Efficacy of a Polyclonal Ovine Fab (PR020) Against SARS-CoV-2 Infection

ABSTRACT

Background. Passive immune therapies may be useful in mitigating severe COVID-19. The hamster model has been successfully used to study efficacy of COVID-19 treatments. Our objective with this research is to demonstrate initial efficacy of a new polyclonal ovine Fab raised against the SARS-CoV-2 spike protein (PR020) as a treatment for COVID-19. Methods. Hamsters were treated with PR020 via intraperitoneal route at a dose of 120 mg/kg or a vehicle control once every 24 hours for 8 days, starting 1 day prior to viral challenge with Victoria/1/2020 SARS-CoV-2. Sampling to detect viral RNA and clinical observations were taken throughout the challenge phase. Necropsy occurred 1 day following the last dose of PR020, and tissues were assessed for histopathology and viral RNA. Results. Hamsters receiving vehicle alone lost weight more rapidly than the PR020 group (Figure 1, p< 0.05 day 4 onward). Clinical illness scores for the PR020 group were lower compared to control animals (Figure 2, p< 0.05 day 3 onward). While viral shedding assessed by throat swab did not differ between groups, viral RNA levels in lung tissue was significantly lower in PR020-treated animals (Figure 3, p< 0.05). PR020-treated animals also showed significantly less pathological changes in the lung compared to controls (Figure 4, p=0.0022). (Figure Presented) Conclusion. Treatment with PR020 resulted in a positive clinical outcome (e.g. less weight loss and lower clinical signs). While treatment appeared to have little effect in the nasopharynx, there was a positive effect in the lower respiratory tract, with substantially less viral RNA in the lungs of the group given PR020 and a decrease in the lung histopathology, including consolidation.