Best Method to Release Virus in the Production of Live Attenuated Hepatitis A Vaccine

ObjectivesIn order to explore the most efficient release of hepatitis A virus(HAV)H2 Strain from the human embryonic lung diploid fibroblast(KMB17)in vaccine production.MethodsThree methods(ultrasonic,deep low temperature freeze-thawing(-70℃)and liquid nitrogen freeze-thawing)were compared according to the index:the rate of celullar lysis,antigenic titer and infectious titer.ResultsBy continuous ultrasonic for three times(90 seconds per time)being handled for four times by freeze-thawing at-70℃,being put into liquid nitrogen for six times,the rate of cellular lysis reached 94%,82%,81% respectively,the antigentiter all were 1:256(log CCID₅₀/ml),infectious titer were 8.67,6.5,6.0 respectively.Further freeze-thawing inliquid nitrogen showed no change in antigen titers,but virus infectious titer decreased down to 210 log CCID₅₀/ml,at the 10th time.ConclusionThe results showed that the ultrasonic is best method to release the virus and do minimal damage to viral proteins and RNA among three ones.