Adenoviruses are small, non-enveloped viruses containing a linear double stranded DNA genome that were first discovered in 1953. The human adenoviruses are associated with a variety of diseases including upper respiratory infections, gastrointestinal illness, and conjunctivitis. Adenovirus infections are a significant clinical problem in transplant recipients, particularly pediatric patients. For many years, these viruses have also been outstanding model systems for the study of DNA replication, RNA synthesis, protein translation, oncogenic transformation, and apoptosis, and more recently interest in adenovirus has expanded due to its potential as a vector for vaccination and human gene transfer studies. Viral gene expression, genome replication, and viral assembly all take place in the nucleus of the infected cell. This project addresses assembly with a focus on the encapsidation of viral DNA. This process requires at least four viral elements: the packaging sequence, which is located near the left end of the genome and is made up of repeated elements called A repeats;the IVa2 protein, which binds to required sequence motifs in this region and is also required for capsid assembly;the L4 22 kDa protein, which forms a complex with the IVa2 protein on the DNA;and the 52/55 kDa protein, which binds both the DNA and the IVa2 protein. The goals of this proposal are to elucidate further the mechanism by which adenovirus encapsidates its DNA, and how this process is linked to capsid formation by the IVa2 protein. The mechanism by which the IVa2 protein facilitates capsid assembly and DNA packaging will be studied by examining the structure of complexes containing the IVa2 and L4 22 kDa proteins and by dissecting the various functions of the IVa2 protein. The role of the 52/55 kDa protein will also be uncovered through the analysis of mutant viruses. These studies will advance our basic understanding of how adenovirus packages its DNA and produces infectious virions. This knowledge will be applicable to the development of anti-viral drugs that block this process, as well as to the development of safer adenovirus vectors and recombinant vaccines.
Adenoviruses are common causes of colds, conjunctivitis (pink eye), and diarrhea. While the infection is rapidly cleared by the immune system in healthy individuals, in persons with compromised immune systems, the infection can become quite severe, with mortality rates approaching 60% in some populations. Currently, useful drugs to treat adenovirus infections are not available. We are studying the final step in the viral life cycle, how the virus produces new infectious particles. We believe that understanding this process may lead to the ability to develop therapies which target viral assembly.
|Christensen, Joan B; Ewing, Sean G; Imperiale, Michael J (2012) Identification and characterization of a DNA binding domain on the adenovirus IVa2 protein. Virology 433:124-30|
|Christensen, Joan B; Byrd, Serena A; Walker, Angela K et al. (2008) Presence of the adenovirus IVa2 protein at a single vertex of the mature virion. J Virol 82:9086-93|
|Tyler, Ryan E; Ewing, Sean G; Imperiale, Michael J (2007) Formation of a multiple protein complex on the adenovirus packaging sequence by the IVa2 protein. J Virol 81:3447-54|
|Ewing, Sean G; Byrd, Serena A; Christensen, Joan B et al. (2007) Ternary complex formation on the adenovirus packaging sequence by the IVa2 and L4 22-kilodalton proteins. J Virol 81:12450-7|
|Perez-Romero, Pilar; Imperiale, Michael J (2007) Assaying protein-DNA interactions in vivo and in vitro using chromatin immunoprecipitation and electrophoretic mobility shift assays. Methods Mol Med 131:123-139|
|Perez-Romero, Pilar; Gustin, Kurt E; Imperiale, Michael J (2006) Dependence of the encapsidation function of the adenovirus L1 52/55-kilodalton protein on its ability to bind the packaging sequence. J Virol 80:1965-71|
|Perez-Romero, Pilar; Tyler, Ryan E; Abend, Johanna R et al. (2005) Analysis of the interaction of the adenovirus L1 52/55-kilodalton and IVa2 proteins with the packaging sequence in vivo and in vitro. J Virol 79:2366-74|
|Imperiale, M J; Kochanek, S (2004) Adenovirus vectors: biology, design, and production. Curr Top Microbiol Immunol 273:335-57|