An article in Nature Microbiology describes how a coinfection of influenza A and RSV can create never before seen hybrid virus particles.
To identify and characterize virus–virus interactions at the cellular level, we coinfected human lung cells with influenza
A virus (IAV) and respiratory syncytial virus (RSV). Super-resolution microscopy, live-cell imaging, scanning electron microscopy and cryo-electron tomography revealed extracellular and membrane-associated filamentous structures consistent with hybrid viral particles (HVPs).
We found that HVPs harbour surface glycoproteins and ribonucleoproteins of IAV and RSV. HVPs use the RSV fusion glycoprotein to evade anti-IAV neutralizing antibodies and infect and spread among cells lacking IAV receptors.
Finally, we show that IAV and RSV coinfection in primary cells of the bronchial epithelium results in viral proteins from both viruses co-localizing at the apical cell surface. Our observations define a previously unknown interaction between respiratory viruses that might affect virus pathogenesis by expanding virus tropism and enabling immune evasion.
“This kind of hybrid virus has never been described before,” said Prof Pablo Murcia, who supervised the research, published in Nature Microbiology. “We are talking about viruses from two completely different families combining together with the genomes and the external proteins of both viruses. It is a new type of virus pathogen.”
Once formed, the hybrid virus was also able to infect neighbouring cells – even in the presence of antibodies against influenza that would usually block infection. Although the antibodies still stuck to influenza proteins on the hybrid virus’s surface, the virus merely used neighbouring RSV proteins to infect lung cells instead. Murcia said: “Influenza is using hybrid viral particles as a Trojan horse.”
