Characterization of Emerging European-Like Porcine Reproductive and Respiratory Syndrome Virus Isolates in the United States

Journal of Virology

Volumn 78, Issue 7, 2004, Pages 3684-3703

  Ropp, Susan L ^a   Wees, Carrie E Mahlum ^b   Fang, Ying ^a   Nelson, Eric A ^a   Rossow, Kurt D ^b   Bien, Melissa ^a   Arndt, Bill ^a   Preszler, Sarah ^a   Steen, Pamela ^a   Christopher Hennings, Jane ^a   Collins, James E ^b   Benfield, David A ^c   Faaberg, Kay S ^b  

^a SOUTH DAKOTA STATE UNIVERSITY   (United States)

^b UNIVERSITY OF MINNESOTA   (United States)

^c OHIO STATE UNIVERSITY   (United States)

Author keywords

[No Author keywords available]

Indexed keywords

MONOCLONAL ANTIBODY; NONSTRUCTURAL PROTEIN 2; NUCLEOTIDE; UNCLASSIFIED DRUG; VIRUS PROTEIN; VIRUS ANTIGEN;

5' UNTRANSLATED REGION; ARTERIVIRUS; ARTICLE; EVOLUTION; GENE DELETION; NONHUMAN; NORTH AMERICA; NUCLEOTIDE SEQUENCE; OPEN READING FRAME; PHYLOGENY; PRIORITY JOURNAL; SEQUENCE ANALYSIS; UNINDEXED SEQUENCE; UNITED KINGDOM; UNITED STATES; VIRUS STRAIN; AMINO ACID SEQUENCE; ANIMAL; CHEMISTRY; DNA SEQUENCE; EUROPE; GENETIC VARIABILITY; GENETICS; ISOLATION AND PURIFICATION; MOLECULAR GENETICS; SWINE; VIROLOGY; VIRUS GENE; VIRUS GENOME; VIRUS INFECTION;

AMINO ACID SEQUENCE; ANIMALS; ANTIGENS, VIRAL; BASE SEQUENCE; EUROPE; GENES, VIRAL; GENOME, VIRAL; MOLECULAR SEQUENCE DATA; OPEN READING FRAMES; PORCINE REPRODUCTIVE AND RESPIRATORY SYNDROME; PORCINE RESPIRATORY AND REPRODUCTIVE SYNDROME VIRUS; SEQUENCE ANALYSIS, DNA; SWINE; UNITED STATES; VARIATION (GENETICS); VIRAL PROTEINS;

EID: 1842509982     PISSN: 0022538X     EISSN: None     Source Type: Journal    
DOI: 10.1128/JVI.78.7.3684-3703.2004     Document Type: Article

References (86)

