Virus World

The COVID-19 pandemic caused by the SARS-CoV-2 virus remains a global public health crisis. Although widespread vaccination campaigns are underway, their efficacy is reduced due to emerging variants of concern (VOCs)1,2. Development of host-directed therapeutics and prophylactics could limit such resistance and offer urgently needed protection against VOCs3,4. Attractive pharmacological targets to impede viral entry include type-II transmembrane serine proteases (TTSPs), such as TMPRSS2, whose essential role in the virus lifecycle is to cleave the viral spike protein to expose the fusion peptide for cell entry5,6.

Here, we identify and characterize a small-molecule compound, N-0385, which exhibits low nanomolar potency and a selectivity index of >106 at inhibiting SARS-CoV-2 infection in human lung cells and in donor-derived colonoids7. In Calu-3 cells it inhibits entry of SARS-CoV-2 VOCs, B.1.1.7, B.1.351, P.1 and B.1.617.2. Importantly, in the K18-human ACE2 transgenic mouse model of severe SARS-CoV-2 disease, we found that N-0385 affords a high level of prophylactic and therapeutic benefit following either multiple or even a single administration. This demonstrates that TTSP-mediated proteolytic maturation of spike is critical for SARS-CoV-2 infection in vivo and suggests that N-0385 provides a novel effective early treatment option against COVID-19 and emerging SARS-CoV-2 VOCs.

Published in Nature (March 28, 2022):

https://doi.org/10.1038/s41586-022-04661-w 

Infection with SARS-CoV-2 has a wide range of clinical presentations, from asymptomatic to life-threatening. Old age is the strongest factor associated with increased COVID19-related mortality, followed by sex and pre-existing conditions. The importance of genetic and immunological factors on COVID19 outcome is also starting to emerge, as demonstrated by population studies and the discovery of damaging variants in genes controlling type I IFN immunity and of autoantibodies that neutralize type I IFNs. The human protein transmembrane protease serine type 2 (TMPRSS2) plays a key role in SARS-CoV-2 infection, as it is required to activate the virus spike protein, facilitating entry into target cells.

We focused on the only common TMPRSS2 non-synonymous variant predicted to be damaging (rs12329760), which has a minor allele frequency of 25% in the population. In a large population of SARS-CoV-2 positive patients, we show that this variant is associated with a reduced likelihood of developing severe COVID19 (OR 0.87, 95%CI:0.79-0.97, p=0.01). This association was stronger in homozygous individuals when compared to the general population (OR 0.65, 95%CI:0.50-0.84, p=1.3x10-3). We demonstrate in vitro that this variant, which causes the amino acid substitution valine to methionine, impacts the catalytic activity of TMPRSS2 and is less able to support SARS-CoV-2 spike-mediated entry into cells. TMPRSS2 rs12329760 is a common variant associated with a significantly decreased risk of severe COVID19. Further studies are needed to assess the expression of the TMPRSS2 across different age groups. Moreover, our results identify TMPRSS2 as a promising drug target, with a potential role for camostat mesilate, a drug approved for the treatment of chronic pancreatitis and postoperative reflux esophagitis, in the treatment of COVID19. Clinical trials are needed to confirm this.

Preprint available at medRxiv (March 8, 2021):

https://doi.org/10.1101/2021.03.04.21252931 

A new study published in April 2020 on the preprint server bioRxiv reports that the different levels of susceptibility of various organs to viral attack by the SARS-CoV-2 virus causing the huge pandemic of COVID-19 sweeping around the world can be predicted from the level of expression of two molecules, the ACE2 receptor, and the TMPRSS2 protein.

The SARS-CoV-2 is a catastrophic medical disaster, in which over 2.47 million cases have been reported with more than 169,000 people dead, as of April 20, 2020. The most common cause of death is pneumonia with acute lung injury, acute respiratory distress syndrome (ARDS) being the final event However, in some patients, many other organs also suffer severe damage leading to multi-organ failure and even death following infection. This motivated the current attempt to identify the organs that are vulnerable to this virus to understand better how it affects the body. It is already known that the virus accomplishes cell entry via a molecule called angiotensin-converting enzyme 2 (ACE2), which acts as a receptor for both this virus and the earlier SARS virus. Another protease, called TMPRSS2, within the cell, enhance the transmissibility of the virus. Thus the investigators determined to test the potential usefulness of measuring the level of expression of these two proteins to predict the risk that any given organ will be susceptible to the virus.

