1887

Abstract

Porcine reproductive and respiratory syndrome (PRRS) has a major negative economic impact on the swine industry worldwide. During the investigation of PRRS virus (PRRSV) in mainland China, European genotype (EU, type 1) PRRSV isolates were detected in swine herds both with and without clinical symptoms. Two complete genome sequences for Chinese type 1 PRRSV isolates were identified from viruses isolated from lung tissue and sera. The two viruses, designated BJEU06-1 and NMEU09-1, produced cytopathic effects in primary porcine alveolar macrophages but not in Marc-145 cells, and had a mean diameter of 55 nm, as measured by transmission electron microscopy . Comparative sequence analysis revealed that they shared 87.0–91.5 % and 58.0–58.2 % identity with the EU and North American genotype (NA, type 2) prototypic strains LV and VR-2332, respectively. Remarkably, these isolates, characterized by concomitant deletions within non-structural protein 2 (Nsp2) and ORF3 hypervariable regions, have never been described. Phylogenetic trees showed that all of the novel Chinese isolates of European genotype are in the pan-European subtype 1 that is predominant in Europe. However, they evolved from different ancestors. These novel viruses are predicted to be products of the divergent evolution of ancestor PRRSV isolates introduced from Europe. This is the first report of type 1 PRRSV wild isolates being in mainland China. Our findings confirm that the Chinese type 1 PRRSV isolates originated from diverse progenitors and the type 1 and type 2 PRRSV isolates, having different biological properties, have coexisted on the Chinese mainland for several years.

Loading

Article metrics loading...

/content/journal/jgv/10.1099/vir.0.027995-0
2011-04-01
2024-03-28
Loading full text...

Full text loading...

/deliver/fulltext/jgv/92/4/880.html?itemId=/content/journal/jgv/10.1099/vir.0.027995-0&mimeType=html&fmt=ahah

