Encephalomyocarditis Virus Strain Research Articles

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.

THE ENCEPHALOMYOCARDITIS VIRUS (EMCV) AND ITS ZOONOTIC POTENTIAL (A LITERATURE REVIEW). PART II. PATHOGENESIS. THE CIRCLE OF SUSCEPTIBLE ORGANISMS

According to literature data, both the direct action of (B2 *, L, 2A) viral proteins and the inflammatory response of the body are distinguished among the Encephalomyocarditis virus (EMCV) virulence factors. Depending on the EMCV strain and the type of the infected animal, the severity and nature of the disease is shown to be characterized by specific clinical manifestations. Differences in the pathogenetic mechanisms of tissue lesions depending on the magnitude of the virus infectious dose are established, e.g., in the development of EMCV-induced diabetes. The EMCV action was studied in vivo on such experimental animals as pigs, rodents and monkeys. The range of affected animals is extremely wide, with the infection being common almost everywhere. Thus, numerous works describe a fairly high immunological stratum among people, as well as disease outbreaks among the population. It is concluded that EMCV is dangerous not only for zoos and primatological centres, but also has a clear zoonotic potential.

Isolation and genetic characterization of encephalomyocarditis virus 1 from a deceased captive hamadryas baboon

In 2007, numerous hamadryas baboons (Papio hamadryas) died suddenly in an aviary of a primate institute in Sochi, Russia, in the absence of prior clinical signs. Necropsies were suggestive of encephalomyocarditis virus infection, but RT-PCR assays with commonly used primers were negative. Here we report the histopathological results obtained during necropsies and the isolation and genomic characterization of a divergent strain of encephalomyocarditis virus 1 (EMCV-1) from heart tissue of one of the succumbed hamadryas baboons. Phylogenetic analysis indicates that the isolated virus belongs to the newly proposed EMCV-1 lineage G, which clusters alongside lineage C (“Mengo virus”). This study is the first report describing a lineage G strain of EMCV-1 as the etiological agent of a lethal disease outbreak among captive nonhuman primates in Europe.

Complete genome sequences and phylogenetic analysis of encephalomyocarditis virus strains isolated from pigs and rats origin

In order to evaluate the genetic variability of encephalomyocarditis virus (EMCV), the whole genomes of six EMCV field isolates originating from pigs and rats origin in different regions of central China, were phylogenetically and comparatively analyzed. Phylogenetic analysis of whole genome sequences, open reading frame (ORF), capsid coding region (CCR) and VP3/VP1 using neighbor-joining analysis revealed that these isolates belonged to lineage 1. Nucleotide sequences of six isolates showed more than 99% pairwise identity rates, and the sequences of isolates from pig and boar in the same region were completely identical with each other, without any genetic deletion or insertion. From comparative analysis of variability of each EMCV protein coding region, 3D and VP3 regions showed that the highest average identity rates, and was confirmed as highly conserved. In contrast, the protein coding regions 3A and 3B was confirmed to be highly variable region with the lowest average identity rate. Our data confirmed that the EMCV strains isolated from pigs and rats origin had high homology with each other, which implied rats may play an important role in EMCV transmission between domestic pigs and wild boars.

Isolation and Characterization of Encephalomyocarditis Virus from Dogs in China

Encephalomyocarditis virus (EMCV) is as a potential zoonotic agent with a wide host range. Here, we describe an EMC virus isolate, identified as EMCV C15, which was successfully obtained from the serum of dogs from animal hospitals. Virus production in cell culture was confirmed by EMCV-specific real-time RT-PCR, indirect immunofluorescence assays and electron microscopy. In addition, the open reading frame sequence (ORF) of the EMCV C15 virus was determined. From sequence comparison and phylogenetic analysis among 24 reference EMCV strains, it appears that the EMCV C15 strain is closely genetically related to strain BEL2887A/91 (>99.0% nucleotide identity). In artificially challenged dogs, the heart and brain were important targets of EMCV C15. This study provides genetic and pathogenic characterization of the EMCV C15 strain isolated in Beijing and calls for sustained surveillance of EMCV infection in China to support better prevention and control of the disease.

