Infection and Immunity
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* Dữ liệu chỉ mang tính chất tham khảo
Sắp xếp:
Hoá miễn dịch của polysaccharide vỏ và đặc tính độc lực của type VI Streptococcus agalactiae (liên cầu khuẩn nhóm B) Đã tiến hành nghiên cứu hoá miễn dịch của polysaccharide vỏ và đặc tính độc lực của liên cầu khuẩn nhóm B (GBS), type VI. Bằng phương pháp sắc ký anion áp suất cao và điện áp kế xung, cũng như phân tích cộng hưởng từ hạt nhân 13C, cả các polysaccharide ngoại bào và gắn vào tế bào đều có chứa glucose, galactose và axit N-acetylneuraminic theo tỷ lệ mol là 2:2:1. Khác với tất cả các serotype GBS đã được mô tả đến nay (Ia, Ib, II, III, IV và V), không có N-acetylglucosamine hiện diện, bất kể nguồn gốc của chất liệu (tiết ra hoặc gắn vào tế bào; tham khảo hoặc phân lập lâm sàng). Axit sialic có lẽ liên quan đến cấu trúc xác định miễn dịch của serotype mới này vì việc cắt đường này ra khỏi polysaccharide đã tạo ra một kháng nguyên phản ứng rất yếu với kháng huyết thanh type VI và một dòng kết tủa trong mô hình khuếch tán miễn dịch không đồng nhất với polysaccharide type VI tự nhiên. Sử dụng kháng huyết thanh type VI và kỹ thuật protein A-vàng, một viên nang lớn đã được quan sát thấy ở chủng tham khảo GBS type VI qua kính hiển vi điện tử. Tất cả các chủng type VI được kiểm tra đều gây tử vong cho chuột nhắt CD-1, liều gây chết 50% sau khi thử thách trong phúc mạc dao động từ 1.0 (+/- 0.9, độ lệch chuẩn) x 10(5) đến 2.5 (+/- 1.5, độ lệch chuẩn) x 10(5) CFU mỗi con chuột. Kháng huyết thanh của thỏ chống lại polysaccharide vỏ cho thấy hoạt động bảo vệ đối với chuột tiêm trong phúc mạc với chủng tham khảo type VI hoặc với các phân lập lâm sàng, và hoạt động opsonic trong thí nghiệm thực bào.
Infection and Immunity - Tập 61 Số 4 - Trang 1272-1280 - 1993
#polysaccharide vỏ #liên cầu khuẩn nhóm B #type VI #hoá miễn dịch #độc lực #Streptococcus agalactiae #axit sialic #sắc ký anion #cộng hưởng từ hạt nhân #kháng huyết thanh #thực bào #kính hiển vi điện tử #dịch suyễn
Plasmid-controlled colonization factor associated with virulence in Esherichia coli enterotoxigenic for humans An enterotoxin-producing strain of Escherichia coli isolated from a case of cholera-like diarrhea (E. coli strain H-10407) was found to possess a surface-associated colonization factor. Colonization was manifested as the ability of small inocula (10(5) bacteria) to attain large (10(9)) populations in the infant rabbit intestine with a concomitant diarrheal response. A laboratory-passed derivative of E. coli H-10407, designated H-10407-P, failed to exhibit an increase in population in the infant rabbit and also failed to induce diarrhea. Cell-free culture supernatant fluids of E. coli H-10407 and H-10407-P produced equivalent enterotoxic responses in infant and in adult rabbits. Specific anti-colonization factor antiserum was produced by adsorbing hyperimmune anti-H-10407 serum with both heat-killed and living cells E. coli H-10407-P. This specific adsorbed serum protected infant rabbits from challenge with living E. coli H-10407 although the serum did not possess bactericidal activity. The anti-colonization factor serum did not agglutinate a strain of E. coli K-12 possessing the K88 colonization factor peculiar to E. coli enterotoxigenic for swine. By electron microscopy it was demonstrated that E. coli H-10407, but not H10407-, possessed pilus-like surface structures which agglutinated with the specific adsorbed (anti-colonization factor) antiserum. E. coli H-10407 possessed three species of plasmid deoxyribonucleic acid, measuring 60 X 10(6), 42 X 10(6), and 3.7 X 10(6) daltons, respectively. E. coli H-10407-P possessed only the 42 X 10(6)- and the 3.7 X 10(6)-dalton plasmid species. Spontaneous loss of the specific H-10407 surface-associated antigen was accompanied by loss of the 60 X 10(6)-dalton species of plasmid deoxyribonucleic acid and loss of colonizing ability. Thus, it is concluded that the E. coli colonization factor described here is a virulence factor which may play an important and possibly essential role in naturally occurring E. coli enterotoxic diarrhea in man.
