Assay for nucleic acid sequences in an unpurified sample

A method for detecting at least one polynucleotide sequence from a microorganism or eucaryotic source in a biological test sample, comprising the steps of:

• (a) without prior centrifugation or filtration treating said biological test sample to lyse cells and to release nucleic acids therefrom,
• (b) without purification or isolation of specific nucleic acid sequences, photochemically labeling released sample nucleic acids directly in the lysate produced in step (a),
• (c) contacting the resulting labeled nucleic acids, under hybridization conditions, with at least one immobilized oligonucleotide or nucleic acid probe hybridizable with the sequence or sequence to be detected, thereby to form hybridized labeled nucleic acids, and
• (d) assaying for the hybridized nucleic acids by detecting the label.