Even if the new thesis does not see adenoviruses as a direct cause of the hepatitis cases, they play an important role.
The mysterious liver inflammation in children remains unexplained. A new thesis now brings Sars-CoV-2 into play. The previously suspected adenoviruses remain crucial.
Since the beginning of April, cases of severe liver inflammation in children have been increasing worldwide, only Switzerland has apparently been spared so far. The cause remains unclear. So far, adenoviruses of subtype 41F have been considered the most likely cause of these hepatitis cases. What is curious, however, is that the suspected viruses have been associated with cold-like symptoms in previously healthy children, rather than severe hepatitis. A new thesis was put forward on May 13 in the medical journal “The Lancet”.
Sars-CoV-2 plays a central role in this. After a Covid-19 illness – even if it is symptom-free – viruses can remain in the body, for example in the gastrointestinal tract, and form a reservoir. From there, proteins of the viruses can repeatedly get into the bloodstream and trigger an immune reaction each time. This immune reaction might be amplified by an additional infection with adenoviruses in such a way that the liver becomes inflamed.
A superantigen might be the culprit
Similar mechanisms have already been observed in mice. After infection with adenoviruses, these had an increased susceptibility to severe disease caused by Staphylococcus bacteria with liver failure and death as a result. The reason for this is the enterotoxin B contained in staphylococci, a so-called superantigen.
Superantigens trigger a broad, non-specific immune response. For this purpose, T-cells of the immune system are activated, which then release large amounts of signaling substances. One of these signaling substances is the so-called interferon-gamma, which in turn activates other immune cells and thereby triggers a massive inflammatory reaction.
A structure similar to enterotoxin B was found in the spike protein of the new coronavirus. This, together with the amplifying effect of the adenoviruses, might explain the cases of hepatitis in children.
The thesis will now be tested. Remaining viruses of a past Covid-19 disease might be detected in the stool. If elevated levels of interferon gamma were also measured in children with hepatitis, that would be solid evidence. This would be a big step towards a specific treatment.
