NITRIC OXIDE INHIBITS THE REPLICATION CYCLE OF SARS CORONAVIRUS
PLEASE NOTE: The article below was written in 2005 in reference to SARS, (Severe Acute Respiratory Syndrome) a novel coronavirus. While it has yet to be proven that Nitric Oxide has a direct effect on Covid-19, the article below suggests that further investigation may be warranted. There is currently an on-going clinical trial into NO's effect on CoronaVirus Covid-19. Below are excerpts from a journal that appears in the US National Library of Medicine, National Institutes of Health.
Nitric oxide (NO) is an important signaling molecule between cells which has been shown to have an inhibitory effect on some virus infections. The purpose of this study was to examine whether NO inhibits the replication cycle of the severe acute respiratory syndrome coronavirus (SARS CoV) in vitro. We found that an organic NO donor, S-nitroso-N-acetylpenicillamine, significantly inhibited the replication cycle of SARS CoV in a concentration-dependent manner. We also show here that NO inhibits viral protein and RNA synthesis. Furthermore, we demonstrate that NO generated by inducible nitric oxide synthase, an enzyme that produces NO, inhibits the SARS CoV replication cycle.
Severe acute respiratory syndrome (SARS), which is associated with a novel coronavirus (CoV), was first identified during fall 2002 in Guangdong Province, China (24, 32, 34). The mortality rate of SARS appears to range from 6 to 55% (12, 20, 21). Coronaviruses are enveloped single-stranded positive-sense RNA viruses with genomes of about 27 to 30 kb (21). Coronaviruses belong to the family Coronaviridae, in which SARS CoV forms a distinct group within the genus Coronavirus (9, 29).
Nitric oxide (NO) is an important signaling molecule between cells and is involved in a wide range of processes (9, 27). An anti-microbial activity of NO has been described for several bacteria and protozoa and for some viruses (1, 18, 27). NO is produced by three enzymes that catalyze the oxidation of l-arginine to NO and l-citrulline (9). Two of the enzymes, neuronal nitric oxide synthase (nNOS) and endothelial NOS (eNOS), are constitutively expressed and are calcium dependent (27). Inducible NOS (iNOS) is expressed only in activated cells and is calcium independent (11). The up-regulation of iNOS is common during an infection, and it is known that some viruses and bacteria are either inhibited or stimulated by increased levels of NO (1, 2, 11, 26, 30). It has also been demonstrated that iNOS is expressed after interferon stimulation in murine macrophages, mouse T cells, human hepatocytes, mononuclear cells, human airway epithelial cells, and alveolar macrophages (6, 13, 15, 25, 31, 33).