMCV, is described. An EMCV specific reverse transcription-polymerase chain reaction (RT-PCR), using primers located in a conserved region of the 3D gene of the viral genome, was developed and tested on 114 different EMCV isolates. The identity of the respective amplicons was confirmed by sequencing. The potential of this assay for future diagnostic purposes was demonstrated by applying the RT-PCR on tissue samples collected from an experimentally infected piglet.

Encephalomyocarditis virus infections in an Australian zoo

Fatal encephalomyocarditis virus (EMCV) infections in a ring-tailed lemur (Lemur catta), a squirrel monkey (Saimiri sciureus), three mandrills (Mandrillus sphinx), a chimpanzee (Pan troglodytes), a pygmy hippopotamus (Choeropsis liberiensis), and two Goodfellows tree kangaroos (Dendrolagus goodfellowi) occurred at Taronga Zoo. This is the first description of EMCV in a zoological collection outside of the United States. Regardless of species, the most common clinical presentation was sudden death. The gross pathologic changes were diffuse or focal pallor of the myocardium with occasional marked pulmonary congestion. Necrotizing nonsuppurative myocarditis was consistently present. EMCV was isolated from only one of 54 feral rodents examined. No antibodies to EMCV were detected with a serum neutralization test in 79 stored sera from a wide variety of zoo mammals. Titers of 1:16, 1:16, and 1:4 were recorded for a spider monkey (Aeteles geoffroyi), a lion (Panthera leo), and an orangutan (Pongo pygmaeus), respectively. Of seven mandrills tested in 1988, six had measurable virus titers. Later testing indicated that these titers did not persist, and one mandrill with a titer > 1:128 in 1988 subsequently succumbed to EMCV infection in 1991.

Utilization of the herpes simplex virus type 1 latency-associated regulatory region to drive stable reporter gene expression in the nervous system

The ability of herpes simplex virus type 1 (HSV-1) to establish a lifelong, transcriptionally active, latent infection in neurons has led to much interest in developing HSV-based vectors for gene delivery to the nervous system. A prerequisite of such vectors is that they should be capable of directing long-term transgene expression in latently infected neurons. The continued transcription of HSV-1 latency-associated transcripts (LATs) during neuronal latency suggests that regulatory sequences which mediate expression of LATs could be utilized for long-term expression of heterologous genes in the mammalian nervous system. In addition to upstream regulatory elements which are important for LAT promoter-mediated transcription during neuronal latency, there is growing evidence that sequences downstream of the LAT transcription start site play an important role in facilitating long-term latent-phase transcription. In order to maintain the integrity of both upstream and downstream regulatory elements of the LAT promoter, we constructed viruses which contained the lacZ and lacZ-neo reporter genes linked to the encephalomyocarditis virus internal ribosomal entry site (IRES) (viruses LbetaA and LbetaB, respectively) inserted approximately 1.5 kb downstream of the LAT transcription start site. These viruses expressed low levels of beta-galactosidase in lytically infected Vero cells and in cervical dorsal root ganglion neurons during the acute stage of infection in vivo. In contrast, at later times postinfection and consistent with the establishment of latency, increases both in the numbers of neurons expressing beta-galactosidase and in the intensity of staining were observed. Examination of the brain stems and spinal cords of animals latently infected with LbetaA, sampled at time points from 72 to 307 days postinfection, revealed the stable expression of beta-galactosidase within neurons located in facial and hypoglossal nerve nuclei and the upper cervical spinal cord. We conclude that the insertion of an IRES linked to a reporter gene 1.5 kb downstream from the LAT transcription start site does not disrupt elements of the LAT promoter necessary for long-term gene expression and, in both the peripheral and central nervous systems, facilitates beta-galactosidase expression in a wide variety of neurons.