Encephalomyocarditis virus infection in Macaca sylvanus and Hystrix cristata from an Italian rescue centre for wild and exotic animals.

BackgroundThe Encephalomyocarditis virus (EMCV) is a small, non enveloped, positive sense single-stranded RNA virus in the genus Cardiovirus, family Picornaviridae, with two known serotypes. It is spread worldwide and infects a huge range of vertebrate hosts with zoonotic potential for humans. The pig is the mammal most likely to be impacted on with the disease, but EMCV occurrence has also been reported in non-human primates and in a variety of domestic, captive and wild animals. Until now, human cases have been very rare and the risk appears to be almost negligible in spite of human susceptibility to the infection.Case presentationBetween September and November 2012 a fatal Encephalomyocarditis virus outbreak involving four Barbary macaques and 24 crested porcupines occurred at a rescue centre for wild and exotic animals in Central Italy. In this open-field zoo park located near Grosseto, Tuscany about 1000 animals belonging to different species, including various non-human primates were hosted at that time. Sudden deaths were generally observed without any evident symptoms or only with mild nonspecific clinical signs. The major gross change was characterised by grey-white necrotic foci in the myocardium and the same EMCV strain was isolated both in macaques and crested porcupines. Phylogenetic analysis has confirmed that only one EMCV strain is circulating in Italy, capable of infecting different animal species.ConclusionsThis report confirms the susceptibility of non-human primates to the EMCV infection and describes the disease in porcupine, a common wild Italian and African species. No human cases were observed, but given the zoonotic potential of EMCV these findings are of importance in the context of animal-human interface.

Isolation and molecular and phylogenetic analyses of encephalomyocarditis virus from wild boar in central China

Encephalomyocarditis virus (EMCV) can infect many host species and cause acute myocarditis and respiratory failure in piglets, reproductive failure in pregnant sows. In this study, an EMCV strain, designated JZ1202, was isolated from semi-captive wild boars that presented with acute myocarditis and sudden death in central China. It was identified by hemagglutination inhibition (HI) assay, reverse transcription polymerase chain reaction (RT-PCR) and genome sequencing. The subsequent results showed that the virus could produce a specific cytopathic effect on BHK cells and could cause clinical symptoms and pathological changes in mice. Complete genome sequencing and multiple sequence alignment indicated that JZ1202 strain was 81.3%–99.9% identical with other isolates worldwide. Phylogenetic analysis of the whole genome, ORF, VP3/VP1 and 3D genes using neighbor-joining method revealed that JZ1202 isolate was grouped into lineage 1. The results of this study confirmed that an EMCV strain JZ 1202 isolated from wild boar in central China was fatal to mice and provided new epidemiologic data on EMCV in China.

VIRAL DIABETES: VIRUS DIABETOGENICITY AND HOST SUSCEPTIBILITY

Diabetes mellitus (DM) is on the rise worldwide, and is associated with improvement in socioeconomic conditions, increasing wealth, high caloric and fat intake, and reduced physical activity. Accumulating evidence also suggests a causal/triggering link with environmental factors, such as toxins and viruses. A variety of viral infections have been associated with the development of diabetes. There might be no ‘diabetes virus’, but there might be a variety of ‘diabetogenic viruses’ that contribute to diabetes in people who are particularly susceptible due to genetic or physiologic conditions. Increasing evidence is showing that human enteroviruses (EVs) are prominent among possible causal candidates for type 1 diabetes mellitus (T1D). However, evidence for diabetogenicity of viruses is still missing. For a pathogen, causality should fulfill the etiologic criteria known as ‘modified Koch’s postulates’. Recently, we presented evidence that mutations of Tyk2 gene are responsible for diabetes susceptibility of mice infected with the diabetogenic D strain of encephalomyocarditis virus (EMC-D). Observations have been extended to identify the human polymorphism of TYK2 gene associated with increased risk for virus-induced diabetes in humans. An update is given on the possible diabetogenic role of EVs with reference to experimental work in animals and to human studies (viral serology, pancreas histopathology, virus detection in blood and in tissues of diabetic patients). For the identification of a diabetogenic virus, the development of a sensitive experimental model is imperative. In vivo assay systems should include an animal model appropriately simulating a susceptible human and carrying susceptibility genes or factors. This work summarizes current knowledge on virus-induced diabetes together with evidence from experimental models, susceptibility genes in mice, candidate diabetogenic viruses and susceptibility genes in humans. Perspectives on the identification of diabetogenic viruses - which may possibly lead to innovative strategies for the cure or prevention of diabetes – are also presented.

