Flavivirus genome recoding by codon optimisation confers genetically stable in vivo attenuation in both mice and mosquitoes.

Autor: Chin, Wei-Xin, Kong, Hao Yuin, Zhu, Isabelle Xin Yu, Teo, Zi Yun, Faruk, Regina, Lee, Regina Ching Hua, Ho, Si Xian, Aw, Zhen Qin, Yi, Bowen, Hou, Xin Jun, Tan, Antson Kiat Yee, Yogarajah, Thinesshwary, Huber, Roland G., Cai, Yu, Wan, Yue, Chu, Justin Jang Hann
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Zdroj: PLoS Pathogens; 10/26/2023, Vol. 19 Issue 10, p1-28, 28p
Abstrakt: Virus genome recoding is an attenuation method that confers genetically stable attenuation by rewriting a virus genome with numerous silent mutations. Prior flavivirus genome recoding attempts utilised codon deoptimisation approaches. However, these codon deoptimisation approaches act in a species dependent manner and were unable to confer flavivirus attenuation in mosquito cells or in mosquito animal models. To overcome these limitations, we performed flavivirus genome recoding using the contrary approach of codon optimisation. The genomes of flaviviruses such as dengue virus type 2 (DENV2) and Zika virus (ZIKV) contain functional RNA elements that regulate viral replication. We hypothesised that flavivirus genome recoding by codon optimisation would introduce silent mutations that disrupt these RNA elements, leading to decreased replication efficiency and attenuation. We chose DENV2 and ZIKV as representative flaviviruses and recoded them by codon optimising their genomes for human expression. Our study confirms that this recoding approach of codon optimisation does translate into reduced replication efficiency in mammalian, human, and mosquito cells as well as in vivo attenuation in both mice and mosquitoes. In silico modelling and RNA SHAPE analysis confirmed that DENV2 recoding resulted in the extensive disruption of genomic structural elements. Serial passaging of recoded DENV2 resulted in the emergence of rescue or adaptation mutations, but no reversion mutations. These rescue mutations were unable to rescue the delayed replication kinetics and in vivo attenuation of recoded DENV2, demonstrating that recoding confers genetically stable attenuation. Therefore, our recoding approach is a reliable attenuation method with potential applications for developing flavivirus vaccines. Author summary: The mosquito-borne flaviviruses such as dengue virus (DENV) and Zika virus (ZIKV) have established themselves as major human pathogens. Live attenuated vaccines are seen as the most effective method for preventing flavivirus infection. Flavivirus genome recoding has emerged as a next-generation vaccine development method that acts by rewriting the flavivirus genome. Previous flavivirus genome recoding attempts were based on deoptimising the flavivirus genome. However, these deoptimised flaviviruses were found to be attenuated in a species dependent manner. For example, deoptimised DENV and ZIKV did not demonstrate attenuation in mosquito cells or mosquito animal models, which is undesirable because these mosquito-borne flaviviruses should be attenuated in their mosquito vector to prevent vaccine escape. To overcome these limitations, we adopted a flavivirus genome recoding approach based on the contrary approach of optimising the flavivirus genome and applied it to DENV2 and ZIKV. We found that this genome recoding approach of codon optimisation could confer attenuation in both mouse and mosquito animal models. This indicates that our flavivirus genome recoding approach may be used as a reliable method to construct attenuated vaccine backbones for the mosquito-borne-flaviviruses in general. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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