Construction and identification of chikungunya virus infectious clones

Abstract

Objective To construct chikungunya virus (CHIKV) infectious clones based on the Ross strain of the Eastern-Central-Southern African (ECSA) genotype and the LR2006 strain of the Indian Ocean lineage (IOL). Methods The genome fragments of CHIKV Ross strain and LR2006 strains were separately synthesized. The complete genomic transcriptional plasmids were constructed. The genomic RNAs were prepared by transcription and capping, and then were transfected into Vero cells. The supernatant was collected and inoculated Vero cells to amplify the viruses. The amplified viruses were used to infect the Huh7 cells to detect the viral proteins expression. Each virus at the titer of 106 PFU was intranasally inoculated five C57BL/6 mice. The body weight changes and survival of the mice were observed. Results Full-length genomic transcription plasmids of two CHIKV strains were constructed. Infectious CHIKV could be detected in the supernatant of each viral genomic RNA transfected Vero cells. The mice infected with the recovered Ross strain showed a significant decrease in body weight from 6 days after infection (P<0.05) and all died on the 11th day. Only one of the mice infected with the LR2006 strain died, and all the mice had no significant body weight loss. Conclusions The infectious clones of CHIKV Ross strain and LR2006 strain were successfully constructed, and the pathogenicity of the Ross strain was stronger than that of the LR2006 strain in C57BL/6 mice. Key words: Chikungunya virus; Ross strain; LR2006 strain; Infectious clones