Picornaviruses cause a wide range of significant human and animal diseases, including poliomyelitis, hepatitis, encephalitis, myocarditis, and the common cold. Since they are among the most genetically simple of all RNA viruses, members of the picornavirus family must usurp host cell functions and modify the cytoplasmic environment to facilitate viral translation, RNA replication, and virion biogenesis. Among the many ways that picornaviruses alter host cell functions is by re-localizing them from the nucleus to the cytoplasm where viral replication takes place. The nuclear versus cytoplasmic separation of the major processes that lead to the expression of protein-coding genes in eukaryotes requires a complex transport process that allows RNAs and proteins to move between these two cellular compartments. The Picornaviridae family is one of several virus families that disrupt the nucleo-cytoplasmic trafficking of cells to promote viral replication. Viral proliferation requires the activity of host RNA-binding proteins that normally function in cellular gene expression and are primarily localized to the nucleus. Picornaviruses alter nucleo-cytoplasmic trafficking to exploit these and other nuclear proteins that are subsequently delivered to the cytoplasm to facilitate efficient viral replication. Our recently-published analysis of the nuclear versus cytoplasmic proteome in human rhinovirus-infected cells has established the identities of a large cohort of nuclear proteins that re-localize to the cytoplasm during infection. In this application, state-of-the-art molecular and cell biology experiments are proposed to determine the functional significance of this protein redistribution on human rhinovirus replication, focusing on nuclear RNA binding proteins involved in mRNA splicing/processing and 3’ polyadenylation. A global analysis of protein distribution during rhinovirus infection of different human lung cell lines by quantitative mass spectrometry is also proposed to uncover novel virus-host interactions that may be respiratory cell-type specific. Results from these studies should reveal novel mechanistic insights into how a respiratory virus like human rhinovirus co-opts specific host nuclear functions and how these functions are altered or re-purposed for specific steps in viral replication. Detailed knowledge of such interactions, particularly at essential interfaces between host proteins and viral proteins and/or viral RNA sequences, promises to reveal new targets for antiviral therapies.

Picornaviruses are significant pathogens worldwide, causing some of the highest levels of human morbidity of all known viruses. These RNA-containing viruses include human rhinovirus, poliovirus, coxsackievirus, enterovirus 71, enterovirus D68, and many others. The project described in this application will explore how rhinoviruses hijack specific nuclear proteins during infection of human cells to carry out functions essential for viral replication in the cytoplasm.