1. Allende, R., T. L. Lewis, Z. Lu, D. L. Rock, G. F. Kutish, A. Ali, A. R. Doster, and F. A. Osorio. 1999. North American and European porcine reproductive and respiratory syndrome viruses differ in non-structural protein coding regions. J. Gen. Virol. 80:307-315.
2. Arold, S., P. Franken, M. P. Strub, F. Hoh, S. Benichou, R. Benarous, and C. Dumas. 1997. The crystal structure of HIV-1 Nef protein bound to the Fyn kinase SH3 domain suggests a role for this complex in altered T cell receptor signaling. Structure 5:1361-1372.
3. Benfield, D. A., E. Nelson, J. E. Collins, L. Harris, S. M. Goyal, D. Robison, W. T. Christianson, R. B. Morrison, D. Gorcyca, and D. Chladek. 1992. Characterization of swine infertility and respiratory syndrome (SIRS) virus (isolate ATCC VR-2332). J. Vet. Diagn. Investig. 4:127-133.
4. Black, A. R., J. D. Black, and J. Azizkhan-Clifford. 2001. Sp1 and kruppel-like factor family of transcription factors in cell growth regulation and cancer. J. Cell. Physiol. 188:143-160.
5. Botner, A., B. Strandbygaard, K. J. Sorensen, P. Have, K. G. Madsen, E. S. Madsen, and S. Alexandersen. 1997. Appearance of acute PRRS-like symptoms in sow herds after vaccination with a modified live PRRS vaccine. Vet. Rec. 141:497-499.
6. Cavanaugh, D. 1997. Nidovirales: a new order comprising Coronaviridae and Arteriviridae. Arch. Virol. 142:629-633.
7. Cicchetti, P., B. J. Mayer, G. Thiel, and D. Baltimore. 1992. Identification of a protein that binds to the Sh3 region of Abi and is similar to Bcr and Gap-Rho. Science 257:803-806.
8. Cohen, G. B., R. B. Ren, and D. Baltimore. 1995. Modular binding domains in signal-transduction proteins. Cell 80:237-248.
9. Collins, J. E., D. A. Benfield, W. T. Christianson, L. Harris, J. C. Hennings, D. P. Shaw, S. M. Goyal, S. McCullough, R. B. Morrison, H. S. Joo, D. E. Gorcyca, and D. W. Chladek. 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. Investig. 4:117-126.
10. Conzelmann, K., N. Visser, P. van Woensel, and H. Thiel. 1993. Molecular characterization of porcine reproductive and respiratory syndrome virus, a member of the arterivirus group. Virology 193:329-339.
11. Dea, S., C. A. Gagnon, H. Mardassi, B. Pirzadeh, and D. Rogan. 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.
12. Den Boon, J. A., E. J. Snijder, E. D. Chirnside, A. F. de Vries, M. C. Horzinek, and W. J. M. Spaan. 1991. Equine arteritis virus is not a togavirus but belongs to the cornaviruslike superfamily. J. Virol. 65:2910-2920.
13. Den Boon, J. A., K. S. Faaberg, J. J. M. Meulenberg, A. L. M. Wassenaar, P. G. W. Plagemann, A. E. Gorbelenya, and E. J. Snijder. 1995. Processing and evolution of the N-terminal region of the arterivirus replicase ORF1a protein: identification of two papainlike cysteine proteases. J. Virol. 69:4500-4505.
14. de Vries, A. A. F., E. D. Chirnside, P. J. Bredenbeek, L. A. Gravestein, M. C. Horzinek, and W. J. M. Spaan. 1990. The genome organization of the nidovirales: similarities and difference between arteri-, toro- and coronaviruses. Semin. Virol. 8:33-47.
15. Dewey, C., G. Charbonneau, S. Carman, A. Hamel, G. Nayar, R. Friendship, K. Eernisse, and S. Swenson. 2000. Lelystad-like strain of porcine reproductive and respiratory syndrome virus (PRRSV) identified in Canadian swine. Can. Vet. J. 21:493-494.
16. Dougherty, W. G., and B. L. Semler. 1993. Expression of virus-encoded proteinases: functional and structural similarities with cellular enzymes. Microbiol. Rev. 57:781-822.
17. Drew, T. W., J. P. Lowings, and F. Yapp. 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.
