Circularized templates for sequencing

Abstract

The invention provides methods of forming a circular template for sequencing a target nucleic acid. The circular template is generated by amplification of a segment of the target nucleic acid with chimeric primers with complementary 5' ends. The circular template has a single nick or gap providing a site for initiation of template-directed extension for sequence analysis. Sequencing of a single template generates reads of alternating segments of the same strand of the target nucleic spaced by primer segments. The different reads of the same strand of the target nucleic acid can be compiled to generate a consensus sequence. Because only one strand of the target nucleic acid is sequenced per reaction, the present method avoids errors introduced by unwittingly combining sequences of both strands of a heteroduplex PCR product. Because only one strand of the target nucleic acid is sequenced per reaction, the present method avoids errors introduced by unwittingly combining sequences of both strands of a heteroduplex PCR product.