Nnalue N A
Department of Medical Microbiology, Faculty of Medicine and Health Sciences, United Arab Emirates University, Al Ain, United Arab Emirates.
Infect Immun. 1998 Sep;66(9):4389-96. doi: 10.1128/IAI.66.9.4389-4396.1998.
To define cross-reactive epitopes in Salmonella lipopolysaccharide (LPS), antisera designated anti-S, anti-Ra, and anti-Re were generated against smooth (S), complete-core (Ra), and deep-core mutant (Re) strains, respectively, and characterized immunochemically. The reactivities of anti-Ra and anti-S with rough LPS (rLPS) chemotypes in enzyme-linked immunosorbent assays (ELISA) decreased progressively with increasing truncation of the complete-core oligosaccharide (e.g., Ra > Rb1 >.Re), while that of anti-Re increased (Ra < Rb1 <.Re). Anti-Ra was relatively more reactive with nonhomologous smooth LPS (sLPS) than anti-S, which in turn was more reactive than anti-Re. This order reflected the relative reactivities of these sera with outer-core rLPS but not those with inner-core rLPS, which suggests that the cross-reactivities of all three sera with sLPS were mediated by antibodies which bind outer-core determinants. Anti-Ra, but not anti-S or anti-Re, reacted with molecules substituted by O chains in immunoblots and revealed ladder-like patterns in sLPSs of various serospecificities. Anti-Ra, however, did not react with O-antigen-specific neoglycoconjugates in ELISA, thus demonstrating specificity for core epitopes. Ra and Rb1 but not other Salmonella core chemotypes inhibited the reactivity of anti-Ra with sLPS in ELISA, which showed that the terminal outer-core disaccharide, alpha-GlcNAc-1-->2-alpha-Glc (GlcNAc-->Glc), was the major epitope of cross-reactive antibodies in the serum. GlcNAc-->Glc represents the conserved motif alpha-hexose-1-->2-alpha-hexose in cores of the Enterobacteriaceae, other homologues of which should likewise be cross-reactive. These results demonstrate that S or Re strains do not elicit cross-reactive antibodies and indicate that immunization with Ra strains may represent a general strategy for eliciting cross-reactive antibodies against LPSs from enteric bacteria.
为了确定沙门氏菌脂多糖（LPS）中的交叉反应表位，分别针对光滑型（S）、全核心型（Ra）和深核心突变型（Re）菌株制备了名为抗-S、抗-Ra和抗-Re的抗血清，并进行了免疫化学表征。在酶联免疫吸附测定（ELISA）中，抗-Ra和抗-S与粗糙型LPS（rLPS）化学型的反应性随着全核心寡糖截短程度的增加而逐渐降低（例如，Ra > Rb1 > Re），而抗-Re的反应性则增加（Ra < Rb1 < Re）。抗-Ra与非同源光滑型LPS（sLPS）的反应性相对高于抗-S，抗-S的反应性又高于抗-Re。这种顺序反映了这些血清与外核心rLPS的相对反应性，但不是与内核心rLPS的反应性，这表明所有三种血清与sLPS的交叉反应是由结合外核心决定簇的抗体介导的。抗-Ra在免疫印迹中与被O链取代的分子发生反应，但抗-S和抗-Re则不反应，并且在各种血清特异性的sLPS中呈现出梯状模式。然而，抗-Ra在ELISA中不与O抗原特异性新糖缀合物发生反应，从而证明了其对核心表位的特异性。Ra和Rb1，但不是其他沙门氏菌核心化学型，在ELISA中抑制了抗-Ra与sLPS的反应性，这表明末端外核心二糖α-GlcNAc-1→2-α-Glc（GlcNAc→Glc）是血清中交叉反应抗体的主要表位。GlcNAc→Glc代表肠杆菌科核心中保守的基序α-己糖-1→2-α-己糖，其其他同源物同样应该具有交叉反应性。这些结果表明S或Re菌株不会引发交叉反应抗体，并表明用Ra菌株进行免疫可能是引发针对肠道细菌LPS的交叉反应抗体的一种通用策略。