18. Forsberg, R., M. B. Oleksiewicz, A.-M. K. Petersen, J. Hein, A. Botner, and T. Storgaard. 2001. A molecular clock dates the common ancestor of European-type porcine reproductive and respiratory syndrome virus at more than 10 years before the emergence of disease. Virology 289:174-179.
19. Forsberg, R., T. Storgaard, H. S. Nielsen, M. B. Oleksiewicz, P. Cordioli, G. Sala, J. Hein, and A. Botner. 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.
20. Godeny, E. K., L. Chen, S. N. Kumar, S. L. Methven, E. V. Koonin, and M. A. Brinton. 1993. Complete genomic sequence and phylogenetic analysis of the lactate dehydrogenase-elevating virus (LDV). Virology 194:585-596.
21. Goldberg, T. L., E. C. Hahn, R. M. Weigel, and G. Scherba. 2000. Genetic, geographical and temporal variation of porcine reproductive and respiratory syndrome virus in Illinois. J. Gen. Virol. 81:171-179.
22. Herold, J., A. E. Gorbalenya, V. Thiel, B. Schelle, and S. G. Siddell. 1998. Proteolytic processing at the amino terminus of human coronavirus 229E gene 1-encoded polyproteins: identification of a papain-like proteinase and its substrate. J. Virol. 72:910-918.
23. Huang, P., and M. M. Lai. 2001. Heterogeneous nuclear ribonucleoprotein al binds to the 3′-untranslated region and mediates potential 5′-3′-end cross talks of mouse hepatitis virus RNA. J. Virol. 75:5009-5017.
24. Hwang, Y.-K., and M. A. Brinton. 1998. A 68-nucleotide sequence within the 30 noncoding region of simian hemorrhagic fever virus negative-strand RNA binds to four MA 104 cell proteins. J. Virol. 72:4341-4351.
25. Kapur, V., M. R. Elam, T. M. Pawlovich, and M. P. Murtaugh. 1996. Genetic variation in porcine reproductive and respiratory syndrome virus isolates in the midwestern United States. J. Gen. Virol. 77:1271-1276.
26. Katz, J. B., A. L. Shafer, K. A. Eernisse, J. G. Landgraf, and E. A. Nelson. 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. 44:65-75.
27. Keffaber, K. K. 1989. Reproductive failure of unknown etiology. Am. Assoc. Swine Prac. Newsl. 1:1-10.
28. Kim, H. S., J. Kwang, I. J. Yoon, H. S. Joo, and M. L. Frey. 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.
29. Lee, C. H., B. Leung, M. A. Lemmon, J. Zheng, D. Cowburn, J. Kuriyan, and K. Saksela. 1995. A single amino acid in the SH3 domain of Hck determines its high affinity and specificity in binding to HIV-1 Nef protein. EMBO J. 14:5006-5015.
30. Le Gall, A. L., E. Albine, R. Magar, and J. P. Gauthier. 1998. Antigenic variability of porcine reproductive and respiratory syndrome (PRRS) virus isolates: influence of virus passage in pig. Virus Res. 28:247-257.
31. Madsen, K. G., C. M. Hansen, E. S. Madsen, B. Strandbygaard, A. Botner, and K. J. Sorensen. 1998. Detection of porcine reproductive and respiratory syndrome virus of the American type in Danish swine herds. Arch. Virol. 143:1683-1700.
32. Magar, R., R. Larochelle, E. A. Nelson, and C. Charreyre. 1997. Differential reactivity of a monoclonal antibody directed to the membrane protein of porcine reproductive and respiratory syndrome virus. Can. J. Vet. Res. 61:69-71.
33. Mateu, E., M. Martin, and D. Vidal. 2003. Genetic diversity and phylogenetic analysis of glycoprotein 5 of European-type porcine reproductive and respiratory virus strains in Spain. J. Gen. Virol. 84:529-534.
34. Meng, X. J. 2000. Heterogeneity of porcine reproductive and respiratory syndrome virus: implications for current vaccine efficacy and future vaccine development. Vet. Microbiol. 74:309-329.
35. Mengeling, W. L., K. M. Lager, A. C. Vorwald, and D. F. Clouser. 2003. Comparative safety and efficacy of attenuated single-strain and multi-strain vaccines for porcine reproductive and respiratory syndrome. Vet. Microbiol. 93:25-38.
