Hybridization method and probe for detecting nucleic acid sequences

A method for detecting the presence of specific nucleic acid base sequences in a sample suspected of containing said sequences in single-stranded form comprising:

• providing nucleic acid probe molecules which in single-stranded form are capable of binding specifically to said suspected nucleic acid base sequences and contain at least one thionucleotide;
• converting any double-stranded probe molecules to single-stranded form;
• annealing said single-stranded, thionucleotide-containing probe molecules to said suspected nucleic acid base sequences in the presence of a concentration of multivalent cations selected from the group consisting of those transition metals in groups VIII, IB and IIB of the periodic table;
• subsequent to said annealing, detecting the presence of any said probe molecules annealed to said suspected nucleic acid base sequences;
• and
• prior to said detecting, providing said probe molecules with a detectable label to provide a means for later detecting the presence of any said probe molecules annealed to said suspected nucleic acid base sequences.

A method for detecting the presence of specific nucleic acid base sequences in a sample suspected of containing said sequences in single-stranded form comprising:

• providing nucleic acid probe molecules which in single-stranded form are capable of binding specifically to said suspected nucleic acid base sequences and contain at least one thionucleotide;
• providing said probe molecules with a detectable label;
• converting any double-stranded probe molecules to single-stranded form;
• thereafter annealing said labelled, single-stranded thionucleotide-containing probe molecules to said suspected nucleic acid base sequences in the presence of a concentration of multivalent cations selected from the group consisting of those transition metals in groups VIII and IB of the periodic table;
• thereafter detecting the presence of any said labelled probe molecules annealed to said suspected nucleic acid base sequences.

A method for detecting the presence of specific nucleic acid base sequences in a sample suspected of containing said sequences in single-stranded form comprising:

• providing nucleic acid probe molecules which in single-stranded form are capable of binding specifically to said suspected nucleic acid base sequences and contain at least one thionucleotide;
• converting any double-stranded probe molecules to single-stranded form;
• annealing said single-stranded, thionucleotide-containing probe molecules to said suspected nucleic acid base sequences in the presence of a concentration of multivalent cations selected from the group consisting of those transition metals in groups VIII and IB of the periodic table;
• thereafter providing said probe molecules with a detectable label;
• and
• detecting the presence of any said labelled probe molecules annealed to said suspected nucleic acid base sequences.

A hybridization probe for detecting the presence of specific nucleic acid base sequences in a sample suspected of containing said sequences comprising:

• labelled single-stranded nucleic acid probe molecules having essentially complementary base sequences to defined regions in said suspected nucleic acid base sequences;
• a detectable label attached to said probe molecules;
• and
• one or more phosphorothioate groups attached to said probe molecules which are capable of forming crosslinking ionic bonds with each other to bond together multiple labelled probe molecules, said phosphorothioate groups being non-radioactive.