Antibody Against Clostridium perfringens Type A Enterotoxin in Human Sera

Antibody against Clostridium perfringens type A enterotoxin was found in 82% of Brazilian and 65% of American serum samples.     

Properties of Human Anti-Group B Streptococcal Type III Capsular IgG Antibody

The group B streptococcus is the commonest cause of bacterial infection in the newborn. In an attempt to prevent these infections, various vaccines are in development, most of which contain at least one of the capsular carbohydrates of the bacterium. We present new detailed data on the natural human antibody response to the type III capsular carbohydrate as we believe it is important to ascertain equivalent data for any new candidate vaccine in order to predict efficacy. We demonstrate that naturally occurring IgG is opsonically active in a complement-dependent manner, that fractions of differing avidity isolated from single donors have broadly similar opsonic activity, that the clonotypes from four individuals are restricted in number to a maximum of 15, and that binding kinetics ascertained using a resonant mirror biosensor show that specific antibodies have a moderately high affinity (meanK_d= 1.1e-8 M).     

Immunochromatographic Detection of the Group B Streptococcus Antigen from Enrichment Cultures

Group B Streptococcus (GBS; Streptococcus agalactiae) is a leading cause of serious neonatal infections. The Centers for Disease Control and Prevention recommends GBS screening for all pregnant women during the 35th to 37th weeks of gestation. Although GBS screening has been performed mainly by the culture-based method, it takes several days to obtain a reliable result. In this study, we developed a rapid immunochromatographic test (ICT) for the detection of GBS-specific surface immunogenic protein in 15 min using an overnight enrichment culture. The ICT was prepared using two anti-Sip monoclonal antibodies. This ICT was able to detect recombinant Sip levels of 0.5 ng/ml, or about 10⁶ CFU/ml of GBS cells, in tests with 9 GBS strains of different serotypes. The cross-reactivity test using 26 species of microorganism showed no detectable false-positive result. Reactivity of the ICT with 229 GBS strains showed one false-negative result that was attributable to the production of truncated Sip. Among 260 enrichment cultures of vaginal swabs, 17 produced red to orange pigments in Granada medium, and they were all GBS and Sip positive. Among 219 pigment-negative cultures, 12 were GBS positive and 10 were Sip positive. Two Sip-negative cultures contained GBS cells below the limit of detection by the ICT. Among 207 GBS-negative cultures, only one was Sip positive, which was attributable to GBS cell debris. Thus, the sensitivity and specificity of the ICT appeared to be 93.1% and 99.6%, respectively. The newly developed ICT is readily applicable to clinical use in the detection of GBS.     

Antibody Specificity for HL-A in Human Myeloma Sera and Immune Rabbit Sera

Antibodies specific for HL-A antigens were found in sera of two out of four patients with multiple myeloma or gammopathy in the absence of known histoincompatible stimulation. By column chromatography fractionation of the sera the antibody activity was found in the abnormal immunoglobulin peak, and technical difficulties of cytotoxic testing of gammopathy sera were eliminated. Rabbit immune anti-human sera were shown to exhibit cytotoxic reaction patterns similar to one of the myeloma sera with a normal cell donor panel, which suggests the presence of an HL-A core substance or closely associated antigenic material.     

Human B Lymphocyte In Vitro Response to the Group B Streptococcal Type III Capsular Carbohydrate

Anti-group B streptococcal type III polysaccharide-specific human B cells from the peripheral circulation can be activated and delected in an in vitro culture system. It is possible to detect both IgM- and IgG-producing cells from both seropositive and seronegative donors. The specificity of the response was demonstrated by inhibition with excess liquid phase antigen and the use of related but antigenically distinct control antigens. The response was absent without the addition of T cells, optimal at 10% and 25% T cells respectively for IgM- and IgG-secreting cells, and undetectable using 50% T cells. The optimal antigen concentration for in vitro B-cell activation is 2.5 × 10⁻⁴ μ /ml. Cells from 5 of 6 seropositive donors and 3 of 7 seronegative donors produced specific IgM antibody after culture with antigen. We conclude that the control of the human antibody response to the group B streptococcal type III polysaccharide is influenced by T cells. The response seen in the culture system may be of value in assessing future vaccine candidates designed to prevent neonatal infections.     

