Boosting of SARS-CoV-2 immunity in nonhuman primates using an oral rhabdoviral vaccine.

An orally active vaccine capable of boosting SARS-CoV-2 immune responses in previously infected or vaccinated individuals would help efforts to achieve and sustain herd immunity. Unlike mRNA-loaded lipid nanoparticles and recombinant replication-defective adenoviruses, replicating vesicular stomatitis viruses with SARS-CoV-2 spike glycoproteins (VSV-SARS2) were poorly immunogenic after intramuscular administration in clinical trials. Here, by G protein trans-complementation, we generated VSV-SARS2(+G) virions with expanded target cell tropism. Compared to parental VSV-SARS2, G-supplemented viruses were orally active in virus-naive and vaccine-primed cynomolgus macaques, powerfully boosting SARS-CoV-2 neutralizing antibody titers. Clinical testing of this oral VSV-SARS2(+G) vaccine is planned.

Evaluation of Copper Alloy Surfaces for Inactivation of Tulane Virus and Human Noroviruses.

ABSTRACT: This study evaluated the efficacy of copper alloy surfaces for inactivation of Tulane virus (TV), assessed by plaque assay and porcine gastric mucin-conjugated magnetic bead (PGM-MB) binding assay, followed by quantitative reverse transcription PCR (PGM-MB-RT-qPCR assay). In addition, the efficacy of a copper surface for inactivation of human norovirus (HuNoV) GII.4 Sydney and GI.3B Potsdam strains was evaluated by PGM-MB-RT-qPCR assay. Results of time-dependent inactivation of viruses on copper, bronze, and brass coupons revealed that 15 min of surface treatments of each of the copper and copper alloys achieved >4-log reduction of purified TV, as assessed by plaque assay, while up to 20 min of copper alloy surface treatments only achieved ∼2-log reduction, as assessed by PGM-MB-RT-qPCR assay. As assessed by PGM-MB-RT-qPCR assay, 10 min of copper surface treatments achieved reductions of 3 and 4 log units for HuNoVs GII.4 Sydney and GI.3B Potsdam, respectively. Results from this study suggest that even though PGM-MB-RT-qPCR assay underestimated the efficacy of copper alloy surface inactivation of TV, copper alloy surfaces were able to effectively inactivate TV and HuNoVs. Therefore, copper alloys can be used as a preventive measure to prevent HuNoV infection and are an effective surface treatment for HuNoVs.

Development and validation of IMMUNO-COV™: a high-throughput clinical assay for detecting antibodies that neutralize SARS-CoV-2.

We here describe the development and validation of IMMUNO-COV™, a high-throughput clinical test to quantitatively measure SARS-CoV-2-neutralizing antibodies, the specific subset of anti-SARS-CoV-2 antibodies that block viral infection. The test measures the capacity of serum or purified antibodies to neutralize a recombinant Vesicular Stomatitis Virus (VSV) encoding the SARS-CoV-2 spike glycoprotein. This recombinant virus (VSV-SARS-CoV-2-S-Δ19CT) induces fusion in Vero cell monolayers, which is detected as luciferase signal using a dual split protein (DSP) reporter system. VSV-SARS-CoV-2-S-Δ19CT infection was blocked by monoclonal α-SARS-CoV-2-spike antibodies and by plasma or serum from SARS-CoV-2 convalescing individuals. The assay exhibited 100% specificity in validation tests, and across all tests zero false positives were detected. In blinded analyses of 230 serum samples, only two unexpected results were observed based on available clinical data. We observed a perfect correlation between results from our assay and 80 samples that were also assayed using a commercially available ELISA. To quantify the magnitude of the anti-viral response, we generated a calibration curve by adding stepped concentrations of α-SARS-CoV-2-spike monoclonal antibody to pooled SARS-CoV-2 seronegative serum. Using the calibration curve and a single optimal 1:100 serum test dilution, we reliably measured neutralizing antibody levels in each test sample. Virus neutralization units (VNUs) calculated from the assay correlated closely (p < 0.0001) with PRNT EC50 values determined by plaque reduction neutralization test against a clinical isolate of SARS-CoV-2. Taken together, these results demonstrate that the IMMUNO-COV™ assay accurately quantitates SARS-CoV-2 neutralizing antibodies in human sera and therefore is a potentially valuable addition to the currently available serological tests. The assay can provide vital information for comparing immune responses to the various SARS-CoV-2 vaccines that are currently in development, or for evaluating donor eligibility in convalescent plasma therapy studies.