COVID-19 Weekly Briefing for Monday, March 14, 2022
The new antiviral nasal spray is here; a new theory of autoimmunity after viral infections.
The new intranasal antiviral spray has arrived: a discussion of how it works and how to use it; An unusually high percentage people infected with the virus that causes COVID-19 produce markers of autoimmunity: a discussion of why this is happening; amidst a widspread dropping of pandemic mitigation measures, new data show that masking and isolation within the home is still the best way to avoid transmission to household members.
Enovid/NONS
1532 - 1537. For some time now, I have been writing about how we might find a way out of the pandemic’s grip. In a recent Weekly Briefing, I outlined a four point plan that includes new intranasal pan-beta coronavirus vaccines, new antiviral medicines, rapid antigen tests (RATs), and SARS-CoV-2 (Scov2) wastewater surveillance.
This Weekly Briefing begins with the announcement that we have received our first shipment of Enovid at the office. Enovid uses nitric oxide (NO) to treat viral infections in the nasal passages. It comes in a spray form and the act of initiating the spray mechanism combines the formula’s components which are housed in two separate chambers, to create a reaction that causes the production of NO gas which goes into the solution the way that a jetstream puts soda bubbles into water.
It is sold as Enovid in Isreal, FabiSpray in India, and NONS (nitric oxide nasal spray) in various other countries where it has been approved for use against COVID-19 (C19).
Mechanisms of action
Enovid has 6 separate mechanisms of action that contribute to its anti-viral effectiveness:
When sprayed into each nostril, the liquid surfactant which contains suspended NO gas coats the nasal mucosa, improving the mechanical barrier against viral infection due to its having a higher viscosity than normal mucous. In other words, the medicine makes a sticky coating that can trap the virus.
The coating is low in pH. This acidic high-viscosity liquid is hostile to Scov2 (the virus that causes C19), creating a chemical barrier against the virus.
Scov2 initiates an infection when projections on its stippled surface, known as the spike protein, binds to a protein called ACE2 on the surface of a human cell. The spike protein contains iron and NO has an affinity for iron-based targets. NO binds to the spike protein and when it does, it alters the shape of the spike’s receptor binding domain. This prevents it from being able to bind to ACE2 receptors on cell surfaces: if the virus’s spike is like a key and ACE2 receptors on the surface of nasal epithelial cells are like locks, NO bends the key so it can’t fit into the lock.
In addition to the spike, NO also binds to the cell’s ACE2 receptor. Like filling a keyhole with putty, NO blocks the virus’ key (the spike protein) from being inserted into the cell’s lock (the ACE2 receptor).
NO is a tiny lipophilic molecule (it can dissolve into or penetrate through fat). As such, it is able to pass through nasal mucosal membranes and enter cells. Once inside the cell, NO interferes with viral replication (the process wherein the virus takes over the cell’s protein-making machinery to run off copies of itself).
Finally, in order to spread the infection, after manufacturing about 100K copies of itself, the virus bursts the cell (a process called lysis) to release the newly minted viral copies to travel through the body and infect new cells. However, within infected cells, NO (again) binds to and twists the spike protein, hampering the virus’ ability to cause lysis and thereby, shutting down its ability to spread.
Randomized clinical trial results
We have seen evidence from prior studies that lower peak viral loads correlate with less severe disease. In randomized clinical trials, Enovid was shown to lower viral loads by > 99% after 2 days of use and cut the symptomatic period of infection in half, from 8 days to 4 days. Knocking down viral loads also reduces the likelihood that an infected person will spread the virus to others.
Safety
NO has been used for more than 20 years, administered via ventilator to treat blue baby syndrome and persistent pulmonary hypertension at concentrations 200 times higher than that used in Enovid/NONS. No systemic side effects have been reported with Enovid/NONS which is available in some countries by prescription and in others over-the-counter, including Israel (Enovid), India (where it is sold as FabiSpray), Bahrain, New Zealand, Thailand, and elsewhere. It has been in wide-scale use for more than a year now.
NO is not a drug. It is a naturally occurring molecule that is produced by nearly every type of cell in the human body. In the airways, it is upregulated as part of the natural defense system during infection. It is also upregulated in the nasal passages during humming.
Use
The course of care involves two sprays into each nostril approximately every 2 hours, for a total of 5 treatments per day. It causes some sensation–very minor, brief, unpleasantness, not pain. NO has been shown to be effective against cold and flu viruses as well.
It has a relatively stable shelf-life but, once opened, each bottle is good for one month and then should be discarded.
Issues with testing
Once a person initiates antiviral therapy with Enovid, RATs should no longer be performed by harvesting the sample from a nasal or combined throat and nasal swab. Rather, throat swabs alone should be performed. Why? Enovid kills the virus in the nose but not in the throat (or elsewhere, such as the lungs). Testing by nasal swab can therefore produce false-negative results.
