An oral SARS-CoV-2 Mpro inhibitor clinical candidate for the treatment of COVID-19.

The worldwide outbreak of COVID-19 caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a global pandemic. Alongside vaccines, antiviral therapeutics are an important part of the healthcare response to countering the ongoing threat presented by COVID-19. Here, we report the discovery and characterization of PF-07321332, an orally bioavailable SARS-CoV-2 main protease inhibitor with in vitro pan-human coronavirus antiviral activity and excellent off-target selectivity and in vivo safety profiles. PF-07321332 has demonstrated oral activity in a mouse-adapted SARS-CoV-2 model and has achieved oral plasma concentrations exceeding the in vitro antiviral cell potency in a phase 1 clinical trial in healthy human participants.

Calcium phosphate nanoparticle (CaPNP) for dose-sparing of inactivated whole virus pandemic influenza A (H1N1) 2009 vaccine in mice.

The emergence of pandemic influenza strains, particularly the reemergence of the swine-derived influenza A (H1N1) in 2009, is reaffirmation that influenza viruses are very adaptable and influenza remains as a significant global public health treat. As recommended by the World Health Organization (WHO), the use of adjuvants is an attractive approach to improve vaccine efficacy and allow dose-sparing during an influenza emergency. In this study, we utilized CaPtivate Pharmaceutical's proprietary calcium phosphate nanoparticles (CaPNP) vaccine adjuvant and delivery platform to formulate an inactivated whole virus influenza A/CA/04/2009 (H1N1pdm) vaccine as a potential dose-sparing strategy. We evaluated the relative immunogenicity and the efficacy of the formulation in BALB/c mice following single intramuscularly administration of three different doses (0.3, 1, or 3µg based on HA content) of the vaccine in comparison to non-adjuvanted or alum-adjuvant vaccines. We showed that, addition of CaPNP in vaccine elicited significantly higher hemagglutination inhibition (HAI), virus neutralization (VN), and IgG antibody titers, at all dose levels, relative to the non-adjuvanted vaccine. In addition, the vaccine containing CaPNP provided equal protection with 1/3rd of the antigen dose as compared to the non-adjuvanted or alum-adjuvanted vaccines. Our data provided support to earlier studies indicating that CaPNP is an attractive vaccine adjuvant and delivery system and should play an important role in the development of safe and efficacious dose-sparing vaccines. Our findings also warrant further investigation to validate CaPNP's capacity as an alternative adjuvant to the ones currently licensed for influenza/pandemic influenza vaccination.

Effects of TheraMax on influenza virus infections in cell culture and in mice.

BACKGROUND: Limited in vivo studies in the scientific literature suggest that components of green tea and elderberry may be beneficial in treating influenza virus infections. They are thought to act by blocking virus adsorption to cells. TheraMax(®) is a proprietary medication administered by nasal spray that contains both green tea and elderberry extracts that was evaluated for antiviral activity. METHODS: TheraMax was tested by dilution in Madin-Darby canine kidney cell cultures in standard viral cytopathic effect (CPE) inhibition and virucidal assays against eight influenza A and B strains. It was also administered intranasally to mice to determine protective activity compared to oral oseltamivir against an influenza A/NWS/33 (H1N1) infection. RESULTS: In cell culture assays, TheraMax was found to inhibit viral CPE by 50% at a 1:20 dilution for seven of the eight virus strains, with no virucidal activity at 1:2 dilution. The undiluted product was administered to anaesthetized mice twice daily for 4 days starting 2 h before or 12 h after infection. Alternatively, TheraMax and virus were combined for treatment and infection. Oseltamivir was given orally twice daily for 5 days at 10 mg/kg/day starting at -2 h. TheraMax (combined directly with virus) and oseltamivir each prevented death and curtailed weight loss during the infection, and improved lung haemorrhage scores on day 6. TheraMax starting at -2 h or 12 h significantly delayed death by >2 days and reduced lung haemorrhage scores, but most animals died. CONCLUSIONS: These combined results indicate that TheraMax delayed symptoms during animal infections, likely through blocking of virus adsorption.

Combinations of oseltamivir and peramivir for the treatment of influenza A (H1N1) virus infections in cell culture and in mice.

Oseltamivir and peramivir are being considered for combination treatment of serious influenza virus infections in humans. Both compounds are influenza virus neuraminidase inhibitors, and since peramivir binds tighter to the enzyme than oseltamivir carboxylate (the active form of oseltamivir), the possibility exists that antagonistic interactions might result when using the two compounds together. To study this possibility, combination chemotherapy experiments were conducted in vitro and in mice infected with influenza A/NWS/33 (H1N1) virus. Treatment of infected MDCK cells was performed with combinations of oseltamivir carboxylate and peramivir at 0.32-100µM for 3 days, followed by virus yield determinations. Additive drug interactions with a narrow region of synergy were found using the MacSynergy method. In a viral neuraminidase assay with combinations of inhibitors at 0.01-10nM, no significant antagonistic or synergistic interactions were observed across the range of concentrations. Infected mice were treated twice daily for 5 days starting 2h prior to virus challenge using drug doses of 0.05-0.4mg/kg/day. Consistent and statistically significant increases in the numbers of survivors were seen when twice daily oral oseltamivir (0.4mg/kg/day) was combined with twice daily intramuscular peramivir (0.1 and 0.2mg/kg/day) compared to single drug treatments. The data demonstrate that combinations of oseltamivir and peramivir perform better than suboptimal doses of each compound alone to treat influenza infections in mice. Treatment with these two compounds should be considered as an option.