NUNZIUM

Each year, about 5 million people are hospitalized with influenza A worldwide. Another common virus, the Respiratory Syncytial Virus (RSV), is the leading cause of acute infections of the lower respiratory tract in children under five years old. It can spread to the lower respiratory tract, causing pneumonia or bronchiolitis - an inflammation of the small airway passages entering the lungs. Although co-infection is common, it was still unclear how these viruses would respond if they are together in the same cell. A recent study published in Nature Microbiology - led by Prof. Pablo Murcia from the University of Glasgow - showed that the two viruses, rather than competing with one another, can fuse to form a hybrid virus: a more potent and new type of pathogen. Whereas influenza usually infects cells in the nose, RSV tends to go lower down into the respiratory tract reaching the lung cells. The possibility of forming a hybrid may increase the chances of triggering severe lung infections. The study has shown that once formed, the hybrid can infect neighboring cells even in presence of neutralizing antibodies against influenza - which would normally block the infection. A likely explanation is that, although the antibodies still attack the hybrid’s surface, the RSV viral proteins are used as a Trojan horse to resist the attack and penetrate the cells. It is the very first time that such cooperation between two common respiratory viruses has been observed. Researchers believe that these findings could explain why co-infections can lead to significantly worse diseases in some patients, including hard-to-treat viral pneumonia.