Beneficial effects of amlodipine in a murine model of congestive heart failure induced by viral myocarditis. A possible mechanism through inhibition of nitric oxide production

BACKGROUND

Although calcium channel blockers have not been shown to be beneficial for the treatment of patients with heart failure, a recent clinical trial demonstrated a favorable effect of amlodipine on the survival of patients with heart failure resulting from nonischemic dilated cardiomyopathy. We investigated the effects of amlodipine on a murine model of congestive heart failure induced by the M variant of encephalomyocarditis virus (EMCV).

METHODS AND RESULTS

Four-week-old male DBA/2 mice were inoculated with EMCV and administered amlodipine, diltiazem, or vehicle PO for 2 weeks. The heart weight-to-body weight ratio and the histopathological grades of myocardial lesions were significantly lower and survival was significantly increased in the amlodipine-treated group (P < .01, P < .05, and P < .05, respectively) than in the control group. In vitro, amlodipine added to murine J774A.1 macrophages concomitant with EMCV inhibited nitrite formation in a concentration-dependent manner, but diltiazem did not. Furthermore, NG-monomethyl-L-arginine, an inhibitor of NO synthesis, decreased myocardial lesions significantly in this murine model. Immunohistochemistry revealed that the number of cells stained with antibody against an inducible NO synthase decreased significantly in the amlodipine-treated group compared with that in the control group (P < .01).

CONCLUSIONS

Amlodipine appears to have a protective effect against myocardial injury in this animal model of congestive heart failure. The therapeutic effect of amlodipine may be in part resulting from inhibition of overproduction of NO.

Variation in serum creatine phosphokinase activity as indicated in two-phase EMC-D virus-induced myocarditis

In this study, myocardial damage in the D-variant of encephalomyocarditis (EMC-D) virus-induced myocarditis has been investigated consecutively by measuring serum creatine phosphokinase (CPK) activity. CPK activity in 8 week-old male BALB/cAJcl mice inoculated with EMC-D virus increased to a peak at 4 or 5 days postinoculation (DPI) and then gradually decreased. The CPK activity rose again after 7 DPI until it reached a second peak. In view of the kinetics of CPK activity, two-phase (early and late phase) myocardial damage in EMC virus infection were considered. In the late phase, an increase in cellular infiltration in the myocardium and a decrease in viral titer in the heart were observed. It was therefore suspected that the increase in CPK in the late phase may be caused by cellular infiltration, but not by viral replication. In our results, we suggested that a serial measurement of serum CPK activity might be a useful method for throwing more light on the myocardial damage caused by the autoimmune response. We also used a pathological (TUNEL) method to detect apoptotic cells and some apoptotic myocytes in the myocardium in late phase EMC virus-induced myocarditis.

Modification of viral myocarditis in mice by interleukin-6

Inflammatory cytokines play a key role in the myocardial injury produced by viral myocarditis. Although interleukin-6 (IL-6) reportedly possesses antiviral properties, its effect in viral myocarditis is unclear. To investigate the role of IL-6 in viral myocarditis induced by encephalomyocarditis virus (EMCV) in mice, we evaluated (1) the survival rate following IL-6 administration, (2) the viral titer in the heart, (3) viral replication in the heart by in situ hybridization, (4) histopathological changes using immunohistochemical staining, (5) neutralizing antibody against EMCV, (6) circulating interferon and tumor necrosis factor-alpha (TNF-alpha), (7) viral suppression in vitro by IL-6, and (8) natural killer (NK)-cell activity. Eight-week-old C3H/HeJ mice were injected intraperitoneally with EMCV (day 0) and were also injected subcutaneously twice daily for 4 consecutive days with 10 micrograms/0.1 mL of human IL-6 on day -4 (group A), day 0 (group B), or day +4 (group D) for 4 days. As a control, 0.1 mL PBS instead of IL-6 was injected on day 0 for 4 days (group C). Certain mice were killed on day 4. The myocardial virus titers, viral replication in situ, and NK-cell activity in the spleen were determined. Decreased viral titer and viral replication in the heart reduced the titer of circulating TNF-alpha, and lower NK-cell activity was observed in group B versus group C (control group). The titer of neutralizing antibodies against EMCV was significantly (P < .05) increased in group B compared with group C. The remaining mice were killed on days 10 and 30 after infection. The ratio of heart weight (HW) to body weight (BW) and myocardial injury in group B were reduced versus group C on days 10 and 30. The HW of group B on day 30 did not differ from the normal control group. The ratio of splenic weight to BW and the ratio of thymic weight to BW of group B increased on day 10, with expanded follicles observed in the spleen and enlargement of the medulla observed in the thymus. Immunohistochemical study revealed an increased percentage of macrophages in the heart and spleen of group B. In summary, IL-6 reduces myocardial damage in mice with viral myocarditis. Modification of immune responses together with reduction in viral replication appears to be the mechanism of the IL-6 effect. Although IL-6 is likely important in the process of viral antigen presentation, early activation of immune responses and attenuation of viral replication appear most significant, as reflected in the limited time window during which IL-6 is effective in myocarditis.

