In vivo and in vitro transcription of small mRNAs containing a leader sequence from mouse hepatitis virus strain JHM.

Two additional small RNAs, named mRNA8 and 9, are transcribed from mouse hepatitis virus (MHV) in virus-infected mouse DBT cells. This report shows that the small mRNAs (mRNA8 and 9) were observed at 3 hr post infection (p.i.) in DBT cells infected with the JHM strain of MHV. This result suggested that products from mRNA8 and 9 may play a role in the early stage of the viral replication cycle in the infected DBT cells. The mRNA8 is initiated from a perfectly conserved intergenic site, but mRNA9 is from an imperfectly conserved intergenic sequence. Since mRNA8 and 9 were found in the liver and brain of an infected mouse, it was suggested that the imperfect intergenic sequence of MHV may serve as an initiation site for leader-primed transcription in vivo.