Adaptability and genetic stability of hepatitis A virus SYX_1 strain in human diploid cell MRC-5 / 中国生物制品学杂志

ABSTRACT

@#Abstract：Objective To investigate the adaptability and genetic stability of hepatitis A virus（HAV）SYX1 strain in human diploid cell MRC⁃5. Methods HAV SYX1 strain isolated from feces of patients with hepatitis A was continuously propagated in MRC⁃5 cells for 28 passages，of which the 1st ~ 26th passages were determined for antigen contents and virus titers，the 6th passage was observed for the morphology under microscope and detected for physicochemical properties，and the 13th ~ 15th passages were studied for virus proliferation dynamics to determine the peak yield of virus proliferation. Genomic RNA was extracted from the 8th，12th，18th，20th，22nd，25th，26th and 28th passages and sequenced to analyze the genetic stability. The main seed batch and working seed batch of HAV SYX1 strain were established and verified according to the requirements of Chinese Pharmacopoeia（VolumeⅢ，2020 edition）. Results The antigen content of HAV SYX1 was stable at 160 ~ 320 EU／mL and the titer was maintained at 7. 3 ~ 8. 3 lgCCID50／mL after the 8th passages in MRC 5 cells；Virus particles showed two types：hollow and solid，with a diameter of 27 ~ 32 nm，spherical，without envelope and protrusions on the surface，which tolerated low pH value and ether. The peak period of virus proliferation was 10 d with an antigen content of more than 160 EU／mL and a virus titer of more than 7. 0 lgCCID50／mL. HAV SYX1 was a subtype of HAV IB，and no mutation in the coding region of all structural proteins during passage was observed. The verification results of main seed batch and working seed batch of HAV all met the relevant requirements. Conclusion HAV SYX1 strain showed good adapt⁃ ability and genetic stability in MRC⁃5，which might be used for the development and production of inactivated hepatitis A vaccine.