Abstract
Targeted RNA recombination was the first reverse genetics system devised for coronaviruses at a time when it was not clear whether the construction of full-length infectious cDNA clones would become possible. In its current state targeted RNA recombination offers a versatile and powerful method for the site-directed mutagenesis of the downstream third of the coronavirus genome, which encodes all the viral structural proteins. The development of this system is described, with an emphasis on recent improvements, and multiple applications of this technique to the study of coronavirus molecular biology and pathogenesis are reviewed. Additionally, the relative strengths and limitations of targeted RNA recombination and infectious cDNA systems are contrasted.
Keywords: Infectious Bronchitis Virus, Mouse Hepatitis Virus, Reverse Genetic System, Defective Interfere, Murine Coronavirus
Contributor Information
Luis Enjuanes, Email: [email protected].
P. S. Masters, Email: [email protected]
P. J. M. Rottier, Email: [email protected]
References
- Almazán F., González J.M., Pánzes Z., Izeta A., Calvo E., Plana-Durán J., Enjuanes L. Engineering the largest RNA virus genome as an infectious bacterial artificial chromosome. Proc Natl Acad Sci USA. 2000;97:5516–5521. doi: 10.1073/pnas.97.10.5516. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Banner L.R., Keck J.G., Lai M.M.C. A clustering of RNA recombination sites adjacent to a hypervariable region of the peplomer gene of murine coronavirus. Virology. 1990;175:548–555. doi: 10.1016/0042-6822(90)90439-X. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Banner L.R., Lai M.M.C. Random nature of coronavirus RNA recombination in the absence of selective pressure. Virology. 1991;185:441–445. doi: 10.1016/0042-6822(91)90795-D. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Baric R.S., Fu K., Schaad M.C., Stohlman S.A. Establishing a genetic recombination map for murine coronavirus strain A59 complementation groups. Virology. 1990;177:646–656. doi: 10.1016/0042-6822(90)90530-5. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Brian D.A., Spaan W.J.M. Recombination and coronavirus defective interfering RNAs. Semin Virol. 1997;8:101–111. doi: 10.1006/smvy.1997.0109. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Casais R., Thiel V., Siddell S.G., Cavanagh D., Britton P. Reverse genetics system for the avian coronavirus infectious bronchitis virus. J Virol. 2001;75:12359–12369. doi: 10.1128/JVI.75.24.12359-12369.2001. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Cavanagh D., Davis P., Cook J., Li D. Molecular basis of the variation exhibited by avian infectious bronchitis coronavirus (IBV) Adv Exp Med Biol. 1990;276:369–372. doi: 10.1007/978-1-4684-5823-7_50. [DOI] [PubMed] [Google Scholar]
- Chang R.-Y., Hofmann M.A., Sethna P.B., Brian D.A. A cis-acting function for the coronavirus leader in defective interfering RNA replication. J Virol. 1994;68:8223–8231. doi: 10.1128/jvi.68.12.8223-8231.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Curtis K.M., Yount B., Baric R.S. Heterologous gene expression from transmissible gastroenteritis virus replicon particles. J Virol. 2002;76:1422–1434. doi: 10.1128/JVI.76.3.1422-1434.2002. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Das Sarma J., Fu L., Tsai J.C., Weiss S.R., Lavi E. Demyelination determinants map to the spike glycoprotein gene of coronavirus mouse hepatitis virus. J Virol. 2000;74:9206–9213. doi: 10.1128/JVI.74.19.9206-9213.2000. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Das Sarma J., Scheen E., Seo S.H., Koval M., Weiss S.R. Enhanced green fluorescent protein expression may be used to monitor murine coronavirus spread in vitro and in the mouse central nervous system. J Neurovirol. 2002;8:381–391. doi: 10.1080/13550280260422686. [DOI] [PMC free article] [PubMed] [Google Scholar]
- deHaan C.A.M., Kuo L., Masters P.S., Vennema H., Rottier P.J.M. Coronavirus particle assembly: primary structure requirements of the membrane protein. J Virol. 1998;72:6838–6850. doi: 10.1128/jvi.72.8.6838-6850.1998. [DOI] [PMC free article] [PubMed] [Google Scholar]
