Inactivated Poliovirus Vaccine Induces Antibodies that Inhibit RNA Synthesis of SARS-CoV-2: An open-label, pre-post vaccine clinical trial
Abstract
Background
Poliovirus vaccination induces an adaptive humoral immune response; in vitro experiments show polio-immune sera contain antibodies against the poliovirus RNA transcriptase that cross-react with SARS-CoV-2. While structural similarities between poliovirus and SARS-CoV-2 could have major implications for the COVID-19 response worldwide, polio-induced immune responses against SARS-CoV-2 have not been confirmed in prospective clinical trials.
Objective
To evaluate whether immune sera from adults who recently received inactivated poliovirus vaccination (IPV) can block SARS-CoV-2’s ability to synthesize RNA.
Intervention
IPV intramuscular injection.
Measurements
Pre-inoculation and 4-weeks post-inoculation sera were tested for anti-3Dpol (RNA-dependent RNA polymerase, RdRp) antibodies using enzyme-linked immunosorbent assays (ELISA). To assess IPV’s ability to induce antibodies that inhibit SARS-CoV-2 RNA synthesis, immune-based detection assays tested RdRp enzymatic activity in polio-immune sera.
Results
298 of the 300 enrolled participants completed both on-site visits. Comparing pre-inoculation to 4-week samples, 85.2% of participants demonstrated an increase in anti-3Dpolantibodies against RdRp proteins. Among tested post-inoculation samples, 94.4% demonstrated inhibition of SARS-CoV-2 RNA synthesis. Few inoculation-related side effects were reported (2.0%), all were minor.
Limitations
Participants were not systematically tested for COVID-19, though known exposures were reported and positive results (1.7%) were documented.
Conclusion
IPV can induce antibodies that inhibit SARS-CoV-2 RNA synthesis, minimizing the risk of viral replication in infected individuals. This finding has practical implications for resource-deficient areas that may have limited access to newly developed COVID-19 vaccines and/or areas with low COVID-19 vaccination rates due to hesitancy.
Funding Source
Private donors.
Registration
<ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="uri" xlink:href="http://ClinicalTrials.gov">ClinicalTrials.gov</ext-link>: <ext-link xmlns:xlink="http://www.w3.org/1999/xlink" ext-link-type="clintrialgov" xlink:href="NCT04639375">NCT04639375</ext-link>.
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