Many thanks for the information on uracil. I will look at is with interest. I wrote this post barely believing it myself. But the more I looked the more plausible the claims of D-Salud appeared. Many of the questions I had about the formation of sense and antisense strand between the markers have now been answered by an excellent essay by Dr Lanka. I'll share it here.
I have looked for the negative control experiments in the "discovery" of all viruses. So far I haven't found any. I am starting to think that virology itself is a croc. That jars with my own beliefs. So I will keep looking for evidence.
https://davidicke.com/wp-content/uploads/2020/07/Paper-Virus-Lanka-002.pdf
Many thanks for your encouragement.