Distribution of viral RNA in the spinal cord of DBA/2 mice developing biphasic paralysis following infection with the D variant of encephalomyocarditis virus (EMC-D)

DBA/2 mice infected with the D variant of encephalomyocarditis virus (EMC-D) (10(1) PFU/head) developed biphasic hind limb paralysis. As a first step in clarifying its pathogenesis, we examined the distribution of viral RNA in the spinal cord using in situ hybridization. At 3 days post inoculation (DPI), in the spinal cord of mice showing slight paralysis, viral RNA was observed in capillary endothelial cells and a few adjacent glia cells in the funiculus lateralis from thoracic to lumbar enlargement. At 7 DPI, in the spinal cord of mice showing apparent paralysis, viral RNA was observed in a larger number of glia cells in the demyelinated lesion associated with infiltration of macrophages in the funiculus lateralis and in a small number of degenerated neurons in the cornu ventrale. In the funiculus lateralis, viral RNA could not be observed after 28 DPI. On the other hand, viral RNA was observed in degenerated neurons in the cornu ventrale of mice showing the second phase paralysis at 42 DPI. Many CD4+T cells infiltrated around these degenerated neurons. These results suggest that: (1) the viral entry zone was the capillary endothelial cells in the funiculus lateralis; (2) first phase paralysis was due to demyelination caused by EMC-D and associated with macrophage infiltration; (3) second phase paralysis was due to degeneration of motor neurons bearing viral RNA associated with infiltration by CD4+T cells.

A retrospective serological survey of the encephalomyocarditis virus among pigs in Chiba prefecture, Japan

One thousand two hundred and forty pigs' sera collected from 1975 to 1992 on 240 farms in Chiba prefecture were subjected to a neutralization test for the encephalomyocarditis (EMC) virus. Seven (23.3%) of 30 pigs in 1975 had neutralizing antibodies against the EMC virus. The antibody positive rates each year ranged from 16.7% (1976) to 56.3% (1981). The differences of antibody positive rates between districts were not great after 1985. These serological results suggested that the EMC virus infection had already been introduced by 1975 and that it is prevalent among pigs in Chiba prefecture.

Iodine-mediated inactivation of lipid- and nonlipid-enveloped viruses in human antithrombin III concentrate

Human plasma-derived protein concentrates intended for clinical use must be treated for viral inactivation to ensure patient safety. This study explored the use of liquid iodine for inactivation of several lipid- and nonlipid-enveloped viruses in an antithrombin III (AT-III) concentrate. Iodine at levels of 0.01% to 0.02% caused between 43% and 94% loss of AT-III activity, as well as degradation of AT-III as shown by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western blot analysis. However, addition of up to 0.1% human albumin protected the AT-III against both inactivation and fragmentation. At albumin levels sufficient to retain greater than 75% of AT-III activity, greater than 6 logs of sindbis, encephalomyocarditis, and vesicular stomatitis viruses, greater than 4 logs of pseudorabies, and greater than 3 logs of human immunodeficiency virus were inactivated. Except with sindbis virus, this represented complete inactivation of all the viruses spiked into the AT-III concentrate.