Healthy University of Utah scientists are leading effort to determine if salivary glands infected with the virus that causes COVID-19 could decrease a person’s long-term immunity to the disease after being immunized or after recovering from illness.
The investigation, supported by a two-year grant from the National Institutes of Health, will explore whether salivary glands affected by SARS-CoV-2 can reduce the body’s ability to make antibodies that would protect it against reinfection with the virus.
Viruses like SARS-CoV-2 are commonly found in the salivary glands. How SARS-CoV-2 achieves this, however, remains a mystery. Typically, viruses can enter the salivary glands through the moist inner wall of the oral cavity, called the mucosa, or travel there via the bloodstream, says Melodie Weller, Ph.D., assistant professor of dentistry who heads the new study.
Like some other parts of the body, the salivary glands have what is called an “immune privilege,” which means that even if they are infected, the immune system may not effectively clear pathogens in the glands. As a result, the salivary glands can be a persistent repository for viruses such as SARS-CoV-2 and other viruses.
The proteins we are exposed to in our digestive tract can trigger what is called “oral tolerance”. As a result, our immune system will not produce antibodies against these proteins, such as those found in the foods we eat, Weller explains. However, since viruses contain protein, they can also be overlooked by the immune system of the gastrointestinal tract.
If viral proteins are released into the saliva – and we swallow a lot of saliva every day – then they may have the ability to decrease our ability to make antibodies. This may have an impact on the duration of immunity. So, the better we can understand the role of SARS-CoV-2 in the salivary glands, the better we will understand how post-vaccination re-infection and breakthrough infections occur during this pandemic. “
Melodie Weller, Ph.D., assistant professor of dentistry
Researchers suspect that SARS-CoV-2 released by the salivary glands may inhibit the production of antibodies and, therefore, increase the risk of relapse or reinfection. They could also limit the long-term effectiveness of vaccines.
Weller and his colleagues are testing this hypothesis in mice, expressing the viral proteins of SARS-CoV-2 in the salivary glands. They plan to vaccinate these animals to see how they react.
“If they are exposed to viral proteins in the gut by swallowing saliva, we will likely see a decrease in immunity or a decrease in the duration of the immune response,” Weller said.
Utah University of Health