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Principal Investigator: Dr. Klaus Osterrieder
Contact Information: E-mail: no34@cornell.edu - Phone: 607-253-4045
Sponsor: NIH-NIAID
Grant Number: 1 R56 AI063048-01A1
Title: In Vivo Effects of MHC1 Down Regulation in Herpesviruses
Annual Direct Cost: $225,000
Project Period: 09/15/06-08/31/07
DESCRIPTION (provided by applicant): Marek's disease virus (MDV) is a member of the Alphaherpesvirinae. Its ability to establish an infection in circulating CD4+ T cells is required for delivery of virus to the site of free virus production, the skin. In this respect, MDV shares fundamental biological properties with varicella zoster virus, and is presented as a small animal model for this important viral infection of man. As in other herpesviruses, down regulation of cell surface MHC class I glycoprotein expression is a hallmark of lytic MDV. Our long-term goal is to gain a complete understanding of the significance of MHC class I down regulation with regard to virus delivery to the site of free virus production in the skin, the establishment of latent infection in T cells, and tumor formation. We hypothesize that down regulation of MHC class I on the surface of MDV-infected cells by several viral gene products expressed during the lytic replication cycle facilitates virus spread and the establishment of latent infection by escaping immune control. The hypothesis is tested by three specific aims.
Specific aim 1: To identify viral protein(s) responsible for alphaherpesvirus-induced MHC class I down regulation. A transposon-based mutagenesis approach of MDV BAC clones will be used to identify viral genes in addition to the already identified UL49.5 and US3 genes that express proteins responsible for blocking MHC class I cell surface expression.
Specific aim 2: To determine the relevance of the virus-induced block in MHC class I antigen presentation on virus replication in vivo. MDV unable to express the UL49.5, US3 protein or other gene products interfering with the MHC class I antigen presentation pathway will be compared with revertant and parental viruses for their ability to induce T cell-associated viremia and/or latency in chickens.
Specific aim 3: To identify the cellular partners of viral proteins and to determine the mechanism(s) of virus-specific MHC class I down regulation. The subcellular distribution of MHC class I molecules in the presence of UL49.5p, US3p or other MHC class I interference genes will be analyzed, along with the glycosylation patterns and the half life of MHC class I on the cell surface. Peptide translocation to the ER will be measured in cells expressing UL49.5, US3 or other viral MHC class I interference genes to determine whether the TAP peptide transporters are involved in virus-induced impairment of MHC class I traffic. Cellular partners of viral proteins are identified by pull-down experiments with epitope-tagged viral proteins followed by mass spectrometry.
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