- de Haan C.A.M., Masters P.S., Shen X., Weiss S., Rottier P.J.M. The group-specific murine coronavirus genes are not essential, but their deletion, by reverse genetics, is attenuating in the natural host. Virology. 2002;296:177–189. doi: 10.1006/viro.2002.1412. [DOI] [PMC free article] [PubMed] [Google Scholar]
- de Haan C.A.M., Volders H., Koetzner C.A., Masters P.S., Rottier P.J.M. Coronaviruses maintain viability despite dramatic rearrangements of the strictly conserved genome organization. J Virol. 2002;76:12491–12502. doi: 10.1128/JVI.76.24.12491-12502.2002. [DOI] [PMC free article] [PubMed] [Google Scholar]
- de Haan C.A.M., van Genne L., Stoop J.N., Volders H., Rottier P.J.M. Coronaviruses as vectors: position dependence of foreign gene expression. J Virol. 2003;77:11312–11323. doi: 10.1128/JVI.77.21.11312-11323.2003. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fischer F., Peng D., Hingley S.T., Weiss S.R., Masters P.S. The internal open reading frame within the nucleocapsid gene of mouse hepatitis virus encodes a structural protein that is not essential for viral replication. J Virol. 1997;71:996–1003. doi: 10.1128/jvi.71.2.996-1003.1997. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fischer F., Stegen C.F., Koetzner C.A., Masters P.S. Analysis of a recombinant mouse hepatitis virus expressing a foreign gene reveals a novel aspect of coronavirus transcription. J Virol. 1997;71:5148–5160. doi: 10.1128/jvi.71.7.5148-5160.1997. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fischer F., Stegen C.F., Masters P.S., Samsonoff W.A. Analysis of constructed E gene mutants of mouse hepatitis virus confirms a pivotal role for E protein in coronavirus assembly. J Virol. 1998;72:7885–7894. doi: 10.1128/jvi.72.10.7885-7894.1998. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fu K., Baric R.S. Map locations of mouse hepatitis virus temperature-sensitive mutants: confirmation of variable rates of recombination. J Virol. 1994;68:7458–7466. doi: 10.1128/jvi.68.11.7458-7466.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Godeke G.J., de Haan C.A., Rossen J.W., Vennema H., Rottier P.J.M. Assembly of spikes into coronavirus particles is mediated by the carboxy-terminal domain of the spike protein. J Virol. 2000;74:1566–1571. doi: 10.1128/JVI.74.3.1566-1571.2000. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Goebel S.J., Hsue B., Dombrowski T.F., Masters P.S. Characterization of the RNA components of a putative molecular switch in the 3′ untranslated region of the murine coronavirus genome. J Virol. 2004;78:669–682. doi: 10.1128/JVI.78.2.669-682.2004. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Haijema B.J., Volders H., Rottier P.J.M. Switching species tropism: an effective way to manipulate the feline coronavirus genome. J Virol. 2003;77:4528–4538. doi: 10.1128/JVI.77.8.4528-4538.2003. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Herrewegh A.A., Vennema H., Horzinek M.C., Rottier P.J.M., de Groot R.J. The molecular genetics of feline coronaviruses: comparative sequence analysis of the ORF7a/7b transcription unit of different biotypes. Virology. 1995;212:622–631. doi: 10.1006/viro.1995.1520. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Herrewegh A.A., Smeenk I., Horzinek M.C., Rottier P.J.M., de Groot R.J. Feline coronavirus type II strains 79-1683 and 79-1146 originate from a double recombination between feline coronavirus type I and canine coronavirus. J Virol. 1998;72:4508–4514. doi: 10.1128/jvi.72.5.4508-4514.1998. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hingley S.T., Leparc-Goffart I., Seo S.H., Tsai J.C., Weiss S.R. The virulence of mouse hepatitis virus strain A59 is not dependent on efficient spike protein cleavage and cell-to-cell fusion. J Neurovirol. 2002;8:400–410. doi: 10.1080/13550280260422703. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hsue B., Masters P.S. A bulged stem-loop structure in the 3′ untranslated region of the genome of the coronavirus mouse hepatitis virus is essential for replication. J Virol. 