The baculoviruses are a family of large DNA viruses pathogenic to insects. They are currently employed as important biological controls of insect pests and are being engineered for improved toxicity and wider host ranges. Evaluations on the safety of these viruses in regard to non-target organisms, including humans, have demanded an increased understanding of their molecular biology and the mechanisms which govern their replication. From a virological perspective, the baculoviruses are of interest because of their large, superhelical genome, their complex replicative cycle resulting in an unusual production of two infectious forms of progeny, and the ability of the viral genome to incorporate host- derived transposable elements. We propose to examine the molecular mechanisms involved in the expression of the earliest of viral genes using the model baculovirus, Autographa californica nuclear polyhedrosis virus (AcNPV). Our objectives include defining the cis-acting DNA sequences which mediate immediate- early (IE) transcription employing both transient expression of chimeric genes and expression of such genes after their transfer back into the viral genome. We will characterize the products of two adjacent IE genes and examine their potential regulation by overlapping, anti-sense RNAs. A major portion of this proposal also examines the nature and mutagenic effects of a newly identified transposable element (TED) inserted within an IE region of the AcNPV genome. TED is a retrotransposon which upon integration directs abundant transcription of neighboring viral genes. Retrotransposons closely resemble the retroproviruses and represent an important class of insertion mutagens in eukaryotes. The exact mechanisms of their mutagenesis are unknown. We will analyze in detail the effects of TED integration on the expression of AcNPV genes. In addition, we will take advantage of the clonal isolate of TED within the viral genome to examine the structural organization and regulation of expression of a transcriptionally active retrotransposon. These studies are expected to yield further insight into the mechanisms of genetic alterations caused by these mobile elements as well as information on the complex mechanisms which control eukaryotic gene expression.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
7R29AI025557-02
Application #
3454472
Study Section
Virology Study Section (VR)
Project Start
1988-02-01
Project End
1993-01-31
Budget Start
1989-02-01
Budget End
1990-01-31
Support Year
2
Fiscal Year
1989
Total Cost
Indirect Cost
Name
University of Wisconsin Madison
Department
Type
Graduate Schools
DUNS #
161202122
City
Madison
State
WI
Country
United States
Zip Code
53715
Byers, Nathaniel M; Vandergaast, Rianna L; Friesen, Paul D (2016) Baculovirus Inhibitor-of-Apoptosis Op-IAP3 Blocks Apoptosis by Interaction with and Stabilization of a Host Insect Cellular IAP. J Virol 90:533-44
Vandergaast, Rianna; Mitchell, Jonathan K; Byers, Nathaniel M et al. (2015) Insect inhibitor-of-apoptosis (IAP) proteins are negatively regulated by signal-induced N-terminal degrons absent within viral IAP proteins. J Virol 89:4481-93
Mitchell, Jonathan K; Byers, Nathaniel M; Friesen, Paul D (2013) Baculovirus F-box protein LEF-7 modifies the host DNA damage response to enhance virus multiplication. J Virol 87:12592-9
Taggart, David J; Mitchell, Jonathan K; Friesen, Paul D (2012) A conserved N-terminal domain mediates required DNA replication activities and phosphorylation of the transcriptional activator IE1 of Autographa californica multicapsid nucleopolyhedrovirus. J Virol 86:6575-85
Mitchell, Jonathan K; Friesen, Paul D (2012) Baculoviruses modulate a proapoptotic DNA damage response to promote virus multiplication. J Virol 86:13542-53
Vandergaast, Rianna; Schultz, Kimberly L W; Cerio, Rebecca J et al. (2011) Active depletion of host cell inhibitor-of-apoptosis proteins triggers apoptosis upon baculovirus DNA replication. J Virol 85:8348-58
Kopek, Benjamin G; Settles, Erik W; Friesen, Paul D et al. (2010) Nodavirus-induced membrane rearrangement in replication complex assembly requires replicase protein a, RNA templates, and polymerase activity. J Virol 84:12492-503
Cerio, Rebecca J; Vandergaast, Rianna; Friesen, Paul D (2010) Host insect inhibitor-of-apoptosis SfIAP functionally replaces baculovirus IAP but is differentially regulated by Its N-terminal leader. J Virol 84:11448-60
Schultz, Kimberly L W; Friesen, Paul D (2009) Baculovirus DNA replication-specific expression factors trigger apoptosis and shutoff of host protein synthesis during infection. J Virol 83:11123-32
Schultz, Kimberly L W; Wetter, Justin A; Fiore, Diccon C et al. (2009) Transactivator IE1 is required for baculovirus early replication events that trigger apoptosis in permissive and nonpermissive cells. J Virol 83:262-72