A study of couples in which both partners were exposed to the coronavirus but only one person got infected is helping to shed light on why some people may be naturally resistant to the virus.
The researchers had believed such cases were rare, but a call for volunteers who fit that profile turned up roughly a thousand couples. Ultimately, they took blood samples from 86 couples for detailed analysis.
The results suggest resistant partners more often have genes that contribute to more efficient activation of so-called natural killer (NK) cells, which are part of the immune system’s initial response to germs.
When NKs are correctly activated, they are able to recognize and destroy infected cells, preventing the disease from developing, the researchers explained in a report published on Tuesday in Frontiers in Immunology.
“Our hypothesis is that the genomic variants most frequently found in the susceptible spouse lead to the production of molecules that inhibit activation of NKs,” study leader Mayana Zatz of the University of São Paulo, Brazil, said in a statement. The current study cannot prove this is happening, she added.
Even if the findings are confirmed with more research, the contributions of other immune mechanisms would also need to be investigated, the researchers said.