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cbd as an antiviral

Cbd as an antiviral

National Institutes of Health grant P30 CA014599 (University of Chicago Comprehensive Cancer Center Support grant)

One potential mechanism by which CBD could suppress viral infection and promote degradation of viral RNA is through induction of the interferon signaling pathway. Interferons are among the earliest innate immune host responses to pathogen exposure ( 18 ). SARS-CoV-2 infection suppresses the interferon signaling pathway ( 19 ) ( Fig. 5A , and fig. S9). Some genes that are induced by CBD in both the absence and presence of the virus include receptors for interferons beta and gamma as well as mediators of the signaling pathway such as STATs 1 and 2 ( Fig. 5A and fig. S10). Other genes in the pathway like OAS1, an interferon-induced gene that leads to activation of RNase L and RNA degradation ( 20 ), are not significantly induced by CBD unless in the presence of the virus ( Fig. 5A and fig. S11). These latter results are consistent with the possibility that CBD lowers the effective viral titer sufficiently to enable normal host activation of the interferon pathway. At the same time, CBD effectively reverses viral induction of cytokines that can lead to the deadly cytokine storm at later stages of infection ( Fig. 5B ). Collectively, these results suggest that CBD inhibits SARS-CoV-2 infection in part by activating the interferon pathway leading to degradation of viral RNA and subsequent viral-induced changes in host gene expression, including cytokines.

(A) A549 cells with ACE2 overexpression (A549-ACE2) were treated with indicated doses of CBD, KPT-9274, or URMC-099 followed by infection with SARS-CoV-2 at a multiplicity of infection (MOI) of 0.5 for 48 hours. The cells were stained for spike protein and the percentage of cells expressing the spike protein in each condition was plotted. EC50 values are indicated. (B) The 1 H qNMR spectra of CBD from a reference material and CBD samples from three different suppliers A, B, and C. (C) A549-ACE2 cells were treated with indicated doses of CBD from three different suppliers followed by infection with SARS-CoV-2 at an MOI of 0.5 for 48 hours. The cells were stained for spike protein and the percentage of cells expressing the spike protein in each condition was plotted. EC50 values are indicated.

Competing interests:

Our results suggest that CBD can block SARS-CoV-2 infection at early stages of infection, and CBD administration is associated with a lower risk of SARS-CoV-2 infection in humans. Furthermore, the active compound in patients is likely to be 7-OH-CBD, the same metabolite implicated in CBD treatment of epilepsy. The substantial reduction in SARS-CoV-2 infection risk of approximately an order of magnitude in patients who took FDA-approved CBD highlights the potential efficacy of this drug in combating SARS-CoV-2 infection. Finally, the ability of CBD to inhibit replication of MHV raises the possibility that CBD may have efficacy against new pathogenic viruses arising in the future.

SARS-CoV-2 is a positive-sense single-stranded RNA (+ssRNA) enveloped virus composed of a lipid bilayer and four structural proteins that drive viral particle formation. The spike (S), membrane (M), and envelope (E) are integral proteins of the virus membrane and serve to drive virion budding, while also recruiting the nucleocapsid (N) protein and the viral genomic RNA into nascent virions. Like SARS-CoV, SARS-CoV-2 primarily enters human cells by the binding of the viral S protein to the angiotensin converting enzyme 2 (ACE2) receptor ( 3 – 5 ), after which the S protein undergoes proteolysis by transmembrane protease, serine 2 (TMPRSS2) or other proteases into two non-covalently bound peptides (S1, S2) that facilitate viral entry into the host cell. The N-terminal S1 binds the ACE2 receptor, and the C-terminal S2 mediates viral-cell membrane fusion following proteolytic cleavage by TMRSS2 or other proteases. Depending upon the cell type, viral entry can also occur after ACE2 binding, independent of proteolytic cleavage ( 6 – 8 ). Following cell entry, the SARS-CoV-2 genome is translated into two large polypeptides that are cleaved by two viral proteases, MPro and PLPro ( 9 , 10 ), to produce 15 proteins, in addition to the synthesis of subgenomic RNAs that encode another 10 accessory proteins plus the 4 structural proteins. These proteins enable viral replication, assembly, and budding. In an effort to suppress infection by the SARS-CoV-2 beta-coronavirus as well as other evolving pathogenic viruses, we tested the antiviral potential of a number of small molecules that target host stress response pathways.

