Construction of Full-length Infectious Clone for Encephalomyocarditis Virus BJC3 and Identification of the Rescued Virus

The objective of this study was to construct the infectious clone of encephalomyocarditis virus (EMCV) BJC3 strain.The genomic cDNA of the virus was amplified by three overlapping segments using RT-PCR,and cloned into low-copy plasmid pWSK29 to construct the full-length cDNA clone pWSKBJC3/ w.The pWSKBJC3/w was in vitro transcribed and transfected into BHK-21 cells to rescue the virus.The results showed that the full-length cDNA clone was infectious and the virus could be rescued in BHK-21 cells.The rescued virus designated RvBJC3W was identified by RT-PCR and indirect immunofluorescence assay(IFA).The rescued virus had similar growth characteristics to its parental virus BJC3 and retained pathogenicity for mice.Our results indicate that the first infectious cDNA clone of EMCV in China has been successfully established and provides an essential tool for investigating the molecular basis of pathogenicity of EMCV.

Detection and characterization of Hepatitis E virus from commercial rabbit livers in Hebei, China

Rabbit hepatitis E virus(HEV)has been reported for years and is thought to have the potential for zoonotic transmission from rabbits to humans.As reported,HEV genotype 3(gt3)is the most prevalent form of HEV in rabbits.To determine the prevalence of HEV in commercial rabbit livers,176 liver samples were collected from an abattoir in Hebei Province,China.Three(1.7%)samples tested positive for RNA of HEV-0RF2(open reading frames-2).Sequence analysis showed that the three isolates shared high identities with each other(94.08-98.85%).Further analysis showed that all the rabbit strains clustered together in the branch of HEV gt3.Further study by immunohistochemistry(IHC)assays showed that 131(74.4%)liver samples were positive for HEV ORF2 protein.Pathological changes including cell degeneration,inflammatory cell infiltration and bile duct epithelial cell hyperplasia were observed under microscopy.These findings indicated the presence of HEV in commercial livers of rabbits.Additional studies should be conducted to investigate the infectivity of rabbit HEV(rHEV)and the potential risks of zoonotic transmission of rHEV from rabbits to human beings.

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.

Transmembrane domain of IFITM3 is responsible for its interaction with influenza virus HA_(2) subunit

Interferon-inducible transmembrane protein 3(IFITM3)inhibits influenza virus infection by blocking viral membrane fusion,but the exact mechanism remains elusive.Here,we investigated the function and key region of IFITM3 in blocking influenza virus entry mediated by hemagglutinin(HA).The restriction of IFITM3 on HAmediated viral entry was confirmed by pseudovirus harboring HA protein from H5 and H7 influenza viruses.Subcellular co-localization and immunocoprecipitation analyses revealed that IFITM3 partially co-located with the full-length HA protein and could directly interact with HA_(2) subunit but not HA_(1) subunit of H5 and H7 virus.Truncated analyses showed that the transmembrane domain of the IFITM3 and HA_(2) subunit might play an important role in their interaction.Finally,this interaction of IFITM3 was also verified with HA_(2) subunits from other subtypes of influenza A virus and influenza B virus.Overall,our data demonstrate for the first time a direct interaction between IFITM3 and influenza HA protein via the transmembrane domain,providing a new perspective for further exploring the biological significance of IFITM3 restriction on influenza virus infection or HA-mediated antagonism or escape.

Assessment of vaccination strategies against highly pathogenic avian influenza in China

Vaccination for highly pathogenic avian influenza(HPAI)has been implemented in China for a decade,however,the virus is still present in poultry.A series of recombinant vaccines,Re-1 to Re-7,have been developed and used,and Re-8 will also be used in clinical settings to prevent the prevailing flu strains.The question remains,when can China eradicate the disease?Here,we review the epidemiology of H5 HPAI along with the development,usage and problems of vaccines.Further suggestions for controlling the disease in China are provided.

Polymorphism analysis and supertype definition of swine leukocyte antigen class I molecules in three-way crossbred(Landrace,Duroc,and Yorkshire)pigs:implications for the vaccine development of African swine fever virus

Dear Editor,Swine major histocompatibility complex(MHC)is a highly polymorphic gene in pigs and is also called swine leukocyte antigen(SLA)(Fan et al.,2018).SLA is divided into three major categories,SLA I(SLA-1,-2,-3),SLA II,and SLA III(Smith et al.,2005).SLA I plays an important role in cellular immunity which can eliminate viruses and other foreign antigens in pigs(Macdonald et al.,2010).SLA-1,SLA-2 and SLA-3 are important SLA I alleles and are highly polymorphic.Polymorphism causes extreme difficulties in screening broadly protective cytotoxic lymphocyte(CTL)epitope antigens.The supertype which is built based on peptide-binding specificity of each SLA I can overcome this difficulty to some extent(Thomsen et al.,2013).

Neospora caninum immune mapped protein 1(NcIMP1) is a novel vaccine candidate against neosporosis

The Neospora caninum immune mapped protein 1(Nc IMP1) was identified as a membrane protein,and a previous study indicated that Nc IMP1 could be a promising vaccine candidate against neosporosis. In this study, the immune response and protection efficacy of Nc IMP1 were evaluated. The coding sequence of Nc IMP1 was inserted into the eukaryotic expression vector pc DNA3.1(+), resulting in the recombination plasmid pc DNAIMP1, which was used for the intramuscular immunization of BALB/c mice. After immunization, the immune response was evaluated using a lymphoproliferative assay and cytokine and antibody measurements. Quantification of the cerebral parasite burden of mice challenged with 2106 N. caninum was performed 14 days after the last immunization. The results showed that the mice immunized with pc DNA-IMP1 developed a high level of specific antibody responses against recombinant Nc IMP1,with a mixed Ig G1/Ig G2 a response and a predominance of Ig G2 a production. The cellular immune response was associated with the production of IFN-γ, IL-2, IL-4 and IL-10 cytokines. The experiment was terminated 30 days p.i.,and the cerebral parasite burden in each mouse was assessed by quantitative PCR. The parasite burden was significantly reduced in the pc DNA-IMP1-vaccinated mice. These data suggest that IMP1 is a promising vaccine candidate against neosporosis.