Baculovirus superinfection: a probable restriction factor on the surface display of proteins for library screening.
In addition to the expression of recombinant proteins, baculoviruses have been developed as a platform for the display of complex eukaryotic proteins on the surface of virus particles or infected insect cells. Surface display has been used extensively for antigen presentation and targeted gene delivery but is also a candidate for the display of protein libraries for molecular screening. However, although baculovirus gene libraries can be efficiently expressed and displayed on the surface of insect cells, target gene selection is inefficient probably due to super-infection which gives rise to cells expressing more than one protein. In this report baculovirus superinfection of Sf9 cells has been investigated by the use of two recombinant multiple nucleopolyhedrovirus carrying green or red fluorescent proteins under the control of both early and late promoters (vAcBacGFP and vAcBacDsRed). The reporter gene expression was detected 8 hours after the infection of vAcBacGFP and cells in early and late phases of infection could be distinguished by the fluorescence intensity of the expressed protein. Simultaneous infection with vAcBacGFP and vAcBacDsRed viruses each at 0.5 MOI resulted in 80% of infected cells co-expressing the two fluorescent proteins at 48 hours post infection (hpi), and subsequent infection with the two viruses resulted in similar co-infection rate. Most Sf9 cells were re-infectable within the first several hours post infection, but the re-infection rate then decreased to a very low level by 16 hpi. Our data demonstrate that Sf9 cells were easily super-infectable during baculovirus infection, and super-infection could occur simultaneously at the time of the primary infection or subsequently during secondary infection by progeny viruses. The efficiency of super-infection may explain the difficulties of baculovirus display library screening but would benefit the production of complex proteins requiring co-expression of multiple polypeptides.
College of Life Sciences, Northwest A&F University, Yangling, Shaanxi, P R China.
Xiaodong
X
Xu
Yuanrong
Y
Chen
Yu
Y
Zhao
Xiaofen
X
Liu
Beitao
B
Dong
Ian M
IM
Jones
Hongying
H
Chen
D000818:Animals; D016367:Baculoviridae / Q000235:genetics*; D015870:Gene Expression; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins; D057166:High-Throughput Screening Assays / Q000592:standards; D008164:Luminescent Proteins; D019151:Peptide Library; D011401:Promoter Regions, Genetic; D011994:Recombinant Proteins / Q000096:biosynthesis* / Q000235:genetics; D061987:Sf9 Cells; D018411:Spodoptera; D000097573:Red Fluorescent Protein
D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D019151:Peptide Library; D011994:Recombinant Proteins; D000097573:Red Fluorescent Protein