Data across countries has shown that age and underlying health conditions make people more vulnerable to the novel coronavirus SARS-CoV-2. A new study has now suggested a possible genetic explanation for this. A group of molecules that should be fighting the virus are diminished with age and chronic health problems, researchers report in the journal Aging and Disease.
These molecules are tiny RNA, called microRNA, and are non-coding molecules, meaning that they do not translate into protein. MicroRNAs play a major role in our body in controlling the expression of genes, and more importantly in the context of Covid-19, they are part of our line of attack against a viral infection. They fight the virus by latching on to the virus’s genetic material (RNA) and cutting it.
But with age and some chronic medical conditions, the attacking microRNA numbers dwindle. The researchers describe this as being much like not having enough troops on the ground in an actual war. The coronavirus is thus better able to hijack our cell machinery so that it can replicate.
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In the study, the reporters identified what appear to be the key microRNAs involved in responding to this virus. Then they looked at existing literature on these microRNAs, specifically in the context of age and certain health conditions.
“We identified these miRNA based on miRNA sequence and coronavirus RNA genome sequence. Then co-related with existing literature in aging and underlying conditions,” Dr Sadanand Fulzele, researcher on ageing at the Medical College of Georgia at Augusta University, told The Indian Express by email.
They looked at the RNA sequence of two coronaviruses: SARS-CoV (which causes SARS) and SARS-CoV-2 (which causes Covid-19). The samples were taken between January and April 2020 from 17 countries.
The researchers observed the sequence of the microRNAs that appeared to be attacking the virus, then used computer simulation to figure out that 848 microRNAs target the SARS genome, and 873 microRNAs target the SARS-CoV-2 genome (558 of these target both viruses).
Correlating with existing literature, the researchers found that many of the microRNAs targeting SARS-CoV-2 are known to become dysregulated and/or diminish in number with age and with underlying medical conditions like diabetes and cardiovascular disease. This is a likely factor in the increased disease presentation and death rates seen in these individuals, they said.
The researchers have a longer-term goal of identifying the most significant microRNAs and replenishing those. Cocktails of multiple key microRNA might help restore sufficient levels of the key virus fighters, the researchers said.
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