Whether or not this will affect our protocols for ending isolation after infection remains to be seen. It is possible, given the shorter symptomatic and infectious period, that our protocols might need to be adjusted at some point for those who use Enovid.
Autoimmunity after C19
1538 - 1555. In order for the immune system to fight off viruses, bacteria, and fungi–collectively referred to as pathogens–it must first be able to distinguish between what belongs to the body (self) and what does not (non-self).
Proteins are made up of building blocks called amino acids. Every protein has its own number of amino acids arranged in a particular sequence unique to that protein and the immune system knows ahead of time all the sequences found in normal self-proteins. When it encounters a combination of amino acids that do not belong to any self protein, it intiates the immune defense forces.
But sometimes the immune system makes a mistake distinguishing between self and non-self and starts attacking proteins that exist normally in the body. This is known as an autoimmune disease. Autoimmune diseases can take many different forms depending on which body tissues are targeted.
For example, if the immune target is a self-protein found in joints, as we see in rheumatoid arthritis, the result is painful, swollen joints (inflammatory arthritis). If the immune system instead targets proteins in the cells of the pancreas that make insulin (the hormone that lowers blood sugar), the result is type-1 diabetes (T1D). Or, if it attacks cells in the thyroid gland that make thyroid hormone, the result is fatigue, dry skin, and body aches associated with Hashimoto’s thyroiditis. These are a few of the many common examples of autoimmune diseases.
How does the immune system get things wrong?
The onset of autoimmune diseases has been linked to viral infections for some time. Recently, for example, I presented data in a Weekly Briefing showing that multiple sclerosis (MS) could be triggered by activation of Epstein Barr virus (EBV) which causes mono (infectious mononucleosis). Also, in a prior Briefing, I presented studies showing that infection with Scov2 initiates the production of high levels of autoimmune antibodies and T cells, as well as other markers of autoimmunity, even among those with mild COVID-19 (C19).
How do viruses cause autoimmunity? One theory is that, as the body builds its defenses against the particular amino acid sequences (called antigens) of a virus, it occasionally comes across a sequence that is the same or extremely similar to one seen on a self-protein found normally somewhere in the body. As the immune system builds T cells and antibodies to attack the viral antigens, they also begin to attack the similar-looking self-antigens.
This is known as antigenic mimicry and it seems to be the current prevailing theory among experts regarding how viral infections can sometimes provoke autoimmune diseases. Today’s Briefing includes a new study which challenges (or perhaps adds to) the concept of antigenic mimicry.
But before I present those findings, it might be helpful to have a very brief overview of how the immune system is supposed to work.
A brief review of immunity
The immune system is extremely complex but in very broad strokes, it consists of two arms: innate and adaptive.
Innate immunity consists of barriers like skin and mucous membranes; fluids like mucous, saliva, and tears; and the immune cells and proteins that live on, in, and around those things which react to anything that looks foreign by attacking it. The innate immune system responds generically to non-self antigens by trying to wash them away or gobble them up and has limited powers of self-defense. That’s why we have a backup system.
Adaptive immunity kicks in if innate immunity fails to clear a pathogen. It identifies the non-self antigens and builds unique proteins (called antibodies) and cells (B and T cells) that target the pathogen and infected cells for destruction. This takes time but it is more accurate and powerful.
Within our bodies exist immune organs or ‘hubs’ that make immune cells. Bone marrow, for example, is the immune hub that makes B cells (‘B’ for bone marrow). B cells make antibodies–about a quintillion (a billion billion) different ones–and each one targets one specific antigen of a protein in one specific pathogen. Antibodies are like smart bombs that home in on a very specific target.
The thymus gland, located just above the heart in the front of the chest, is another immune hub. It makes two kinds of T cells (‘T’ for thymus). ‘Killer T cells’ identify infected cells in the body and destroy them. ‘Helper T cells’ activate B cells to produce antibodies.
Once we have cleared an infection, for example by a virus, the adaptive immune system 'remembers’ the pathogen by keeping bits of its antigen-containing protein along with activated B and T cells in immune hubs. There, those bits of viral antigen generate low levels of antibodies and ‘memory’ cells which mutate over time in an attempt to predict how the virus might itself be mutating out in the world.
The next time the virus is encountered, the adaptive immune system can respond much more quickly. Sometimes, if the virus has not mutated much or if it has mutated in a way that was correctly predicted by antibody and cellular mutations in immune hubs, the immune system can knock out the infection before it has a chance to cause symptoms (or at least before it can progress to cause severe illness). This is also how vaccination works.