References

  1. Allende, R., Lewis, T. L., Lu, Z., Rock, D. L., Kutish, G. F., Ali, A., Doster, A. R. & Osorio, F. A.(1999). North American and European porcine reproductive and respiratory syndrome viruses differ in non-structural protein coding regions. J Gen Virol 80, 307–315. [Google Scholar]
  2. Amonsin, A., Kedkovid, R., Puranaveja, S., Wongyanin, P., Suradhat, S. & Thanawongnuwech, R.(2009). Comparative analysis of complete nucleotide sequence of porcine reproductive and respiratory syndrome virus (PRRSV) isolates in Thailand (US and EU genotypes). Virol J 6, 143.[CrossRef] [Google Scholar]
  3. Balka, G., Hornyák, A., Bálint, A., Kiss, I., Kecskeméti, S., Bakonyi, T. & Rusvai, M.(2008). Genetic diversity of porcine reproductive and respiratory syndrome virus strains circulating in Hungarian swine herds. Vet Microbiol 127, 128–135.[CrossRef] [Google Scholar]
  4. Bøtner, A., Strandbygaard, B., Sørensen, K. J., Have, P., Madsen, K. G., Madsen, E. S. & Alexandersen, S.(1997). Appearance of acute PRRS-like symptoms in sow herds after vaccination with a modified live PRRS vaccine. Vet Rec 141, 497–499.[CrossRef] [Google Scholar]
  5. Cavanagh, D.(1997).Nidovirales: a new order comprising Coronaviridae and Arteriviridae. Arch Virol 142, 629–633. [Google Scholar]
  6. Chen, N. H., Chen, X. Z., Hu, D. M., Yu, X. L., Wang, L. L., Han, W., Wu, J. J., Cao, Z., Wang, C. B. & Zhang, Q.(2009). Rapid differential detection of classical and highly pathogenic North American Porcine Reproductive and Respiratory Syndrome virus in China by a duplex real-time RT-PCR. J Virol Methods 161, 192–198.[CrossRef] [Google Scholar]
  7. Chen, Z., Zhou, X., Lunney, J. K., Lawson, S., Sun, Z., Brown, E., Christopher-Hennings, J., Knudsen, D., Nelson, E. & Fang, Y.(2010). Immunodominant epitopes in Nsp2 of porcine reproductive and respiratory syndrome virus are dispensable for replication, but play an important role in modulation of the host immune response. J Gen Virol 91, 1047–1057.[CrossRef] [Google Scholar]
  8. Collins, J. E., Benfield, D. A., Christianson, W. T., Harris, L., Hennings, J. C., Shaw, D. P., Goyal, S. M., McCullough, S., Morrison, R. B. & other authors(1992). Isolation of swine infertility and respiratory syndrome virus (isolate ATCC VR-2332) in North America and experimental reproduction of the disease in gnotobiotic pigs. J Vet Diagn Invest 4, 117–126.[CrossRef] [Google Scholar]
  9. Conzelmann, K. K., Visser, N., Van Woensel, P. & Thiel, H. J.(1993). Molecular characterization of porcine reproductive and respiratory syndrome virus, a member of the arterivirus group. Virology 193, 329–339.[CrossRef] [Google Scholar]
  10. Dea, S., Gagnon, C. A., Mardassi, H., Pirzadeh, B. & Rogan, D.(2000). Current knowledge on the structural proteins of porcine reproductive and respiratory syndrome (PRRS) virus: comparison of the North American and European isolates. Arch Virol 145, 659–688.[CrossRef] [Google Scholar]
  11. de Lima, M., Pattnaik, A. K., Flores, E. F. & Osorio, F. A.(2006). Serologic marker candidates identified among B-cell linear epitopes of Nsp2 and structural proteins of a North American strain of porcine reproductive and respiratory syndrome virus. Virology 353, 410–421.[CrossRef] [Google Scholar]
  12. Dewey, C., Charbonneau, G., Carman, S., Hamel, A., Nayar, G., Friendship, R., Eernisse, K. & Swenson, S.(2000). Lelystad-like strain of porcine reproductive and respiratory syndrome virus (PRRSV) identified in Canadian swine. Can Vet J 41, 493–494. [Google Scholar]
