The origin and evolutionary relationship of viruses is poorly understood. This makes archaeal virus-host systems of particular interest because the hosts generally root near the base of phylogenetic trees, while some of the viruses have clear structural similarities to those that infect prokaryotic and eukaryotic cells. Despite the advantageous position for use in evolutionary studies, little is known about archaeal viruses or how they interact with their hosts, compared to viruses of bacteria and eukaryotes. In addition, many archaeal viruses have been isolated from extreme environments and present a unique opportunity for elucidating factors that are important for existence at the extremes. In this article we focus on virus-host interactions using a proteomics approach to study Sulfolobus Turreted Icosahedral Virus (STIV)
infection of Sulfolobus solfataricus P2. Using cultures grown from the ATCC cell stock, a single cycle of STIV
infection was sampled six times over a 72 h period. More than 700
proteins were identified throughout the course of the experiments. Seventy one host
proteins were found to change their concentration by nearly twofold (p < 0.05) with 40 becoming more abundant and 31 less abundant. The modulated
proteins represent 30 different cell pathways and 14 clusters of orthologous groups. 2D gel analysis showed that changes in post-translational modifications were a common feature of the affected
proteins. The results from these studies showed that the prokaryotic
antiviral adaptive immune system
CRISPR-associated proteins (CAS
proteins) were regulated in response to the
virus infection. It was found that regulated
proteins come from mRNAs with a shorter than average half-life. In addition, activity-based
protein profiling (ABPP) profiling on 2D-gels showed
caspase,
hydrolase, and
tyrosine phosphatase enzyme activity labeling at the
protein isoform level. Together, this data provides a more detailed global view of archaeal cellular responses to
viral infection, demonstrates the power of quantitative two-dimensional differential gel electrophoresis and ABPP using 2D gel compatible
fluorescent dyes.