请教表达重组蛋白如何选择有抗原性的氨基酸片段

我的要表达一个重组蛋白做疫苗研究，原来打算弄全长，但全长707个氨基酸，太大，不好表达。现在想取其中一部分来表达，但不知道如何选择有意义的片段，请各位大侠帮忙，下面是氨基酸序列和其抗原性分析，谢谢各位啦！
MKKTLLLSLSLSLSFLLHAEDDGFYTSVGYQIGEAAQMVKNTKGIQELSDNYEKLNNLLNNYSTLNTLIKLSADPSAINDARDNLGSSSRNLLDVKTNSPAYQAVLLALNAAVGLWQVTSYAFTACGPGSNENANGGIQTFNNVPGQDTTTITCNSYYEPGHGGPISTANYAKINQAYQIIQKALTANGANGDGVPVLSNTTTKLDFTINGDKRTGGKPNTPEKFPWSDGKYIHTQWINTIVTPTETNINTENNAQELLKQASIIITTLNEACPNFQNGGRSYWQGISGNGTMCGMFKNEISAIQGMIANAQEAVAQSKIVSENAQNQNNLDTGKPFNPYTDASFAQSMLKNAQAQAEILNQAEQVVKNFEKIPTAFVSDSLGVCYEVQGGERRGTNPGQVTSNTWGAGCAYVKQTITNLDNSIAHFGTQEQQIQQAENIADTLVNFKSRYSELGNTYNSITTALSKVPNAQSLQNVVSKKNNPYSPQGIETNYYLNQNSYNQIQTINQELGRNPFRKVGIVNSQTNNGAMNGIGIQVGYKQFFGQKRKWGARYYGFFDYNHAFIKSSFFNSASDVWTYGFGADALYNFINDKATNFLGKNNKLSVGLFGGIALAGTSWLNSEYVNLATVNNVYNAKMNVANFQFLFNMGVRMNLARSKKKGSDHAAQHGIELGLKIPTINTNYYSFMGAELKYRRLYSVYLNYVFAY

There are 26 antigenic determinants in your sequence:
n Start Sequence End
Position Position
1 4 TLLLSLSLSLSFLLH 18
2 24 FYTSVGY 30
3 64 TLNTLIKLSAD 74
4 89 SRNLLDV 95
5 99 SPAYQAVLLALNAAVGLWQVTSYAFTACG 127
6 173 KINQAYQIIQKA 184
7 193 DGVPVLS 199
8 256 QELLKQASIII 266
9 269 LNEACPN 275
10 311 AQEAVAQSKIVS 322
11 341 TDASFAQ 347
12 361 NQAEQVVKN 369
13 372 KIPTAFVSDSLGVCYEV 388
14 407 GAGCAYVKQ 415
15 441 ADTLVNF 447
16 461 ITTALSKVPNA 471
17 473 SLQNVVS 479
18 517 RKVGIVN 523
19 534 IGIQVGYKQ 542
20 559 DYNHAFIKS 567
21 572 SASDVWT 578
22 582 GADALYN 588
23 602 NKLSVGLFGGIALAG 616
24 621 NSEYVNL 627
25 665 HAAQHGIELGLKI 677
26 691 ELKYRRLYSVYLN 703

是用http://mif.dfci.harvard.edu/Tools/antigenic.pl在线预测的，现在急需各位帮忙，非常感谢。