  13. Drew, T. W., Lowings, J. P. & Yapp, F.(1997). Variation in open reading frames 3, 4 and 7 among porcine reproductive and respiratory syndrome virus isolates in the UK. Vet Microbiol 55, 209–221.[CrossRef] [Google Scholar]
  14. Fang, Y. & Snijder, E. J.(2010). The PRRSV replicase: exploring the multifunctionality of an intriguing set of nonstructural proteins. Virus Res 154, 61–76.[CrossRef] [Google Scholar]
  15. Fang, Y., Kim, D. Y., Ropp, S., Steen, P., Christopher-Hennings, J., Nelson, E. A. & Rowland, R. R.(2004). Heterogeneity in Nsp2 of European-like porcine reproductive and respiratory syndrome viruses isolated in the United States. Virus Res 100, 229–235.[CrossRef] [Google Scholar]
  16. Fang, Y., Schneider, P., Zhang, W. P., Faaberg, K. S., Nelson, E. A. & Rowland, R. R.(2007). Diversity and evolution of a newly emerged North American Type 1 porcine arterivirus: analysis of isolates collected between 1999 and 2004. Arch Virol 152, 1009–1017.[CrossRef] [Google Scholar]
  17. Fang, Y., Christopher-Hennings, J., Brown, E., Liu, H., Chen, Z., Lawson, S. R., Breen, R., Clement, T., Gao, X. & other authors(2008). Development of genetic markers in the non-structural protein 2 region of a US type 1 porcine reproductive and respiratory syndrome virus: implications for future recombinant marker vaccine development. J Gen Virol 89, 3086–3096.[CrossRef] [Google Scholar]
  18. Forsberg, R., Storgaard, T., Nielsen, H. S., Oleksiewicz, M. B., Cordioli, P., Sala, G., Hein, J. & Bøtner, A.(2002). The genetic diversity of European type PRRSV is similar to that of the North American type but is geographically skewed within Europe. Virology 299, 38–47.[CrossRef] [Google Scholar]
  19. Gao, Z. Q., Guo, X. & Yang, H. C.(2004). Genomic characterization of two Chinese isolates of porcine respiratory and reproductive syndrome virus. Arch Virol 149, 1341–1351. [Google Scholar]
  20. Gorbalenya, A. E., Enjuanes, L., Ziebuhr, J. & Snijder, E. J.(2006). Nidovirales: evolving the largest RNA virus genome. Virus Res 117, 17–37.[CrossRef] [Google Scholar]
  21. Guo, B. Q., Chen, Z. S., Liu, W. X. & Cui, Y. Z.(1996). Isolation of PRRSV from aborted fetus with typical clinical PRRS manifestations. Chin J Prev Vet Med 2, 1–5 (in Chinese). [Google Scholar]
  22. Han, J., Wang, Y. & Faaberg, K. S.(2006). Complete genome analysis of RFLP 184 isolates of porcine reproductive and respiratory syndrome virus. Virus Res 122, 175–182.[CrossRef] [Google Scholar]
  23. Han, J., Liu, G., Wang, Y. & Faaberg, K. S.(2007). Identification of nonessential regions of the Nsp2 replicase protein of porcine reproductive and respiratory syndrome virus strain VR-2332 for replication in cell culture. J Virol 81, 9878–9890.[CrossRef] [Google Scholar]
  24. Han, W., Wu, J. J., Deng, X. Y., Cao, Z., Yu, X. L., Wang, C. B., Zhao, T. Z., Chen, N. H., Hu, H. H. & other authors(2009). Molecular mutations associated with the in vitro passage of virulent porcine reproductive and respiratory syndrome virus. Virus Genes 38, 276–284.[CrossRef] [Google Scholar]
  25. Jeanmougin, F., Thompson, J. D., Gouy, M., Higgins, D. G. & Gibson, T. J.(1998). Multiple sequence alignment with clustalx. Trends Biochem Sci 23, 403–405.[CrossRef] [Google Scholar]
  26. Kapur, V., Elam, M. R., Pawlovich, T. M. & Murtaugh, M. P.(1996). Genetic variation in porcine reproductive and respiratory syndrome virus isolates in the midwestern United States. J Gen Virol 77, 1271–1276.[CrossRef] [Google Scholar]
