Construction of STxB-VP1 and MDC-VP1 fusion DNA vaccine and study on its immunological effects on mice / 解放军医学杂志

ABSTRACT

Objective To Construct fusion gene DNA vaccine pcDNA3/STxB-VP1 and fusion gene DNA vaccine pcDNA3/MDC-VP1,then the two vaccines were inoculated to mice and stuy their immunological effects.Methods B subunit of Shiga Toxin(STxB)gene fragment were amplified by PCR from the DNA of Shigella dysenteriae and Macrophage-derived chemokine(MDC)gene fragment was amplified by RT-PCR from the total RNA of a mouse spleen cells.The DNA fragments of STxB and MDC waere respectively linked to coxsackievirus B3(CVB3)VP1 by a DNA sequence which encode a flexible polypeptide(15 amino acids)to construct eukaryotic expression plasmids pcDNA3/STxB-VP1 and pcDNA3/MDC-VP1.BALB/c mice were randomized to 6 groups which were respectively immunized pcDNA3,pcDNA3/STxB,pcDNA3/MDC,pcDNA3/VP1,pcDNA3/STxB-VP1 and pcDNA3/MDC-VP1 for 3 times at 3-week intervals,intramuscularly(i.m.)in tibialis anterior muscle.The levels of the serum neutralizing antibodies were detected 20d after each inoculation.The mice were challenged with 7 LD50 CVB3 3 weeks after the last immunization.Results The fusion gene vaccines pcDNA3/STxB-VP1 and pcDNA3/MDC-VP1 were constructed successfully.The survival rates of each group were 10%,10%,15%,40%,20% and 75%,respectively,and the levels of neutralizing antibody titers,virused titers,were all consistent with those survive rates in each group.Conclusion Comparing with pcDNA3/VP1,pcDNA3/MDC-VP1 vaccine can induce a high level of neutralizing antibody titers and result in a higher survival rate in mice,while pcDNA3/STxB-VP1 induce a low level of neutralizing antibody titers and result in a lower survival rate in mice.