One Antibody nasal spray to prevent Covid. A 'joker' weapon against different mutants of the Sars-CoV-2 virus, also promising against influenza and other infections. The scientists from the Swedish Karolinska Institutet, which every year decides the winners of the Nobel Prize for Medicine, describe it in 'Pnas'. Researchers have demonstrated, so far in mice, that genetically modified IgA antibodies “can strengthen protection against new viral variants. They are not intended to replace vaccines”, specifies Harold Marcottefirst author of the study, but they will be able to offer an additional defense for the frail, for the highest risk categories “such as the elderly or immunocompromised patients”.
The work was conducted within the European research consortium Atac and thanks to a Sweden-China collaboration which involved, among others, the universities of Linköping, Beijing and Fudan, the Institutes of Biomedicine and Health of Guangzhou, the Peking Union Medical College, the Wuhan Institute of Virology and the Kunming Institute of Zoology. Different types of antibodies perform different functions, scientists explain. Immunoglobulins A (IgA) are part of the so-called adaptive immune system and 'live' in the mucous membranes of the airways; if they are absent, or present at low levels, the risk of infection increases. Current anti-Covid vaccines primarily stimulate an IgG antibody response within the body, and previous studies have indicated that their ability to protect against contagion caused by Omicron variants of Sars-CoV-2 is limited.
To overcome this problem, using genetic engineering the team led by Qiang Pan-Hammarström from Karolinska Institutet created IgA antibodies that bind to the Spike protein of the pandemic coronavirus in a similar way to IgG antibodies. Mice infected with the Omicron variant of Sars-CoV-2 received these 'gm' IgA antibodies nasally. The administered drops significantly reduced the viral load in the trachea and lungs of infected mice, the researchers report. Compared to IgG antibodies, they noted, laboratory-engineered IgA antibodies bound more strongly to the Spike protein and were more effective at neutralizing the virus.
“Traditional vaccines elicit an active immune response from the body, while this is a passive immunization strategy“, clarifies Marcotte. “An active immunization approach that induces an immune response of the mucosa would be ideal – the expert points out – but we hope that our approach is suitable for protecting the most vulnerable people”.
“We believe that this will be a very promising strategy not only for Covid-19 and the new variants” of Sars-CoV-2, “but also for other infectious diseases – says Pan-Hammarström – including influenza, other respiratory infections and infections of the gastric mucosa such as those associated with the bacterium Helicobacter pylori, for which there is no vaccine.
The study was funded by the EU's Horizon 2020 programme, a joint VR-NCSF grant, the Knut and Alice Wallenberg Foundation and the Swiss National Science Foundation.
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