  27. Katz, J. B., Shafer, A. L., Eernisse, K. A., Landgraf, J. G. & Nelson, E. A.(1995). Antigenic differences between European and American isolates of porcine reproductive and respiratory syndrome virus (PRRSV) are encoded by the carboxyterminal portion of viral open reading frame 3. Vet Microbiol 44, 65–76.[CrossRef] [Google Scholar]
  28. Keffaber, K. K.(1989). Reproductive failure of unknown etiology. Am Assoc Swine Prac Newsl 1, 1–10. [Google Scholar]
  29. Kim, H. S., Kwang, J., Yoon, I. J., Joo, H. S. & Frey, M. L.(1993). Enhanced replication of porcine reproductive and respiratory syndrome (PRRS) virus in a homogeneous subpopulation of MA-104 cell line. Arch Virol 133, 477–483.[CrossRef] [Google Scholar]
  30. Kim, D. Y., Kaiser, T. J., Horlen, K., Keith, M. L., Taylor, L. P., Jolie, R., Calvert, J. G. & Rowland, R. R.(2009a). Insertion and deletion in a non-essential region of the nonstructural protein 2 (Nsp2) of porcine reproductive and respiratory syndrome (PRRS) virus: effects on virulence and immunogenicity. Virus Genes 38, 118–128.[CrossRef] [Google Scholar]
  31. Kim, H. K., Yang, J. S., Moon, H. J., Park, S. J., Luo, Y., Lee, C. S., Song, D. S., Kang, B. K., Ann, S. K. & other authors(2009b). Genetic analysis of ORF5 of recent Korean porcine reproductive and respiratory syndrome viruses (PRRSVs) in viremic sera collected from MLV-vaccinating or non-vaccinating farms. J Vet Sci 10, 121–130.[CrossRef] [Google Scholar]
  32. Kim, S. H., Roh, I. S., Choi, E. J., Lee, C., Lee, C. H., Lee, K. H., Lee, K. K., Song, Y. K., Lee, O. S. & Park, C. K.(2010). A molecular analysis of European porcine reproductive and respiratory syndrome virus isolated in South Korea. Vet Microbiol 143, 394–400.[CrossRef] [Google Scholar]
  33. Kleiboeker, S. B., Schommer, S. K., Lee, S. M., Watkins, S., Chittick, W. & Polson, D.(2005). Simultaneous detection of North American and European porcine reproductive and respiratory syndrome virus using real-time quantitative reverse transcriptase-PCR. J Vet Diagn Invest 17, 165–170.[CrossRef] [Google Scholar]
  34. Labarque, G., Reeth, K. V., Nauwynck, H., Drexler, C., Van Gucht, S. & Pensaert, M.(2004). Impact of genetic diversity of European-type porcine reproductive and respiratory syndrome virus strains on vaccine efficacy. Vaccine 22, 4183–4190.[CrossRef] [Google Scholar]
  35. Li, Y., Wang, X., Jiang, P., Chen, W. & Wang, X.(2008). Genetic analysis of two porcine reproductive and respiratory syndrome viruses with different virulence isolated in China. Arch Virol 153, 1877–1884.[CrossRef] [Google Scholar]
  36. Li, B., Fang, L., Xu, Z., Liu, S., Gao, J., Jiang, Y., Chen, H. & Xiao, S.(2009a). Recombination in vaccine and circulating strains of porcine reproductive and respiratory syndrome viruses. Emerg Infect Dis 15, 2032–2035.[CrossRef] [Google Scholar]
  37. Li, Y., Wang, X., Jiang, P., Wang, X., Chen, W., Wang, X. & Wang, K.(2009b). Genetic variation analysis of porcine reproductive and respiratory syndrome virus isolated in China from 2002 to 2007 based on ORF5. Vet Microbiol 138, 150–155.[CrossRef] [Google Scholar]
  38. Meng, X. J., Paul, P. S., Halbur, P. G. & Lum, M. A.(1995). Phylogenetic analyses of the putative M (ORF 6) and N (ORF 7) genes of porcine reproductive and respiratory syndrome virus (PRRSV): implication for the existence of two genotypes of PRRSV in the U.S.A. and Europe. Arch Virol 140, 745–755.[CrossRef] [Google Scholar]
