Persistence of viral genomes after autoclaving

The ability of autoclaving to degrade viral genomes was investigated by real-time PCR and real-time reverse-transcription (RT)-PCR. Several factors were considered: the nucleic acid composition of the virus (DNA or RNA), hydration state of the sample, and the duration of autoclaving. Viral genomes were damaged more easily under hydrated conditions compared to dry conditions. The genomes of RNA viruses, such as MS2 and norovirus degraded more readily than DNA virus (adenovirus). MS2 genome was the most vulnerable among those tested, with no amplification observed after 18min of autoclaving. Adenovirus genomes, on the other hand, were detected after autoclaving for 36min under hydrated or dry conditions. For norovirus, 18min of autoclaving under hydrated condition or 36min under dry conditions was enough to destroy noroviral genomes. For noroviral samples, 1.1% of noroviral gene segments were remained after autoclaving for 18min under dry conditions; however, when a two-step approach was used for the RT-PCR reaction with priming at the poly-A tail about 2552bp from the qPCR amplification site, the gene segment was not amplified after autoclaving for 18min. Thus, norovirus amplification observed after 18min of autoclaving in the dry sample is likely from less than full length genomic segments of norovirus RNA remaining in the sample.