text: Yo, listen up, I got a tale to tell,
  'Bout them H7 avian influenza viruses from hell.
  They be causin' infections in humans, no doubt,
  Showin' us the potential for a pandemic to sprout.
  
  But hold up, we still ain't got all the facts,
  Tryna understand what makes 'em thrive in mammals' tracks.
  So we took a reassortant H7N1 virus, you see,
  And made mouse-adapted variants to set the truth free.
  
  Them lethal doses in mice got reduced real quick,
  More than 10,000 times, that's the trick.
  Them adapted variants, they got that speed,
  Replicatin' like crazy, fulfillin' their greed.
  
  In the lab and in vivo, they were goin' strong,
  Spreadin' through multiple organs, that's how they belong.
  We checked them genomes, and what did we find?
  Amino acid changes, the key to their design.
  
  PB2 got that E627K, a switch in the game,
  HA with E114K, G205E, and G218E, nothin' the same.
  NA got that S350N, makin' moves,
  These changes in the proteins, they got the groove.
  
  And yo, here's the kicker, pay attention now,
  Some of these amino acids were found in H7 isolates, wow!
  Our results show how they team up, no joke,
  Boostin' that wild bird-origin H7N1 to make mice choke.
  
  So now we know, it's a tale complete,
  With amino acid substitutions, it's the ultimate feat.
  Them H7 AIVs, they ain't playin' nice,
  Ready to replicate, cause disease, rollin' the dice.