Proteomic and Phosphoproteomic Analysis of Chicken Embryo Fibroblasts Infected with Cell Culture-Attenuated and Vaccine Strains of Marek’s Disease Virus

Vaccination is an effective strategy to reduce the loss
of chickens
in the poultry industry caused by Marek’s Disease (MD), an
avian lymphoproliferative disease. The vaccines currently used are
from attenuated serotype 1 Marek’s disease virus (MDV) or naturally
nononcogenic MDV strains. To prepare for future immunity breaks, functional
genomic and proteomic studies have been used to better understand
the underlying mechanisms of MDV pathogenicity and the effects induced
by the vaccine viruses. In this study, a combined approach of quantitative
GeLC–MSE and qualitative ERLIC/IMAC/LC–MS/MS
analysis were used to identify abundance changes of proteins and the
variations of phosphorylation status resulting from the perturbations
due to infection with an attenuated oncogenic virus strain (Md11/75C)
and several nononcogenic virus strains (CVI988, FC126 and 301B) in vitro. Using this combined approach, several signal transduction
pathways mapped by the identified proteins were found to be altered
at both the level of protein abundance and phosphorylation. On the
basis of this study, a kinase-dependent pathway to regulate phosphorylation
of 4E-BP1 to modulate assembly of the protein translation initiation
complex was revealed. The differences of 4E-BP1 phosphorylation patterns
as well as the measured abundance changes among several other proteins
that regulate host transcriptional and translational activities across
the virus strains used in this study provide new insight for future
functional and biochemical characterization of specific proteins involved
in MDV pathogenesis.