Covid-19 Vaccine Produces Antibodies in Preclinical Test

(Gerd Altmann, Pixabay)

20 May 2020. Tests with lab animals show a Covid-19 vaccine now in clinical trials produces neutralizing antibodies to prevent coronavirus infections. Results of the research testing the vaccine made by Inovio, a biotechnology company in Plymouth Meeting, Pennsylvania, appear in today’s issue of the journal Nature Communications.

Inovio is one of the companies originally contracted by Coalition for Epidemic Preparedness Innovations, or CEPI, to develop a Covid-19 vaccine in January 2020, when it was still called the novel coronavirus. The company’s vaccine code-named INO-4800, is now in an early-stage clinical trial, with results expected next month. Moderna Inc., the other biotechnology company tasked at the time by CEPI with producing a vaccine, reported first results from an early-stage trial on Monday.

INO-4800 is made with Inovio’s synthetic DNA technology called DMab, short for DNA monoclonal antibody. In DMab, DNA plasmids — round, double strands of DNA — are ingested into cells, where they’re exposed to a series of mild electrical pulses. These electrical pulses from a Cellectra device, also developed by Inovio, increase the uptake of DNA into the cells, to produce a stronger immune response..

The company designed its Covid-19 vaccine based on an earlier vaccine protecting against Middle East Respiratory Syndrome, or MERS, an earlier coronavirus outbreak. In a clinical trial reported last month, Inovio says the vaccine generated both neutralizing antibodies and T-cells protecting against MERS viruses, with no serious adverse effects associated with the vaccine.

In the Nature Communications paper, a team led by Kate Broderick, Inovio’s senior vice president for research and development, tested INO-4800’s ability to produce antibodies and T-cells in lab mice and guinea pigs. Like the MERS vaccine, DNA plasmids in INO-4800 are designed to prevent proteins in the coronavirus’s spike region from penetrating and infecting cells.

Results show both mice and guinea pigs receiving INO-4800 produce antibodies from B-cells in the immune system that can neutralize SARS-CoV-2 viruses, as well as invoke T-cells protecting against the invaders. In guinea pigs, the researchers simulated clinical delivery of the vaccine and found the vaccine produces antibody concentrations that block the coronavirus spike protein from interacting with the receptor proteins in cells. Moreover, the researchers found evidence of antibodies and T-cells produced in the lungs of the animals, indicating a key protective property of the vaccine.

Broderick notes in an Inovio statement that the results mirror findings from the company’s MERS vaccine clinical trial, and adds, “The potent neutralizing antibody and T cell immune responses generated in multiple animal models are supportive of our currently on-going INO-4800 clinical trials.”

The company’s clinical trial testing INO-4800 is an early stage study with 40 healthy volunteers. Participants are receiving two injections of the vaccine, each 1 milligram, with the second injection given four weeks after the first, as well as a Cellectra electronic stimulus. Half of the sample is randomly assigned to receive two injections of INO-4800 instead of one, in the same dosage. The study team is looking for signs of adverse reactions to the vaccine, as well as production of binding antibodies and enzymes indicating an anti-viral reaction from the immune system. Inovio expects to report results from the trial next month.

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