Evaluation of lyophilized PCR mixes stable at room temperature for detection of viruses

Polymerase chain reaction is the most common laboratory method used in diagnosis of infectious diseases. It still requires cold-chain transportation and storage of reaction components, adequate instrumentation, as well as a skilled specialist during the preparation of reaction mixes. This study was focused on the evaluation of pre-prepared freeze-dried PCR mixes for virus detection in ready-to-use form. PCR mixes with new commercial glycerol-free DNA polymerase, cryoprotectants as trehalose, dextran or mannitol and other PCR components were lyophilized and stored at room temperature for several months. Our study revealed that 10 % trehalose, 5 % dextran and their combination stabilized PCR mixes for the detection of porcine circovirus 2 (PCV2) and hepatitis E virus (HEV) for 3 months. The freeze-dried PCR mixes detected those viruses in concentrated and 10 to 100-fold diluted clinical samples. The lyophilized PCR mixes containing commercially available glycerol-free DNA polymerase stabilized with sugar cryoprotectants were suitable for the preparation of diagnostic PCR kits.