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      Analysis of Genetic Variation of Two NADC30-like Strains of Porcine Reproductive and Respiratory Syndrome Virus in China

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          NADC30-like strains of porcine reproductive and respiratory syndrome virus first appeared in Chinese swine herds in 2012.

          Objective and Method:

          To explore the possible genetic diversity of these strains, we sequenced and analyzed the complete genomes of two NADC30-like strains. These isolates shared 95.4% homology with NADC30.


          The two strains displayed a discontinuous deletion of 131 amino acids in NSP2, mutations of amino acids in GP3 and GP5, and a 3-nucleotide deletion in the 3′ untranslated region. Phylogenetic analysis showed that the two isolates formed a new branch and clustered in a subgroup with NADC30 isolates from North America.


          We conclude that the above two NADC30-like strains may have been introduced from North America to China, where they acquired new genetic diversity.

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          Most cited references 30

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          MEGA4: Molecular Evolutionary Genetics Analysis (MEGA) software version 4.0.

           K Tamura,  J. Dudley,  M Nei (2007)
          We announce the release of the fourth version of MEGA software, which expands on the existing facilities for editing DNA sequence data from autosequencers, mining Web-databases, performing automatic and manual sequence alignment, analyzing sequence alignments to estimate evolutionary distances, inferring phylogenetic trees, and testing evolutionary hypotheses. Version 4 includes a unique facility to generate captions, written in figure legend format, in order to provide natural language descriptions of the models and methods used in the analyses. This facility aims to promote a better understanding of the underlying assumptions used in analyses, and of the results generated. Another new feature is the Maximum Composite Likelihood (MCL) method for estimating evolutionary distances between all pairs of sequences simultaneously, with and without incorporating rate variation among sites and substitution pattern heterogeneities among lineages. This MCL method also can be used to estimate transition/transversion bias and nucleotide substitution pattern without knowledge of the phylogenetic tree. This new version is a native 32-bit Windows application with multi-threading and multi-user supports, and it is also available to run in a Linux desktop environment (via the Wine compatibility layer) and on Intel-based Macintosh computers under the Parallels program. The current version of MEGA is available free of charge at (
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            Mystery swine disease in The Netherlands: the isolation of Lelystad virus.

            In early 1991, the Dutch pig-industry was struck by the so-called mystery swine disease. Large-scale laboratory investigations were undertaken to search for the etiological agent. We focused on isolating viruses and mycoplasmas, and we tested paired sera of affected sows for antibodies against ten known pig viruses. The mycoplasmas M. hyosynoviae, M. hyopneumoniae, and Acholeplasma laidlawii, and the viruses encephalomyocarditis virus and porcine enterovirus types 2 and 7 were isolated from individual pigs. An unknown agent, however, was isolated from 16 of 20 piglets and from 41 of 63 sows. This agent was characterised as a virus and designated Lelystad virus. No relationship between this virus and other viruses has yet been established. Of 165 sows reportedly afflicted by the disease, 123 (75 per cent) seroconverted to Lelystad virus, whereas less than 10 per cent seroconverted to any of the other virus isolates or to the known viral pathogens. Antibodies directed against Lelystad virus were also found in pigs with mystery swine disease in England, Germany, and in the United States. We conclude that infection with Lelystad virus is the likely cause of mystery swine disease.
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              Emergence of Fatal PRRSV Variants: Unparalleled Outbreaks of Atypical PRRS in China and Molecular Dissection of the Unique Hallmark

              Porcine reproductive and respiratory syndrome (PRRS) is a severe viral disease in pigs, causing great economic losses worldwide each year. The causative agent of the disease, PRRS virus (PRRSV), is a member of the family Arteriviridae. Here we report our investigation of the unparalleled large-scale outbreaks of an originally unknown, but so-called “high fever” disease in China in 2006 with the essence of PRRS, which spread to more than 10 provinces (autonomous cities or regions) and affected over 2,000,000 pigs with about 400,000 fatal cases. Different from the typical PRRS, numerous adult sows were also infected by the “high fever” disease. This atypical PRRS pandemic was initially identified as a hog cholera-like disease manifesting neurological symptoms (e.g., shivering), high fever (40–42°C), erythematous blanching rash, etc. Autopsies combined with immunological analyses clearly showed that multiple organs were infected by highly pathogenic PRRSVs with severe pathological changes observed. Whole-genome analysis of the isolated viruses revealed that these PRRSV isolates are grouped into Type II and are highly homologous to HB-1, a Chinese strain of PRRSV (96.5% nucleotide identity). More importantly, we observed a unique molecular hallmark in these viral isolates, namely a discontinuous deletion of 30 amino acids in nonstructural protein 2 (NSP2). Taken together, this is the first comprehensive report documenting the 2006 epidemic of atypical PRRS outbreak in China and identifying the 30 amino-acid deletion in NSP2, a novel determining factor for virulence which may be implicated in the high pathogenicity of PRRSV, and will stimulate further study by using the infectious cDNA clone technique.

                Author and article information

                Open Virol J
                Open Virol J
                The Open Virology Journal
                Bentham Open
                30 June 2017
                : 11
                : 90-97
                China Animal Disease Control Center, OIE Porcine Reproductive and Respiratory Syndrome Reference Laboratory, No. 20 Maizidian Street, Chaoyang District, Beijing 100125, China.
                Author notes
                [* ]Address correspondence to this author at the China Animal Disease Control Center, No. 20 Maizidian Street, Chaoyang District, Beijing, 100125, P. R. China; Tel: +86-10-59198898; Fax: +86-10-59198899; E-mail: Zhaixy2010@
                © 2017 zhou et al.

                This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 International Public License (CC-BY 4.0), a copy of which is available at: This license permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

                Suppl-1, M7

                Microbiology & Virology

                genetic diversity, pprsv, nadc30-like strain, virus


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