A型口蹄疫合成肽疫苗的免疫效力评价

Evaluation of synthetic peptide vaccines againstfoot-and-mouth disease type A

【目的】研制A型口蹄疫(foot-and-mouth disease,FMD)新型合成肽疫苗,为畜牧业减少经济损失。【方法】应用两种含有口蹄疫病毒(foot-and-mouth disease virus,FMDV)AF/72株VP1[131-159]、VP4[20-35]、3A[21-35]和3B[29-42]4个抗原表位的合成肽联合CpG寡聚脱氧核苷酸(5'-TCGCGAACGTTCGCCCGATCGTCGGTA-3')在豚鼠上进行了免疫效力评价。【结果】2.5μg/只的合成肽364能保护4/5的豚鼠免受FMDV AF/72株的攻击,灭活苗组获得完全保护,其他组的保护效力仅为3/5;保护效力最高的两组的外周血CD4+T淋巴细胞含量高达33.7%和36.6%,而其他组不超过27.7%,PBS组仅为18.1%。【结论】本研究筛选出一组免疫效力较好的口蹄疫A型合成肽疫苗,可以作为候选疫苗进行进一步评价。

[Objective] We developed a synthetic vaccine against foot-and-mouth disease type A.[Methods] We studied two peptide-based vaccines containing residues 131 to 159 of VP1,20 to 35 of VP4,21 to 35 of 3A and 29 to 42 of 3B of the AF/72 strain of foot-and-mouth disease virus（FMDV） coupled with a CpG oligodeoxynucleotide（5′-TCGCGAACGTTCGCCCGATCGTCGGTA-3′） in guinea pigs.We assayed the FMDV-specific IgG level,serum neutralizing antibody titer,splenic lymphocytes proliferative capacity and peripheral blood T lymphocyte CD4-CD8 subsets distribution.[Results] The data show that high dose did not ensure a good immunity.In our study,8%（4/5） of peptide 364-2.5-inoculated guinea pigs（2.5 μg of peptide 364 per animal） were protected against AF/72 strain challenge,while the protection ratio from other peptide-immunized groups was lower except the inactivated vaccine-inoculated group which showed a full protection.Our results also indicated that the stimulatory ability of CD4＋ T lymphocyte response played a key role in evaluating effective FMDV vaccine.The highest percentage of CD4＋ T lymphocyte was 36.6% appeared in inactivated vaccine-immunized guinea pigs,the second was 33.7% in peptide 364-2.5-vaccinated group,whereas the remaining ranged from 18.1% to 27.7%.There was no obvious relation between CD8＋ T cells and anti-FMDV infection;our data showed that the CD4/CD8 ratio was not always appropriate for assessing the immune system status.[Conclusion] In general,we not only designed an effective vaccine against FMDV type A,but also discovered some useful information of humoral and cellular responses induced by foot-and-mouth disease vaccines.