Chondroitinase from baculovirus Bombyx mori nucleopolyhedrovirus and chondroitin sulfate from silkworm Bombyx mori

Abstract

Chondroitin sulfate (CS) is a linear polysaccharide composed of repeating disaccharide units of glucuronic acid (GlcUA) and N-acetyl-d-galactosamine (GalNAc) with sulfate groups at various positions. Baculovirus is an insect-pathogenic virus that infects Lepidoptera larvae. Recently, we found that the occlusion-derived virus envelope protein 66 (ODV-E66) from Autographa californica nucleopolyhedrovirus (AcMNPV) exhibits chondroitin (CH)-digesting activity with distinct substrate specificity. Here, we demonstrate that the ODV-E66 protein from Bombyx mori nucleopolyhedrovirus (BmNPV) exhibits 92% homology to the amino acid sequence and 83% of the CH lyase activity of ODV-E66 from AcMNPV. ODV-E66 cleaves glycosyl bonds at nonreducing sides of disaccharide units consisting of nonsulfated and 6-O-sulfated GalNAc residues. We then investigated CS in the silkworm, Bombyx mori, which is the host of BmNPV. CS was present in insect tissues such as the midgut, peritrophic membrane, silk gland and skin. The polysaccharide consisted of a nonsulfated disaccharide unit, mono-sulfated disaccharide at Position 4 of the GalNAc residue and mono-sulfated disaccharide at Position 6 of the GalNAc residue. With regard to immunohistochemical analysis, the staining patterns of the silkworm tissues were different among anti-CS antibodies. Chondroitn sulfate that is digestible by ODV-E66 exists sufficiently in the peritrophic membrane protecting the midgut epithelium from ingested pathogens. Our results suggest that ODV-E66 facilitates the primary infection of the virus by digestion of CS in the peritrophic membrane.

RNA-Seq Analyses for Two Silkworm Strains Reveals Insight into Their Susceptibility and Resistance to Beauveria bassiana Infection

“…We propose that the cytochrome P450, carboxylesterase, and UDP-glucuronosyltransferase function effectively in the detoxification of toxins such as cyclic peptide toxins secreted by B. bassiana , which delayed the death of the K8 strain. Besides, genes in the RIG-I-like receptor signaling pathway can initiate immune activation in a variety of cell types [44] and this pathway is related to host immune response [45,46]. A previous study showed that this pathway is enriched with positive selected genes in the silkworm, which might be a result of the selection against pathogens during silkworm domestication [47].…”

Chromosomal resolution reveals symbiotic virus colonization of parasitic wasp genomes

“…3D). In baculoviruses, odv-e66 encodes a viral chondroitinase 30 involved in digesting the peritrophic membrane lining the gut, thus allowing access to target cells during primary infection. Different ODV-E66 proteins may similarly allow BVs to cross various host barriers, and BV infection to spread to virtually all Lepidoptera tissues 31,32 .…”

Genome Sequencing of the Behavior Manipulating Virus LbFV Reveals a Possible New Virus Family

“…CSPGs are present in various insects’ tissues. In the silkworm, where its distribution has been analyzed in detail (Sugiura et al 2013), CSPGs seem to concentrate at the peritropic membrane where baculovirus infection initiates. Interestingly, it has been found that ODV-e66 has a chondroitinase activity that may facilitate infection during oral infection (Sugiura et al 2011).…”