An immune epigenetic insight to COVID-19 infection.

Severe acute respiratory syndrome coronavirus-2 is a positive-sense RNA virus, a causal agent of ongoing COVID-19 pandemic. ACE2R methylation across three CpG sites (cg04013915, cg08559914, cg03536816) determines the host cell's entry. It regulates ACE2 expression by controlling the SIRT1 and KDM5B activity. Further, it regulates Type I and III IFN response by modulating H3K27me3 and H3K4me3 histone mark. SARS-CoV-2 protein with bromodomain and protein E mimics bromodomain histones and evades from host immune response. The 2'-O MTases mimics the host's cap1 structure and plays a vital role in immune evasion through Hsp90-mediated epigenetic process to hijack the infected cells. Although the current review highlighted the critical epigenetic events associated with SARS-CoV-2 immune evasion, the detailed mechanism is yet to be elucidated.

Epigenetic mechanisms regulating COVID-19 infection.

Coronavirus disease 2019 (COVID-2019) outbreak originating in December 2019 in Wuhan, China has emerged as a global threat to human health. The highly contagious SARS-CoV-2 infection and transmission presents a diversity of human host and increased disease risk with advancing age, highlighting the importance of in-depth understanding of its biological properties. Structural analyses have elucidated hot spots in viral binding domains, mutations, and specific proteins in the host such as the receptor angiotensin-converting enzyme 2 (ACE2) and the transmembrane protease serine 2 (TMPRSS2) to be implicated in cell entry and viral infectivity. Furthermore, epigenetic changes that regulate chromatin structure have shown a major impact in genome stabilization and maintenance of cellular homoeostasis and they have been implicated in the pathophysiology of the virus infection. Epigenetic research has revealed that global DNA methylation along with ACE2 gene methylation and post-translational histone modifications may drive differences in host tissue-, biological age- and sex-biased patterns of viral infection. Moreover, modulation of the host cells epigenetic landscape following infection represents a molecular tool used by viruses to antagonize cellular signalling as well as sensing components that regulate the induction of the host innate immune and antiviral defence programmes in order to enhance viral replication and infection efficiency. In this review, we provide an update of the main research findings at the interface of epigenetics and coronavirus infection. In particular, we highlight the epigenetic factors that interfere with viral replication and infection and may contribute to COVID-19 susceptibility, offering new ways of thinking in respect to host viral response.