36. Meulenberg, J. J. M., M. M. Hulst, E. J. de Meijer, R. J. L. M. Moonen, A. den Besten, E. P. de Kluyver, G. Wensvoort, and R. J. M. Moormann. 1993. Lelystad virus, the causative agent of porcine epidemic abortion and respiratory syndrome (PEARS), is related to LDV and EAV. Virology 192:62-72.
37. Mounir, S., H. Mardassi, and S. Dea. 1995. Identification and characterization of the porcine reproductive and respiratory virus ORFs 7, 5 and 4 products. Adv. Exp. Med. Biol. 380:317-320.
38. Nakagawa, H., T. Inomoto, and A. K. Rustgi. 1997. A CACCC box-like cis-regulatory element of the Epstein-Barr virus ED-L2 promoter interacts with a novel transcriptional factor in tissue-specific squamous epithelia. J. Biol. Chem. 272:16688-16699.
39. Nelsen, C. J., M. P. Murtaugh, and K. S. Faaberg. 1999. Porcine reproductive and respiratory syndrome virus comparison: divergent evolution on two continents J. Virol. 73:270-280.
40. Nelson, E., J. C. Hennings, L. Harris, J. E. Collins, D. E. Gorcyca, D. W. Chladek, and D. A. Benfield. 1992. Characterization of monoclonal antibodies to an isolate of porcine epidemic abortion and respiratory syndrome virus. Proc. Int. Pig Vet. Soc. 12:121.
41. Nelson, E. A., J. Christopher-Hennings, T. Drew, G. Wensvoort, J. Collins, and D. A. Benfield. 1993. Differentiation of U. S. and European isolates of porcine reproductive and respiratory syndrome virus by monoclonal antibodies. J. Clin. Microbiol. 31:3184-3189.
42. Nelson, E. A., J. Christopher-Hennings, and D. A. Benfield. 1995. Structural proteins of porcine reproductive and respiratory syndrome virus (PRRSV). Adv. Exp. Med. Biol. 380:321-323.
43. Nelson, J. W., J. Zhu, C. C. Smith, M. Kulka, and L. Aurelian. 1996. ATP and SH3 binding sites in the protein kinase of the large subunit of herpes simplex virus type 2 of ribonucleotide reductase (ICP10). J. Biol. Chem. 271:17021-17027.
44. Okumura, K., G. Sakaguchl, S. Takagi, K. Naito, T. Mimori, and H. Igarashi. 1996. Sp1 family proteins recognize the U5 repressive element of the long terminal repeat of human T cell leukemia virus type I through binding to the CACCC core motif. Proc. Natl. Acad. Sci. USA 271:12944-12950.
45. Oleksiewicz, M. B., A. Botner, J. Nielsen, and T. Storgaard. 1999. Determination of 5′-leader sequences from radically disparate strains of porcine reproductive and respiratory syndrome virus reveals the presence of highly conserved sequence motifs. Arch. Virol. 144:981-987.
46. Oleksiewicz, M. B., A. Botner, P. Toft, T. Grubbe, J. Nielsen, S. Kamstrup, and T. Storgaard. 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.
47. Olekslewicz, M. B., A. Botner, P. Toft, P. Normann, and T. Storgaard. 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.
48. Ostrowski, M., J. A. Galeota, A. M. Jar, K. B. Platt, F. A. Osorio, and O. J. Lopez. 2002. Identification of neutralizing and nonneutralizing epitopes in the porcine reproductive and respiratory syndrome virus GP5 ectodomain. J. Virol. 76:4241-4250. (Erratum, 76:6863.)
49. Palmenberg, A. C., and J.-Y. Sgro. 1997. Topological organization of picornaviral genomes: statistical prediction of RNA structural signals. Semin. Virol. 8:231-241.
50. Pasternak, A. O., E. van den Born, W. J. Spaan, and E. J. Snijder. 2001. Sequence requirements for RNA strand transfer during nidovirus discontinuous subgenomic RNA synthesis. EMBO J. 20:7220-7228.
51. Pawson, T. 1995. Protein modules and signaling networks. Nature 373:573-580.
52. Plrzadeh, B., C. A. Gagnon, and S. Dea. 1998. Genetic and antigenic variation of porcine reproduction and respiratory syndrome virus major envelope GP5 glycoprotein. Can. J. Vet. Res. 62:170-177.
53. Plagemann, P. G., R. R. Rowland, and K. S. Faaberg. 2002. The primary neutralization epitope of porcine respiratory and reproductive syndrome virus strain VR-2332 is located in the middle of the GP5 ectodomain. Arch. Virol. 147:2327-2347.