Recombinant Encephalomyocarditis Viruses Elicit Neutralizing Antibodies against PRRSV and CSFV in Mice.

Encephalomyocarditis virus (EMCV) is capable of infecting a wide range of species and the infection can cause myocarditis and reproductive failure in pigs as well as febrile illness in human beings. In this study, we introduced the entire ORF5 of the porcine reproductive and respiratory syndrome virus (PRRSV) or the neutralization epitope regions in the E2 gene of the classical swine fever virus (CSFV), into the genome of a stably attenuated EMCV strain, T1100I. The resultant viable recombinant viruses, CvBJC3m/I-ΔGP5 and CvBJC3m/I-E2, respectively expressed partial PRRSV envelope protein GP5 or CSFV neutralization epitope A1A2 along with EMCV proteins. These heterologous proteins fused to the N-terminal of the nonstructural leader protein could be recognized by anti-GP5 or anti-E2 antibody. We also tested the immunogenicity of these fusion proteins by immunizing BALB/c mice with the recombinant viruses. The immunized animals elicited neutralizing antibodies against PRRSV and CSFV. Our results suggest that EMCV can be engineered as an expression vector and serve as a tool in the development of novel live vaccines in various animal species.

Porcine encephalomyocarditis virus strain BD2 isolated from northern China is highly virulent for BALB/c mice.

Encephalomyocarditis virus (EMCV) can cause acute myocarditis in young pigs or reproductive failure in sows. The BD2 strain was isolated from the suspected piglets with EMCV in China. In order to establish an experimental animal model of EMCV, eight-weeks-old male BALB/c mice were intraperitonealy inoculated with 0.1 ml of 4×10(5) TCID50 suspension of the EMCV. Infected mice demonstrated hind limb paralysis, and movement disorder. The mortality rate of the infected group was 100% during the one-week observation period. The viral load in the brain of challenged mice gradually increased, with a peak level being 6.53 log CCID50/0.1 ml 5 days post infection. The pathological injury in infected mice was presented as neuronal necrosis. Brown positive staining could be detected in the cytoplasm of cerebral neurons. These results indicate that the porcine EMCV isolated from China could replicate in brain tissues and induce acute encephalitis in BALB/c mice.

Isolation, molecular and phylogenetic analysis of encephalomyocarditis virus strain GS01 in China

Encephalomyocarditis virus (EMCV) is a small non-enveloped, single-stranded RNA virus. It can infect many host species and cause acute myocarditis and respiratory failure in piglets, reproductive failure in pregnant sows. Diseases caused by EMCV currently affect the swine industry worldwide. In this study, an EMCV strain was isolated from an aborted fetus in western China. It was identified by reverse-transcription polymerase chain reaction (RT-PCR) and genome sequencing. The subsequent results showed that the virus could produce a specific cytopathic effect on BHK-21 cells and could cause severe clinical symptoms and pathological changes in mice. Complete genome sequencing and multiple sequence alignment indicated that the GS01 strain was 79.9–99.9% identical with other isolates worldwide. Phylogenetic analysis showed that EMCV isolates fell into five clusters: lineage 1, 2, 3, 4, and 5 based on the nucleotide sequences of the entire ORF and VP3/VP1 junction, as well as 3D gene. GS01 isolate was grouped into lineage 1. The results of this study confirmed that an EMCV strain GS01 isolated from an aborted pig fetus in western China was fatal to mice and provided new epidemiologic data on EMCV in China.

