Eri silkworm (Samia ricini), a non-mulberry host system for AcMNPV mediated expression of recombinant proteins

• AcMNP baculovirus replicates in Eri silkworm larvae leading to productive infection.
• Upon intrahaemocoelical inoculation of AcMNPV carrying GFP reporter gene, virus localization was evidenced in various tissues.
• Eri silkworm insect larva serves as mini biofactory as shown by the expression of FMDV protein 3ABC.
• The Eri silkworm larval system could be used as a new low cost platform for scaling up of recombinant proteins.

The baculovirus expression system (BVES) based on Autographa californica nucleopolyhedrovirus (AcMNPV) is widely used for the expression of eukaryotic proteins. Several insect cells/larvae that are permissive to AcMNPV have been routinely used as hosts to express heterologous proteins. Domesticated Eri silkworm (Samia ricini), reared in many parts of India, Japan and China, is a non-mulberry silkworm. The present study shows that the Eri silkworm larvae are susceptible to intra-haemocoelical inoculation of AcMNPV. The virus replicates in the larva, as indicated by an increased viral loads in the haemolymph upon injection of a recombinant AcMNPV carrying green fluorescent protein gene. The virus showed localized replication in different tissues including the fat body, haemocytes, tracheal matrix and in the Malphigian tubules. The larval system was successfully used to express heterologous protein, by infecting with a recombinant AcMNPV carrying the 3ABC coding sequence of foot-and-mouth disease virus (FMDV). The study shows that the Eri silkworm larva can be a potential alternative bioreactor, for scaling up of the recombinant proteins employing the baculovirus system.