Analysis of titer stability and inactivation kinetics of harvest solution of SARS-CoV-2 / 中国生物制品学杂志

ABSTRACT

@#Objective To investigate the titer stability of the harvest solution of severe acute respiratory syndrome coronavirus2(SARS-CoV-2)at 2 ～ 8 ℃ and the inactivation effect of β-propiolactone inactivator on the virus.Methods Three batches of SARS-CoV-2 harvest solution(batch numbers202111001,202111002 and 202111003)were stored at 2 ～ 8 ℃ for 12 d and sampled every 3 d(0,3,6,9 and 12 d)for detection of the titers by Karber method;Three batches of virus harvest solution equilibrated overnight at 2 ～ 8 ℃ were inactivated by adding β-propiolactone at a volume fraction of 1∶4 000 and detected for the titers at different inactivation time points(0,0.5,1,1.5,2,3,4,8,16 and 24 h),of which samples inactivated for 8,16 and 24 h were taken for inactivation verification,and samples inactivated for 24 h were observed by transmission electron microscope.Results The titers of SARS-CoV-2 decreased with the prolongation of storage time at 2 ～8 ℃,which showed no obvious decrease during 0 ～ 3 d,while decreased from the initial 7.75,6 and 7.5 lgCCID_(50)/mL to5.75,4.625 and 6.25 lgCCID_(50)/mL on day 12,indicating that the virus activity showed a gradual decrease trend at 2 ～8 ℃；With the inactivation time,the virus titer decreased continuously and could not be detected after inactivation for 3 h.Transmission electron microscope observation showed that the inactivated virus particles were intact and the spike protein was evenly distributed.Conclusion The virulence of SARS-CoV-2 stored at 2 ～ 8 ℃ was unstable,so the subsequent inactivation and purification process should be carried out as soon as possible;The titer of virus could not be detected after3 h of inactivation,which provided a reference for the determination of the inactivation process.