Nucleic acid, composition and conjugate comprising the same, and preparation method and use thereof

A siRNA, comprising a sense strand and an antisense strand, each nucleotide in the siRNA being independently a modified or unmodified nucleotide, wherein the sense strand comprises a nucleotide sequence I, and the antisense strand comprises a nucleotide sequence II;

• the nucleotide sequence I and the nucleotide sequence II are at least partly reverse complementary to form a double stranded region;
• wherein the nucleotide sequence I comprises a nucleotide sequence A, which has the same length as the nucleotide sequence shown in SEQ ID NO:
• 1 with no more than 3 nucleotide differences;
• and the nucleotide sequence II comprises a nucleotide sequence B, which has the same length as the nucleotide sequence shown in SEQ ID NO:
• 2 with no more than 3 nucleotide differences:
• (SEQ ID NO:
• 1)
• 5′-UGCUAUGCCUCAUCUUCUZ-3′;
• (SEQ ID NO:
• 2)
• 5′-Z′AGAAGAUGAGGCAUAGCA-3′;
• wherein,
• Z is A;
• Z′ is U;
• and
• the nucleotide sequence A comprises a nucleotide ZA at the position corresponding to Z;
• the nucleotide sequence B comprises a nucleotide Z′B at the position corresponding to Z′;
• the nucleotide Z′B is the first nucleotide at 5′ terminal of the antisense strand.