New polynucleotides, having diagnostic and therapeutic applications - include one or more phosphoro-di:thioate inter-nucleotide linkages

Polynucleotides, in which all the internucleotide linkages between individual nucleotide groups in the polynucleotide are phosphorodithioate internucleotide linkages, are new. Also claimed are: (A) polynucleotides which have at least one phosphorodithioate internucleotide linkage in combination with phosphate, phosphorothioate or phosphorothioamidate internucleotide linkages; (B) polynucleotides which have both phosphorodithioate and phosphate internucleotide linkages; (C) oligonucleotides, in protected or unprotected form, which have at least one phosphorodithioate internucleotide linkage; and (D) oligonucleotides, in protected or unprotected form, comprising dinucleosides which have H-phosphonothioate internucleotide linkages.