An infectious recombinant equine arteritis virus expressing green fluorescent protein from its replicase gene.
Thus far, systems developed for heterologous gene expression from the genomes of nidoviruses (arteriviruses and coronaviruses) have relied mainly on the translation of foreign genes from subgenomic mRNAs, whose synthesis is a key feature of the nidovirus life cycle. In general, such expression vectors often suffered from relatively low and unpredictable expression levels, as well as genome instability. In an attempt to circumvent these disadvantages, the possibility to express a foreign gene [encoding enhanced green fluorescent protein (eGFP)] from within the nidovirus replicase gene, which encodes two large polyproteins that are processed proteolytically into the non-structural proteins (nsps) required for viral RNA synthesis, has now been explored. A viable recombinant of the arterivirus Equine arteritis virus, EAV-GFP2, was obtained, which contained the eGFP insert at the site specifying the junction between the two most N-proximal replicase-cleavage products, nsp1 and nsp2. EAV-GFP2 replication could be launched by transfection of cells with either in vitro-generated RNA transcripts or a DNA launch plasmid. EAV-GFP2 displayed growth characteristics similar to those of the wild-type virus and was found to maintain the insert stably for at least eight passages. It is proposed that EAV-GFP2 has potential for arterivirus vector development and as a tool in inhibitor screening. It can also be used for fundamental studies into EAV replication, which was illustrated by the fact that the eGFP signal of EAV-GFP2, which largely originated from an eGFP-nsp2 fusion protein, could be used to monitor the formation of the membrane-bound EAV replication complex in real time.
van den Born
Erwin
E
Molecular Virology Laboratory, Department of Medical Microbiology, Center of Infectious Diseases, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands.
Posthuma
Clara C
CC
Molecular Virology Laboratory, Department of Medical Microbiology, Center of Infectious Diseases, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands.
Knoops
Kèvin
K
Section Electron Microscopy, Department of Molecular Cell Biology, Leiden University Medical Center (LUMC), PO Box 9600, 2300 RC Leiden, The Netherlands.
Snijder
Eric J
EJ
Molecular Virology Laboratory, Department of Medical Microbiology, Center of Infectious Diseases, Leiden University Medical Center, PO Box 9600, 2300 RC Leiden, The Netherlands.
D000818:Animals; D002460:Cell Line; D002522:Chlorocebus aethiops; D006224:Cricetinae; D007240:Equartevirus / Q000235:genetics* / Q000254:growth & development; D017930:Genes, Reporter; D005814:Genes, Viral; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins / Q000096:biosynthesis* / Q000235:genetics; D008969:Molecular Sequence Data; D012367:RNA, Viral / Q000235:genetics; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics* / Q000502:physiology; D011817:Rabbits; D017422:Sequence Analysis, DNA; D013194:Staining and Labeling; D017361:Viral Nonstructural Proteins / Q000235:genetics; D014773:Virology / Q000379:methods*
D012367:RNA, Viral; D017361:Viral Nonstructural Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D012324:RNA-Dependent RNA Polymerase