Autographa californicamultiple nucleopolyhedrovirus (AcMNPV), the type species of the family Baculoviridae, is an insect-specific virus that can enter a variety of mammalian cells. The potential of this versatile virus for protein expression or gene therapy in mammalian cells has become the focus of many studies. In most mammalian cells, transduced AcMNPV genes are either not expressed or expressed at an extremely low level. Here, we studied the effects of the two major AcMNPV trans-activators, IE1 and IE2, on the activation of AcMNPV genome in Vero E6 cells. Microarray analysis showed that when IE1 was overexpressed, it significantly activated genes gp64 and pe38, and upregulated ie2, he65, pcna, orf16, orf17 and orf25. Although, there were only two genes, pe38 and orf17, that were activated by IE2, we discovered interestingly that the combination of IE1 and IE2 factors had a synergistic effect on activation of the AcMNPV genome in mammalian cells, and activated around 38 %, or 59 out of the 155 genes placed on the microarray. This is the first detailed study of baculoviral transcription regulation in mammalian cells, and it shows that the baculoviral genome can be activated in a mammalian system, and also that the two major trans-activators, IE1 and IE2, play a central role in this activation.
AbeT.,
HemmiH.,
MiyamotoH.,
MoriishiK.,
TamuraS.,
TakakuH.,
AkiraS.,
MatsuuraY.2005; Involvement of the Toll-like receptor 9 signaling pathway in the induction of innate immunity by baculovirus. J Virol 79:2847–2858[CrossRef]
AyresM. D.,
HowardS. C.,
KuzioJ.,
Lopez-FerberM.,
PosseeR. D.1994; The complete DNA sequence of Autographa californica nuclear polyhedrosis virus. Virology 202:586–605[CrossRef]
BlissardG. W.,
RohrmannG. F.1991; Baculovirus gp64 gene expression: analysis of sequences modulating early transcription and transactivation by IE1. J Virol 65:5820–5827
CarsonD. D.,
GuarinoL. A.,
SummersM. D.1988; Functional mapping of an AcNPV immediately early gene which augments expression of the IE1 trans-activated 39K gene. Virology 162:444–451[CrossRef]
ChoiJ.,
GuarinoL. A.1995; The baculovirus transactivator IE1 binds to viral enhancer elements in the absence of insect cell factors. J Virol 69:4548–4551
DaiX.,
WillisL. G.,
HuijskensI.,
PalliS. R.,
TheilmannD. A.2004; The acidic activation domains of the baculovirus transactivators IE1 and IE0 are functional for transcriptional activation in both insect and mammalian cells. J Gen Virol 85:573–582[CrossRef]
GossenM.,
BujardH.1992; Tight control of gene expression in mammalian cells by tetracycline-responsive promoters. Proc Natl Acad Sci U S A 89:5547–5551[CrossRef]
GuarinoL. A.,
SummersM. D.1986; Functional mapping of a trans -activating gene required for expression of a baculovirus delayed-early gene. J Virol 57:563–571
HillsD.,
Crane-RobinsonC.1995; Baculovirus expression of human basic fibroblast growth factor from a synthetic gene: role of the Kozak consensus and comparison with bacterial expression. Biochim Biophys Acta 1260:14–20[CrossRef]
HofmannC.,
SandigV.,
JenningsG.,
RudolphM.,
SchlagP.,
StraussM.1995; Efficient gene transfer into human hepatocytes by baculovirus vectors. Proc Natl Acad Sci U S A 92:10099–10103[CrossRef]
HuserA.,
RudolphM.,
HofmannC.2001; Incorporation of decay-accelerating factor into the baculovirus envelope generates complement-resistant gene transfer vectors. Nat Biotechnol 19:451–455[CrossRef]
KenoutisC.,
EfroseR. C.,
SweversL.,
LavdasA. A.,
GaitanouM.,
MatsasR.,
IatrouK.2006; Baculovirus-mediated gene delivery into mammalian cells does not alter their transcriptional and differentiating potential but is accompanied by early viral gene expression. J Virol 80:4135–4146[CrossRef]
KostT. A.,
CondreayJ. P.,
JarvisD. L.2005; Baculovirus as versatile vectors for protein expression in insect and mammalian cells. Nat Biotechnol 23:567–575[CrossRef]
KovacsG. R.,
ChoiJ.,
GuarinoL. A.,
SummersM. D.1992; Functional dissection of the Autographa californic a nuclear polyhedrosis virus immediate-early 1 transcriptional regulatory protein. J Virol 66:7429–7437
LeisyD. J.,
RasmussenC.,
KimH. T.,
RohrmannG. F.1995; The Autographa californica nuclear polyhedrosis virus homologous region 1a: identical sequences are essential for DNA replication activity and transcriptional enhancer function. Virology 208:742–752[CrossRef]
ShojiI.,
AizakiH.,
TaniH.,
IshiiK.,
ChibaT.,
SaitoI.,
MiyamuraT.,
MatsuuraY.1997; Efficient gene transfer into various mammalian cells, including non-hepatic cells, by baculovirus vectors. J Gen Virol 78:2657–2664
YooS.,
GuarinoL. A.1994; Functional dissection of the ie2 gene product of the baculovirus Autographa californica nuclear polyhedrosis virus. Virology 202:164–172[CrossRef]
ZhengD.,
ConstantinidouC.,
HobmanJ. L.,
MinchinS. D.2004; Identification of the CRP regulon using in vitro and in vivo transcriptional profiling. Nucleic Acids Res 32:5874–5893[CrossRef]