Abstract:

Objective To investigate the influence of different inactivating conditions on nucleic acid determination for respiratory pathogens. Methods A total of 12 patients who were positive of adenovirus,Mycoplasma,influenza A virus or influenza B virus in nasopharyngeal swabs were enrolled. Different inactivating temperatures and times were designed as follows：the samples were inactivated for 30 min in 56,66,76 and 86 ℃,as well as they were inactivated in 56 ℃ for 30,60,120,240,480 and 960 min. The real-time fluorescence quantitative polymerase chain reaction（qPCR） results were compared between the groups before and after inactivation. Results For adenovirus and Mycoplasma,no statistical significance was found in cycling threshold（Ct） values among the groups that were inactivated for 30 min in 56 and 66 ℃ and non-inactivation（P>0.05）. An increase was determined in the groups that were inactivated for 30 min in 76 and 86 ℃（P<0.05）. Inactivation in 56 ℃ for 30,60,120 and 240 min did not result in changes in Ct values of samples（P>0.05）. Inactivation in 56 ℃ for 480 and 960 min would reduce the Ct values of samples（P<0.05）. For influenza A virus and influenza B virus,no statistical significance was found in Ct values between the groups that were inactivated for 30 min in 56 ℃ and non-inactivation（P>0.05）. An increase was determined in the groups that were inactivated for 30 min in 66,76 and 86 ℃（P<0.05）. Inactivation in 56 ℃ for 30,60 and 120 min did not result in changes in Ct values of samples（P>0.05）. Inactivation in 56 ℃ for 240,480 and 960 min would reduce the Ct values of samples（P<0.05）. Conclusions The samples inactivated in 56 ℃ no more than 120 min would not influence the Ct values in qPCR. Inactivation for severe acute respiratory syndrome coronavirus 2（SARS-CoV-2） does not have effect on nucleic acid determination in other respiratory pathogens.

Key words: Respiratory pathogen, Inactivation, Temperature, Time, Real-time fluorescence quantitative polymerase chain reaction