1997;71:7567–7578. doi: 10.1128/jvi.71.10.7567-7578.1997. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hsue B., Masters P.S. Insertion of a new transcriptional unit into the genome of mouse hepatitis virus. J Virol. 1999;73:6128–6135. doi: 10.1128/jvi.73.7.6128-6135.1999. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Hsue B., Hartshorne T., Masters P.S. Characterization of an essential RNA secondary structure in the 3′ untranslated region of the murine coronavirus genome. J Virol. 2000;74:6911–6921. doi: 10.1128/JVI.74.15.6911-6921.2000. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jia W., Karaca K., Parrish C.R., Naqi S.A. A novel variant of avian infectious bronchitis virus resulting from recombination among three different strains. Arch Virol. 1995;140:259–271. doi: 10.1007/BF01309861. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Keck J.G., Stohlman S.A., Soe L.H., Makino S., Lai M.M.C. Multiple recombination sites at the 5′-end of murine coronavirus RNA. Virology. 1987;156:331–341. doi: 10.1016/0042-6822(87)90413-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Keck J.G., Matsushima G.K., Makino S., Fleming J.O., Vannier D.M., Stohlman S.A., Lai M.M.C. In vivo RNA-RNA recombination of coronavirus in mouse brain. J Virol. 1988;62:1810–1813. doi: 10.1128/jvi.62.5.1810-1813.1988. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Keck J.G., Soe L.H., Makino S., Stohlman S.A., Lai M.M.C. RNA recombination of murine coronaviruses: recombination between fusion-positive mouse hepatitis virus A59 and fusion-negative mouse hepatitis virus 2. J Virol. 1988;62:1989–1998. doi: 10.1128/jvi.62.6.1989-1998.1988. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kirkegaard K., Baltimore D. The mechanism of RNA recombination in poliovirus. Cell. 1986;47:433–443. doi: 10.1016/0092-8674(86)90600-8. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Koetzner C.A., Parker M.M., Ricard C.S., Sturman L.S., Masters P.S. Repair and mutagenesis of the genome of a deletion mutant of the coronavirus mouse hepatitis virus by targeted RNA recombination. J Virol. 1992;66:1841–1848. doi: 10.1128/jvi.66.4.1841-1848.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kottier S.A., Cavanagh D., Britton P. Experimental evidence of recombination in coronavirus infectious bronchitis virus. Virology. 1995;213:569–580. doi: 10.1006/viro.1995.0029. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kuo L., Godeke G.-J., Raamsman M.J.B., Masters P.S., Rottier P.J.M. Retargeting of coronavirus by substitution of the spike glycoprotein ectodomain: crossing the host cell species barrier. J Virol. 2000;74:1393–1406. doi: 10.1128/JVI.74.3.1393-1406.2000. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kuo L., Masters P.S. Genetic evidence for a structural interaction between the carboxy termini of the membrane and nucleocapsid proteins of mouse hepatitis virus. J Virol. 2002;76:4987–4999. doi: 10.1128/JVI.76.10.4987-4999.2002. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kuo L., Masters P.S. The small envelope protein E is not essential for murine coronavirus replication. J Virol. 2003;77:4597–4608. doi: 10.1128/JVI.77.8.4597-4608.2003. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Kusters J.G., Jager E.J., Niesters H.G.M., van der Zeijst B.A.M. Sequence evidence for RNA recombination in field isolates of avian coronavirus infectious bronchitis virus. Vaccine. 1990;8:605–608. doi: 10.1016/0264-410X(90)90018-H. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lai M.M.C., Baric R.S., Makino S., Keck J.G., Egbert J., Leibowitz J.L., Stohlman S.A. Recombination between nonsegmented RNA genomes of murine coronaviruses. J Virol. 1985;56:449–456. doi: 10.1128/jvi.56.2.449-456.1985. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lai M.M.C. RNA recombination in animal and plant viruses. Microbiol Rev. 1992;56:61–79. doi: 10.1128/mr.56.1.61-79.1992. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lai M.M.C. Recombination in large RNA viruses: coronaviruses. Semin Virol. 1996;7:381–388. doi: 10.1006/smvy.1996.0046. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ledinko N. Genetic recombination with poliovirus type 1: studies of crosses between a normal horse serum-resistant mutant and several guanidine-resistant mutants of the same strain. Virology. 1963;20:107–119. doi: 10.1016/0042-6822(63)90145-4. [DOI] [PubMed] [Google Scholar]
