抗金黄色葡萄球菌肠毒素B单克隆抗体的特性与中和保护作用

四川大学硕士学位论文ABSTRACTStaphylococcal enterotoxin B (SEB)belongs to a family of pyrogenic toxinsuperantigens (SAgs)which activate T-cells proliferation and massive release ofinflammatory cytokines,leading to toxic shock syndrome and death.It is an urgentneed for the development of a passive immunotherapy against SEB.Ten clones ofMAbs against SEB were prepared and characterized in this investigation.Four amongthese ten clones were evaluated for their neutralization effects in vitro and in vivo,andtheir affinity for SEB.Surface plasmon resonance (SPR)indicated that 4A3,3C1,3E2and 1A5 had similar affinities for SEB.In vitro and in vivo assays showed that theneutralization abilities of 4A3,3C1 and 3E2 were more effective than that of 1A5.Epitopes of MAbs were identified by phage display technology.Epitope mappingrevealed that the epitopes of 4A3 and 3C1 localized to TCR binding sites of SEB,and3E2 to MHC II binding sites;while the epitope of 1A5 was near MHC II binding sites.Finally,we prepared bispecific (3C1-3E2)antibody by conjugating 3C1 and 3E2,anddemonstrated 3C1-3E2 function synergistically to neutralize SEB in vitro and in vivo.These results suggest that 3C1-3E2 neutralizes SEB more effectively than each of theMAbs alone.We predict that bispecific antibody produced by fusing two MAbs,which recognize different function epitopes on SEB,could have better neutralizationpotential against SEB and serve as a novel immunotherapeutic candidate.2