Role of Filamentous Virion Morphology during Influenza Virus Infection

Influenza A virus is a very important pathogen as it can cause both health and economic burden around the world. It causes annual epidemics and occasional pandemics. IAV is a negative sensed enveloped RNA virus. Influenza is pleomorphic in nature, meaning it can form different morphologies, mainly spherical and filamentous. Filamentous viruses are well documented, but how and why they form is still not known. However, it is known that filamentous viruses enter host cells by macropinocytosis, while spherical viruses mostly enter by clathrin mediated endocytosis (Rossman et al., 2012).

Influenza virus uses clathrin mediated endocytosis and macropinocytosis to enter host cells. When both the pathways are blocked it was thought that infection should decrease. However, it was noticed that blocking clathrin mediated endocytosis and micropinocytosis increases infectivity of spherical viruses. We are proposing that IAV can enter cells by a third pathway.

Understanding the morphology of filaments is a complex process. This study looked at filamentous virion's infectivity through cellular entry and the effects of host's innate immunity.