Hou S, Chen J, Feng R, Xu X, Liang N, Champer J. A homing rescue gene drive with multiplexed gRNAs reaches high frequency in cage populations but generates functional resistance.
J Genet Genomics 2024:S1673-8527(24)00070-5. [PMID:
38599514 DOI:
10.1016/j.jgg.2024.04.001]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2023] [Revised: 04/02/2024] [Accepted: 04/02/2024] [Indexed: 04/12/2024]
Abstract
CRISPR homing gene drives have considerable potential for managing populations of medically and agriculturally significant insects. They operate by Cas9 cleavage followed by homology-directed repair, copying the drive allele to the wild-type chromosome and thus increasing in frequency and spreading throughout a population. However, resistance alleles formed by end-joining repair pose a significant obstacle. To address this, we create a homing drive targeting the essential hairy gene in Drosophila melanogaster. Nonfunctional resistance alleles are recessive lethal, while drive carriers have a recoded "rescue" version of hairy. The drive inheritance rate is moderate, and multigenerational cage studies show drive spread to 96%-97% of the population. However, the drive does not reach 100% due to the formation of functional resistance alleles, despite using four gRNAs. These alleles have a large deletion but likely utilize an alternate start codon. Thus, revised designs targeting more essential regions of a gene may be necessary to avoid such functional resistance. Replacement of the rescue element's native 3' UTR with a homolog from another species increases drive inheritance by 13%-24%. This was possibly because of reduced homology between the rescue element and surrounding genomic DNA, which could also be an important design consideration for rescue gene drives.
Collapse