Supplementary Material

Consistent with this interpretation, RNA-seq analysis of infected A549-ACE2 cells treated with CBD for 24 hours shows a striking suppression of SARS-CoV-2-induced changes in gene expression. CBD effectively eradicated viral RNA expression in the host cells, including RNA coding for spike, membrane, envelope and nucleocapsid proteins ( Figs. 4 A and ​ andB). B ). Both SARS-CoV-2 and CBD each induced significant changes in cellular gene expression, including a number of transcription factors (figs. S5 and S6). Principal component analysis of host cell RNA shows almost complete reversal of viral changes but, rather than returning to a normal cell state, the CBD+virus infected cells resemble those treated with CBD alone ( Fig. 4C ). Clustering analysis using Metascape reveals some interesting patterns and associated themes ( Fig. 4D , figs. S7, and S8). For example, viral induction of genes associated with chromatin modification and transcription (Cluster 1) is reversed by CBD although CBD alone has no effect. Similarly, viral inhibition of genes associated with ribosomes and neutrophils (Cluster 3) is largely reversed by CBD, but the drug alone has no effect. This contrasts with Clusters 5 and 6 where CBD alone induces strong activation of genes associated with the host stress response. Together these results suggest that CBD acts to prevent viral protein translation and associated cellular changes.

CBD is rapidly metabolized in the liver and gut into two main metabolites, 7-carboxy-cannabidiol (7-COOH-CBD) and 7-hydroxy-cannabidiol (7-OH-CBD). Although the levels of 7-COOH-CBD are 40-fold higher than 7-OH-CBD in human plasma, 7-OHCBD is the active ingredient for the treatment of epilepsy ( 14 ). Like CBD but unlike the other cannabinoids, 7-OH-CBD effectively inhibited SARS-CoV-2 replication in A549-ACE2 cells (EC50 3.6 μM; Fig. 2C ) and was non-toxic to cells (fig. S2H). Analysis of blood plasma levels in healthy patients taking FDA-approved CBD (Epidiolex ® ) shows a maximal concentration (Cmax) for CBD in the nM range whereas 7-OH-CBD had a Cmax in the μM range, similar to that observed in cultured cells ( 15 ). These results suggest that CBD itself is not present at the levels needed to effectively inhibit SARS-CoV-2 in people. By contrast, the plasma concentrations of its metabolite 7-OH-CBD, whose Cmax can be increased several-fold by co-administration of CBD with a high-fat meal, are sufficient to potentially inhibit SARS-CoV-2 infection in humans ( 15 ).

In recent days, NORML has issued multiple warnings cautioning people to beware of online misinformation surrounding the use of either whole-plant cannabis or CBD as a potential remedy for the COVID-19 virus. Specifically, NORML Executive Director Erik Altieri has stated: “If something sounds too good to be true, it likely is. During these difficult times, we encourage people to be skeptical of any unsubstantiated claims, particularly those circulating online, surrounding the use of cannabis or any other uncorroborated treatment for COVID-19.”

A team of researchers from Italy and the United Kingdom performed a systematic review of peer-reviewed papers specific to the application of CBD in viral diseases. They reported “circumstantial evidence” suggesting that CBD may possess antiviral activity in a limited number of conditions, specifically in the treatment of hepatitis C and Karposi sarcoma. However, this preliminary finding was based solely upon the interpretation of preclinical data. By contrast, authors reported that there exists “no evidence from properly designed clinical trials to support the use of CBD for the treatment” of these or other conditions, such as the flu, West Nile virus, Ebola, or common cold viruses.

Varese, Italy: There is an absence of clinical data supporting the efficacy of CBD as an antiviral agent, according to a systematic literature review published in the journal Cannabis and Cannabinoid Research.

They concluded: “CBD sellers should stop promoting claims that are not backed by scientific evidence. Misleading claims represent both a threat to public health and a violation of consumer access to accurate information.”

Yet, despite this lack of clinical data, authors identified numerous commercial websites touting CBD as a clinically beneficial antiviral agent. They reported, “Claims about the benefits of using CBD on viral infections were largely supported by CBD online retailers and most often appear to be a biased interpretation of the scientific literature or a dishonest manipulation of the information for commercial purposes.”

Full text of the study, “Cannabidiol for viral diseases: Hype or hope?” appears in Cannabis and Cannabinoid Research.