- Lee C.W., Jackwood M.W. Evidence of genetic diversity generated by recombination among avian coronavirus IBV. Arch Virol. 2000;145:2135–2148. doi: 10.1007/s007050070044. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Lee C.W., Jackwood M.W. Spike gene analysis of the DE072 strain of infectious bronchitis virus: origin and evolution. Virus Genes. 2001;22:85–91. doi: 10.1023/A:1008138520451. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Leparc-Goffart I., Hingley S.T., Chua M.M., Phillips J., Lavi E., Weiss S.R. Targeted recombination within the spike gene of murine coronavirus mouse hepatitis virus-A59: Q159 is a determinant of hepatotropism. J Virol. 1998;72:9628–9636. doi: 10.1128/jvi.72.12.9628-9636.1998. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Li K., Chen Z., Plagemann P. High-frequency homologous genetic recombination of an arterivirus, lactate dehydrogenase-elevating virus, in mice and evolution of neuropathogenic variants. Virology. 1999;258:73–83. doi: 10.1006/viro.1999.9660. [DOI] [PubMed] [Google Scholar]
- Luytjes W., Bredenbeek P.J., Noten A.F.H., Horzinek M.C., Spaan W.J.M. Sequence of mouse hepatitis virus A59 mRNA2: indications for RNA recombination between coronaviruses and influenza C virus. Virology. 1988;166:415–422. doi: 10.1016/0042-6822(88)90512-0. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Makino S., Fleming J.O., Keck J.G., Stohlman S.A., Lai M.M.C. RNA recombination of coronaviruses: localization of neutralizing epitopes and neuropathogenic determinants on the carboxyl terminus of peplomers. Proc Natl Acad Sci USA. 1987;84:6567–6571. doi: 10.1073/pnas.84.18.6567. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Masters P.S., Koetzner C.A., Kerr C.A., Heo Y. Optimization of targeted RNA recombination and mapping of a novel nucleocapsid gene mutation in the coronavirus mouse hepatitis virus. J Virol. 1994;68:328–337. doi: 10.1128/jvi.68.1.328-337.1994. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Masters P.S. Reverse genetics of the largest RNA viruses. Adv Virus Res. 1999;53:245–264. doi: 10.1016/S0065-3527(08)60351-6. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Méndez A., Smerdou C., Izeta A., Gebauer F., Enjuanes L. Molecular characterization of transmissible gastroenteritis coronavirus defective interfering genomes: packaging and heterogeneity. Virology. 1996;217:495–507. doi: 10.1006/viro.1996.0144. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Motokawa K., Hohdatsu T., Aizawa C., Koyama H., Hashimoto H. Molecular cloning and sequence determination of the peplomer protein gene of feline infectious peritonitis virus type I. Arch Virol. 1995;140:469–480. doi: 10.1007/BF01718424. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Nagy P.D., Simon A. New insights into the mechanisms of RNA recombination. Virology. 1997;235:1–9. doi: 10.1006/viro.1997.8681. [DOI] [PubMed] [Google Scholar]
- Navas S., Seo S.-H., Chua M.M., Das Sarma J., Lavi E., Hingley S.T., Weiss S.R. Murine coronavirus spike protein determines the ability of the virus to replicate in the liver and cause hepatitis. J Virol. 2001;75:2452–2457. doi: 10.1128/JVI.75.5.2452-2457.2001. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Neuman B., Cavanagh D., Britton P. Use of defective RNAs containing reporter genes to investigate targeted recombination for avian infectious bronchitis virus. Adv Exp Med Biol. 2001;494:513–518. doi: 10.1007/978-1-4615-1325-4_74. [DOI] [PubMed] [Google Scholar]
