Brown Silas S, Chen Yun-Wen, Wang Ming, Clipson Alexandra, Ochoa Eguzkine, Du Ming-Qing
University of Cambridge Computer Laboratory, 15 JJ Thompson Avenue, Cambridge, CB3 0FD, UK.
Department of Pathology, Division of Cellular and Molecular Pathology, University of Cambridge, CB2 0QQ, UK.
Biol Methods Protoc. 2017 May 12;2(1):bpx006. doi: 10.1093/biomethods/bpx006. eCollection 2017 Jan.
Targeted next-generation sequencing based on PCR amplification involves pooling of hundreds to thousands of primers, for preamplification and subsequent parallel single/multiplex PCR. It is often necessary to allocate the set of primers into subpools, a common issue being potential cross-hybridization. For smaller numbers of primers, pool division can be done manually using trial and error to minimize potential hybridization, but this becomes inefficient and time consuming with increasing numbers of primer pairs. We developed PrimerPooler that automates swapping of primer pairs between any user-defined number of subpools to obtain combinations with low-potential interactions. PrimerPooler performs inter-/intra-primer hybridization analysis to identify the adverse interactions, as well as simultaneous mapping of all primers onto a genome sequence in a single run without requiring a prior index of the genome. This allows detection of overlapping primer pairs and allocation of these primer pairs into separate subpools where tiling approaches are used. Using PrimerPooler, 1153 primer pairs were assigned to three preamplification pools (388, 389 and 376 primer pairs each), then 144 subpools of six- to nine-plex PCR for Fluidigm Access Array PCR, followed by Illumina MiSeq sequencing. With optimized experimental protocols, an average of 3269 reads was achieved for the targeted regions, with 95% of targets covered by at least 50 reads, the minimal depth of reads for confident variant calling. PrimerPooler provides a fast and highly efficient stratification of primer pairs for targeted enrichment, thus ensuring representative amplification of the targeted sequences. PrimerPooler is also able to analyse degenerate primers, and is thus also useful for microbiological identification and related target sequencing.
基于PCR扩增的靶向新一代测序涉及数百至数千种引物的混合,用于预扩增和随后的平行单重/多重PCR。通常需要将引物组分配到子池中,一个常见问题是潜在的交叉杂交。对于较少数量的引物,可以通过反复试验手动进行池划分,以尽量减少潜在的杂交,但随着引物对数量的增加,这会变得效率低下且耗时。我们开发了PrimerPooler,它可以自动在任何用户定义数量的子池之间交换引物对,以获得具有低潜在相互作用的组合。PrimerPooler进行引物间/引物内杂交分析,以识别不利的相互作用,并在单次运行中将所有引物同时映射到基因组序列上,而无需预先建立基因组索引。这允许检测重叠的引物对,并将这些引物对分配到使用平铺方法的单独子池中。使用PrimerPooler,将1153对引物分配到三个预扩增池(每个池分别为388、389和376对引物),然后分配到用于Fluidigm Access Array PCR的144个六重至九重PCR子池,随后进行Illumina MiSeq测序。通过优化的实验方案,目标区域平均获得3269条读数,95%的目标至少被50条读数覆盖,这是进行可靠变异检测所需的最小读数深度。PrimerPooler为靶向富集提供了快速且高效的引物对分层,从而确保目标序列的代表性扩增。PrimerPooler还能够分析简并引物,因此也可用于微生物鉴定和相关目标测序。