单克隆抗体AU_（14－1）测定人血清宫颈癌抗原

本研究应用抗小鼠宫颈癌单克隆抗体ＡＵ_１４－１所建立的夹心ＥＬＩＳＡ法，测定了人血清宫颈癌抗原．以４０例正常妇女血清的Ａ４９０均值加３个标准差之和（０．２０Ａ４９０Ｕ）作为阳性阈值，对２５例宫颈癌、５２例宫颈炎和１２例其他妇科疾患病人血清进行检测，结果宫颈癌为２５／２５阳性，宫颈炎２／５２阳性（其中１例阳性者为重度宫颈糜烂），其他妇科疾患均为阴性．此外，１例卵巢癌腹水亦为阴性．经统计学分析，ＡＵ１４－１确定的宫颈癌抗原存在于宫颈鳞癌和腺癌病人血清中，其阳性率均为１００％，敏感性１００％，特异性９６．２％．与目前研究的宫颈癌血清标志物ＳＣＣ和ＣＡ—１２５比较，ＡＵ１４－１—ＥＬＩＳＡ对人血清官颈癌抗原的检测，具有较高的敏感性和特异性以及较好的临床应用前景，并进一步证明了肿瘤“进化抗原”的理论．     

Improvements of a Radioimmunoassay for Measurement of Viral Antibody in Human Sera

Modifications were made which increased the sensitivity of a solid-phase radioimmunoassay for serum antibody to human herpesviruses. Quantitation of antibody can be accomplished by referring to standard curve titrations.     

Tandem Repeat Deletion in the Alpha C Protein of Group B Streptococcus Is recA Independent

Group B streptococci (GBS) contain a family of protective surface proteins characterized by variable numbers of repeating units within the proteins. The prototype alpha C protein of GBS from the type Ia/C strain A909 contains a series of nine identical 246-bp tandem repeat units. We have previously shown that deletions in the tandem repeat region of the alpha C protein affect both the immunogenicity and protective efficacy of the protein in animal models, and these deletions may serve as a virulence mechanism in GBS. The molecular mechanism of tandem repeat deletion is unknown. To determine whether RecA-mediated homologous recombination is involved in this process, we identified, cloned, and sequenced the recA gene homologue from GBS. A strain of GBS with recA deleted, A909DeltarecA, was constructed by insertional inactivation in the recA locus. A909DeltarecA demonstrated significant sensitivity to UV light, and the 50% lethal dose of the mutant strain in a mouse intraperitoneal model of sepsis was 20-fold higher than that of the parent strain. The spontaneous rate of tandem repeat deletion in the alpha C protein in vitro, as well as in our mouse model of immune infection, was studied using A909DeltarecA. We report that tandem repeat deletion in the alpha C protein does occur in the absence of a functional recA gene both in vitro and in vivo, indicating that tandem repeat deletion in GBS occurs by a recA-independent recombinatorial pathway.     

人源性抗HBsAg单抗重链可变区基因序列分析

应用生物工程菌表达法，本文建立了抗ＨＢｓＡｇ单克隆抗体片段组合文库。并筛选阳性株制备了相应的抗体活性片段。人工法对５个阳性株的抗体编码ＤＮＡ重链可变区序列进行了分析，结果表明，５株中有２株ＤＮＡ序列相同，与国外学者所作同类抗体的序列不同，提示是具有抗体活性的不同菌株。同时比较ＤＮＡ、序列发现，氨基酸排列的异同决定抗体的结合活性。ＤＮＡ序列相同的２株其抗体片段的表达能力也相似，表现为酶免疫测定时Ａ值近似。抗体编码基因的序列分析有助于深入探讨抗体的表达能力、亲和力等特性。     

Antibody to group B Streptococcus type III in human sera measured by a mouse protection test.

