Novel macula-like virus identified in Bombyx mori cultured cells.
We identified a novel, 6,513-bp-long RNA, termed Bombyx mori macula-like latent virus (BmMLV) RNA, which abundantly expressed in B. mori cultured BmN cells. BmMLV RNA potentially encodes two proteins, putative RNA replicase and coat protein, which share structural features and sequence similarities with those of a plant RNA virus, the genus Maculavirus. Northern blot analysis showed that two transcripts were expressed in BmN cells: a 6.5-kb-long RNA, which contains both putative RNA replicase and coat protein genes, and a 1.2-kb-long RNA, which contains only a coat protein gene. Southern blot analysis showed that BmMLV RNA is not carried by the B. mori genome. RT-PCR analysis also revealed the presence of BmMLV RNA in several B. mori cell lines other than BmN cells, suggesting that BmMLV RNA latently exists in B. mori cultured cells. Infection studies showed that BmMLV virions were able to infect BmMLV-negative Spodoptera frugiperda Sf-9 cells and B. mori larvae. Electron microscopy and Northern blot analysis of a purified BmMLV revealed that isometric virions appear to be 28 to 30 nm in diameter and contain a 6.5-kb genomic RNA. These results showed that BmMLV is a novel macula-like virus infectious to and replicable in B. mori-derived cells.
Katsuma
Susumu
S
Department of Agricultural and Environmental Biology, Graduate School of Agricultural and Life Sciences, University of Tokyo, Yayoi 1-1-1, Bunkyo-ku, Tokyo 113-8657, Japan.
Tanaka
Shinichiro
S
Omuro
Naoko
N
Takabuchi
Lisa
L
Daimon
Takaaki
T
Imanishi
Shigeo
S
Yamashita
Shuichi
S
Iwanaga
Masashi
M
Mita
Kazuei
K
Maeda
Susumu
S
Kobayashi
Masahiko
M
Shimada
Toru
T
D000595:Amino Acid Sequence; D000818:Animals; D012831:Bombyx / Q000254:growth & development / Q000821:virology*; D036022:Capsid Proteins / Q000235:genetics; D002478:Cells, Cultured; D005260:Female; D007814:Larva; D008297:Male; D008969:Molecular Sequence Data; D010802:Phylogeny; D012367:RNA, Viral / Q000235:genetics; D012324:RNA-Dependent RNA Polymerase / Q000235:genetics; D016415:Sequence Alignment; D046830:Tymoviridae / Q000235:genetics / Q000302:isolation & purification*
D036022:Capsid Proteins; D012367:RNA, Viral; D012324:RNA-Dependent RNA Polymerase