Role of primary constitutive phosphorylation of Sendai virus P and V proteins in viral replication and pathogenesis

Functional analysis of the primary constitutive phosphorylation of Sendai v irus P and V proteins was performed using both in vitro and in vivo systems . Sendai virus minigenome transcription and replication in transfected cell s were not significantly affected in the presence of primary phosphorylatio n deficient P protein (S249A, S249D, P250A) as measured by either the lucif erase activity or the Northern blot analysis. Similarly, recombinant Sendai viruses lacking the primary phosphorylation in P grew to titers close to t he wild-type virus in cell cultures and in the natural host of Sendai virus , the mouse. Mutant viruses showed no altered pathogenesis in mice lungs. O ligomerization of P by binding WT P or mutant P to GST-P (WT) Sepharose bea ds revealed that the primary phosphorylation was not crucial for P protein oligomerization. Similar to P protein primary phosphorylation, the V protei n primary phosphorylation at serine249 was not essential for minigenome tra nscription and replication, as both WT and mutant V proteins were found equ ally inhibitory to the minigenome replication. These results show that the primary phosphorylation of P protein has no essential role in Sendai virus transcription, replication, and pathogenesis. (C) 1999 Academic Press.