CRISPR/Cpf1 mediated genome editing enhancesBombyx moriresistance to BmNPV

Abstract

18CRISPR/Cas12a (Cpf1) is a single RNA-guided endonuclease that provides new 19 opportunities for targeted genome engineering through the CRISPR/Cas9 system. Only 20 AsCpf1 have been developed for insect genome editing, and the novel Cas12a orthologs 21 nucleases and editing efficiency require more study in insect. We compared three 22 Cas12a orthologs nucleases, AsCpf1, FnCpf1, and LbCpf1, for their editing efficiencies 23 and antiviral abilities in vitro. The three Cpf1 efficiently edited the BmNPV genome 24 and inhibited BmNPV replication in BmN-SWU1 cells. The antiviral ability of the 25 FnCpf1 system was more efficient than the SpCas9 system after infection by BmNPV. 26 We created FnCpf1×gIE1 and SpCas9×sgIE1 transgenic hybrid lines and evaluated the 27 gene editing efficiency of different systems at the same target site. We improved the 28 antiviral ability using the FnCpf1 system in transgenic silkworm. This study 29 demonstrated use of the CRISPR/Cpf1 system to achieve high editing efficiencies in 30 the silkworm, and illustrates the use of this technology for increasing disease resistance. 31Genome editing is a powerful tool that has been widely used in gene function, gene 36 therapy, pest control, and disease-resistant engineering in most parts of pathogens 37 research. Since the establishment of CRISPR/Cas9, powerful strategies for antiviral 38 therapy of transgenic silkworm have emerged. Nevertheless, there is still room to 39 expand the scope of genome editing tool for further application to improve antiviral 40 research. Here, we demonstrate that three Cpf1 endonuclease can be used efficiency 41 editing BmNPV genome in vitro and in vivo for the first time. More importantly, this 42 Cpf1 system could improve the resistance of transgenic silkworms to BmNPV compare 43 with Cas9 system, and no significant cocoons difference was observed between 44 transgenic lines infected with BmNPV and control. These broaden the range of 45 application of CRISPR for novel genome editing methods in silkworm and also enable 46 sheds light on antiviral therapy.47 49 Genome editing introduces DNA mutations in the form of insertions, deletions or 50 base substitutions within selected DNA sequences [1]. Clustered regularly interspaced 51 short palindromic repeats (CRISPR) gene editing technology has been used in gene 52 function research, genetic improvement, modelling biology and gene therapy [2-5]. 53 Three effector proteins of class 2 type V CRISPR systems, the CRISPR/CRISPR-54 associated 12a (Cas12a, known as Cpf1) proteins of Lachnosperaceae bacterium 55 (LbCpf1), Francisella novicida (FnCpf1) and Acidaminoccocus sp. (AsCpf1), have 56 been shown to efficiently edit mammalian cell genomes with more efficient genome 57 editing than the widely used Streptococcus pyogenes Cas9 (SpCas9) [6-8]. However, 58 the CRISPR/Cpf1 system was rarely used for insect genome editing research and 59 antiviral therapy [9].60 The silk industry (Bombyx mori, B. mori), suffers great economic losses due to B. 61 mori nucleopolyhedr...