A team of researchers at the University of Würzburg is testing a novel approach for a vaccine against the coronavirus - to swallow. The advantages: Comparatively cheap to produce, easy to administer and relatively stable even at normal temperatures.
If Prof. Thomas Rudel of the Julius Maximilian University of Würzburg and the biopharmaceutical company Aeterna Zentaris in Frankfurt have their way, there could possibly be significant reinforcements in the fight against the worldwide corona pandemic in the future: a vaccine that is not administered by syringe, but as a capsule that can simply be swallowed. Preclinical development has already begun.
Thomas Rudel holds the Chair of Microbiology at the Julius-Maximilians-University of Würzburg (JMU) and already had the idea for the oral vaccination a good year ago: "We are using an approach that has already been in use for many years, millions of times over, as protection against typhoid infection". The oral typhoid vaccine is based on a special bacterial strain, Salmonella Typhi Ty21a.
Rudel and the scientists in his laboratory are now also working with this bacterial strain - with a significant modification: "We have programmed the bacteria to produce SARS-CoV-2 antigens," explains the microbiologist. Rudel was supported in this by microbiologist Dr. Birgit Bergmann. Protected in a capsule from the attack of gastric acid, the bacteria are supposed to unfold their effect in the human small intestine after passing through the stomach. The scientific approach assumes that the bacteria can present the antigens to the immune system there.
"Special cells in the intestinal wall are supposed to ensure that bacteria and the antigens are taken up by immune cells and transported further into lymphoid tissue," says Rudel. There, they could in turn activate other cells of the immune system - so-called B cells and T cells - and initiate an immune response. Rudel hopes that, if successful, this immune response will be so strong that all of the human mucous membranes will be put on alert, and as a result coronaviruses will already be prevented from entering the body there.
Advantages are obvious
In order to remain effective against newly emerging virus mutations, Rudel's team has developed the bacteria in such a way that they produce not one, but two antigens. So if one antigen is only weakly effective due to a viral change, the second antigen could serve as a "safety anchor": It is based on a gene that has been shown to mutate only rarely.
The vaccine from the Franconian laboratory would also have several advantages: It would be cheap to produce, easy to administer and relatively stable even at normal temperatures.
Optimistic and realistic
The development of the vaccine strains and the preclinical work is financially supported by Aeterna Zentaris GmbH. The pharmaceutical company would take over the subsequent clinical trials. Rudel is confident that the necessary approvals could be obtained relatively quickly. A few years ago, Aeterna Zentaris had already worked with a similar procedure on a vaccine against prostate cancer that was about to enter clinical trials and had been approved by the authorities for clinical testing. The team can now build on this experience.
Nevertheless, Rudel is cautiously optimistic. There is no guarantee that an oral vaccine against Covid-19 will soon be available in pharmacies, Rudel warns. After all, many active substances have failed even at a late stage of development because they were not sufficiently effective or showed unexpected and undesirable effects.