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A viral histone H4 suppresses expression of a transferrin that plays a role in the immune response of the diamondback moth, Plutella xylostella
Author(s) -
Kim J.,
Kim Y.
Publication year - 2010
Publication title -
insect molecular biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.955
H-Index - 93
eISSN - 1365-2583
pISSN - 0962-1075
DOI - 10.1111/j.1365-2583.2010.01014.x
Subject(s) - biology , diamondback moth , plutella , gene expression , spodoptera , microbiology and biotechnology , bacillus thuringiensis , gene , botany , biochemistry , genetics , larva , bacteria , recombinant dna
A transferrin ( Tf ) gene has been predicted from an expressed sequence tag of the diamondback moth, Plutella xylostella . It encodes 681 amino acid residues that share 80–90% sequence homologies with other lepidopteran Tf s. The gene was constitutively expressed in all developmental stages of P. xylostella . Double‐stranded RNA (dsRNA) specific to the Tf gene was prepared and microinjected into the larvae. We hypothesize that the dsRNA treatment suppressed the Tf gene expression level and it significantly inhibited haemocyte nodule formation in response to bacterial challenge. The larvae treated with dsRNA also showed a significantly enhanced susceptibility to an entomopathogenic bacterium, Bacillus thuringiensis . An endoparasitoid wasp, Cotesia plutellae , parasitized the larvae of P. xylostella , which showed significant reduction of Tf expression. The suppression of Tf expression was mimicked by transient expression of a viral gene CpBV‐H4 , encoded in the symbiotic virus of C . plutellae . A truncated form of CpBV‐H4 prepared by deleting an extended N‐terminal 38 amino acid residue lost its inhibitory activity against the Tf gene expression. These results suggest that Tf of P. xylostella plays an immunological role in P. xylostella and that the suppression of its expression in the parasitized larvae is caused by a viral histone H4 in an epigenetic mode.