Hyperforin, the major metabolite of St. John's wort, exhibits pan-coronavirus antiviral activity.

Introduction: The COVID-19 pandemic caused by the SARS-CoV-2 virus has underscored the urgent necessity for the development of antiviral compounds that can effectively target coronaviruses. In this study, we present the first evidence of the antiviral efficacy of hyperforin, a major metabolite of St. John's wort, for which safety and bioavailability in humans have already been established. Methods: Antiviral assays were conducted in cell culture with four human coronaviruses: three of high virulence, SARS-CoV-2, SARS-CoV, and MERS-CoV, and one causing mild symptoms, HCoV-229E. The antiviral activity was also evaluated in human primary airway epithelial cells. To ascertain the viral step inhibited by hyperforin, time-of-addition assays were conducted. Subsequently, a combination assay of hyperforin with remdesivir was performed. Results: The results demonstrated that hyperforin exhibited notable antiviral activity against the four tested human coronaviruses, with IC50 values spanning from 0.24 to 2.55 µM. Kinetic studies indicated that the observed activity occur at a post-entry step, potentially during replication. The antiviral efficacy of hyperforin was additionally corroborated in human primary airway epithelial cells. The results demonstrated a reduction in both intracellular and extracellular SARS-CoV-2 viral RNA, confirming that hyperforin targeted the replication step. Finally, an additive antiviral effect on SARS-CoV-2 was observed when hyperforin was combined with remdesivir. Discussion: In conclusion, hyperforin has been identified as a novel pan-coronavirus inhibitor with activity in human primary airway epithelial cells, a preclinical model for coronaviruses. These findings collectively suggest that hyperforin has potential as a candidate antiviral agent against current and future human coronaviruses.

Vaccination with BCGΔBCG1419c protects against pulmonary and extrapulmonary TB and is safer than BCG.

A single intradermal vaccination with an antibiotic-less version of BCGΔBCG1419c given to guinea pigs conferred a significant improvement in outcome following a low dose aerosol exposure to M. tuberculosis compared to that provided by a single dose of BCG Pasteur. BCGΔBCG1419c was more attenuated than BCG in murine macrophages, athymic, BALB/c, and C57BL/6 mice. In guinea pigs, BCGΔBCG1419c was at least as attenuated as BCG and induced similar dermal reactivity to that of BCG. Vaccination of guinea pigs with BCGΔBCG1419c resulted in increased anti-PPD IgG compared with those receiving BCG. Guinea pigs vaccinated with BCGΔBCG1419c showed a significant reduction of M. tuberculosis replication in lungs and spleens compared with BCG, as well as a significant reduction of pulmonary and extrapulmonary tuberculosis (TB) pathology measured using pathology scores recorded at necropsy. Evaluation of cytokines produced in lungs of infected guinea pigs showed that BCGΔBCG1419c significantly reduced TNF-α and IL-17 compared with BCG-vaccinated animals, with no changes in IL-10. This work demonstrates a significantly improved protection against pulmonary and extrapulmonary TB provided by BCGΔBCG1419c in susceptible guinea pigs together with an increased safety compared with BCG in several models. These results support the continued development of BCGΔBCG1419c as an effective vaccine for TB.

Characterizing the BCG Induced Macrophage and Neutrophil Mechanisms for Defense Against Mycobacterium tuberculosis.

The live attenuated Mycobacterium bovis strain, Bacille Calmette Guérin (BCG) is a potent innate immune stimulator. In the C57BL/6 mouse model of tuberculosis, BCG vaccination leads to a significant reduction of Mycobacterium tuberculosis burden after aerogenic infection. Our studies indicated that BCG induced protection against pulmonary tuberculosis was independent of T cells and present as early as 7 days after vaccination. This protection showed longevity, as it did not wane when conventional T cell and TNF-α deficient mice were infected 30 days post-vaccination. As BCG induced mycobacterial killing after 7 days, this study investigated the contributions of the innate immune system after BCG vaccination to better understand mechanisms required for mycobacterial killing. Subcutaneous BCG inoculation resulted in significant CD11b+F4/80+ monocyte subset recruitment into the lungs within 7 days. Further studies revealed that killing of mycobacteria was dependent on the viability of BCG, because irradiated BCG did not have the same effect. Although others have identified BCG as a facilitator of trained innate immunity, we found that BCG reduced the mycobacterial burden in the absence of mechanisms required for trained innate immunity, highlighting a role for macrophages and neutrophils for vaccine induced killing of M. tuberculosis.