Differences in the control of virus mRNA splicing during permissive or abortive infection with influenza A (fowl plague) virus.

Spliced transcripts of influenza A (fowl plague) virus (FPV) RNA (vRNA) segments 7 and 8 accumulate to a much greater extent during non-productive infection of mouse L cells, than they do during productive infection in primary chick embryo fibroblasts (CEF). Virus-specific protein synthesis, or a consequent event in virus replication appears necessary to promote splicing of vRNA segment 8-encoded mRNAs in both cell types, and of vRNA segment 7-encoded mRNAs in CEF. In L cells, however, splicing of the segment 7-encoded mRNAs seems to be independent of such virus-specific control. This observation is discussed in relation to the defect in expression of vRNA 7 which has been observed previously in FPV-infected L cells, and which is thought to account for the failure of virus replication.