Coronavirus accessory protein ORF3 biology and its contribution to viral behavior and pathogenesis

Coronavirus porcine epidemic diarrhea virus (PEDV) is classified in the genu

Molecular epidemiology of hepatitis E virus infections in Shanghai, China

<p>Abstract</p> <p>Background</p> <p>Hepatitis E virus (HEV) causes acute or fulminant hepatitis in humans and is an important public health concern in many developing countries. China has a high incidence of HEV epidemics, with at least three genotypes (1, 3 and 4) and nine subtypes (1b, 1c, 3b, 4a, 4b, 4d, 4g, 4h and 4i) so far identified. Since genotype 3 and the newly identified subtype 4i have been exclusively limited geographically to Shanghai and its neighboring provinces, the epidemiology of HEV infections within the municipality, a major industrial and commercial center, deserves closer attention.</p> <p>Findings</p> <p>A total of 65 sequences, 60 located within the HEV SH-SW-zs1 genome [GenBank:<ext-link ext-link-id="EF570133" ext-link-type="gen">EF570133</ext-link>], together with five full-length swine and human HEV genomic sequences, all emanating from Shanghai, were retrieved from GenBank. Consistent with the primary role of genotype 4 in China overall, analysis of the sequences revealed this to have been the dominant genotype (58/65) in Shanghai. Six HEV subtypes (3b, 4a, 4b, 4d, 4h and 4i) were also represented. However, although subtype 4a is the dominant subtype throughout China, subtype 4i (29/65) was the most prevalent subtype among the Shanghai sequences, followed by subtypes 4d (10/65) and 4h (9/65). Subtypes 4h, 4i and 4d were found in both swine and humans, whereas 4b was found only in swine and subtype 4a only in humans.</p> <p>Conclusions</p> <p>Six different swine and human HEV subtypes have so far been documented in Shanghai. More molecular epidemiological investigations of HEV in swine, and particularly among the human population, should be undertaken.</p

Screening of specific diagnostic peptides of swine hepatitis E virus

© 2009 Zhao et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

Experimental study on creep-feed grinding burn of DD9 Nickel-based single crystal superalloy

Aiming at the problem of grinding burns on the third-generation single crystal superalloy DD9, a three-factor and five-level experiment is designed in this paper. From the perspectives of surface morphology, microhardness and microstructure, the effect of grinding process parameters on grinding burns are studied. The experimental results show that: when the workpiece feed speed is less than 250 mm/min, the grinding surface roughness Ra changes slightly around 0.8 μm, and the surface quality is good. When the feed speed is more than 250 mm/min and the grinding depth is more than 1.0 mm, the temperature in the grinding area rises sharply, the grinding lines are destroyed, grinding defects such as coating and pits appear, and the surface of the workpiece burns. The surface and surface of DD9 alloy are work hardened by slow feed grinding. The microhardness range is 400 to 600 HV, the depth of hardened layer is 50 to 110 μm, and the thickness range of plastic deformation layer is 1 to 10 μm. The recommended combination of DD9 grinding process parameters is: grinding wheel linear velocity vs=20 m/s, feed speed vw=250 mm/min, grinding depth ap=0.6 mm

Determination of the full-genome sequence of hepatitis E virus (HEV) SAAS-FX17 and use as a reference to identify putative HEV genotype 4 virulence determinants

Abstract Background Four major genotypes of hepatitis E virus (HEV), the causative agent of hepatitis E, have so far been recognized. While genotypes 3 and 4 are both zoonotic, the disease symptoms caused by the latter tend to be more severe. To examine if specific nucleotide/amino acid variations between genotypes 3 and 4 play a role in determining the severity of hepatitis E disease, the complete genome of one swine HEV genotype 4 isolate, SAAS-FX17, was determined and compared with other genotype 4 and genotype 3 genomes to identify putative HEV genotype 4 virulence determinants. Results A total of 42 conformable nt/aa variations between genotype 3 and 4 HEVs were detected, of which 19 were proposed to be potential disease severity determinants for genotype 4 strains. Conclusions One potential determinant was located in each of the 5'-UTR and 3'-UTR, 3 and 12 within ORF1 and ORF2 respectively, and 2 in the junction region.</p

