Delta variant of coronavirus could evade human immune system better: CCMB study

Hyderabad: A group of researchers from Hyderabad-based Centre for Cellular and Molecular Biology (CCMB) in a study have found that human immunity could not produce the necessary defense molecules against the Delta variants of SARs-CoV-2, as effectively as they did with the other variants.

The study, which was published recently in the Microbiology Spectrum journal, has demonstrated that how Delta variant could evade the human immune system effectively, when compared to other variants of SARs-CoV-2.

While infection due to the other four variants alerted the immune system quickly, the Delta variant could silently replicate in the host cells, the CCMB researchers said. Two different groups led by Dr. Krishnan Harshan and Dr. Divya Tej Sowpati conducted the study at CCMB.

The researchers tried to understand if humans infected by the virus, react differently to the different SARS-CoV-2 variants. They selected five different SARS-CoV-2 variants including Alpha, Delta, and three other variants that emerged before the Alpha variant, and studied how the human immune system responds to the variants.

Upon viral infection, the first line of attack by the host’s immune system is by producing certain defense chemicals that break down the viruses. The researchers studied how their production responds to these five variants.

CCMB researchers

“We infected the human cells in a cell culture system with these different variants of the virus and monitored the production of known immune defense molecules and the activation of signaling pathways associated with them,” said Dixit Tandel, the first author of the study.

“We navigated through the hundreds of immune pathways known to us using high throughput sequencing and analysis,” said Dr. Nitesh Kumar Singh, who worked on the project with Dr Sowpati.

“We have identified that molecular mechanisms regulating the host immune response have not been as potent against the Delta variant of SARS-CoV-2. This also includes the production of interferons, immune molecules often used for antiviral therapies. The study hints at why the Delta variant could spread more easily,” said Dr. Krishnan Harshan, the lead investigator in this work. He added that the study also helps us understand how viruses evolve with changing effects on human hosts.