Inhibition of the accumulation of virus-specific translatable mRNA and structural polypeptides by guanidine hydrochloride in the midgut of the silkworm, Bombyx mori, infected with infectious flacherie virus
Choi, H.K.bayashi, M.K.wase, S.
Journal of invertebrate pathology 53(3): 392-400
ISSN/ISBN: 0022-2011 DOI: 10.1016/0022-2011(89)90105-5
Effect of guanidine hydrochloride (GH) on the accumulation of translatable mRNA and structural polypeptides of the virus was investigated in the larval midgut of the silkworm, Bombyx mori, infected with infectious flacherie virus (IFV). When GH was ingested continuously by the IFV-infected larvae from the beginning of virus infection, the accumulation of both the viral translatable mRNA and its structural polypeptides was inhibited. The inhibition, however, ended shortly after the cessation of GH ingestion as a result of molting or maturation of IFV-infected larvae. The fact indicates that the inhibitory effect of GH was reversible. Upon reversal of GH treatment, appearance of viral translatable mRNA in the IFV-infected midgut preceded that of viral structural polypeptides by 12 to 24 hr, suggesting the inhibitory effect of GH on accumulation of viral structural polypeptides is secondary to that on translatable mRNA. In an experiment using newly ecdysed fifth instar larvae, it was found that IFV inoculated per os was able to persist in the GH-treated midgut for a significant peroid of time in a state capable of completing its multiplication cycle upon removal of GH treatment. This excludes the possibility that GH acted to inhibit the step of adsorption and/or internalization of the virus inoculated. Thus, our data suggest that the inhibition of IFV multiplication occurs at either the translation of input genomic RNA or the synthesis of virus-specific negative- or positive-stranded RNA.