Antigenicity Alternations of Variant PEDV S Protein Disclosed by Linear B Cell Epitope Mapping

The spike protein (S) plays a crucial role in porcine epidemic diarrhea virus (PEDV) infection and induces neutralizing antibodies. Mutations of the S protein are supposed to provide the main antigenic shift leading to the antigenic escape of PEDVs. It is therefore a significant question how much accumulation of antigenic shift could lead to the antigenic escape of the variant PEDV. To provide an answer in the study, B cell epitopes (BCEs) on the S protein of the PEDV vaccine strain CV777 (SCV777) and variant strain SD2014 (SSD2014) were mapped using biosynthetic peptides and rabbit anti-PEDV S serum. Seventy-nine and 68 linear BCEs were identified from SCV777 and SSD2014, respectively. While 66.2% of the BCEs of SSD2014 could be recognized by anti-SCV777 serum and 67.1% of SCV777 BCEs could be recognized by anti-SSD2014 serum, more than 40% of the BCEs identified using anti-SCV777 serum on SCV777 could not be recognized by anti-SSD2014 serum and vice versa. The completely shared BCEs took low percentages of 29.4% and 25.3% for SSD2014 and SCV777, respectively. These results indicate a low conservation of antigenicity of the S protein compared to a relatively high amino acid sequence similarity of 92.2% between the two strains. The study provided a BCE shift reference of PEDV antigenic escape and surveillance control

Porcine Epidemic Diarrhea Virus (PEDV) ORF3 Enhances Viral Proliferation by Inhibiting Apoptosis of Infected Cells

The genomes of coronaviruses carry accessory genes known to be associated with viral virulence. The single accessory gene of porcine epidemic diarrhea virus (PEDV), ORF3, is dispensable for virus replication in vitro, while viral mutants carrying ORF3 truncations exhibit an attenuated phenotype of which the underlying mechanism is unknown. Here, we studied the effect of ORF3 deletion on the proliferation of PEDV in Vero cells. To this end, four recombinant porcine epidemic diarrhea viruses (PEDVs) were rescued using targeted RNA recombination, three carrying the full-length ORF3 gene from different PEDV strains, and one from which the ORF3 gene had been deleted entirely. Our results showed that PEDVs with intact or naturally truncated ORF3 replicated to significantly higher titers than PEDV without an ORF3. Further characterization revealed that the extent of apoptosis induced by PEDV infection was significantly lower with the viruses carrying an intact or C-terminally truncated ORF3 than with the virus lacking ORF3, indicating that the ORF3 protein as well as its truncated form interfered with the apoptosis process. Collectively, we conclude that PEDV ORF3 protein promotes virus proliferation by inhibiting cell apoptosis caused by virus infection. Our findings provide important insight into the role of ORF3 protein in the pathogenicity of PEDV

Co3O4 /N-doped RGO nanocomposites derived from MOFs and their highly enhanced gas sensing performance

Co3O4/N-doped reduced graphene oxide (N-RGO) nanocomposite with mesoporous structure was fabricated by using metal organic frameworks (MOFs) as both template and precursor growing on RGO sheets. Porous Co3O4 cubes were assembled and grown on the surface of N-RGO layers, while N was doped into RGO to form N-RGO in situ synthesis route. The effect of RGO initial concentration on structure, component and gas-sensing properties of Co3O4/N-RGO nanocomposite was studied. The gas-sensing result demonstrated that the sensor based-on Co3O4/N-RGO-0.5 (the mass of RGO was 0.5 mg) nanocomposite possessed better gas-sensing performances to ethanol, such as higher response, faster response-recovery time and lower working temperature than that of other samples. The enhanced gas-sensing properties of sensor based-on Co3O4/N-RGO-0.5 nanocomposite to ethanol could be attributed to increasing of specific surface area, coupling effect between Co3O4 and nitrogen doped RGO as well as the existence of N-doping RGO which improved electron transferring of material in sensing process. Co3O4/N-RGO-0.5 nanocomposite has been proved to be a promising gas-sensing material for detecting ethanol at a low temperature