Over 200 viruses cause influenza and influenza-like illness which produce the same symptoms (fever, headache, aches and pains, cough and runny noses). Without laboratory tests, doctors cannot tell the two illnesses apart. Both last for days and rarely lead to death or serious illness. At best, vaccines might be effective against only Influenza A and B, which represent about 10% of all circulating viruses.” (Source: Cochrane Summaries).” [emphasis added]
Viruses use virions to spread between hosts, and virion composition is therefore the primary determinant of viral transmissibility and immunogenicity.” [emphasis added]
However, the virions of many viruses are complex and pleomorphic, making them difficult to analyze in detail”
Here we address this by identifying and quantifying viral proteins with mass spectrometry, producing a complete and quantifiable model of the hundreds of viral and host-encoded proteins that make up the pleomorphic virions of influenza virus. We show that a conserved influenza virion architecture, which includes substantial quantities of host proteins as well as the viral protein NSI, is elaborated with abundant host-dependent features. As a result, influenza virions produced by mammalian and avian hosts have distinct protein compositions.”
Finally, we note that influenza virions share an underlying protein composition with exosomes, suggesting that influenza virions form by subverting micro vesicle” production.