Covid-19 vaccine that can cope with mutated viruses

A new DNA-based vaccine against covid-19 is being tested for the first time on healthy participants at Karolinska University Hospital. The vaccine has been developed at Karolinska Institutet and target multiple parts of the virus, making it less vulnerable to mutated strains and potentially effective against new variants.

“This vaccine makes the immune system’s reaction more similar to what it looks like in the event of a real infection compared to today’s vaccines. We hope that it will produce a broader immune response, which can be helpful for people who have difficulty forming antibodies due to, for example, being on dialysis or taking drugs that are immunosuppressive,” says Matti Sällberg, Professor in Biomedical Analysis at at Karolinska Institutet.

Today´s covid-19 vaccines target so-called spike proteins of the virus. The spike proteins resemble as grappling hooks that the virus uses to hook onto cells and start a covid-19 infection. Therefore it is effective to build vaccines against them, but also problematic because it is part of the virus that easily mutates, making the vaccine ineffective.

“The new vaccine is based on parts of spike proteins from three different corona strains, but also targets two other parts of the virus that are more genetically stable. This means that it also works well against omicron and perhaps also future variants of the virus,” says Matti Sällberg.

DNA vaccines have only now begun to be used clinically, but research has been conducted on them for 20 years or more. The DNA vaccine being tested at Karolinska University Hospital is an innovation by Matti Sällberg’s group at Karolinska Institutet. It is supported by the EU and has been developed within the OPENCORONA project.
Matti Sällberg is the founder and co-owner of SVF Vaccines AB, which has patented the vaccine.

The ongoing phase 1 clinical trial includes 16 healthy adults, aged 18 to 65 years, who are being monitored at the Phase 1 unit of the Center for Clinical Cancer Studies in Huddinge, in collaboration with the Medical Unit for Infectious Diseases at Karolinska University Hospital. All participants received their third dose of mRNA vaccine no later than six months ago. Their health status and immune responses to the vaccine are being monitored for a period of three months, including weekly COVID testing.
“It is important that we test this type of new vaccine that can provide a broader immune response and potentially offer better protection against new variants of Covid-19,” says Soo Aleman, Professor and Senior Consultant at the Medical Unit for Infectious Diseases at Karolinska University Hospital.

The fact that the vaccine is based on DNA has its advantages and disadvantages. Unlike mRNA, DNA does not require strict storage at -40 degrees Celsius. However, after the DNA vaccine is injected, an electric pulse, known as electroporation, needs to be delivered to the patient immediately to enable the DNA to enter the cell nuclei.

“Within the OPENCORONA project, a special instrument has been developed for use during DNA injection. It is called an EPSgun and delivers a small electric pulse. The arm may twitch slightly, which can be felt, but it quickly subsides. The patients’ experience of the injection is recorded as an important part of the research,” says Matti Sällberg.