Researchers at the Karolinska Institute have shown that nasal drops with IgA antibodies can protect mice from infection with the new coronavirus. The results of the study, published in PNASinvolve a new way to protect people at high risk from different variants of the SARS-CoV-2 virus and possibly other infections.
Different types of antibodies have different functions in the body. IgA antibodies are part of the so-called adaptive immune system and reside naturally in the mucous membranes of the respiratory tract. Absence or low levels of mucosal IgA are known to be associated with an increased risk of breakthrough SARS-CoV-2 infections.
Current COVID-19 vaccines primarily stimulate an IgG antibody response in the body, and previous studies have shown that their ability to protect against infection with new omicron variants of the virus is limited.
To overcome this, the group led by Professor Qiang Pan-Hammarström at the Karolinska Institute used genetic engineering to create IgA antibodies that bind to the SARS-CoV-2 spike protein in a similar way to IgG antibodies.
Mice infected with the omicron variant received IgA antibody treatment via nasal administration. Nasal drops significantly decreased the viral load in the trachea and lungs of infected mice. IgA antibodies were shown to bind stronger to the SARS-CoV-2 spike protein and were more effective in neutralizing the virus compared to the original IgG antibodies.
“The results show that these genetically modified antibodies “strengthen protection against new variants of the virus, but are not intended to replace current vaccines,” says Harold Marcotte, associate professor at the Department of Medical Biochemistry and Biophysics at the Karolinska Institutet and first author of the article.
Passive immunization against new variants of coronavirus and flu
“Traditional vaccines provoke an active immune response from the body, while this is a passive immunization strategy,” he continues. “Ideally, an active immunization approach that induces a mucosal immune response would be appropriate, but we hope that our approach will be suitable to protect more vulnerable individuals, such as the elderly or immunocompromised.”
There are also hopes that the method can be used to neutralize other current and emerging variants of the virus.
“We believe that this will be a very promising strategy, not only for COVID-19 and the new variants, but also for other infectious diseases, including influenza and other respiratory infections and gastric mucosal infections such as Helicobacter pylori, for which we do not There is a vaccine available at the moment,” says Qiang Pan-Hammarström, professor in the same department and last author of the article.