- Ontiveros E., Kuo L., Masters P.S., Perlman S. Inactivation of expression of gene 4 of mouse hepatitis virus strain JHM does not affect virulence in the murine CNS. Virology. 2001;289:230–238. doi: 10.1006/viro.2001.1167. [DOI] [PubMed] [Google Scholar]
- Ortego J., Escors D., Laude H., Enjuanes L. Generation of a replication-competent, propagation-deficient virus vector based on the transmissible gastroenteritis coronavirus genome. J Virol. 2002;76:11518–11529. doi: 10.1128/JVI.76.22.11518-11529.2002. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Parker M.M., Masters P.S. Sequence comparison of the N genes of five strains of the coronavirus mouse hepatitis virus suggests a three domain structure for the nucleocapsid protein. Virology. 1990;179:463–468. doi: 10.1016/0042-6822(90)90316-J. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Pasternak A.O., van den Born E., Spaan W.J.M., Snijder E.J. Sequence requirements for RNA strand transfer during nidovirus discontinuous subgenomic RNA synthesis. EMBO J. 2001;20:7220–7228. doi: 10.1093/emboj/20.24.7220. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Peng D., Koetzner C.A., Masters P.S. Analysis of second-site revertants of a murine coronavirus nucleocapsid protein deletion mutant and construction of nucleocapsid protein mutants by targeted RNA recombination. J Virol. 1995;69:3449–3457. doi: 10.1128/jvi.69.6.3449-3457.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Peng D., Koetzner C.A., McMahon T., Zhu Y., Masters P.S. Construction of murine coronavirus mutants containing interspecies chimeric nucleocapsid proteins. J Virol. 1995;69:5475–5484. doi: 10.1128/jvi.69.9.5475-5484.1995. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Phillips J.J., Chua M.M., Lavi E., Weiss S.R. Pathogenesis of chimeric MHV4/MHV-A59 recombinant viruses: the murine coronavirus spike protein is a major determinant of neurovirulence. J Virol. 1999;73:7752–7760. doi: 10.1128/jvi.73.9.7752-7760.1999. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Phillips J.J., Chua M., Seo S.H., Weiss S.R. Multiple regions of the murine coronavirus spike glycoprotein influence neurovirulence. J Neurovirol. 2001;7:421–431. doi: 10.1080/135502801753170273. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Phillips J.J., Chua M.M., Rall G.F., Weiss S.R. Murine coronavirus spike glycoprotein mediates degree of viral spread, inflammation, and virus-induced immunopathology in the central nervous system. Virology. 2002;301:109–120. doi: 10.1006/viro.2002.1551. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Plyusnin A., Kukkonen S.K., Plyusnina A., Vapalahti O., Vaheri A. Transfection-mediated generation of functionally competent Tula hantavirus with recombinant S RNA segment. EMBO J. 2002;21:1497–1503. doi: 10.1093/emboj/21.6.1497. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Rottier P.J.M. The coronavirus membrane glycoprotein. In: Siddell S.G., editor. The Coronaviridae. New York: Plenum Press; 1995. pp. 115–139. [Google Scholar]
- Sánchez C.M., Izeta A., Sánchez-Morgado J.M., Alonso S., Sola I., Balasch M., Plana-Durán J., Enjuanes L. Targeted recombination demonstrates that the spike gene of transmissible gastroenteritis coronavirus is a determinant of its enteric tropism and virulence. J Virol. 1999;73:7607–7618. doi: 10.1128/jvi.73.9.7607-7618.1999. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sethna P.B., Hung S.-L., Brian D.A. Coronavirus subgenomic minus-strand RNAs and the potential for mRNA replicons. Proc Natl Acad Sci USA. 1989;86:5626–5630. doi: 10.1073/pnas.86.14.5626. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Shen X., Masters P.S. Evaluation of the role of heterogeneous nuclear ribonucleoprotein A1 as a host factor in murine coronavirus discontinuous transcription and genome replication. Proc Natl Acad Sci USA. 2001;98:2717–2722. doi: 10.1073/pnas.031424298. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Sturman L.S., Eastwood C., Frana M.F., Duchala C., Baker F., Ricard C.S., Sawicki S.G., Holmes K.V. Temperature-sensitive mutants of MHV-A59. Adv Exp Med Biol. 1987;218:159–168. doi: 10.1007/978-1-4684-1280-2_20. [DOI] [PubMed] [Google Scholar]