Antibody to group B Streptococcus type III (GBS-III) was measured in human plasma and sera by using a test which measures the ability to protect outbred albino mice from an intraperitoneal challenge of GBS-III calculated to be lethal to 90% of the mice (LD90 dose). Of three samples from three different lots of commercial human immune serum globulin, none were protective despite the presence of antibody to the native type III polysaccharide. Nine specimens were tested from recipients of multivalent pneumococcal vaccine, and none were protective. Five specimens were tested from recipients of GBS-III polysaccharide vaccines who had responded with greater than 50 micrograms of specific antibody per ml in the blood. All of these were protective and could be diluted to titers of 1:10 to 1:40. Of two prevaccination sera with low levels of specific antibody, neither was protective. An unexpected finding which may limit the sensitivity of the mouse protection assay was that the human immune serum globulin and human serum with a very low level of antibody appeared to increase the lethality of the GBS-III test strain, resulting in LD50 values reduced to 0.01 of the usual LD50.     

确证TRFIA检测乙肝病毒表面抗体结果的研究

建立简易时间分辨免疫荧光法(TRFIA)检测乙型肝炎病毒表面抗体(抗-HBs)的中和试验方法,验证TRFIA检测结果.收集乙型肝炎病毒表面抗原(HBsAg)异常值血清,确定TRFIA中和抑制试验中和比为0.25-1.26ng/mL∶1mIU/mL,对抗-HBs的定量结果进行确认.结果显示,使用TRFIA定量检测的结果与...     

Purification and Immunobiological Properties of R Antigen and Its Relation to M Protein of Type 3 Group A Streptococcus

R protein was extracted from type 3 group A streptococci with hot (95 degrees C) HCl and was purified by ammonium sulfate precipitation followed by molecular-sieve and ion exchange chromatography. Although the R3 antigen was present in a heterogeneous population of proteins ranging from 78,000 to 100,000 daltons in size, we were able to separate an R-rich fraction that contained minimal amounts of heterogeneous proteins as indicated by electrophoresis in sodium dodecyl sulfate-polyacrylamide gels. The final yield of the purified R protein was approximately 15 mug (dry weight) per g (wet weight) of washed and sedimented streptococci. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated a molecular size of approximately 78,000 daltons. Amino acid analysis showed lysine, glutamic acid, alanine, and aspartic acid as the predominant amino acids. A detailed comparison of the purified R3 protein with type 3 M protein indicated a similarity in composition and order of frequency of amino acids. However, the R3 antigen was found to be distinctive from the M3 antigen in agar gel diffusion tests. In addition, R3 and M3 proteins behaved differently in opsonophagocytosis tests and opsonization inhibition tests. Thus, R3 and M3 proteins produced precipitin lines of nonidentity with an unabsorbed antiserum against whole type 3 streptococci: M3-specific antiserum, but not R3-specific antiserum, enhanced the phagocytosis of type 3 streptococci. Purified M3 but not R3 protein was capable of inhibiting the type-specific opsonization of type 3 streptococci. The physicochemical resemblance between M and R proteins in general suggests a common genetic origin. Perhaps R proteins are variant forms of M proteins from which the antiopsonic determinant has been deleted.     

Changing Molecular Epidemiology of Group B Streptococcus in Korea

The prevalence of group B streptococcus (GBS) among pregnant women and disease burdens in neonates and adults are increasing in Korea. Colonizing isolates, collected by screening pregnant women (n=196), and clinical isolates collected from clinical patients throughout Korea (n=234), were serotyped and screened for antibiotic resistance. Serotype III (29.8%) and V (27.7%) predominated, followed by Ia (17.0%). Antibiotic resistance was higher among clinical than colonizing isolates for erythromycin (35.1% and 26.9%; P=0.10) and for clindamycin (49.4% and 42.1%; P=0.17). erm(B) occurred in 91.9% of erythromycin resistant isolates, and 84.0% of isolates resistant to clindamycin. Only five isolates (4.2%) resistant to erythromycin were susceptible to clindamycin; by contrast, and unique to Korea, 34% of isolates resistant to clindamycin were erythromycin susceptible. Among these 60 erythromycin-susceptible & clindamycin-resistant isolates, 88% was serotype III, and lnu(B) was found in 89% of strains. Four fifths of the serotype V isolates were resistant to both erythromycin and clindamycin. Further characterization of the genetic assembly of these resistance conferring genes, erm(B) and lnu(B), will be useful to establish the clonal lineages of multiple resistance genes carrying strains.