54. Plagemann, P. G. W., and V. Moenning. 1992. Lactate dehydrogenase elevating virus, equine arteritis virus and simian hemorrhagic fever virus: a new group of positive strand RNA virus. Adv. Virus Res. 41:99-192.
55. Plagemann, P. G. W. 1996. Lactate dehydrogenase-elevating virus and related viruses, p. 1105-1120. In B. Fields (ed.), Fields virology, 3rd ed. Lippincott-Raven, Philadelphia, Pa.
56. Ramachandran, A., A. Jain, P. Arora, M. D. Bashyam, U. Chatterjee, S. Ghosh, V. K. Parnaik, and S. E. Hasnain. 2001. Novel Sp family-like transcription factors are present in adult insect cells and are involved in transcription from the polyhedrin gene initiator promoter. J. Biol. Chem. 276:23440-23449.
57. Rossow, K. D., E. M. Bautista, S. M. Goyal, T. W. Molitor, M. P. Murtaugh, R. B. Morrison, D. A. Benfield, and J. E. Collins. 1994. Experimental porcine reproductive and respiratory syndrome virus infection in one-, four-, and 10-week old pigs. J. Vet. Diagn. Investig. 6:3-12.
58. Rossow, K. D. 1998. Porcine reproductive and respiratory syndrome. Vet. Pathol. 35:1-20.
59. Rossow, K. D., J. L. Shiver, P. E. Yeske, D. D. Polson, R. R. R. Rowland, S. R. Lawson, M. P. Murtaugh, E. A. Nelson, and J. E. Collins. 1999. Porcine reproductive and respiratory syndrome virus infection in neonatal pigs characterized by marked neurovirulence. Vet. Rec. 144:444-448.
60. Rowland, R. R., M. Steffen, T. Ackerman, and D. A. Benfield. 1999. The evolution of porcine reproductive and respiratory syndrome virus: quasispecies and emergence of a virus subpopulation during infection of pigs with VR-2332. Virology 259:262-266.
61. Shen, S., J. Kwang, W. Liu, and D. X. Lui. 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.
62. Snijder, E. J., A. L. M. Wassenaar, and W. J. M. Spaan. 1992. The 5′ end of the equine arteritis virus replicase gene encodes a papainlike cysteine protease. J. Virol. 66:7040-7048.
63. Snijder, E. J., A. L. M. Wassenaar, and W. J. M. Spaan. 1994. Proteolytic processing of the replicase ORF1a protein of equine arteritis virus. J. Virol. 68:5755-5764.
64. Snijder, E. J., A. L. M. Wassenaar, W. J. M. Spaan, and A. E. Gorbalenya. 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.
65. Snijder, E. J., and J. J. M. Meulenberg. 1998. The molecular biology of arteriviruses. J. Gen. Virol. 79:961-979.
66. Snijder, E. J., H. van Tol, N. Roos, and K. W. Pedersen. 2001. Non-structural proteins 2 and 3 interact to modify host cell membranes during the formation of the arterivirus replication complex. J. Gen. Virol. 82:985-994.
67. Stadejek, T., A. Stankevicius, T. Storgaard, M. B. Oleksiewiez, S. Belak, T. W. Drew, and Z. Pejsak. 2002. Identification of radically different variants of porcine reproductive and respiratory syndrome virus in Eastern Europe: towards a common ancestor for European and American viruses. J. Gen. Virol. 83:1861-1873.
68. Strimmer, K., and A. von Haeseler. 1996. Quartet puzzling: a quartet maximum likelihood method for reconstructing tree topologies. Mol. Biol. Evol. 13:964-969.
69. Suarez, P., R. Zardoya, M. J. Martin, C. Prieto, J. Dopazo, A. Soana, and J. M. Castro. 1996. Phylogenetic relationship of European strains of porcine reproductive and respiratory syndrome virus (PRRSV) inferred from DNA sequences of putative ORF-5 and ORF-7 genes. Virus Res. 42:159-165.
70. Tan, S. L., H. Nakao, Y. He, S. Vijaysri, P. Neddermann, B. L. Jacobs, B. J. Mayer, and M. G. Katze. 1999. NS5A, a nonstructural protein of hepatitis C virus, binds growth factor receptor-bound protein 2 adaptor protein in a Src homology 3 domain/ligand-dependent manner and perturbs mitogenic signaling. Proc. Natl. Acad. Sci. USA 96:5533-5538.
