Resistance to Bombyx mori nucleopolyhedrovirus via overexpression of an endogenous antiviral gene in transgenic silkworms

Abstract

Transgenic technology is a powerful tool for improving disease-resistant species. Bmlipase-1, purified from the midgut juice of Bombyx mori, showed strong antiviral activity against B. mori nucleopolyhedrovirus (BmNPV). In an attempt to create an antiviral silkworm strain for sericulture, a transgenic vector overexpressing the Bmlipase-1 gene was constructed under the control of a baculoviral immediate early-1 (IE1) promoter. Transgenic lines were generated via embryo microinjection. The mRNA level of Bmlipase-1 in the midguts of the transgenic line was 27.3 % higher than that of the non-transgenic line. After feeding the silkworm with different amounts of BmNPV, the mortality of the transgenic line decreased to approximately 33 % compared with the non-transgenic line when the virus dose was 10(6) OB/larva. These results imply that overexpressing endogenous antiviral genes can enhance the antiviral resistance of silkworms.

Comparative proteomic analysis of hemolymph proteins from Autographa californica multiple nucleopolyhedrovirus (AcMNPV)-sensitive or -resistant silkworm strains during infections

“…In the case of NPVs, no RNAi pathway proteins from Lepidopteran insects have been reported as suppressors limiting viral replications. Interestingly, emerging research shows that potential host factors are also involved in recognition/replication of NPVs (Terenius, 2008;Kang et al, 2011;Jiang et al, 2012;Lü et al, 2013;Turkki et al, 2013;Makkonen et al, 2013;Jin et al, 2014). However, factors affecting host cell permissiveness to BV infection/transduction remain largely unknown.…”

Screening and optimization of an efficient Bombyx mori nucleopolyhedrovirus inducible promoter

“…Transgenic technology, including RNA interference silencing of essential baculovirus genes such as immediate early-1 (ie-1), late expression factor-1 (lef-1), gp64; and overexpression of resistance genes, such as Bmlipase-1, and hycu-ep32 (Isobe et al, 2004;Jiang et al, 2012b;Kanginakudru et al, 2007;Ponnuvel et al, 2003;Zhang et al, 2014b;Zhang et al, 2014c), is one of the most important methods for curbing silkworm disease. However, studies of silkworm antivirals have been plagued by problems such as inefficient promoter thus poor expression of exogenous proteins and host toxicity in stable expression studies.…”

“…Currently, RNA interference (RNAi) and gene overexpression are extremely important fields for breeding of BmNPV-resistant strains (Jiang et al, 2012b;Kanginakudru et al, 2007;Zhang et al, 2014b;Zhang et al, 2014c). Unfortunately, currently available promoters for long-term expression of exogenous protein or RNA are not efficient and result in high toxicity for the host.…”

Engineering Silkworms for Resistance to Baculovirus Through Multigene RNA Interference

“…Recently, Jiang et al (2012) revealed an anti-BmNPV activity in the gut juice of transgenic silkworm that could be enhanced by 33% by overexpressing the Bmlipase-1 which is shown to have antiviral activity. Modifying the host gene could help developing control strategies, but, at the moment, the effects are measurable only at sublethal doses of virus.…”