Epigenetic Landscape during Coronavirus Infection

Epigenetic Landscape during Coronavirus Infection

Alexandra Schäfer and Ralph S. Baric

Coronaviruses (CoV) make up a large group of human and animal pathogens. Two of the most familiar coronaviruses include SARS-CoV (severe respiratory syndrome coronavirus) and MERS-CoV (Middle East respiratory syndrome coronavirus. Recently, studies show that viruses have complex processes that regulate the host epigenome and control innate antiviral defense processes, allowing for virus replication and pathogenesis. This paper looks at emerging coronvirus infections and the resulting new viral defense mechanisms.

Coronaviruses are enveloped RNA viruses and the viral particles are surrounded by ‘spike’-shaped glycoproteins, which give the viruses their characteristic microscopic ‘corona-like’ appearance. Both pathogens cause respiratory tract infections, with the most impacted individuals developing acute respiratory distress syndrome (ARDS).  Asymptomatic infections were rare during the SARS-CoV epidemic, MERS-CoV infections frequently result in asymptomatic infections leading to asymptomatic spread--similar to the asymptomatic spread of COVID-19 currently. 

As we discussed last week, Epigenetics is the study of any potentially stable and, ideally, heritable change in gene expression or cellular phenotype that occurs without changes in the underlying DNA. Viruses interfere with epigenetic regulatory programs within the host, such as histone modification, chromatin remodeling, and viral proteins that interact with the modified histones. Prior studies have noted viruses impacting the immune response by altering the epigenetic gene expression (turn on and off). The evolution of viral defenses and epigenetic effects that allow viruses to attack gene clusters, should be studied in the future.

I sent this paper out as a follow-up, but after reading the book, I thought it would be interesting to post about. This paper goes over two different coronaviruses, SARS-CoV (2002/2003) and MERS-CoV (2012), and touches on the selective pressure that increases the adaptability of the pathogen as a marker of success. Co-evolution is an important mechanism to ensure the viability within a host (and their immune response). Additionally, it is an in-depth article covering epigenetic mechanisms, gene activation and expression, and using epigenetics as a way to identify genes and develop antiviral drugs.

IMAGE: Epigenetic modification infection with highly virulent respiratory viruses--changes in the base state of host chromatin. Infection with H1N1-09 and SARS-CoV results in enrichment of H3K4me3 incorporation (green ovals) and depletion of H3K27 (red diamonds), and therefore in open, transcription-active chromatin. In contrast, H5N1-VN1203 and Middle East respiratory syndrome coronavirus (MERS-CoV) infection drives H3K27me3 enrichment and depletes H3K4me3 for a subset of genes, favoring a closed chromatin conformation that inhibits interferon-stimulated gene (ISG) expression


Kailie Batsche
Potluck for 14 April 2020
Link: https://www.ncbi.nlm.nih.gov/pubmed/28212305