So far across the world, 190 mystery cases of acute hepatitis in children have been reported, with 140 of them in Europe, mostly in the UK (110 cases). Further cases have been found in Israel and in the United States. Seventeen children became so sick they needed liver transplants.

The US Centers for Disease Control and Prevention said in a nationwide health alert last week that the first US cases were identified in October in Alabama. The first UK cases were recorded in January.

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        Adenoviruses (AdVs) are common pathogens in human, causing diseases not only in airways, eyes, and intestine but also in the liver, urinary tract, and/or adenoids (1). To date, more than 100 human AdV (HAdV) types have been isolated, characterized, and classified into seven species (A to G) (2). In addition to causing serious diseases in humans, several AdVs are being explored as vaccine vehicles against infectious diseases such as coronavirus disease 2019, Middle East respiratory syndrome (MERS), Ebola disease, AIDS, Lassa fever, and Zika disease (3). These efforts include a vaccine candidate based on HAdV-F41 that elicits neutralizing antibodies against MERS coronavirus in vivo (4). The two sole members of HAdV species F, HAdV-F40 and HAdV-F41, stand out as the only HAdVs with a pronounced gastrointestinal tropism. These so-called enteric AdVs are a leading cause of diarrhea and diarrhea-associated mortality (5) in young children, inferior only to Shigella and rotavirus (6). Diarrhea is estimated to cause ~530,000 deaths/year in children younger than 5 years worldwide (7). Thus, there are strong incentives to understand the structural and molecular basis of enteric HAdVs.

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