Human immune system could not defend against Delta Covid-19 variant: Study

Hyderabad: CCMB-CSIR study shows that the human immune system could not produce the defense molecules against the Delta variant of SARS-Cov 2 as effectively as it could for other variants. The study published in the journal Microbiology Spectrum was carried out by Dr. Krishnan Harshan's group in collaboration with Dr. Divya Tej Sowpati's group at CSIR-Centre for Cellular and Molecular Biology.

The researchers found that infection from the Delta variant did not alert the immune system. Due to this reason, the virus entered the body and replicated the host cells silently. The researchers selected five different SARS-Cov 2 variants—Delta, Alpha, and the other three variants that emerged from Alpha. They carried out the research in the laboratory by infecting human cells in a cell culture system.

Dixit Tandel, the first author of the study, says, "After the human cells were infected, we monitored the production of known immune defence molecules and pathway signals associated with them. We navigated through hundreds of pathway systems and known defence mechanisms of the body."

It was found that for variants other than Delta, the immune system was alert and responded effectively. "We have identified the molecular mechanisms regulating the host immune response which did not work in the case of the Delta variant. This also includes the production of interferons, immune molecules often used for antiviral therapies. We believe that as it replicated the host cells easily, it spread silently and quickly," says Dr. Krishnan Harshan, the lead investigator of the study.

The study helps to understand how viruses evolve with the changing effects on human hosts.