ATTAAAGGTT TATACCTTCC CAGGTAACAA ACCAACCAAC TTTCGAT... is part of the 5'UTR of genome of an RNA virus SARS-Cov-2.
RNA contains letters C+G+A+U.
DNA contains letters C+G+A+T.
Why are there letters T, in the SARS-Cov-2 genome, instead of U?