| In recent years,the global cancer incidence rate and mortality present a continuous and rapid increasing tendency,and the condition is particularly severe in developing countries.Cancer has already become a major diseases that seriously threat to human health and life.Currently,the standard therapeutic methods of cancer in clinic include surgery,radiotherapy,chemotherapy.In the past decade,cancer immunotherapy has gradually developed into the fourth strategy to treat cancer.As one way of cancer immunotherapies,tumor gene vaccine has been widely studied in the field of medical immunology,and various tumor gene vaccines have already achieved some exciting results in clinical research.Tumor gene vaccine was composed of the genes that encod tumor associated antigen or tumor specific antigen and the eukaryotic expression vector or viral vector.DNA or viral vector delivers the tumor antigen gene into human or animal's body,then the antigen gene express antigen protein which can stimulate the body's specific humoral and cellular immune response,and exert antitumor immune protection.There are many crucial factors for design a tumor gene vaccine,such as target antigens,vaccine carrier,immune adjuvant and immunization strategy.Start from 1982 the recombinant DNA technology was first applied in the study of vaccinia virus,many kinds of poxvirus,like vaccinia virus,fowlpox virus,canarypox virus etc,were extensively applied to develop the genetic engineering live vaccines and biological drugs.It involved the prevention and treatment of a variety of diseases,such as cancer,HIV/AIDS,hepatitis C,malaria and tuberculosis.MVA(Modified Vaccinia Virus Ankara)is such a highly attenuated and host-restricted vaccinia virus,which has several special biological features,including large packaging capacity for forgein gene,precise and high expression of exogenous gene,unique safety,and high immnogenicity.As a vaccine vector,MVA was utilized for preventing and treating the numbers of infectious diseases and cancers in some preclinical and human clinical trialsIn our group preliminary work,one kind of DNA vaccine(CpDV-IL2-sPD1/MS)targeting tumor antigen Survivin and MUC1 and using CpG,IL2 and sPD1 as molecular adjuvants was designed.In addition,a recombinant adenovirus vaccine Ad-MS was constructed.Applying the DNA prime-Ad boost immunization strategy successfully induced strongly immune response in tumor-bearing mouse model and generated remarkerable antitumor effect.Then,whether the recombinant MVA-based vaccine can produce the similar or more effective antitumor effect?On the basis of previous work,in this paper such an recombinant MVA-based vaccine that fusionally express sPD1(soluble programmed cell death 1)and tumor antigen MUC1 and Survivin was prepared.We have explored the vaccine's anti-tumor activity from different aspects.The main research contents are as follows:First of all,we designed and builded the shuttle expression plasmid pSC11M1-sPD1/MS.Then it was recombined with MVA,by doing a lot of screening work,the stably high expression of foreign proteins recombinant MVA-based vaccine was successfully prepared.Meanwhile,in order to find a desired vaccine evaluation subject,we also established a stable over-expression tumor antigen MUCl and Survivin melanoma cell line(RFP-MS+B16)and tumor-bearing mouse model.Then we explored the recombinant vaccine rMVA's antitumor effect on melanoma tumor-bearing mouse model.Results showed that there was no significant suppression of tumor growth compared with the control PBS group.In order to improve the immunogenicity and anti-tumor protection,we combined the rMVA vaccine with DNA vaccine which we have been used,using DNA prime-rMVA boost immune strategy to improve the immunogenicity and antitumor effect.Firstly,the humoral and celluar immunity stimulated by the combined vaccine was estimated in C57/BL/6 mice.The results indicated that the heterologous prime-boost immunization strategy distinctly promoted the secretion of IFN-y,but did not increase specific CTL response in terms of cellular immunity.In the aspect of the humoral immunity,the specific antibodies were also induced in mice's sera.Moreover,the scheme also didn't genenrate obviously suppression of tumor growth in the antitumor expriment.After adjusting the immunization schedules and dose,the inhibition of tumor growth was enhanced in the rMVA group.It was better than the combinant vaccine group.However,the capabilities of the secretion of IFN-?and antibody levels of both the rMVA group and the DNA combinant rMVA group were enhanced.In summary,the viral vector vaccine rMVA can enhance the body's immune response,and play a role in inhibition of tumor growth to a certain extent,but the ability is limited.In addition,although the rMVA combine with DNA vaccine and the DNA prime-rMVA boost enhanced the immune response in mice,but there is still no improvement of antitumor protection.The concrete mechanism needs further research. |
PDF Full Text Request