Autographa californica nucleopolyhedrovirus infection of Spodoptera frugiperda cells: a global analysis of host gene regulation during infection, using a differential display approach

Abstract

Autographa californica nucleopolyhedrovirus (AcMNPV), the type member of the virus family Baculoviridae, infects pest insects and has been the subject of many studies for its development as a biopesticide. It is also the virus upon which most of the commercial baculovirus protein expression systems are based. AcMNPV infection of cultured host Spodoptera frugiperda (Sf9) cells can induce a number of alterations of host cell properties including altering the cellular cytoskeleton, an arrest of the cell cycle in G 2 /M, and the global shutoff of host protein translation. Additionally, several cellular transcripts have been shown to be down-regulated following AcMNPV infection. In this study, we take a differential display approach to address whether a global down-regulation of Sf9 host transcripts occurs at late times of infection. Additionally, we also use this approach to search for host mRNAs which are up-regulated at early times of infection, and may be important for facilitating baculovirus infection. From these experiments we can confirm a global down-regulation of Sf9 mRNA levels at late times of infection. We also found that up-regulation of individual host gene RNA levels at early times of infection did not occur frequently. One host transcript which was found to be transiently up-regulated as a result of AcMNPV infection was an Sf9 Hsc70 gene. Hsc70 proteins have been shown to play a vital role in the life-cycle of other large DNA viruses, which suggests that this protein is also important for baculovirus infection.

Temporal expression profiling of novel Spodoptera litura nucleopolyhedrovirus-encoded microRNAs upon infection of Sf21 cells

“…Furthermore, it is known that baculoviral infection is associated with global shutdown of host protein synthesis at 12-18 h p.i., the mechanism of which is still unknown (Nobiron et al, 2003;Ooi & Miller, 1988;Tjia et al, 1979). It is interesting to note that most of the baculoviral miRNAs in our deep-sequencing analysis also start to appear by 12 h p.i.…”

Molecular Cloning and Functional Characterization of a Lepidopteran Insect β4-N-Acetylgalactosaminyltransferase with Broad Substrate Specificity, a Functional Role in Glycoprotein Biosynthesis, and a Potential Functional Role in Glycolipid Biosynthesis

“…To date, we are unaware of any structural evidence that LacDiNAc has been found in the N-glycans of any recombinant glycoprotein produced in baculovirus-infected T. ni cells or larvae. In fact, considering that the expression of most or all host cell genes is repressed during baculovirus infection (96), and that ␤4-Nacetylgalactosaminyltransferase activity is dramatically reduced during baculovirus infection (30), it seems rather unlikely that LacDiNAc will occur in recombinant N-glycoproteins produced using the baculovirus expression system. It is interesting to consider in retrospect that we actually intended to isolate an insect ␤4-galactosyltransferase cDNA in this study.…”

Baculovirus IE2 stimulates the expression of heat shock proteins in insect and mammalian cells to facilitate its proper functioning

“…Given that the heat shock cognate protein gene (hsc70) is the only gene that has been sequenced among the HSP/HSC70 family in S. frugiperda cells [24], and that it has been found to be transiently up-regulated during baculovirus infection [24,25], we chose hsc70 as a representative of the heat shock response in S. frugiperda cells. Transcripts from the infected cells were collected at 0, 2, 4, 6, 8 hpi and quantified by RT-qPCR.…”

“…We found that heat shock proteins (HSPs) are one of the major components that complex with the IE2 protein. Stimulation of a heat shock response during baculovirus infection and its importance for virus amplification has been frequently mentioned in the literature [23][24][25][26]. However, the viral factors that are responsible for this effect and the mechanism underlying the interaction between viral factors and HSPs are still unclear [27].…”