Complete Genome Sequence of Porcine Encephalomyocarditis Virus from an Aardvark in China

A strain of encephalomyocarditis virus, HNXX13, was isolated from an aardvark in central China. The complete genome was sequenced and analyzed, and phylogenetic analysis suggests that HNXX13 belongs to encephalomyocarditis virus group 1.

Isolation and molecular analysis of porcine encephalomyocarditis virus strain BD2 from northern China

Encephalomyocarditis virus (EMCV) can cause acute myocarditis in young pigs or reproductive failure in sows. In this study, an EMCV strain (BD2) was isolated from the suspected piglets with EMCV in China. It was identified by an indirect immunofluorescence assay and reverse-transcription polymerase chain reaction. The virus could reproduce on BHK-21 cells and reach a peak titer by 16hpi with maximum titers of 108.22TCID50/0.1ml. Phylogenetic analyses of open reading frame and the VP3/VP1 genes using neighbor-joining method revealed that EMCV isolates fell into two clusters: groups I and II. The BD2 isolate belonged to group I, along with strains NJ08, HB1, BJC3, CBNU, K3, K11, BEL-2887A, GX0601, GXLC, pEC9, and PV21, whereas four strains (D variant, EMCV-B, EMCV-D, and PV2) belonged to group II.

Complete Nucleotide Sequence of Encephalomyocarditis Virus Isolated from South China Tigers in China

A strain of encephalomyocarditis virus (EMCV), strain FJ13, has been isolated from South China tigers in China, and its complete genome has been sequenced and analyzed. Phylogenetic analysis suggests that FJ13 belongs to the EMCV-1 serotype, and it is highly prevalent in China.

Encephalomyocarditis virus infection in a splenectomised calf

Encephalomyocarditis (EMC) caused by EMC virus (EMCV) was diagnosed in a 5-month-old splenectomised calf, which died suddenly on an experimental farm that had a high infestation of rodents. At postmortem examination, the lungs were dark purple and diffusely congested. On histological examination, the calf had severe necrotising myocarditis. EMCV was isolated from the heart. The polyprotein gene of the EMCV isolate was amplified by PCR and had 85-91% identity with published EMCV sequences, including 89% identity with isolates from Queensland. On phylogenetic analysis, the polyprotein gene had highest sequence identity with South Korean EMCV strain, CBNU. This is the first report of naturally occurring EMC in cattle in Australia and the first report of naturally occurring bovine EMC from which EMCV has been isolated.

Preliminary study on the identification methods for encephalomyocarditis virus

Objective To explore and develop methods for encephalomyocarditis virus (EMCV) identification.Methods According to the genetic sequence VR-129B of EMCV recorded in the GenBank,five gene fragments were selected to design primer sequence pairs.RNA was extracted to run RT-PCR,and then the products of amplification were identified by agarose gel electrophoresis.The results of DNA sequences were compared with the sequences in GenBank of the same EMCV strains.Antiserum was prepared based on the EMCV cultured in RK cells for establishing indirect immunofluorescence assay (IIFA) and neutralization test method,and verification for precision and specificity of the two methods were carried out after it.Antiserum that was prepared with GST-VP1 and GST-VP2 expressed in E.coli was reacted with the purified EMCV in Western blot test.Results By sequencing and comparing,the similarity of DNA fragments between the obtained and the GenBank recorded was reached 98％ to 100％.The antiserum of No.20100901 batch that was chosen as the first antibody at a dilution of 1 ∶ 160 to develop IIFA brought about a better specificity.The neutralization titers of 20100901 batch antiserum was 1 ∶ 30 211 measured by fixing virus and diluting serum method,which showed good specificity and precision.The results of the Western blot test showed two clear bands above and under 33×103 respectively,which matched the theoretical value.Conclusion The RT-PCR,indirect immunofluorescence,neutralization test and Western blot method for EMCV strains identification were established initially. Key words: Encephalomyocarditis virus; Indirect immunofluorescence assay; Neutralization test

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.

