**4.19 Polymerase spiral reaction (PSR)**

This technique makes use of both conventional PCR and isothermal amplification as in LAMP and is completed within one and a half hour. Here mostly an exogenous sequence from an unrelated species or of botanical origin is incorporated at the 5′ end into the primer sequences used in PSR if a human or veterinary pathogen is targeted. PSR has been successfully used to detect all CPV antigenic variants with ten-fold higher sensitivity than traditional PCR [71].
