Epigenetics is the study of how your behaviors and environment can cause changes that affect the way your genes work. Unlike genetic changes, epigenetic changes are reversible and do not change your DNA sequence, but they can change how your body reads a DNA sequence.
Gene expression refers to how often or when proteins are created from the instructions within your genes. While genetic changes can alter which protein is made, epigenetic changes affect gene expression to turn genes “on” and “off.” Since your environment and behaviors, such as diet and exercise, can result in epigenetic changes, it is easy to see the connection between your genes and your behaviors and environment.
Aging is a biological process related to diseases and mortality. Previous research has identified certain viral infections (including HIV, HBV, CMV) and bacterial infections can increase the rate at which the cells in the body age.
The biological process in aging is reflected by molecular hallmarks, which include epigenetic modifications and telomere shortening. DNA methylation correlates with aging process and can be used to estimate epigenetic aging across tissues. The deviation between DNA methylation age (DNAm age) and chronological age has been proposed as a biomarker for aging and has been related to risk and survival outcomes in age-related diseases.
In humans, telomere shortening is associated in the body with the aging process and, in the cells, with cellular replicative senescence (decreased cellular replication and cellular "death"). Telomeres possess properties that make them suitable as biomarkers in several diseases or conditions, including cancer, CVDs, and aging. The inverse correlation between telomere length (TL) and chronological age has been used for age prediction.
Interestingly, telomere length and the epigenetic clock do not correlate with one another, suggesting that DNAm age and TL measure different aspects of biological aging.
RNA viruses such as severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) are capable of inducing immune dysfunction through hijacking host immune cell epigenomes and altering transcriptional programs to evade immune defenses. Epigenetics offers a window into understanding host‐pathogen interactions decoding the biologic dialogue between host and pathogen and understanding pathogen‐related disease outcomes.
Increasing evidence has shown that various components of the host immune system are dramatically altered during SARS‐CoV‐2 infection and the extent of immune dysregulation relates to severe COVID‐19 disease and mortality.
In order for SARS-CoV-2 to be successful in entering human cells and causing infections it must be able to continuously use the cell's metabolism machinery to replicate and invade. To do that it hijacks the host epigenetic mechanisms like DNA-methylation, acetylation, histone modifications etc.