Involvement of the leader sequence in Sendai virus pathogenesis revealed by recovery of a pathogenic field isolate from cDNA.
We previously demonstrated that a systematic passage of a pathogenic field isolate of Sendai virus (SeV), the Hamamatsu strain, in embryonated eggs caused attenuation of virulence to mice, and we isolated viral clones of distinct virulence (K. Kiyotani et al. Arch. Virol. 146:893-908, 2001). One of the clones, E15cl2, which was obtained from the virus at the 15th egg passage of E0, the parental Hamamatsu clone for egg passage, had 165-fold-attenuated virulence to mice and possessed only four mutations in the entire 15,384-base genome: in an antigenomic sense, U to A at position 20 (U20A) and U to A at position 24 (U24A) in the leader sequence, the promoter for transcription and replication, and A to G at position 9346 (silent) and A to U at position 12174 (Ser to Cys) in the L gene. To examine the possibility that leader mutations affect virus pathogenesis, we recovered live viruses from cDNA derived from the Hamamatsu strain. A mutant virus possessing either a mutation of U20A or U24A in the leader sequence showed a slightly lower pathogenicity than that of the parental virus, whereas a double mutant virus possessing both of the mutations showed 25-fold-attenuated virulence, accompanying a significantly lower virus replication in the mouse lung. Replications of the leader mutant viruses were also impaired in a primary culture of mouse pulmonary epithelial cells but not in chicken embryo fibroblasts. These findings suggest that leader mutations of SeV affect virus pathogenesis by altering virus replication in a host-dependent manner.
Fujii
Yutaka
Y
Department of Virology, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima 734-8551, Japan.
Sakaguchi
Takemasa
T
Kiyotani
Katsuhiro
K
Huang
Cheng
C
Fukuhara
Noriko
N
Egi
Yoshiko
Y
Yoshida
Tetsuya
T
D020121:5' Untranslated Regions / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D002478:Cells, Cultured; D002642:Chick Embryo; D018076:DNA, Complementary / Q000235:genetics*; D004847:Epithelial Cells / Q000821:virology; D008168:Lung / Q000166:cytology / Q000821:virology; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D008969:Molecular Sequence Data; D009154:Mutation; D010253:Respirovirus Infections / Q000821:virology*; D029082:Sendai virus / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity* / Q000502:physiology; D012692:Serial Passage; D014774:Virulence; D014779:Virus Replication
D020121:5' Untranslated Regions; D018076:DNA, Complementary