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The paramyxovirus, Sendai virus, V protein encodes a luxury function required for viral pathogenesis

Atsushi Kato, Katsuhiro Kiyotani, Yuko Sakai, Tetsuya Yoshida, Yoshiyuki Nagai

Author Affiliations

  1. BIO FROM CONTRIB-GROUP Atsushi Kato1,
  2. BIO FROM CONTRIB-GROUP Katsuhiro Kiyotani2,
  3. BIO FROM CONTRIB-GROUP Yuko Sakai1,
  4. BIO FROM CONTRIB-GROUP Tetsuya Yoshida2 and
  5. BIO FROM CONTRIB-GROUP Yoshiyuki Nagai1
  1. 1 Department of Viral Infection, Institute of Medical Science, University of Tokyo, Minato‐ku, Tokyo, 108, Japan
  2. 2 Department of Bacteriology, Hiroshima University School of Medicine, Hiroshima, 734, Japan

Abstract

The Sendai virus (SeV) V protein is characterized by the unique cysteine‐rich domain in its carboxy‐terminal half which is fused to the amino‐terminal half of the P protein, but its function has remained enigmatic. The V protein‐directing mRNA is generated by a remarkable process known as mRNA editing involving the pseudotemplated addition of a single G residue at a specific septinucleotide locus in the P gene, whereas the unedited exact copy encodes the P protein. Here, we introduced two nucleotide changes in the septinucleotide motif (UUUUCCC to UUCUUCC) in a full‐length SeV cDNA and were able to recover a virus from the cDNA, which was devoid of mRNA editing and hence unable to synthesize the V protein. Compared with the parental wild‐type virus with regard to gene expression, replication and cytopathogenicity in various cell lines in vitro, the V(−) virus was found to be either potentiated or comparable but never attenuated. The V(−) virus, however, showed markedly attenuated in vivo replication capacity in and pathogenicity for mice. Thus, though categorized as a non‐essential gene product, SeV V protein encodes a luxury function required for in vivo pathogenicity.

  • Received September 10, 1996.
  • Revision received October 7, 1996.