THE CONSTRUCTION AND BIOLOGICAL PROPERTIES OF A RECOMBINANT VACCINIA VIRUS(VMS11HAV25)EXPRESSING HEPATITIS A VIRUS ANTIGENS
Gao Feng Guo Kejian Ruan Li Yi YaoLiu Chongbo Zhu Jiming (C.M. Chu )Institute of Virology, Chinese Academy of Preventive Medicine, Beijing
A HAV recombinant vaccinia virus named VMS11HAV25 was constructed by inserting the entire open reading frame of HAV cDNA,driven by a vaccinia promotor P11, into Hind 1 M fragment of Tian Tan strain of vaccinia virus which had been used extensively for over 50 years as a vaccine to eradicate smallpox in China.The inserted HAV cDNA was modified by deleting the majority of 5' noncoding region to prevent the production of infectious hepatitis A viral particles.It is important to know if the insertion of HAV gene affects the biological properties of the vector virus. Results showed that there were not much difference between the recombinant virus and the parental virus. An obvious difference was that the virulence of the recombinant virus was about ten times lower than its parental virus when tested in rabbits intradermally and in mice intracerebrally.The expression of HAV antigen by the recombinant virus at the 15th passage in human lung diploid cells was as good as that at the 4th passage. Southern blot hybridization showed that the inserted HAV cDNA was still located at the correct site after the recombinant virus had undergone 20 passages in the diploid cell culture, indicating the stability of the HAV gene in the vector.