DNA Oligonucleotides as Antivirals and Vaccine Constituents against SARS Coronaviruses: A Prospective Tool for Immune System Tuning

The SARS-CoV-2 pandemic has demonstrated the need to create highly effective antivirals and vaccines against various RNA viruses, including SARS coronaviruses. This paper provides a short review of innovative strategies in the development of antivirals and vaccines against SARS coronaviruses, with a focus on antisense antivirals, oligonucleotide adjuvants in vaccines, and oligonucleotide vaccines. Well-developed viral genomic databases create new opportunities for the development of innovative vaccines and antivirals using a post-genomic platform. The most effective vaccines against SARS coronaviruses are those able to form highly effective memory cells for both humoral and cellular immunity. The most effective antivirals need to efficiently stop viral replication without side effects. Oligonucleotide antivirals and vaccines can resist the rapidly changing genomic sequences of SARS coronaviruses using conserved regions of their genomes to generate a long-term immune response. Oligonucleotides have been used as excellent adjuvants for decades, and increasing data show that oligonucleotides could serve as antisense antivirals and antigens in vaccine formulations, becoming a prospective tool for immune system tuning.

Review of Sertoli cell dysfunction caused by COVID-19 that could affect male fertility

Spermatogenesis is a complex and elaborate differentiation process and is vital for male fertility. Sertoli cells play a major role in fertility and induce spermatogenesis by protecting, nourishing, and supporting germ cells. It has been speculated that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could directly affect the male reproductive system, and therefore heredity and fertility. The similarity of SARS-CoV-2 to SARS-CoV could confirm this hypothesis because both viruses use angiotensin-converting enzyme (ACE2) as the receptor to enter human cells. ACE2 is expressed by Sertoli cells and other testicular cells, therefore COVID-19 has the potential to impair fertility by destroying Sertoli cells. This hypothesis should be evaluated and confirmed by monitoring fertility in patients with COVID-19.

Decreased in-hospital mortality associated with aspirin administration in hospitalized patients due to severe COVID-19

Hypercoagulability and thrombosis caused by coronavirus disease 2019 (COVID‐19) are related to the higher mortality rate. Because of limited data on the antiplatelet effect, we aimed to evaluate the impact of aspirin add‐on therapy on the outcome of the patients hospitalized due to severe COVID‐19. In this cohort study, patients with a confirmed diagnosis of severe COVID‐19 admitted to Imam Hossein Medical Center, Tehran, Iran from March 2019 to July 2020 were included. Demographics and related clinical data during their hospitalization were recorded. The mortality rate of the patients was considered as the primary outcome and its association with aspirin use was assessed. Nine hundred and ninety‐one patients were included, of that 336 patients (34%) received aspirin during their hospitalization and 655 ones (66%) did not. Comorbidities were more prevalent in the patients who were receiving aspirin. Results from the multivariate COX proportional model demonstrated a significant independent association between aspirin use and reduction in the risk of in‐hospital mortality (0.746 [0.560–0.994], p = 0.046). Aspirin use in hospitalized patients with COVID‐19 is associated with a significant decrease in mortality rate. Further prospective randomized controlled trials are needed to assess the efficacy and adverse effects of aspirin administration in this population.

Aspirin administration decrease the rate of mortality in hospitalized patients with severe COVID‐19, independently.

Although the crude analysis showed higher mortality rate in patients recieved aspirin, these patients have higher rate of underlying conditions.

By performing stepwise COX regression analysis and adjusting the effect of comorbidities, aspirin administration was protective in hospitalized patients with severe COVID‐19.

Surveillance testing reveals a significant proportion of hospitalized patients with SARS-CoV-2 are asymptomatic

BACKGROUND

The proportion of positive patients admitted to acute-care hospitals for reasons other than coronavirus disease-19 (COVID-19) is unknown. These patients potentially put other patients and healthcare workers at risk of infection.

OBJECTIVE

The objective of this study was to define the proportion of asymptomatic patients admitted with severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). Secondary objectives were to define the positivity rate, reasons for admission, and the geographic distribution in the region.

METHODS

Universal surveillance testing for SARS-CoV-2 was performed on patients admitted to this hospital over a 12-week period from April 9, 2020 to July 1, 2020. Positive patients were categorized as either symptomatic or asymptomatic as defined by the 11 criteria per the Centers for Disease Control and Prevention. The positivity rate, proportion with and without symptoms, reasons for admission, and geographic distribution in the region were recorded.

RESULTS

The positivity rate ranged from 0.8% to 6.2%. The proportion of asymptomatic patients with SARS-CoV-2 was 37%. Asymptomatic patients primarily presented to the hospital because of either trauma or labor. Some clusters in the region were identified of both symptomatic and asymptomatic patients.

CONCLUSIONS

The proportion of asymptomatic patients admitted with SARS-CoV-2 was significant. Identifying and isolating asymptomatic patients likely prevented exposure and development of hospital-acquired COVID-19 cases among healthcare workers and other patients, supporting the universal surveillance of all admitted patients.

Lost in deletion: The enigmatic ORF8 protein of SARS-CoV-2

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) genome contains nine open reading frames (ORFs) that encode for accessory proteins which, although dispensable for viral replication, are important for the modulation of the host infected cell metabolism and innate immunity evasion. Among those, the ORF8 gene encodes for the homonymous multifunctional, highly immunogenic, immunoglobulin-like protein that was recently found to inhibit presentation of viral antigens by class I major histocompatibility complex, suppress the type I interferon antiviral response and interact with host factors involved in pulmonary inflammation and fibrogenesis. Moreover, the ORF8 is a hypervariable gene rapidly evolving among SARS-related coronaviruses, with a tendency to recombine and undergo deletions that are deemed to facilitate the virus adaptation to the human host. Intriguingly, SARS-CoV-2 variants isolated in the beginning of the coronavirus disease 2019 (Covid-19) pandemic that were deleted of the ORF8 gene have been associated to milder symptoms and better disease outcome. This minireview summarizes the current knowledge on the SARS-CoV-2 ORF8 protein in perspective to its potential as antiviral target and with special emphasis on the biochemical, biophysical and structural aspects of its molecular biology.

Spike Glycoprotein-Mediated Entry of SARS Coronaviruses

Severe acute respiratory syndrome coronavirus (SARS-CoV) and SARS-CoV-2 are enveloped, positive-sense, single-stranded RNA viruses and causes of epidemic diseases that have resulted in public health emergencies worldwide. Angiotensin-converting enzyme 2 (ACE2) is the receptor that allows the entry of these two viruses into host cells, a key step in the life cycle of the pathogens. The characterization of the interactions of ACE2 with the viral spike glycoproteins and structural studies of the ACE2-binding-induced conformational changes in the viral spike glycoproteins have furthered our understanding of the entry processes of these two viruses, and these studies provide useful information that will facilitate the development of antiviral agents and vaccines to control the diseases.