  39. Mengeling, W. L., Lager, K. M. & Vorwald, A. C.(1995). Diagnosis of porcine reproductive and respiratory syndrome. J Vet Diagn Invest 7, 3–16.[CrossRef] [Google Scholar]
  40. Meulenberg, J. J., Hulst, M. M., de Meijer, E. J., Moonen, P. L., den Besten, A., de Kluyver, E. P., Wensvoort, G. & Moormann, R. J.(1993). Lelystad virus, the causative agent of porcine epidemic abortion and respiratory syndrome (PEARS), is related to LDV and EAV. Virology 192, 62–72.[CrossRef] [Google Scholar]
  41. Meulenberg, J. J., Petersen-den Besten, A., De Kluyver, E. P., Moormann, R. J., Schaaper, W. M. & Wensvoort, G.(1995). Characterization of proteins encoded by ORFs 2 to 7 of Lelystad virus. Virology 206, 155–163.[CrossRef] [Google Scholar]
  42. Murtaugh, M. P., Elam, M. R. & Kakach, L. T.(1995). Comparison of the structural protein coding sequences of the VR-2332 and Lelystad virus strains of the PRRS virus. Arch Virol 140, 1451–1460.[CrossRef] [Google Scholar]
  43. Nam, E., Park, C. K., Kim, S. H., Joo, Y. S., Yeo, S. G. & Lee, C.(2009). Complete genomic characterization of a European type 1 porcine reproductive and respiratory syndrome virus isolate in Korea. Arch Virol 154, 629–638.[CrossRef] [Google Scholar]
  44. Nelsen, C. J., Murtaugh, M. P. & Faaberg, K. S.(1999). Porcine reproductive and respiratory syndrome virus comparison: divergent evolution on two continents. J Virol 73, 270–280. [Google Scholar]
  45. Oleksiewicz, M. B., Bøtner, A., Madsen, K. G. & Storgaard, T.(1998). Sensitive detection and typing of porcine reproductive and respiratory syndrome virus by RT-PCR amplification of whole viral genes. Vet Microbiol 64, 7–22.[CrossRef] [Google Scholar]
  46. Oleksiewicz, M. B., Bøtner, A., Toft, P., Grubbe, T., Nielsen, J., Kamstrup, S. & Storgaard, T.(2000). Emergence of porcine reproductive and respiratory syndrome virus deletion mutants: correlation with the porcine antibody response to a hypervariable site in the ORF 3 structural glycoprotein. Virology 267, 135–140.[CrossRef] [Google Scholar]
  47. Oleksiewicz, M. B., Bøtner, A., Toft, P., Normann, P. & Storgaard, T.(2001). Epitope mapping porcine reproductive and respiratory syndrome virus by phage display: the Nsp2 fragment of the replicase polyprotein contains a cluster of B-cell epitopes. J Virol 75, 3277–3290.[CrossRef] [Google Scholar]
  48. Ostrowski, M., Galeota, J. A., Jar, A. M., Platt, K. B., Osorio, F. A. & Lopez, O. J.(2002). Identification of neutralizing and nonneutralizing epitopes in the porcine reproductive and respiratory syndrome virus GP5 ectodomain. J Virol 76, 4241–4250.[CrossRef] [Google Scholar]
  49. Pol, J. M., Wagenaar, F. & Reus, J. E.(1997). Comparative morphogenesis of three PRRS virus strains. Vet Microbiol 55, 203–208.[CrossRef] [Google Scholar]
  50. Ropp, S. L., Wees, C. E., Fang, Y., Nelson, E. A., Rossow, K. D., Bien, M., Arndt, B., Preszler, S., Steen, P. & other authors(2004). Characterization of emerging European-like porcine reproductive and respiratory syndrome virus isolates in the United States. J Virol 78, 3684–3703.[CrossRef] [Google Scholar]
  51. Rossow, K. D.(1998). Porcine reproductive and respiratory syndrome. Vet Pathol 35, 1–20.[CrossRef] [Google Scholar]
  52. Shen, S., Kwang, J., Liu, W. & Liu, D. X.(2000). Determination of the complete nucleotide sequence of a vaccine strain of porcine reproductive and respiratory syndrome virus and identification of the Nsp2 gene with a unique insertion. Arch Virol 145, 871–883.[CrossRef] [Google Scholar]
  53. Snijder, E. J.(1998). The arterivirus replicase. The road from RNA to protein(s), and back again. Adv Exp Med Biol 440, 97–108. [Google Scholar]
