Intermediate class of mRNAs in African swine fever virus.

A transcriptional analysis of the African swine fever virus (ASFV) I226R and I243L genes is presented. Steady-state kinetics and transfection experiments showed the existence of a new temporal class of ASFV mRNAs transcribed from these genes, with the characteristics of the poxvirus intermediate transcripts. Transcription of the I226R gene gave rise to intermediate and late mRNAs that started from different sites, while the I243L gene produced early, intermediate, and late mRNAs, also starting from different sites. The presence of intermediate genes suggests a cascade model for the regulation of ASFV gene expression.