Visualizing the replication cycle of bunyamwera orthobunyavirus expressing fluorescent protein-tagged Gc glycoprotein.
The virion glycoproteins Gn and Gc of Bunyamwera virus (BUNV), the prototype of the Bunyaviridae family and also of the Orthobunyavirus genus, are encoded by the medium (M) RNA genome segment and are involved in both viral attachment and entry. After their synthesis Gn and Gc form a heterodimer in the endoplasmic reticulum (ER) and transit to the Golgi compartment for virus assembly. The N-terminal half of the Gc ectodomain was previously shown to be dispensable for virus replication in cell culture (X. Shi, J. Goli, G. Clark, K. Brauburger, and R. M. Elliott, J. Gen. Virol. 90:2483-2492, 2009.). In this study, the coding sequence for a fluorescent protein, either enhanced green fluorescent protein (eGFP) or mCherry fluorescent protein, was fused to the N terminus of truncated Gc, and two recombinant BUNVs (rBUNGc-eGFP and rBUNGc-mCherry) were rescued by reverse genetics. The recombinant viruses showed bright autofluorescence under UV light and were competent for replication in various mammalian cell lines. rBUNGc-mCherry was completely stable over 10 passages, whereas internal, in-frame deletions occurred in the chimeric Gc-eGFP protein of rBUNGc-eGFP, resulting in loss of fluorescence between passages 5 and 7. Autofluorescence of the recombinant viruses allowed visualization of different stages of the infection cycle, including virus attachment to the cell surface, budding of virus particles in Golgi membranes, and virus-induced morphological changes to the Golgi compartment at later stages of infection. The fluorescent protein-tagged viruses will be valuable reagents for live-cell imaging studies to investigate virus entry, budding, and morphogenesis in real time.
Shi
Xiaohong
X
Centre for Biomolecular Sciences, School of Biology, University of St Andrews, North Haugh, St Andrews, KY16 9ST Scotland, United Kingdom.
van Mierlo
Joël T
JT
French
Andrew
A
Elliott
Richard M
RM
D000818:Animals; D002042:Bunyamwera virus / Q000235:genetics / Q000502:physiology*; D002044:Bunyaviridae Infections / Q000821:virology*; D002460:Cell Line; D006224:Cricetinae; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008856:Microscopy, Fluorescence; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D014759:Viral Envelope Proteins / Q000235:genetics / Q000378:metabolism*; D019065:Virus Assembly; D057074:Virus Release; D014779:Virus Replication
D011993:Recombinant Fusion Proteins; D014759:Viral Envelope Proteins; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins