Linked target capture
The invention generally relates to sequencing library preparation methods. In certain embodiments, two or more template nucleic acids are joined together by a linking molecule, such as a PEG derivative. Identical copies of a nucleic acid fragment or both strands of a duplex fragment may be linked together. The linked nucleic acids are amplified, creating linked amplicons. Emulsion PCR with linked primers creates linked template nucleic acids for seeding sequencing clusters and errors can be readily identified by their presence on only one of the linked fragments.
1. A method for sequencing a region of interest, the method comprising:
providing double-stranded adapters comprising a universal priming site and its compliment;
ligating the double-stranded adapters onto a plurality of duplex nucleic acid fragments wherein the plurality of duplex nucleic acid fragments comprise a sense strand, and antisense strand, and at least one genomic region of interest;
denaturing the plurality of ligated duplex nucleic acid fragments to create single-stranded nucleic acid fragments each comprising one of the universal priming site or its compliment;
amplifying the single-stranded nucleic acid fragments using universal primers, each physically linked to a target probe complimentary to at least a portion of the region of interest or its compliment, to generate a plurality of amplified fragments comprising copies of the sense and antisense strands;
sequencing the plurality of amplified fragments, and
determining the sequence of the region of interest by comparing sequencing reads of at least one sense stand and at least one antisense strand of the amplified fragments and generating a consensus sequence of the region of interest by determining a base call for each position that represents a consensus from the compared sequencing reads.
2. The method of claim 1 , wherein the amplifying step occurs under conditions that require binding of the target probe to the region of interest or its compliment to permit binding of the universal primer to the universal priming site, and wherein the target probe is blocked from extension, wherein amplifying the single-stranded nucleic acid fragments comprises extending the universal primer using a strand displacing polymerase to produce the plurality of amplified fragments.
3. The method of claim 1 , wherein the denaturing and amplifying steps are performed in an emulsion droplet.
4. The method of claim 1 , wherein the double-stranded adapters further comprise barcodes.
5. The method of claim 1 , wherein the amplifying step comprises extending the universal primers using a strand displacing enzyme.
6. The method of claim 1 , wherein the adapters further comprise a unique molecular identifier and its reverse compliment.
7. The method of claim 6 , further comprising creating a consensus sequence for each strand of the one of the plurality of duplex nucleic acid fragments by grouping sequencing reads comprising the unique molecular identifier sequence into a first group and sequencing reads comprising the reverse compliment of the unique molecular identifier sequence into a second group and determining the base call for each position in the first and second groups of sequencing reads.
8. The method of claim 7 , wherein determining the base call comprises comparing each sequencing read in the first and second groups and determining the base found at that position in a majority of each group of sequencing reads.
9. The method of claim 7 , wherein generating the consensus sequence of the region of interest comprises comparing the consensus sequence for each strand of the one of the plurality of duplex nucleic acid fragments and determining a base call at each position based on agreement between the consensus sequence of each strand.