The investigators used a method called scRNA-seq to detect the clustering of the gene expression of cells, and thus identify cell types. While most studies indicate that the virus causes mainly lung injury, it is known that the ACE2 receptor is chiefly expressed in the lung’s type II alveolar cells (AT2). This means this cell type is vulnerable to the virus. The TMPRSS2 is required to initiate the expression of the spike (S) protein, which is key to the entry of the virus and its spread between hosts.

Preprint Available at medRxiv (April 18, 2020):

https://www.biorxiv.org/content/10.1101/2020.04.16.045690v1

The COVID-19 pandemic caused by the SARS-CoV-2 virus remains a global public health crisis. Although widespread vaccination campaigns are underway, their efficacy is reduced against emerging variants of concern (VOCs). Development of host-directed therapeutics and prophylactics could limit such resistance and offer urgently needed protection against VOCs. Attractive pharmacological targets to impede viral entry include type-II transmembrane serine proteases (TTSPs), such as TMPRSS2, whose essential role in the virus lifecycle is responsible for the cleavage and priming of the viral spike protein. Here, we identify and characterize a small-molecule compound, N-0385, as the most potent inhibitor of TMPRSS2 reported to date. N-0385 exhibited low nanomolar potency and a selectivity index of > 1 million at inhibiting SARS-CoV-2 infection in human lung cells and in donor-derived colonoids. Importantly, N-0385 acted as a broad-spectrum coronavirus inhibitor of two SARS-CoV-2 VOCs, B.1.1.7 and B.1.351. Strikingly, single daily intranasal administration of N-0385 early in infection significantly improved weight loss and clinical outcomes, and yielded 100% survival in the severe K18-human ACE2 transgenic mouse model of SARS-CoV-2 disease. This demonstrates that TTSP-mediated proteolytic maturation of spike is critical for SARS-CoV-2 infection in vivo and suggests that N-0385 provides a novel effective early treatment option against COVID-19 and emerging SARS-CoV-2 VOCs.

Preprint available (May 4, 2021):

https://doi.org/10.1101/2021.05.03.442520 

The virus was found within the sperm of some 13% of screened male COVID-19 patients. Males who suffer from moderate or severe cases of COVID-19 could experience reduced fertility, according to a new study conducted by Dr. Dan Aderka of Sheba Medical Center. Aderka reported that not only was the virus found within the sperm of some 13% of screened male COVID-19 patients, but that there was a 50% decrease in the sperm volume, concentration and motility in patients with moderate disease even 30 days post diagnosis. Finally, post-mortem tests of 12 COVID-19 patients demonstrated moderate to severe changes in the testicular cells supporting sperm development and those producing testosterone, the hormone that induces sperm division and multiplication.

Aderka, whose research has not yet been published, told The Jerusalem Post that the cause for this phenomenon seems to be the presence of the ACE2 receptor on the surface the cell of the Sertoli and Leydig cells of the testis, the same receptors on the cells of lungs, kidneys and hearts. The Sertoli cells support sperm maturation. The Leydig cells produce testosterone. He said the coronavirus binds to the ACE2 receptors and destroys the cells, which causes infertility. “As normal sperm maturation takes 70 to 75 days, it is possible that if we are doing a sperm examination two and a half months after recovery, we may see even more reduced fertility,” Aderka said. “It could be even more detrimental.”

He added that it is also still unclear if the effects on the quality and quantity of the sperm are reversible or persistent. He said doctors will need to examine these same patients six months and a year after recovery to see if the damage “stands the test of time.” This is something his team is planning to do. Aderka said that there is another hypothesis that can now be explored, also as a result of his research: “Interestingly, an enzyme called TMPRSS2 assists the virus in binding to the ACE receptor, facilitating its internalization into the cells.” TMPRSS2 is activated by testosterone. “This phenomenon may explain the higher COVID-10 morbidity and mortality of men compared to women,” he told the Post, adding that it also may explain the lower morbidity and mortality of children, whose testosterone levels are low.