Saliva contains enough DNA or mRNA for identification purposes. It is essential that there is a means of positively linking a saliva-containing item to a specific individual and demonstrating that no one else's saliva is present.
Saliva contaminated items include:
(1) cigarette butt or cigar end
(2) straw
(3) stamp requiring licking
(4) envelope flap requiring licking
(5) paper cup, soda can, bottle or other container
(6) chewing gum
(7) pencil or other objected chewed on
(8) tissue paper or napkin
(9) mouthpiece to a musical instrument
The presence of saliva can be confirmed by testing for amylase activity. This can be done by a chromogenic assay that does not consume sample or affect the DNA.
The area contaminated by saliva can be dissected out and the nucleic acids extracted into solution. PCR can then be used to amplify the amount of the target nucleic acid that is present.
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