Broad-spectrum antivirals of protoporphyrins inhibit the entry of highly pathogenic emerging viruses (preprint)

Severe emerging and re-emerging viral infections such as Lassa fever, Avian influenza (AI), and COVID-19 caused by SARS-CoV-2 urgently call for new strategies for the development of broad-spectrum antivirals targeting conserved components in the virus life cycle. Viral lipids are essential components, and viral-cell membrane fusion is the required entry step for most unrelated enveloped viruses. In this paper, we identified a porphyrin derivative of protoporphyrin IX ( PPIX ) that showed broad antiviral activities in vitro against a panel of enveloped pathogenic viruses including Lassa virus (LASV), Machupo virus (MACV), and SARS-CoV-2 as well as various subtypes of influenza A viral strains with IC 50 values ranging from 0.91±0.25 μM to 1.88±0.34 μM. A mechanistic study using influenza A/Puerto Rico/8/34 (H1N1) as a testing strain showed that PPIX inhibits the infection in the early stage of virus entry through biophysically interacting with the hydrophobic lipids of enveloped virions, thereby inhibiting the formation of the negative curvature required for fusion and blocking the entry of enveloped viruses into host cells. In addition, the preliminary antiviral activities of PPIX were further assessed by testing mice infected with the influenza A/Puerto Rico/8/34 (H1N1) virus. The results showed that compared with the control group without drug treatment, the survival rate and mean survival time of the mice treated with PPIX were apparently prolonged. These data encourage us to conduct further investigations using PPIX as a lead compound for the rational design of lipid-targeting antivirals for the treatment of infection with enveloped viruses.

Calcium channel blocker amlodipine besylate is associated with reduced case fatality rate of COVID-19 patients with hypertension (preprint)

The coronavirus disease (COVID-19) caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has now spread to more than 100 countries posing as a serious threat to the public health on a global scale. Patients with comorbidity such as hypertension suffer more severe infection with elevated case fatality rate. Development of effective anti-viral drug is in urgent need to treat COVID-19 patients. Here we report that calcium channel blockers (CCBs), a type of anti-hypertension drugs that are widely used in the clinics, can significantly inhibit the post-entry replication events of SARS-CoV-2 in vitro. Comparison with two other major types of anti-hypertension drugs, the angiotensin converting enzyme inhibitors (ACEI) and angiotensin II receptor blockers (ARB), showed that only CCBs display significant anti-SARS-CoV-2 efficacy. Combined treatment with chloroquine and CCBs significantly enhanced the anti-SARS-CoV-2 efficacy. Retrospective clinical investigation of COVID-19 patients revealed that the CCB amlodipine besylate administration was associated with reduced case fatality rate of patients with hypertension. Results from this study suggest that CCB administration for COVID-19 patients with hypertension as the comorbidity might improve the disease outcome.

Immunoglobulin fragment F(ab')2 against RBD potently neutralizes SARS-CoV-2 in vitro (preprint)

COVID-19 caused by the emerging human coronavirus, SARS-CoV-2, has become a global pandemic, leading a serious threat to human health. So far, there is none vaccines or specific antiviral drugs approved for that. Therapeutic antibodies for SARS-CoV-2, was obtained from hyper immune equine plasma in this study. Herein, SARS-CoV-2 RBD with gram level were obtained through Chinese hamster ovary cells high-density fermentation. The binding of RBD to SARS-CoV-2 receptor, human ACE2, was verified and the efficacy of RBD in vivo was tested on mice and then on horses. As a result, RBD triggered high-titer neutralizing antibodies in vivo, and immunoglobulin fragment F(ab)2 was prepared from horse antisera through removing Fc. Neutralization test demonstrated that RBD-specific F(ab)2 inhibited SARS-CoV-2 with EC50 at 0.07 g/ml, showing a potent inhibitory effect on SARS-CoV-2. These results highlights as RBD-specific F(ab)2 as therapeutic candidate for SARS-CoV-2.

Novel and potent inhibitors targeting DHODH, a rate-limiting enzyme in de novo pyrimidine biosynthesis, are broad-spectrum antiviral against RNA viruses including newly emerged coronavirus SARS-CoV-2 (preprint)

Emerging and re-emerging RNA viruses occasionally cause epidemics and pandemics worldwide, such as the on-going outbreak of coronavirus SARS-CoV-2. Existing direct-acting antiviral (DAA) drugs cannot be applied immediately to new viruses because of virus-specificity, and the development of new DAA drugs from the beginning is not timely for outbreaks. Thus, host-targeting antiviral (HTA) drugs have many advantages to fight against a broad spectrum of viruses, by blocking the viral replication and overcoming the potential viral mutagenesis simultaneously. Herein, we identified two potent inhibitors of DHODH, S312 and S416, with favorable drug-like and pharmacokinetic profiles, which all showed broad-spectrum antiviral effects against various RNA viruses, including influenza A virus (H1N1, H3N2, H9N2), Zika virus, Ebola virus, and particularly against the recent novel coronavirus SARS-CoV-2. Our results are the first to validate that DHODH is an attractive host target through high antiviral efficacy in vivo and low virus replication in DHODH knocking-out cells. We also proposed the drug combination of DAA and HTA was a promising strategy for anti-virus treatment and proved that S312 showed more advantageous than Oseltamivir to treat advanced influenza diseases in severely infected animals. Notably, S416 is reported to be the most potent inhibitor with an EC50 of 17nM and SI value >5882 in SARS-CoV-2-infected cells so far. This work demonstrates that both our self-designed candidates and old drugs (Leflunomide/Teriflunomide) with dual actions of antiviral and immuno-repression may have clinical potentials not only to influenza but also to COVID-19 circulating worldwide, no matter such viruses mutate or not.