Infection and Immunity - Tập 12 Số 3 - Trang 656-667 - 1975
Humoral immune response to the heat-labile enterotoxin of Escherichia coli in naturally acquired diarrhea and antitoxin determination by passive immune hemolysis Acute- and convalescent-phase sera from 132 students attending a university in rural Mexico were assayed for antibody against the heat-labile enterotoxin (LT) of Escherichia coli by neutralization of LT activity in the Y-1 adrenal cell assay and by passive immune hemolysis of LT-sensitized sheep erythrocytes. The two titration methods produced comparable results with respect to antitoxin responses detected. An inverse relationship was found between acute geometric mean antitoxin titer and the occurrence of diarrhea associated with LT-producing E. coli, especially in newly arrived students from the U.S.A. A significant correlation (P less than 0.00 5) was found between a rise in antitoxin titer detectable by the passive immune hemolysis technique and diarrhea with LT-producing E. coli isolated. Thus, humoral antitoxin titers appear to be a useful indicator of immune status with respect to enterotoxigenic (LT) E. coli diarrhea.
Infection and Immunity - Tập 16 Số 3 - Trang 781-788 - 1977
Enterotoxigenicity of Enteropathogenic Serotypes of <i>Escherichia coli</i> Isolated from Infants with Epidemic Diarrhea
Enteropathogenic serotypes of
Escherichia coli
which have been incriminated by epidemiological evidence as responsible for epidemics of acute diarrhea in infants are often found to be nontoxigenic when tested by conventional systems such as Y1-adrenal, Chinese hamster ovary, and suckling mouse assays. Twelve such strains, representing four different enteropathogenic serotypes, were examined for their capacity to elaborate toxic materials which alter water transport. Ultrafiltration fractions prepared to contain either a high-molecular-weight, heatlabile or a low-molecular-weight, heat-stable form of toxin from each strain were perfused through rat jejuna in graded concentrations ranging from 100 μg to 0.1 ng/ml. Ten of the twelve enteropathogenic strains produced one or both toxin forms that induced water secretion at concentrations of 1 to 10 ng/ml. Values in this range are considered indicative of clinically significant enterotoxigenicity in this assay system, and toxins from well-documented toxigenic strains examined in this study were active at these same concentrations. Similar preparations from ten control strains from healthy persons were either inactive or evoked water secretion only at concentrations of 10 to 100 μg/ml. These observations suggest that enteropathogenic serotypes of
E. coli
isolated from epidemics of infantile diarrhea produce diarrhea by elaborating potent heat-labile and heat-stable toxin forms which alter water transport but which are inactive in conventional assay systems. The manner in which these toxins differ either quantitatively or qualitatively from those which stimulate the conventional test systems is unknown.
Infection and Immunity - Tập 21 Số 1 - Trang 171-178 - 1978
Hemagglutination of Human Group A Erythrocytes by Enterotoxigenic <i>Escherichia coli</i> Isolated from Adults with Diarrhea: Correlation with Colonization Factor
Enterotoxigenic
Escherichia coli
(ETEC) of several different serotypes isolated from adults with diarrhea and known to possess the colonization factor antigen (CFA) were found to cause mannose-resistant hemagglutination (HA) of human group A erythrocytes. CFA-negative
E. coli
isolated during the same study did not possess the mannose-resistant hemagglutinin, although some non-ETEC, CFA-negative isolates did exhibit mannose-sensitive HA activity. The mannoseresistant hemagglutinin of ETEC was found to possess many characteristics previously associated with CFA, which is a surface-associated fimbriate heatlabile antigen, and the functionally and morphologically similar K88 and K99 antigens of animal-specific ETEC. Mannose-resistant HA and CFA titers were maximal when ETEC cells were grown on an agar medium (CFA agar) composed primarily of 1% Casamino Acids and 0.15% yeast extract, pH 7.4. Neither CFA nor HA were produced at a growth temperature of 18°C; HA was completely inhibited by pretreatment of CFA-positive cells with the anti-CFA serum. The mannose-resistant hemagglutinin was lost spontaneously and simultaneously with CFA when clinical ETEC isolates were passaged on artificial medium in the laboratory, indicating plasmid control of both entities. The mannose-resistant hemagglutinin of ETEC was shown to be thermolabile, i.e., sensitive to heating at 65°C, as was the CFA. Also, there was correlation between possession of CFA, as detected serologically and by demonstration of biological activity (adherence in the infant rabbit small intestine), presence of CFA-type fimbriae, and the ability of various
E. coli
isolates to cause mannose-resistant HA of human group A erythrocytes. These results indicate that the mannose-resistant HA of ETEC is another manifestation of CFA.
Infection and Immunity - Tập 18 Số 2 - Trang 330-337 - 1977
Direct serological assay for the heat-labile enterotoxin of Escherichia coli, using passive immune hemolysis Sheep erythrocytes sensitized with the heat-labile enterotoxin (LT) of Escherichia coli exhibited passive immune hemolysis (PIH) when exposed to specific antitoxin and complement. Thus, PIH serves as the basis for an in vitro serological assay for LT that is sufficiently specific and sensitive to differentiate LT-positive and LT-negative E. coli isolates. The PIH assay for E. coli LT has been performed with the standard Microtiter system and also by a tube method employing the spectrophotometric determination of hemoglobin release. The spectrophotometric method enhances the sensitivity, accuracy, and objectivity of the PIH assay. The increased sensitivity of the spectrophotometric method also facilitates the identification of LT-positive cultures employing polymyxin "mini-extracts" of whole overnight (18 h) broth cultures of 2.0% Casamino Acid-0.6% yeast extract-salts medium rather than mini-extracts of cells derived from 3.5-h subcultures. Thus, large numbers of E. coli isolates can be individually tested for LT in less than 24 h after broth inoculation by a rapid in vitro assay which requires anti-LT serum as the only specific reagent.