- Thiel V., Herold J., Schelle B., Siddell S.G. Infectious RNA transcribed in vitro from a cDNA copy of the human coronavirus genome cloned in vaccinia virus. J Gen Virol. 2001;82:1273–1281. doi: 10.1099/0022-1317-82-6-1273. [DOI] [PubMed] [Google Scholar]
- Tijms M.A., van Dinten L.C., Gorbalenya A.E., Snijder E.J. A zinc finger-containing papain-like protease couples subgenomic mRNA synthesis to genome translation in a positive-stranded RNA virus. Proc Natl Acad Sci USA. 2001;98:1889–1894. doi: 10.1073/pnas.041390398. [DOI] [PMC free article] [PubMed] [Google Scholar]
- van der Most R.G., Heijnen L., Spaan W.J.M., de Groot R.J. Homologous RNA recombination allows efficient introduction of site-specific mutations into the genome of coronavirus MHV-A59 via synthetic co-replicating RNAs. Nucl Acids Res. 1992;20:3375–3381. doi: 10.1093/nar/20.13.3375. [DOI] [PMC free article] [PubMed] [Google Scholar]
- van Dinten L.C., den Boon J.A., Wassenaar A.L.M., Spaan W.J.M., Snijder E.J. An infectious arterivirus cDNA clone: identification of a replicase point mutation that abolishes discontinuous mRNA transcription. Proc Natl Acad Sci USA. 1997;94:991–996. doi: 10.1073/pnas.94.3.991. [DOI] [PMC free article] [PubMed] [Google Scholar]
- van Vugt J.J., Storgaard T., Oleksiewicz M.B., Botner A. High frequency RNA recombination in porcine reproductive and respiratory syndrome virus occurs preferentially between parental sequences with high similarity. J Gen Virol. 2001;82:2615–2620. doi: 10.1099/0022-1317-82-11-2615. [DOI] [PubMed] [Google Scholar]
- Vennema H., Poland A., Floyd-Hawkins K., Pedersen N.C. A comparison of the genomes of FECVs and FIPVs and what they tell us about the relationships between feline coronaviruses and their evolution. Feline Pract. 1995;23:40–44. [Google Scholar]
- Vennema H., Godeke G.-J., Rossen J.W.A., Voorhout W.F., Horzinek M.C., Opstelten D.-J. E., Rottier P.J.M. Nucleocapsid-independent assembly of coronavirus-like particles by co-expression of viral envelope protein genes. EMBO J. 1996;15:2020–2028. doi: 10.1002/j.1460-2075.1996.tb00553.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Vennema H. Genetic drift and genetic shift during feline coronavirus evolution. Vet Microbiol. 1999;69:139–141. doi: 10.1016/S0378-1135(99)00102-9. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wang L., Junker D., Collisson E.W. Evidence of natural recombination within the S1 gene of infectious bronchitis virus. Virology. 1993;192:710–716. doi: 10.1006/viro.1993.1093. [DOI] [PubMed] [Google Scholar]
- Williams G.D., Chang R.Y., Brian D.A. A phylogenetically conserved hairpin-type 3′ untranslated region pseudoknot functions in coronavirus RNA replication. J Virol. 1999;73:8349–8355. doi: 10.1128/jvi.73.10.8349-8355.1999. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Yount B., Curtis K.M., Baric R.S. Strategy for systematic assembly of large RNA and DNA genomes: transmissible gastroenteritis virus model. J Virol. 2000;74:10600–10611. doi: 10.1128/JVI.74.22.10600-10611.2000. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Yount B., Denison M.R., Weiss S.R., Baric R.S. Systematic assembly of a full-length infectious cDNA of mouse hepatitis virus strain A59. J Virol. 2002;76:11065–11078. doi: 10.1128/JVI.76.21.11065-11078.2002. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Yount B., Curtis K.M., Fritz E.A., Hensley L.E., Jahrling P.B., Prentice E., Denison M.R., Geisbert T.W., Baric R.S. Reverse genetics with a full-length infectious cDNA of severe acute respiratory syndrome coronavirus. Proc Natl Acad Sci USA. 2003;100:12995–13000. doi: 10.1073/pnas.1735582100. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Yuan S., Nelsen C.J., Murtaugh M.P., Schmitt B.J., Faaberg K.S. Recombination between North American strains of porcine reproductive and respiratory syndrome virus. Virus Res. 1999;61:87–98. doi: 10.1016/S0168-1702(99)00029-5. [DOI] [PMC free article] [PubMed] [Google Scholar]