Deletion of a gene encoding an amino acid transporter in the midgut membrane causes resistance to a Bombyx parvo-like virus.
Bombyx mori densovirus type 2 (BmDNV-2), a parvo-like virus, replicates only in midgut columnar cells and causes fatal disease. The resistance expressed in some silkworm strains against the virus is determined by a single gene, nsd-2, which is characterized as nonsusceptibility irrespective of the viral dose. However, the responsible gene has been unknown. We isolated the nsd-2 gene by positional cloning. The virus resistance is caused by a 6-kb deletion in the ORF of a gene encoding a 12-pass transmembrane protein, a member of an amino acid transporter family, and expressed only in midgut. Germ-line transformation with a wild-type transgene expressed in the midgut restores susceptibility, showing that the defective membrane protein is responsible for resistance. Cumulatively, our data show that the membrane protein is a functional receptor for BmDNV-2. This is a previously undescribed report of positional cloning of a mutant gene in Bombyx and isolation of an absolute virus resistance gene in insects.
Ito
Katsuhiko
K
Division of Insect Sciences, National Institute of Agrobiological Sciences, 1-2 Owashi, Tsukuba, Ibaraki 305-8634, Japan.
Kidokoro
Kurako
K
Sezutsu
Hideki
H
Nohata
Junko
J
Yamamoto
Kimiko
K
Kobayashi
Isao
I
Uchino
Keiro
K
Kalyebi
Andrew
A
Eguchi
Ryokitsu
R
Hara
Wajiro
W
Tamura
Toshiki
T
Katsuma
Susumu
S
Shimada
Toru
T
Mita
Kazuei
K
Kadono-Okuda
Keiko
K
D026905:Amino Acid Transport Systems / Q000737:chemistry / Q000235:genetics*; D000818:Animals; D001483:Base Sequence; D012831:Bombyx / Q000235:genetics* / Q000821:virology*; D016386:Chromosome Walking; D017990:Densovirus / Q000502:physiology*; D017353:Gene Deletion; D019476:Insect Proteins / Q000737:chemistry / Q000235:genetics*; D007422:Intestines / Q000821:virology; D008566:Membranes / Q000821:virology; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D011991:Receptors, Virus / Q000737:chemistry / Q000235:genetics*; D017422:Sequence Analysis, DNA
D026905:Amino Acid Transport Systems; D019476:Insect Proteins; D011991:Receptors, Virus