That's nice, but if you really want to know what viruses are what their purpose is, you have to look into what it does inside the cell that causes the cell to rupture and die. That's the real heavy science to comprehend. You'll scratch your head and say "why" ? Everything points to the DNA, that's why. When the DNA makes mRNA where'd you think the amino acids ACTG came from ? The DNA certainly didn't use its own ACTG to make the mRNA; if it did, at 50,000 times a day, the DNA wouldn't exist after 24 hours ! So, Come On ! Think ! It's not hard to figure out ? It's the reason why Viruses have receptors on them in the First Place !