Nucleic acid analysis method

A method of analyzing nucleic acids in a sample,

• the nucleic acids to be amplified comprising a first template nucleic acid and a second template nucleic acid,
• the first template nucleic acid comprising a first sequence located on a 3′ terminal, a first template sequence adjacent to a 5′ side of the first sequence, and a second sequence adjacent to a 5′ side of the first template sequence and located on the 5′ terminal, and
• the second template nucleic acid, which is a strand complementary to the first template nucleic acid, comprising a third sequence located on a 3′ terminal thereof, a second template sequence adjacent to a 5′ side of the third sequence, and a fourth sequence adjacent to a 5′ side of the second template sequence and located on the 5′ terminal,
• the method comprising:
• (a-1) preparing a first primer and a second primer configured to amplify the first template nucleic acid and the second template nucleic acid,
• wherein the first primer comprises an S1 sequence complementary to the first sequence and an S2 sequence joined to a 5′ terminal side of the S1 sequence, the S2 sequence is a sequence, which is same as a sequence of at least a part of the first template sequence, located adjacent to or in a vicinity of a 5′ side of the first sequence on the first template nucleic acid and
• the second primer comprises an S3 sequence complementary to the third sequence and an S4 sequence joined to a 5′ side of the S3 sequence, the S4 sequence is a sequence, which is same as a sequence of at least a part of the second template sequence, located adjacent to or in a vicinity of a 5′ side of the third sequence on the second template nucleic acid;
• further, a first replication strand corresponding to an elongated strand from the first primer forms a first stem-and-loop structural body, the first stem-and-loop structural body comprises a first double strand region and a first single strand region on one strand, the first double strand region comprises a first stem portion derived from the S2 sequence and a sequence derived from a complementary sequence of the first template sequence, the sequence derived from a complementary sequence of the first template sequence is complementary to the first stem portion, the first single strand region forms a first loop portion, and the first single strand region, which forms the first loop portion, comprises the S1 sequence;
• a second replication strand corresponding to an elongated strand from the first primer forms a second stem-and-loop structural body, the second stem-and-loop structural body comprises a second double strand region and a second single strand region on one strand, the second double strand region comprises a second stem portion derived from a complementary sequence of the S4 sequence and a sequence derived from a complementary sequence of the first template sequence, the sequence derived from a complementary sequence of the first template sequence is complementary to the second stem portion, the second single strand region forms a second loop portion, and the second single strand region, which forms the second loop portion, comprises a complementary sequence to the S3 sequence;
• a third replication strand corresponding to an elongated strand from the second primer forms a third stem-and-loop structural body, the third stem-and-loop structural body comprises a third double strand region and a third single strand region on one strand, the third double strand region comprises a third stem portion derived from the S4 sequence and a sequence derived from a complementary sequence of the second template sequence, the sequence derived from a complementary sequence of the second template sequence is complementary to the third stem portion, the third single strand region forms a third loop portion, and the third single strand region, which forms the third loop portion, comprises the S3 sequence;
• and
• a fourth replication strand corresponding to an elongated strand from the second primer forms a fourth stem-and-loop structural body, the fourth stem-and-loop structural body comprises a fourth double strand region and a fourth single strand region on one strand, the fourth double strand region comprises a fourth stem portion derived from a complementary sequence of the S2 sequence and a sequence derived from a complementary sequence of the second template sequence, the sequence derived from a complementary sequence of the second template sequence is complementary to the fourth stem portion, the fourth single strand region forms a fourth loop portion, and the fourth single strand region, which forms the fourth loop portion, comprises a complementary sequence to the S1 sequence;
• (a-2) preparing at least one from the group consisting of a first nucleic acid probe, a second nucleic acid probe, a third nucleic acid probe and a fourth nucleic acid probe, configured to detect the first replication strand and/or the second replication strand,
• wherein the first nucleic acid probe comprises a sequence of at least a part of the first single strand region forming the first loop portion in the first replication strand,
• the second nucleic acid probe comprises a sequence of at least a part of the second single strand region forming the second loop portion in the second replication strand,
• the third nucleic acid probe comprises a sequence of at least a part of the third single strand region forming the third loop portion in the third replication strand, the sequence comprising a sequence of at least a part of the complementary sequence to the S3 sequence, and
• the fourth nucleic acid probe comprises a sequence of at least a part of the fourth single strand region forming the fourth loop portion in the fourth replication strand, the sequence comprising a sequence of at least a part of the S1 sequence;
• (b) amplifying the sample using the first primer and the second primer,
• (c) reacting an amplification product obtained in (b) with the at least one from the group consisting of the first nucleic acid probe, the second nucleic acid probe, the third nucleic acid probe and the fourth nucleic acid probe,
• (d) detecting presence/absence of a hybridization and/or measuring a quantity of the hybridization occurred due to the reaction in the (C), and
• (e) determining presence/absence of the target nucleic acid in the sample and/or determining a quantity of target nucleic acid presence, based on a result in the (d).