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Two Covid-19 Vaccines Show Preclinical Immune Responses

SARS-Cov-2 viruses

Scanning electron microscope image showing SARS-CoV-2 viruses, in yellow. (NIAID, NIH)

30 July 2020. Two candidate vaccines to prevent Covid-19 infections show they generate immune protections in lab monkeys, with one vaccine for 13 weeks. Drug maker Johnson & Johnson reports preliminary results of its study, conducted by researchers at Beth Israel Deaconess Medical Center today in the journal Nature, while biotechnology company Inovio Pharmaceuticals Inc. in Plymouth Meeting, Pennsylvania reports its findings on the bioRxiv preprint server and company web site.

Johnson & Johnson’s vaccine, code-named Ad26.COV2.S employs the company’s technology that harnesses adenoviruses to deliver proteins simulating the SARS-CoV-2 viral antigen for invoking an immune response. Adenoviruses in the wild are responsible for the common cold, but in this case, they’re genetically altered to enter cells, yet not replicate. Janssen Research and Development, Johnson & Johnson’s drug development subsidiary, designed Ad26.COV2.S to produce antibodies to neutralize the proteins on the coronavirus spike that start the infection process in cells.

The Beth Israel Deaconess researchers in Boston tested the vaccine with 52 rhesus macaques, randomly assigned to receive a single dose of Ad26.COV2.S or a sham injection. The animals were then exposed to SARS-CoV-2 viruses placed in their nose and throat tissues, with samples later taken from their lower respiratory tracts and nasal passages. The results show monkeys receiving the vaccine produced a high enough concentration of neutralizing antibodies to provide complete or near-complete protection against infection.

Johnson & Johnson expects to begin clinical trials of Ad26.COV2.S in September, but already is planning new and expanded manufacturing facilities to produce 1 billion doses, if shown safe and effective in clinical trials. Biomedical Advanced Research and Development Authority, or BARDA, the U.S. health emergency preparedness agency, is funding much of the vaccine’s development and manufacturing costs, with BARDA and the company together spending $1 billion.

The Inovio vaccine, code-named, 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, according to the company.

As reported by Science & Enterprise in May, Inovio tested INO-4800 in mice and guinea pigs, with results reported in the journal Nature Communications showing the vaccine produces both antibodies blocking infections from spike proteins, as well as T-cells in the lungs. The new study tested INO-4800 in rhesus macaques, receiving two doses of the vaccine four weeks apart, with the animals challenged by live SARS-CoV-2 viruses 13 weeks after the last dose.

The results — not yet peer-reviewed — show the animals receiving the vaccine experienced high concentrations of neutralizing antibodies and T-cells against the original SARS-CoV-2 virus as well as a more recent mutation. The company says the antibody concentrations produced by the vaccine equal or exceed concentrations in convalescent plasma from recovered Covid-19 patients, and T-cell levels exceed those found in recovered patients.

In addition, the reduced viral loads in the monkeys’ lungs and nasal passages continued when challenged with SARS-CoV-2 viruses after 13 weeks. The company says one injection of INO-4800 also produced high concentrations of neutralizing antibodies and T-cells.

Inovio is now testing INO-4800 in an early-stage clinical trial, with mid- and late-stage trials planned for later in the summer.

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Disclosure: The author owns shares in Johnson & Johnson.

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