Identification of the 3C-protease-mediated 2A/2B and 2B/2C cleavage sites in the nonstructural polyprotein precursor of a dicistrovirus lacking the NPGP motif

Dicistroviruses have motifs for picornavirus 2C, 3C, and 3D proteins in their nonstructural polyprotein C-terminal region. The proteins from the nonstructural, N-terminal region of the polyprotein remain to be characterized. We have identified 3C-mediated cleavage sites in the N-terminal region of the nonstructural polyprotein of the dicistrovirus Plautia stali intestine virus (PSIV). The 2B/2C cleavage site mapped to amino acids (aa) 408-409 (QD). 2B/2C cleavage sites were suggested to be conserved in dicistroviruses. The most N-terminal PSIV cleavage site was aa 286-287 (QS). Including previous results, the polyprotein contains nine proteins arranged as follows: 2A, 2B, 2C, 3A, 3B1, 3B2, 3B3, 3C, and 3D.