Fasola E L, Flores A E, Ferrieri P
Department of Laboratory Medicine and Pathology, University of Minnesota Medical School, Minneapolis 55455, USA.
Clin Diagn Lab Immunol. 1996 May;3(3):321-5. doi: 10.1128/cdli.3.3.321-325.1996.
The R antigen, a trypsin-resistant protein observed in group A, C, F, G, and L streptococci, has also been found in group B streptococci (GBS). Although four species of the R antigen have been described for GBS, the R4 protein is the most prevalent in GBS isolates recovered from humans. This study examined the prevalence of antibodies against the R4 antigen by Western blot (immunoblot) (WB) in sera from 40 mothers colonized with GBS serotype II and III and from 26 noncolonized mothers; 92.5% of the colonized mothers had anti-R4 antibodies, compared with 54% of the noncolonized mothers (P < 0.001). Findings of antibodies in neonatal cord sera (n = 14) were concordant with maternal results by WB analysis for 71% of mother-infant pairs colonized with serotype II and for 57% of pairs colonized with serotype III. Of mothers known to be colonized with type II/R4 or III/R4, 100% (n = 12) had antibody against R4 by WB. This study also evaluated the prevalence of antibody to the GBS R4 antigen in 48 sera from individuals with high and low group A streptococcal anti-DNase B titers. Of those individuals with an anti-DNase B titer of > 640, 64% had a positive WB for anti-R4 antibody, compared with 30% of individuals with low anti-DNase B titers (P < 0.05). The R4 antigen of GBS had immunologic identity to the R4 antigen of group A streptococci. Overall, the findings suggested that antibodies to the streptococcal R4 antigen were commonly present in GBS-colonized mothers and that transplacental passage of these antibodies occurred. The presence of antibody to R4 in non-GBS-colonized individuals may be due to immunologic responses to past exposure to the R antigen present in GBS or other streptococcal groups.
R抗原是在A、C、F、G和L群链球菌中观察到的一种抗胰蛋白酶蛋白，在B群链球菌（GBS）中也有发现。虽然已描述了GBS的四种R抗原，但R4蛋白在从人类分离出的GBS菌株中最为常见。本研究通过蛋白质印迹法（免疫印迹法，WB）检测了40例定植有GBS血清型II和III的母亲以及26例未定植母亲血清中抗R4抗原抗体的流行情况；92.5%的定植母亲有抗R4抗体，相比之下，未定植母亲的这一比例为54%（P<0.001）。通过WB分析，14例新生儿脐带血清中的抗体检测结果与71%血清型II定植母婴对以及57%血清型III定植母婴对的母亲结果一致。在已知定植有II型/R4或III型/R4的母亲中，100%（n=12）通过WB检测有抗R4抗体。本研究还评估了48份来自A群链球菌抗DNA酶B滴度高和低的个体血清中GBS R4抗原抗体的流行情况。在抗DNA酶B滴度>640的个体中，64%的WB检测抗R4抗体呈阳性，相比之下，抗DNA酶B滴度低的个体中这一比例为30%（P<0.05）。GBS的R4抗原与A群链球菌的R4抗原具有免疫同一性。总体而言，研究结果表明，GBS定植母亲中普遍存在抗链球菌R4抗原抗体，且这些抗体可经胎盘传递。未定植GBS个体中存在抗R4抗体可能是由于过去接触GBS或其他链球菌群中存在的R抗原而产生的免疫反应。
