Covid infection changes genetic material in cells: study: The Tribune India


PTI

Washington, November 10

Scientists have shown for the first time that SARS-CoV-2 infection alters the functioning of the host cell’s RNA, a study has found.

Scientists at the Federal University of Sao Paulo (UNIFESP), Brazil, came to this conclusion by analyzing thirteen sets of data obtained during four studies of RNA from viral, human and animal cells.

RNA in a cell, or ribonucleic acid, like DNA, stores genetic information. RNA carries genetic information from DNA to the cytoplasm, the outer space of a cell, and also controls certain chemical processes within the cell.

The most recent study, reported in a paper published in the journal Frontiers in Cellular and Infection Microbiology, examined the epitranscriptome of Vero cells, or monkey-derived cells, and human Calu-3 cells by direct sequencing of the RNA.

An epitranscriptome is a collective log of all biochemical changes in cellular RNA, such as methylation.

“Our first important finding in this study was that SARS-CoV-2 infection increases the level of m6a (N6-methyladenosine), a type of methylation, in host cells compared to uninfected cells,” said study author Marcelo Briones.

Methylation is a biochemical change involving the addition of a methyl group to a substrate, a process that occurs in host cells through the action of enzymes capable of transferring part of one molecule to another. This changes the behavior of proteins, enzymes, hormones and genes.

The researchers, according to the study, quantitatively showed changes in the RNA of infected cells by analyzing all the RNAs present in the cells and qualitatively by locating on a map the number of methylations per region in the nucleotides, the structural unit basis of RNA and DNA.

“Methylation has two functions in viruses. It regulates protein expression and defends the virus against the action of interferon, a potent antiviral substance produced by the host organism,” Briones said.

In both studies, the researchers analyzed m6a because it is the most common type of RNA nucleotide modification and is involved in several important processes, such as intracellular localization and protein translation. .

RNA nucleotides contain nitrogen bases, which are biological compounds containing nitrogen that form these nucleotides, and are either adenine, guanine, uracil or cytosine, running along d a single strand.

The team also found that different strains of the virus had variations in the nitrogen base sequences in their nucleotides. “Some strains can be much more methylated than others. If so, they can multiply better inside host cells,” Briones said.

The virus uses cellular enzymes for its own methylation, producing evolutionary pressure for adaptation of viral DRACH sequences to become more similar to cellular sequences, where the letter D stands for adenine, guanine, or uracil; R for adenine or guanine; A for the methylated residue; C for cytosine; and H for adenine, cytosine or uracil.

The most adaptive viral strains are better able to evade interferon, an antiviral protein produced by the attacked cells.

The increase in cell methylation was mapped by two m6A detection programs. One of them (m6anet) used a machine learning technique called multi-instance learning (MIL). The other (EpiNano) validated the results using a technique called a support vector machine (SVM), according to the study.

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