Induction of P815 tumor immunity by DNA-based recombinant Semliki Forest virus or replicon DNA expressing the P1A gene.
OBJECTIVE
To compare the prophylactic and therapeutic effects of alphaviruses in the same tumor model, we used a DNA-based approach to generate a replicon DNA and recombinant Semliki Forest virus (rSFV) particles expressing P1A, the P815 mastocytoma tumor associated antigen, and compared the immune effect of each vaccine.


METHODS
Six to eight-week-old female DBA/2 mice were inoculated with P1A plasmid or viral vaccines. Spleen cells were assayed for antigen-specific cytotoxic T cell activity. Tumor growth or survival rate was observed in preventive and therapeutic experiments, respectively.


RESULTS
We found that the rSFV particles prevented tumor growth when delivered prior to innoculation of mice with P815 cells, and more importantly, improved survival when delivered after the initiation of tumor growth. Naked P1A replicon DNA also functioned as a protective and therapeutic vaccine, although with less potency than rSFV particles. Virus particles also elicited a stronger cellular immune response as measured by target cell lysis.


CONCLUSIONS
rSFV particles have stronger specific prophylactic and therapeutic immune effects in mice than replicon DNA-based DNA vaccines, though the latter is more effective than traditional plasmid vectors (e.g. pCI-neo vector).
Ni
Bing
B
Institute of Immunology PLA, Department of Immunology, Third Military Medical University, Gaotanyan Street 30#, Shapingba District, Chongqing 400038, PR China.
Lin
Zhihua
Z
Zhou
Liyun
L
Wang
Li
L
Jia
Zhengcai
Z
Zhou
Wei
W
Diciommo
David P
DP
Zhao
Jianping
J
Bremner
Rod
R
Wu
Yuzhang
Y
D000818:Animals; D000951:Antigens, Neoplasm / Q000276:immunology*; D019496:Cancer Vaccines / Q000276:immunology*; D004247:DNA; D005260:Female; D007109:Immunity; D034801:Mastocytoma / Q000276:immunology*; D051379:Mice; D023421:Models, Animal; D012093:Replicon / Q000276:immunology*; D012672:Semliki forest virus / Q000276:immunology*
D000951:Antigens, Neoplasm; D019496:Cancer Vaccines; C076546:tumor rejection antigen P815A, mouse; D004247:DNA