For the first time, researchers have observed that respiratory syncytial virus and influenza viruses can merge to create a hybrid virus capable of evading the immune system, according to findings published Oct. 24 in Nature Microbiology.
To conduct the study, researchers from the University of Glasgow in Scotland coinfected human lung cells with influenza A virus and RSV. The viruses fused together, rather than competing with one another as some other viruses are known to do in a coinfection, researchers told The Guardian.
"This type of hybrid virus has never been described before," Dr. Pablo Murcia, one of the study authors and professor of integrative virology at the University of Glasgow, told the news outlet. "We are talking about viruses from two completely different families combining with the genomes and the external proteins of both viruses. It is a new type of virus pathogen."
Researchers also found the hybrid virus was able to infect neighboring cells, even in the presence of flu antibodies expected to block infection. Instead, the hybrid virus used neighboring RSV proteins to infect lung cells. "Influenza is using hybrid viral particles as a Trojan horse," Dr. Murcia said.
Coinfections are thought to be relatively common, although it's been unclear how viruses would respond if they infect the same cell.
Next, researchers are working to confirm whether hybrid viruses can form in patients with coinfections and which combinations enable the capability.
"We need to know if this happens only with influenza and RSV, or does it extend to other virus combinations as well," Dr. Murcia told the Guardian. "My guess is that it does. And, I would hypothesize that it extends to animal [viruses] as well. This is just the start of what I think will be a long journey of hopefully very interesting discoveries."