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Updated: Aug 14, 2025

Bacterial Artificial Chromosomes: A Functional Genomics Tool for the Study of Positive-strand RNA Viruses
Published on: December 29, 2015
Accidental acquisition of a rescued Japanese encephalitis virus with unspliced introns in the viral genome when using
Ying Huang1, Hongshan Xu2, Shan Liu3
1Laboratory of Protein Engineering, Beijing Institute of Biotechnology, Beijing, 100071, People's Republic of China.
Abstract:
The intron-based stabilization approach is a very useful strategy for construction of stable flavivirus infectious clones. SA14-14-2 is a highly attenuated Japanese encephalitis (JE) live vaccine strain that has been widely used in China since 1989. To develop safe and effective recombinant vaccines with SA14-14-2 as a backbone vector, we constructed the DNA-based infectious clone pCMW-JEV of SA14-14-2 using the intron-based stabilization approach and acquired the rescued virus rDJEV, which retained the biological properties of the parental virus. Unexpectedly, a rescued virus strain with altered virulence, designated rHV-DJEV, was accidentally acquired in one of the transfection experiments. rHV-DJEV showed up to 105-fold increased neurovirulence compared with the SA14-14-2 parental strain. Genome sequencing showed that the inserted introns were still present in the genome of rHV-DJEV. Therefore, we think that the intron-based stabilization approach should be used with caution in vaccine development and direct iDNA immunization.
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