  54. Snijder, E. J. & Meulenberg, J. J.(1998). The molecular biology of arteriviruses. J Gen Virol 79, 961–979. [Google Scholar]
  55. Snijder, E. J., den Boon, J. A., Horzinek, M. C. & Spaan, W. J.(1991). Comparison of the genome organization of toro- and coronaviruses: evidence for two nonhomologous RNA recombination events during Berne virus evolution. Virology 180, 448–452.[CrossRef] [Google Scholar]
  56. Snijder, E. J., Wassenaar, A. L., Spaan, W. J. & Gorbalenya, A. E.(1995). The arterivirus Nsp2 protease. An unusual cysteine protease with primary structure similarities to both papain-like and chymotrypsin-like proteases. J Biol Chem 270, 16671–16676.[CrossRef] [Google Scholar]
  57. Snijder, E. J., Wassenaar, A. L., van Dinten, L. C., Spaan, W. J. & Gorbalenya, A. E.(1996). The arterivirus Nsp4 protease is the prototype of a novel group of chymotrypsin-like enzymes, the 3C-like serine proteases. J Biol Chem 271, 4864–4871.[CrossRef] [Google Scholar]
  58. Stadejek, T., Oleksiewicz, M. B., Potapchuk, D. & Podgórska, K.(2006). Porcine reproductive and respiratory syndrome virus strains of exceptional diversity in eastern Europe support the definition of new genetic subtypes. J Gen Virol 87, 1835–1841.[CrossRef] [Google Scholar]
  59. Stadejek, T., Oleksiewicz, M. B., Scherbakov, A. V., Timina, A. M., Krabbe, J. S., Chabros, K. & Potapchuk, D.(2008). Definition of subtypes in the European genotype of porcine reproductive and respiratory syndrome virus: nucleocapsid characteristics and geographical distribution in Europe. Arch Virol 153, 1479–1488.[CrossRef] [Google Scholar]
  60. Tamura, K., Dudley, J., Nei, M. & Kumar, S.(2007).mega4: molecular evolutionary genetics analysis (mega) software version 4.0. Mol Biol Evol 24, 1596–1599.[CrossRef] [Google Scholar]
  61. Thanawongnuwech, R., Amonsin, A., Tatsanakit, A. & Damrongwatanapokin, S.(2004). Genetics and geographical variation of porcine reproductive and respiratory syndrome virus (PRRSV) in Thailand. Vet Microbiol 101, 9–21.[CrossRef] [Google Scholar]
  62. Tian, K., Yu, X., Zhao, T., Feng, Y., Cao, Z., Wang, C., Hu, Y., Chen, X., Hu, D. & other authors(2007). Emergence of fatal PRRSV variants: unparalleled outbreaks of atypical PRRS in China and molecular dissection of the unique hallmark. PLoS ONE 2, e526.[CrossRef] [Google Scholar]
  63. Urniza, A., Climent, I., Duran, J. P., Cortés, E., Sarraseca, J., Casal, J. I. & Vela, C..(1997). Baculovirus expression of proteins of porcine reproductive and respiratory syndrome virus strain Olot/91. Involvement of ORF3 and ORF5 proteins in protection. Virus Genes 14, 19–29.[CrossRef] [Google Scholar]
  64. van Dinten, L. C., Wassenaar, A. L., Gorbalenya, A. E., Spaan, W. J. & Snijder, E. J.(1996). Processing of the equine arteritis virus replicase ORF1b protein: identification of cleavage products containing the putative viral polymerase and helicase domains. J Virol 70, 6625–6633. [Google Scholar]
  65. van Vugt, J. J., Storgaard, T., Oleksiewicz, M. B. & Bøtner, A.(2001). High frequency RNA recombination in porcine reproductive and respiratory syndrome virus occurs preferentially between parental sequences with high similarity. J Gen Virol 82, 2615–2620. [Google Scholar]
  66. Wassenaar, A. L., Spaan, W. J., Gorbalenya, A. E. & Snijder, E. J.(1997). Alternative proteolytic processing of the arterivirus replicase ORF1a polyprotein: evidence that NSP2 acts as a cofactor for the NSP4 serine protease. J Virol 71, 9313–9322. [Google Scholar]
