Scientists report on the first synthesis of a baculovirus
Advances in synthetic biology have come to an age of whole genome synthesis. Synthetic viruses provide a powerful platform to delve deeper into the nature and function of viruses as well as to engineer viruses with novel properties. To date, most of synthesized viruses have been RNA viruses. RNA viruses normally have a limited genome size with the biggest reported so far are from coronaviruses (∼30 kb). In contrast to RNA viruses, only very few DNA viruses have been synthesized, all with a genome size less than 6 kb.
Baculoviruses are insect-specific and are being used rather widely as environmentally benign biocontrol agents against agricultural and forest insect pests. The baculoviral genome is a closed circular superhelical dsDNA of about 80−180 kb. In a present study, the research group led by Prof. HU Zhihong from Wuhan Institute of Virology of the Chinese Academy of Sciences report that the construction of a synthetic genome of the Autographa californica multiple nucleopolyhedrovirus (AcMNPV), the type species of baculoviruses, by a combination of PCR and transformation-associated recombi-nation (TAR)30 in Saccharomyces cerevisiae. Infectious progeny virus was obtained after Sf9 insect cells were transfected with the synthetic baculovirus genome. One-step growth curves and other properties showed that the synthetic virus was bio-logically very similar to the native virus.
To make sure the fidelity of the synthesized genome, the scientists first sequenced the genome of the parental virus AcMNPV-WT of their virus collection by 454 sequencing. The AcMNPV-WT genome was found to be nearly identical to AcMNPV-E2 strain31 with only 9 nts differences. Then, a synthetic AcMNPV genome was assembled from the parental sequence by a combination of PCR and TAR in 4 steps.
The new technology provides strong tool for basic study in baculovirus, and can be used to generate the even more powerful baculovirus-based expression vectors. As a significant breakthrough in large DNA virus, this study is considered as “a highly significant paper that will serve as a landmark in synthetic biology” by the peer reviewer.
The results have been published in ACS Synthetic biology entitled "Construction and Rescue of a Functional Synthetic Baculovirus ".
This work was supported by the Strategic Priority Research Program of the Chinese Academy of Sciences, grants from the National Science Foundation of China, CAS and the Virology Key Frontier Science Program of the State Key Laboratory of Virology, Wuhan Institute of Virology.
(A) Schematic presentation of the synthesis of the baculovirus. (B) Electron micrographs of OBs of AcMNPV-WIV-Syn1 andAcMNPV-WT. Image by Hu Zhihong.