Encephalomyocarditis virus may use different pathways to initiate infection of primary human cardiomyocytes

Encephalomyocarditis virus (EMCV) can infect a wide range of vertebrate species including swine and non-human primates, but few data are available for humans. We therefore wanted to gain further insight into the mechanisms involved in EMCV infection of human cells. For this purpose, we analyzed the permissiveness of primary human cardiomyocytes towards two strains of EMCV; a pig myocardial strain (B279/95) and a rat strain (1086C). In this study, we show that both strains productively infect primary human cardiomyocytes and induce complete cytolysis. Binding and infection inhibition experiments indicated that attachment and infection are independent of sialic acid and heparan sulfate for B279/95 and dependent for 1086C. Sequence comparison between the two strains and three-dimensional analysis of the capsid revealed that six of the seven variable residues are surface-exposed, suggesting a role for these amino acids in binding. Moreover, analysis of variants isolated from the 1086C strain revealed the importance of lysine 231 of VP1 in the attachment of EMCV to cell-surface sialic acid residues. Together, these results show a potential for EMCV strains to use at least two different binding possibilities to initiate infection and provide new insights into the mechanisms involved in primary human cell recognition by EMCV.

Encephalomyocarditis Virus 2A Protein Is Required for Viral Pathogenesis and Inhibition of Apoptosis

The encephalomyocarditis virus (EMCV), a Picornaviridae virus, has a wide host spectrum and can cause various diseases. EMCV virulence factors, however, are as yet ill defined. Here, we demonstrate that the EMCV 2A protein is essential for the pathogenesis of EMCV. Infection of mice with the B279/95 strain of EMCV resulted in acute fatal disease, while the clone C9, derived by serial in vitro passage of the B279/95 strain, was avirulent. C9 harbored a large deletion in the gene encoding the 2A protein. This deletion was incorporated into the cDNA of a pathogenic EMCV1.26 strain. The new virus, EMCV1.26Δ2A, was capable of replicating in vitro, albeit more slowly than EMCV1.26. Only mice inoculated with EMCV1.26 triggered death within a few days. Mice infected with EMCV1.26Δ2A did not exhibit clinical signs, and histopathological analyses showed no damage in the central nervous system, unlike EMCV1.26-infected mice. In vitro, EMCV1.26Δ2A presented a defect in viral particle release correlating with prolonged cell viability. Unlike EMCV1.26, which induced cytopathic cell death, EMCV1.26Δ2A induced apoptosis via caspase 3 activation. This strongly suggests that the 2A protein is required for inhibition of apoptosis during EMCV infection. All together, our data indicate that the EMCV 2A protein is important for the virus in counteracting host defenses, since Δ2A viruses were no longer pathogenic and were unable to inhibit apoptosis in vitro.

Alteration of encephalomyocarditis virus pathogenicity due to a mutation at position 100 of VP1

Encephalomyocarditis virus (EMCV) infection leads to many diseases including encephalitis, myocarditis and diabetes in its natural host, the mouse. In this study, we generated four cDNA clones with a point mutation at position 100 of VP1. The amino acids isoleucine, alanine, serine and proline were substituted with threonine in the four different clones of EMCV strain BJC3 by site-specific mutagenesis, and viable viruses were rescued. Although all mutants and wild-type viruses display different plaque morphologies, they replicate comparably in BHK-21 cells. The pathogenicity of the mutated viruses was systematically analyzed to investigate the importance of this amino acid in the viral pathogenicity and disease phenotype of EMCV infection in mice. The results showed that the isoleucine- (T1100I) and proline-mutated viruses (T1100P) exhibited a reduced mortality, lower cerebral virus loads and alleviated brain damage while the viruses with serine (T1100S) and alanine (T1100A) substitutions displayed similar properties as the wild-type virus. These findings indicate that the amino acid at position 100 of VP1 is important for EMCV in vivo infection, and its mutation alters the pathogenicity of viral infection in mice.