"Some People Develop COVID-19 Immunity After Having a Cold" ... Possibility of 'Cross Immunity'

A24-Type Leukocyte Antigen Carriers Exhibit Strong 'Cross-Reactivity' in Memory T Cells

COVID-19. /Photo by U.S. Centers for Disease Control and Prevention (CDC)

[Asia Economy Reporter Na Ye-eun] The coronavirus (SARS-CoV-2) and the common cold virus belong to the same family of viruses. Therefore, a study has found that some people who have had a cold may also develop immunity to coronavirus.

Coronaviruses include seven types: COVID-19, SARS (Severe Acute Respiratory Syndrome, SARS-CoV), MERS (Middle East Respiratory Syndrome, MERS-CoV), and four types of seasonal human coronaviruses (HCoVs). Among these, the 'seasonal human coronaviruses' are commonly known as cold viruses.

In other words, humans have been exposed to cold viruses, which are coronaviruses, long before the emergence of COVID-19. This is why many scientists have focused on the possibility of 'cross-immunity' between COVID-19 and cold coronaviruses since the COVID-19 pandemic began.

However, not everyone who has had a cold develops immunity to COVID-19.

A research team led by Dr. Shinichi at the RIKEN Center for Integrative Medical Sciences in Japan announced that "people with a specific type of human leukocyte antigen (HLA) show a strong immune response to COVID-19 after having a cold."

Individuals with this type of antigen exhibited an active response of 'killer T cells' that destroy infected cells when infected with COVID-19. These killer T cells had immune memory that reacted to specific spike protein regions of the cold coronavirus. This means that immune memory from previous cold virus infections stimulated killer T cells to respond to COVID-19.

Photo by Getty Images Bank

Additionally, the research team focused on the A24-type HLA, a human leukocyte antigen common in Japan and several other Asian countries. Through computer simulations, the team identified six antigenic determinants on the COVID-19 spike protein that are likely to bind well with the A24-type HLA. Antigenic determinants refer to amino acid sequences that immune cells respond to.

They then observed the peripheral immune cell responses of A24-type HLA carriers who had never been infected with the novel coronavirus.

As a result, immune cells of A24-type HLA carriers strongly reacted to a single peptide called the 'QYI antigenic determinant,' even without prior infection. Furthermore, the killer T cells of A24-type carriers that remembered this peptide also showed cross-reactivity to antigenic determinants of other coronaviruses.

Dr. Fuji emphasized, "We hope to develop vaccines that strongly stimulate targeted T cell responses in COVID-19 patients. At least for A24-type HLA carriers, we have confirmed that this is possible."

The research team plans to begin studies on other types of HLA carriers soon.

This content was produced with the assistance of AI translation services.