ABSTRACT
The COVID-19 pandemic and the need for additional safe, effective, and affordable vaccines gave new impetus into development of vaccine genetic platforms. Here we report the findings from the phase 1, first-in-human, dose-escalation study of COVID-eVax, a DNA vaccine encoding the receptor binding domain (RBD) of the SARS-CoV-2 spike protein. Sixty-eight healthy adults received two doses of 0.5, 1, or 2 mg 28 days apart, or a single 2-mg dose, via intramuscular injection followed by electroporation, and they were monitored for 6 months. All participants completed the primary safety and immunogenicity assessments after 8 weeks. COVID-eVax was well tolerated, with mainly mild to moderate solicited adverse events (tenderness, pain, bruising, headache, and malaise/fatigue), less frequent after the second dose, and it induced an immune response (binding antibodies and/or T cells) at all prime-boost doses tested in up to 90% of the volunteers at the highest dose. However, the vaccine did not induce neutralizing antibodies, while particularly relevant was the T cell-mediated immunity, with a robust Th1 response. This T cell-skewed immunological response adds significant information to the DNA vaccine platform and should be assessed in further studies for its protective capacity and potential usefulness also in other therapeutic areas, such as oncology.
Subject(s)
COVID-19 , Vaccines, DNA , Adult , Humans , Antibodies, Neutralizing , Antibodies, Viral , COVID-19/prevention & control , COVID-19 Vaccines/adverse effects , Double-Blind Method , Pandemics/prevention & control , SARS-CoV-2 , Vaccines, DNA/adverse effectsABSTRACT
In early 2020 the new respiratory syndrome COVID-19 (caused by the zoonotic SARS-CoV-2 virus) spread like a pandemic, starting from Wuhan, China, causing severe economic depression. Despite some advances in drug treatments of medical complications in the later stages of the disease, the pandemic's death toll is tragic, as no vaccine or specific antiviral treatment is currently available. By using a systems approach, we identify the host-encoded pathway, which provides ribonucleotides to viral RNA synthesis, as a possible target. We show that methotrexate, an FDA-approved inhibitor of purine biosynthesis, potently inhibits viral RNA replication, viral protein synthesis, and virus release. The effective antiviral methotrexate concentrations are similar to those used for established human therapies using the same drug. Methotrexate should be most effective in patients at the earliest appearance of symptoms to effectively prevent viral replication, diffusion of the infection, and possibly fatal complications.