ABSTRACT
Genes contained in the circular genomes of viruses such as bacteriophage T4 and SV40. Early genes are transcribed early in the viral replication cycle, and some of their products are necessary for the transcription or translation of other genes in the genome, which are termed late genes in double-stranded DNA viruses. The early genes tend to be clustered on one DNA strand and late genes on the other; transcription involves both strands, each of which is read in an opposite direction.
