Suppression of Penaeus merguiensis densovirus following oral delivery of live bacteria expressing dsRNA in the house cricket (Acheta domesticus) model

Penaeus merguiensis densovirus (PmergDNV) is a serious pathogen of the banana prawn, Penaeus merguiensis leading to at least 28% production loss due to reduced growth rates and mortality of juveniles. In the present study, we reduced PmergDNV titres and subsequent mortality by feeding Acheta domesticus (previously determined as an appropriate animal model for P. merguiensis) with dsRNA specific to the capsid protein by mixing it into their food. Feeding A. domesticus with PmergDNV-specific dsRNA in advance of viral challenge increased their longevity, decreased mortality by 84.4% and reduced viral loads 24-fold below the threshold level required for mortality. Mortalities and viral loads were significantly (both P < 0.001) lower in treatments challenged with PmergDNV following exposure to bacterially expressed PmergDNV-dsRNA. This is the first study to demonstrate gene silencing via RNAi against PmergDNV in vivo through oral administration of live bacteria expressing dsRNA in a model system.

Highlights► Resistance against a penaeid virus in crickets via oral delivery of bacterially expressed siRNA. ► Significantly lower mortalities in crickets exposed to bacterially expressed PmergDNV-siRNA. ► Significantly lower viral titres in crickets exposed to siRNA before challenged with PmergDNV. ► Plasmid based delivery vectors in bacteria are an effective delivery tool for crickets.