  67. Wensvoort, G., Terpstra, C., Pol, J. M., ter Laak, E. A., Bloemraad, M., de Kluyver, E. P., Kragten, C., van Buiten, L., den Besten, A. & other authors(1991). Mystery swine disease in The Netherlands: the isolation of Lelystad virus. Vet Q 13, 121–130.[CrossRef] [Google Scholar]
  68. Wensvoort, G., de Kluyver, E. P., Pol, J. M., Wagenaar, F., Moormann, R. J., Hulst, M. M., Bloemraad, R., den Besten, A., Zetstra, T. & Terpstra, C.(1992). Lelystad virus, the cause of porcine epidemic abortion and respiratory syndrome: a review of mystery swine disease research at Lelystad. Vet Microbiol 33, 185–193.[CrossRef] [Google Scholar]
  69. Wissink, E. H., van Wijk, H. A., Kroese, M. V., Weiland, E., Meulenberg, J. J., Rottier, P. J. & van Rijn, P. A.(2003). The major envelope protein, GP5, of a European porcine reproductive and respiratory syndrome virus contains a neutralization epitope in its N-terminal ectodomain. J Gen Virol 84, 1535–1543.[CrossRef] [Google Scholar]
  70. Wootton, S., Yoo, D. & Rogan, D.(2000). Full-length sequence of a Canadian porcine reproductive and respiratory syndrome virus (PRRSV) isolate. Arch Virol 145, 2297–2323.[CrossRef] [Google Scholar]
  71. Yoon, K. J., Wu, L. L., Zimmerman, J. J., Hill, H. T. & Platt, K. B.(1996). Antibody-dependent enhancement (ADE) of porcine reproductive and respiratory syndrome virus (PRRSV) infection in pigs. Viral Immunol 9, 51–63.[CrossRef] [Google Scholar]
  72. Yuan, S. & Wei, Z.(2008). Construction of infectious cDNA clones of PRRSV: separation of coding regions for nonstructural and structural proteins. Sci China C Life Sci 51, 271–279.[CrossRef] [Google Scholar]
  73. Yuan, S., Nelsen, C. J., Murtaugh, M. P., Schmitt, B. J. & Faaberg, K. S.(1999). Recombination between North American strains of porcine reproductive and respiratory syndrome virus. Virus Res 61, 87–98.[CrossRef] [Google Scholar]
  74. Zeman, D., Neiger, R., Yaeger, M., Nelson, E., Benfield, D., Leslie-Steen, P., Thomson, J., Miskimins, D., Daly, R. & Minehart, M.(1993). Laboratory investigation of PRRS virus infection in three swine herds. J Vet Diagn Invest 5, 522–528.[CrossRef] [Google Scholar]
  75. Zhou, L. & Yang, H.(2010). Porcine reproductive and respiratory syndrome in China. Virus Res 154, 31–37.[CrossRef] [Google Scholar]
  76. Zhou, L., Chen, S., Zhang, J., Zeng, J., Guo, X., Ge, X., Zhang, D. & Yang, H.(2009a). Molecular variation analysis of porcine reproductive and respiratory syndrome virus in China. Virus Res 145, 97–105.[CrossRef] [Google Scholar]
  77. Zhou, Y. J., Yu, H., Tian, Z. J., Li, G. X., Hao, X. F., Yan, L. P., Peng, J. M., An, T. Q., Xu, A. T. & Wang, Y.-X.(2009b). Genetic diversity of the ORF5 gene of porcine reproductive and respiratory syndrome virus isolates in China from 2006 to 2008. Virus Res 144, 136–144.[CrossRef] [Google Scholar]
  78. Ziebuhr, J., Snijder, E. J. & Gorbalenya, A. E.(2000). Virus-encoded proteinases and proteolytic processing in the Nidovirales. J Gen Virol 81, 853–879. [Google Scholar]
http://instance.metastore.ingenta.com/content/journal/jgv/10.1099/vir.0.027995-0
Loading
/content/journal/jgv/10.1099/vir.0.027995-0
Loading

Data & Media loading...

Supplements

vol. , part 4, pp. 880–892

Primers used for the amplification of the complete genomes of EU genotype PRRSV isolates.

Details of the PRRSV isolates used in this study.

[ Single PDF file] (62kB)



PDF
This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error