cDNA cloning and molecular characterization of a cysteine-rich gene from Campoletis chlorideae polydnavirus

Polydnavirus (PDV) of Campoletis chlorideae (CcIV) is very important for the successful development of the parasitoid progenies. Previous study revealed that the persistence and expression of CcIV in parasitized Helicoverpa armigera larvae continued for 5 days, and the 1.0 kb gene (CcIV 1.0) was most abundantly expressed. In this report, a cDNA library was constructed using the SMART cDNA Synthesis Method, and the CcIV 1.0 was cloned and identified by PCR, Southern blot hybridization and 5' end amplification, this gene is 936 bp long and encodes 207 amino acids with a signal peptide and a cysteine motif. Sequence comparison shows CcIV 1.0 has high identity with VHv 1.4, VHv 1.1 genes (86%, 88%) and WHv 1.6, WHv 1.0 genes (89%, 87%) of Campoletis sonorensis PDV, which might suggest that they have arisen from a common ancestral gene; the homology between CcIV and other PDV genes is not significant.