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Researchers at the Medical Center - University of Freiburg decipher characteristics of an animal influenza virus type that suggest high transmission potential to humans / Publication in Nature Communications

Although bats have long been known as reservoirs for a variety of viruses, it was only recently discovered that they also harbor influenza A viruses (IAV), which include the influenza pathogens. These viruses are known to change rapidly. Researchers at the Medical Center - University of Freiburg and the Friedrich-Loeffler Institute have now shown that a subtype of these viruses found in Egyptian fruit bats is able to overcome the immune system of mammals. The researchers therefore assume that the newly discovered virus type poses a relatively high risk of transmission to humans. The results of the study were published in the journal Nature Communications on April 25, 2024.

High ability to reproduce and transmit

"The virus manages to partially bypass an important defense mechanism of our innate immune system. This gives it a higher pandemic potential than other viruses," says research group leader Prof. Dr. Martin Schwemmle from the Institute for Virology at the Medical Center - University of Freiburg. The influenza A subtype H9N2 succeeds in particular in suppressing the antiviral activity of the so-called myxovirus resistance protein A (MxA). MxA is a human protein that plays a decisive role in defence against RNA viruses such as influenza viruses in particular by recognizing and binding the viruses and disrupting their replication.

In animal models, the virus type showed a high ability to multiply and transmit. In addition, the pathogen was able to successfully infect human lung cells. The current study results also show that the bat H9N2 virus has only a slight antigenic similarity to the components of human influenza viruses. "This means that - in the event of potential transmission to humans - there would be low immunity to the virus in the population and existing influenza vaccines might not be effective against a new H9N2-based influenza," says study leader Dr. Kevin Ciminski from the Institute for Virology at the Medical Center - University of Freiburg. The findings form an important basis for further investigations and preventive measures such as comprehensive surveillance programs in wild animal populations.

Original title of the study: "Bat-borne H9N2 influenza virus evades MxA restriction and exhibits efficient replication and transmission in ferrets"
DOI: 10.1038/s41467-024-47455-6
Link to the study:https://www.nature.com/articles/s41467-024-47455-6