71. Thompson, J. D., T. J. Gibson, F. Plewniak, F. Jeanmoughin, and D. G. Higgins. 1997. The CLUSTAL X windows interface: flexible strategies for multiple sequence alignment aided by quality analysis tools. Nucleic Acids Res. 25:4876-4882.
72. van Marle, G., J. C. Dobbe, A. P. Gultyaev, W. Luytjes W. J. Spaan, and E. J. Snijder. 1999. Arterivirus discontinuous mRNA transcription is guided by base pairing between sense and antisense transcription-regulating sequences. Proc. Natl. Acad. Sci. USA 96:12056-12061.
73. van Vugt, J. J., T. Storgaard, M. B. Oleksiewicz, and A. Botner. 2001. High frequency RNA recombination in porcine reproductive and respiratory syndrome virus occurs preferentially between parental sequences with high similarity J. Gen. Virol. 82:2615-2630.
74. Wensvoort, G., C. Terpstra, J. M. Pol, E. A. Ter Laak, M. Bloemraad, E. P. De Kluyver, C. Kragten, L. Van Buiten, A. den Besten, and F. Wagenaar. 1991. Mystery swine disease in The Netherlands: the isolation of Lelystad virus. Vet. Q. 13:121-130.
75. Wensvoort, G., E. P. de Kluyver, E. A. Luitjze, A. den Besten, L. Harris, J. E. Collins, W. T. Christianson, and D. Chladek. 1992. Antigenic comparison of Lelystad virus and swine infertility and respiratory syndrome (SIRS) virus. J. Vet. Diagn. Investig. 4:134-138.
76. Wissink, E. H., H. A. van Wijk, M. V. Kroese, E. Weiland, J. J. Meulenberg, P. J. Rottier, and P. A. van Rijn. 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.
77. Wootton, S., D. Yoo, and D. Rogan. 2000. Full-length sequence of a Canadian porcine reproductive and respiratory syndrome virus (PRRSV) isolate. Arch. Virol. 145:2297-2323.
78. Wootton, S. K., E. A. Nelson, and D. Yoo. 1998. Antigenic structure of the nucleocapsid protein of porcine reproductive and respiratory syndrome virus. Clin. Diagn. Lab. Immunol. 5:773-779.
79. Wu, W. H., Y. Fang, R. Farwell, M. Steffen-Bien, R. R. Rowland, J. Christopher-Hennings, and E. A. Nelson. 2001. A 10-kDa structural protein of porcine reproductive and respiratory syndrome virus encoded by ORF2b. Virology 287:183-191.
80. Yang, L., K. J. Yoon, Y. Li, J. H. Lee, J. J. Zimmerman, M. L. Frey, K. M. Harmon, and K. B. Platt. 1999. Antigenic and genetic variations of the 15 kD nucleocapsid protein of porcine reproductive and respiratory syndrome virus isolates. Arch. Virol. 144:525-546.
81. Yuan, S., C. J. Nelsen, M. P. Murtaugh, B. J. Schmitt, and K. S. Faaberg. 1999. Recombination between North American strains of porcine reproductive and respiratory syndrome virus. Virus Res. 61:87-98.
82. Yuan, S., D. Mickelson, M. P. Murtaugh, and K. S. Faaberg. 2001. Complete genome comparison of porcine reproductive and respiratory syndrome virus parental and attenuated strains. Virus Res. 79:189-200.
83. Yuan, S., M. P. Murtaugh, and K. S. Faaberg. 2000. Heteroclite RNAs are produced in porcine reproductive syndrome virus infection. Virology 275:158-169.
84. Zeman, D., R. Neiger, M. Yaeger, E. Nelson, D. Benfield, P. Leslie-Steen, J. Thomson, D. Miskimins, R. Daly, and M. Minehart. 1993. Laboratory investigation of PRRS virus infection in three swine herds. J. Vet. Diagn. Investig. 5:522-528.
85. Ziebuhr, J., E. J. Snijder, and A. E. Gorbalenya. 2000. Virus-encoded proteinases and proteolytic processing in the Nidovirales. J. Gen. Virol. 81:853-879.
86. Zimmerman, J., K. J. Yoon, G. Stevenson, and S. A. Dee (ed.). 1998. PRRS compendium: a comprehensive reference on porcine reproductive and respiratory syndrome for pork producers, veterinary practitioners, and researchers, 1st ed., p. 14-17. National Pork Producers Council, Des Moines, Iowa.