Protein synthesis in pupae of the silkworm Bombyx mori after infection with nuclear polyhedrosis virus: resistance to viral infection acquired during pupal period

Abstract

Protein synthesis has been studied in pupae of the silkworm Bombyx mori (Bm) infected with nuclear polyhedrosis virus (BmNPV) at various stages of the pupal period. Nascent proteins were labelled by injection of [3sS]methionine into pupae and then analysed by SDS-PAGE. Temporal regulation of synthesis of infected cell-specific proteins (ICSPs) in pupae was demonstrated by electrophoretic analysis of the proteins labelled at different times post-infection (p.i.). The rate of ICSP synthesis reached a maximum at 4 to 5 days p.i., exceeding the rate of synthesis of cellular proteins in uninfected pupae by about twofold. The viral proteins pl0 and polyhedrin were the most abundant products synthesized late in the infection. Both proteins were found to be associated with the nuclear matrix after fractionation of nuclei from infected pupae. Two virus-induced phosphoproteins, pp35 and ppB, were found to be the major acceptors of labelled phosphate from [~-32p]ATP during in vitro phosphorylation of proteins in pupal homogenates, nuclei and nuclear extracts. These proteins had electrophoretic mobilities comparable to those of structural phosphoproteins of BmNPV virions with Mrs of 35K and 11K to 16K, respectively. The latter polypeptide was identified as the major DNA-binding protein of the virus. The susceptibility of silkworms to BmNPV decreased markedly during the pupal period. Following injection of BmNPV all young pupae acquired polyhedrosis and finally died whereas most of the older pupae did not exhibit disease and completed metamorphosis normally. Moreover, the later in the pupal period the silkworms were infected, the lower the production of polyhedrin in diseased pupae.

Effects of oral recombinant VP28 expressed in silkworm (Bombyx mori) pupa on immune response and disease resistance of Procambarus clarkii

“…Compared with silkworm larvae or insect cells, silkworm pupae are more convenient and economical to be a carrier to efficiently produce large quantities of heterologous proteins Mikhailov et al 1992;Motohashi et al 2005;Wang et al 2005). Experiments demonstrated that the pupae, being non-toxic and highly nutritious Per Se, can be regarded as a top class unconventional protein and energy feed and utilized directly for poultry and fisheries (Khatun et al 2005;Rangacharyulu et al 2003).…”

Glycosyltransferases encoded by viruses

“…There are several benefits to baculoviruses that encode an EGT. Ecdysteroids induce physiological modifications that decrease insect permissivity to baculovirus infection (O'Reilly et al, 1995(O'Reilly et al, , 1998; by altering these hormones, baculoviruses prevent the developmental resistance to virus replication observed in caterpillars (Keeley & Vinson, 1975;Murray et al, 1991;Mikhailov et al, 1992;Engelhard & Volkman, 1995;Washburn et al, 2001). Moults and pupation monopolize important insect biological resources and are associated with an arrest of food ingestion Flipsen et al, 1995;Shikata et al, 1998;Slavicek et al, 1999;Bianchi et al, 2000;Chen et al, 2000;Dai et al, 2000;Wilson et al, 2000;Sun et al, 2002).…”

Pro‐apoptotic protein kinase Cδ is associated with intranuclear inclusions in a transgenic model of Huntington's disease

“…Cell nuclei were isolated from mouse brains according to the procedure described by Mikhailov et al . (1992).…”

“…Cell nuclei were isolated from mouse brains according to the procedure described by Mikhailov et al (1992). Briefly, mouse brains were homogenized on ice in Buffer A (50 mM Tris-HCl, pH 7.5; 10 mM KCl; 10 mM MgCl 2 ; 1 mM CaCl 2 ; 2 mM dithiothreitol; 0.3 M sucrose) (1 brain/4 mL) with a Dounce homogenizer (20 strokes with loose-fitting pestle and 10 strokes with tight-fitting pestle).…”