Infection and Immunity - Tập 16 Số 2 - Trang 604-609 - 1977
Structure and function of a 40,000-molecular-weight protein antigen of Mycobacterium tuberculosis A gene encoding a protein antigen from Mycobacterium tuberculosis with a molecular weight of 40,000 has been sequenced. On the basis of sequence homology and functional analyses, we demonstrated that the protein is an L-alanine dehydrogenase (EC 1.4.1.1). The enzyme was demonstrated in M. tuberculosis and Mycobacterium marinum but not in Mycobacterium bovis BCG. The enzyme may play a role in cell wall synthesis because L-alanine is an important constituent of the peptidoglycan layer. Although no consensus signal sequence was identified, we found evidence which suggests that the enzyme is secreted across the cell membrane. The enzyme was characterized and purified by chromatography, thus enabling further studies of its role in virulence and interaction with the immune system of M. tuberculosis-infected individuals.
Infection and Immunity - Tập 60 Số 6 - Trang 2317-2323 - 1992
Comparison of Bacteroides vulgatus strains in the enhancement of experimental ulcerative colitis Strains of Bacteroides vulgatus from a variety of sources were tested for their abilities to enhance the inflammatory response in an experimental model for ulcerative colitis. Although there were considerable differences noted in inflammatory responses when guinea pigs were immunized with the various strains, there did not appear to be any correlation between the source of the isolates and the severity of the carrageenan-induced lesions. Strains from patients with ulcerative colitis were no more active in the model system than were strains from patients with antibiotic-associated colitis or strains from a healthy human source. The antibody titer to the strain used for immunization did not correlate with the severity of the cecal ulcerations, as determined by histopathologic evaluation.
Infection and Immunity - Tập 55 Số 3 - Trang 835-836 - 1987
Adoptive transfer of immune enhancement of experimental ulcerative colitis Previous experiments with the carrageenan model for ulcerative colitis have shown that the inflammatory response in guinea pigs can be enhanced by immunization with and subsequent feeding of Bacteroides vulgatus to experimental animals. The present studies showed that only certain strains of B. vulgatus are capable of provoking immune enhancement of ulcerative colitis. Animals were fed carrageenan and various strains of viable B. vulgatus after immunization with a strain of B. vulgatus isolated from a guinea pig with experimentally induced colitis. Histological comparison of immune and nonimmune groups revealed that immune animals which received B. vulgatus from a patient with inflammatory bowel disease had a significantly (P less than 0.025) greater number of histopathological lesions at 21 days than did nonimmune animals. Immune animals receiving B. vulgatus isolated from a clinically normal source did not show any significant difference in disease status when compared to nonimmune animals. Additional experiments showed that adoptive transfer of spleen cells from animals immunized with B. vulgatus to nonimmune recipient animals is effective in transferring the immune enhancement demonstrated in actively immunized animals. Animals which received immune spleen cells with concurrent feeding of B. vulgatus showed a significant (P less than 0.005) increase in inflammation over control groups, in the absence of high titers of circulating antibody. These experiments indicate that B. vulgatus strain-specific factors are important to immune enhancement of experimental disease and also suggest an involvement of the cell-mediated immune system in this model.
Infection and Immunity - Tập 46 Số 1 - Trang 64-67 - 1984
Systemic uptake and intestinal inflammatory effects of luminal bacterial cell wall polymers in rats with acute colonic injury The systemic uptake and local intestinal inflammatory potential of luminal bacterial cell wall polymers in rats with normal and acutely inflamed colons were measured. Rats were injected intracecally with either 125I-labeled group A streptococcal peptidoglycan-polysaccharide complexes or equal amounts of Na125I, after either nonspecific colonic injury with 4% acetic acid or injection with buffer. The colons of rats injected with peptidoglycan-polysaccharide had higher inflammatory scores than Na125I-injected rats, a greater incidence of mucosal ulceration and transmural inflammation after acetic acid injury, and an increased frequency of focal accumulations of inflammatory cells in the lamina propria and submucosa after buffer injection. Radioactivity in the liver, spleen, and mesenteric lymph nodes was higher in the colon-injured rats that received peptidoglycan-polysaccharide 48 h before tissue collection than in the noninjured rats (P less than 0.002). Group A streptococcal polysaccharide antigen concentration within the liver, spleen, and mesenteric lymph nodes, measured by enzyme-linked immunosorbent assay, was significantly higher in the colon-injured rats that received cell wall polymers than in noninjured rats. These results indicate that luminal bacterial cell wall polymers with well-described inflammatory and immunoregulatory potential can cross injured colonic epithelia and are capable of initiating and potentiating intestinal inflammation.
Infection and Immunity - Tập 56 Số 8 - Trang 2101-2108 - 1988
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