Central tolerance
Immature T cells migrate to the thymus where they undergo a process of random mutation and differentiation until there is a T cell capable of matching or ‘recognizing’ every possible non-self antigen found in any possible pathogen in nature.
Each new antigen-specific T cell is then vetted to see if it is able to distinguish self from non-self. T cells that fail the test are induced to commit suicide (apoptosis). After all, the immune system does not want T cells that can’t distinguish between self and non-self to get loose as this would cause an autoimmune problem. The process of keeping T cells that can differentiate appropriately between self and non-self while inducing apoptosis in those that can’t is known as central tolerance.
During an infection, bits of non-self antigen protein from the pathogen are carried to the thymus where they are shown around to the resident T cells that have survived the test of central tolerance. Eventually one of the T cells ‘recognizes’ the specific antigen. This activates the T cell to proliferate and leave the thymus to seek and destroy cells infected by the pathogen containing that antigen.
A new paper offers a new causative theory of autoimmunity
As discussed at length in previous Weekly Briefings, infection with Scov2 has been shown to induce or amplify the production of autoimmune antibodies. And new-onset autoimmune diseases have been noted among people after having had C19.
In fact, many experts now suspect that long-covid or PASC (post-acute sequelae of COVID-19) may be a new form of autoimmune disease with symptoms that wax and wane including fatigue, brain fog, body aches, chest pain, and cough. This may be affecting as many as one out of every three people who get C19, including those who only experience a mild acute illness.
Human roseolovirus, a member of the herpesvirus family, is an extremely common pathogen that infects most children by the age of two and up to 90% of people by the time they reach adult age. In most, it causes a brief, minor clinical syndrome of fever and rash (roseola) and then does not recur. Like other herpesviruses, roseola establishes permanent residency in our bodies where, in most people, it remains dormant throughout life.
Mice also get (murine) roseolovirus and in a new study, conducted in mice, we see that roseolovirus infects the thymus where it disrupts the process of vetting T cells for their ability to distinguish between self and non-self antigens (central tolerance). Approximately three months after the virus has been cleared, infected mice developed an autoimmune disease called autoimmune gastritis (AIG) in which T cells attack self-proteins in normal stomach cells.
Human roseolovirus is a close relative of murine roseolovirus, and, given the long-held suspicion that it can trigger, in humans, an autoimmune reaction, this study offers an alternative model to antigenic mimicry. The virus goes to the thymus, interferes with the vetting process of new T cells, and allows some T cells that cannot distinguish between self and non-self to get out and start targeting proteins in normal stomach cells.
If the virus was promptly treated with an antiviral medicine in the first few days following infection, the mice did not develop AIG later on. However, the use of antivirals two months after infection, before the symptoms of AIG had begun, did not prevent autoimmunity from developing at about the three-month mark.
The mice who went on to develop AIG had antibodies that targeted not just self-proteins in the stomach but also a wide array of normal self-proteins commonly associated with other autoimmune conditions. They also developed T cells that targeted various self proteins not just those in the stomach.
Wide populations of autoantibodies and T cells targeting a bunch of different self-antigens in different body tissues speak against the idea of antigenic mimicry. It makes sense that one particular non-self viral antigen might look almost exactly like a self-antigen but not dozens.
This raises new questions about autoimmunity in the time of C19. Does roseolovirus also infect the thymus in humans and, if so, does it interfere with central tolerance? How about other viruses? What about Scov2?
We know that HIV has a profound effect on thymic function and likely can infect the thymus directly. More recently, we learned that Zika virus can as well. There has been some discussion about possible mechanisms whereby Scov2 might enter and infect cells in the thymus. We have seen, for example, that Scov2 can infect T cells which, after they finish their tour of duty on the battlefield of infection, return to the thymus, perhaps to establish a reservoir of memory T cells. Might infected T cells be carrying the virus to the thymus, infecting those cells and interfering with central tolerance the way that roseolovirus does in mice?
We do not yet understand why so many people who contract even mild C19 produce high markers for autoimmunity and/or why so many seem to go on to develop chronic illness that has significant symptomatic overlap with other established autoimmune diseases and post-viral sequellae. Antigenic mimicry is the prevailing theory. Now we have another, perhaps equally compelling theoretical causative mechanism to consider: thymic infection leading to disruption of central tolerance.
Should you isolate if you get infected?
The attack rate (AR) was lower among household contacts of index patients who isolated (41%) compared with those of index patients who did not isolate (68%). Similarly, the AR was lower among household contacts of index patients who wore a mask at home during their potentially infectious period (40%) compared with those of index patients who never wore a mask at home (69%). Isolation and masking of infected persons within the home is still the right strategy if the goal is to not spread C19.