– Cysteine protease that plays an essential role in host liquefaction to facilitate horizontal transmission of the virus. May participate in the degradation of foreign protein expressed by the baculovirus system. ApNPV Viral cathepsin Protein (His & Myc) is expressed in E. coli expression system with N-10xHis and C-Myc tag. The predicted molecular weight is 31.1 kDa and the accession number is Q91CL9.