ABSTRACT
Objective@#To construct a stable infectious clone of live attenuated dengue virus (DENV) type 4 Ban18HK20 strain for better understanding the virulence determinants of DENV and improving the development of chimeric vaccines.@*Methods@#Specific primers were constructed according to the genome of Ban18HK20 strain and used to subclone six cDNA fragments, which were linked into a high-copy plasmid pSPTM to obtain a stable full-length cDNA clone of DENV. RNA was transcribed from the full-length cDNA in vitro and electrotransfected into Vero cells to recover the virus. Biological characteristics of the recovered virus were identified using plaque assay, indirect immunofluorescence assay, growth kinetics test and pathogenicity study in mouse brain. Genetic stability of the virus passaged 15 generations was studied using RT-PCR amplification.@*Results@#Restriction enzyme digestion and sequencing analysis indicated that the infectious clone was constructed successfully. The recovered virus was consistent with the parental virus in terms of plaque morphology, DENV E protein expression, growth characteristics and pathogenicity in mouse brain. Sequencing analysis showed that the recovered virus had the same genome sequence as the parental virus with good hereditary stability.@*Conclusions@#A stable infection clone of Ban18HK20 was constructed and a reverse genetics technology platform for DENV research was established.