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Comparison of type 2 and type 6 fimbriae of Bordetella pertussis by using agglutinating monoclonal antibodies.

Two types of fimbriae have been identified on the pathogenic gram-negative organism Bordetella pertussis. Monoclonal antibodies to these fimbriae were produced to better understand the role of fimbriae as serotype-specific agglutinogens and to investigate the antigenic relationship between these fimbriae. Three monoclonal antibodies were identified that specifically agglutinated B. pertussis cells containing the U.S. Reference Factor 2 agglutinogen, and six monoclonal antibodies were produced that agglutinated only those strains containing the U.S. Reference Factor 6 agglutinogen. Indirect immunofluorescence studies and immunogold electron microscopy demonstrated that these monoclonal antibodies bind to an outer membrane component on serotype-specific strains of B. pertussis. All of the monoclonal antibodies reacted with native or partially assembled type-specific fimbriae but not with monomeric fimbrial subunits as indicated by Western blot (immunoblot) analysis. The fimbrial agglutinogens recognized by the monoclonal antibodies were also uniquely reactive with either U.S. Reference Factor 2 or 6 antiserum (Eldering agglutinogen 2 or 6 polyclonal antiserum) in an indirect ELISA. No cross-reactivity of the monoclonal antibodies with the unrelated fimbriae was observed in any of the comparative immunological studies. Some of the monoclonal antibodies agglutinated certain strains of B. bronchiseptica, suggesting that this closely related species can contain antigenically similar fimbriae. These monoclonal antibodies should prove useful for further structural and functional analysis of Bordetella fimbriae and for studies on the role that these antigens play in prevention of infection and disease.

Agglutination Tests↗

Age-related buildup of humoral immunity against epitopes for rosette formation and agglutination in African areas of malaria endemicity.

In this report, we show an age-related buildup of agglutinating activity as well as serum activity against rosette formation in children living in areas of Kenya and Gabon where malaria is endemic. Sera from Kenyans in general exhibited a stronger and wider immune response toward the epitopes, probably reflecting a difference in transmission patterns between the two areas. Thus, our results indicate that repeated malaria attacks in areas of endemicity, and consequently exposure to different isolate-specific antigens, will elicit an antibody-mediated response eventually enabling recognition of the majority of rosetting and agglutinating antigens. The correlation between antirosetting and agglutinating capacity was poor in individual cases, indicating that the rosetting epitopes are only a minor part of the highly diverse surface-exposed antigens (mainly PfEMP1) on the surface of parasitized erythrocytes toward which antibodies may react. These data together with our previous findings that the protection against cerebral malaria correlates with presence of antirosetting antibodies shed new light on our understanding of the gradual acquisition of immunity toward severe complications of malarial infection which children reared in areas of endemicity attain.

Adolescent↗

Antibody-mediated inhibition of dextran-sucrose-induced agglutination of Streptococcus mutans.

Immune sera to strains of Streptococcus mutans were found to inhibit agglutination of bacterial suspensions to which either high-molecular-weight dextran or sucrose was added. This inhibitory activity was shown to be mediated by antibody of the immunoglobulin G class. A semiquantitative assay was developed which demonstrated cross-inhibition of dextran/sucrose-induced agglutination among several strains of S. mutans. Antiserum to a partially purified glucosyltransferase was found to lack agglutination inhibition activity, consistent with the hypothesis that the dextran-binding antigen detected by the assay is immunologically distinct from the glucan-synthetic enzyme. A model for glucan synthesis and binding consistent with the reported data is described.

Absorption↗

Agglutinating and bactericidal properties of fractions of rabbit anti-Vibrio cholerae serum.

The major portion of the agglutinating and bactericidal activity of the sera of rabbits immunized with live Vibrio cholerae or with cholera vaccine was found in the gammaM fractions during the early stages of immunization. After 5 weeks or more, gammaG fractions accounted for more than half of the agglutinating activity. When late antibody was measured as the amount of protein precipitated by somatic antigens, nearly 3 times as much gammaG as gammaM was required for agglutination, and about 30 times as much gammaG as gammaM was required to kill 50% of a standard inoculum in the presence of complement. The ratio of vibriocidal to agglutinin titer of gammaG fractions at different stages of immunization was more variable than that of gammaM fractions. More complement was required for a vibriocidal effect by gammaG than by gammaM. Increasing the amount of complement decreased the amount of both gammaG and gammaM required to kill, but smaller amounts of gammaM required disproportionately larger amounts of complement. Less time was required by gammaM than by gammaG to kill 50% of the inoculum. Removal of the group-reactive antibody from anti-Ogawa serum and serum fractions by absorption with Inaba reduced the vibriocidal titer by more than one-half.

Agglutination Tests↗

Determination of brucella immunoglobulin G agglutinating antibody titer with dithiothreitol.

The routine brucella agglutination test measures both immunoglobulin M (IgM) and IgG brucella antibody titers; however, only an elevated IgG titer is significant for differentiating active from inactive disease in patients with symptoms lasting 3 or more weeks. The IgG antibody titer can be determined by treating the serum wih 2-mercaptoethanol to inactivate the IgM brucella antibodies while leaving the IgG brucella antibodies intact. Dithiothreitol, which also inactivates IgM, was compared with 2-mercaptoethanol for the determination of IgG brucella agglutination titers. The dithiothreitol and 2-mercaptoethanol test results agreed within +/- 1 dilution step in 103 of 105 serum specimens tested, for a 98.1% rate of agreement. The results indicate that dithiothreitol can be used in place of 2-mercaptoethanol for determining IgG brucella agglutination titers. Dithiothreitol does not have the offensive odor or the irritant properties of 2-mercaptoethanol.

Agglutination Tests↗

Development of a simple serological method for diagnosing leptospirosis: a microcapsule agglutination test.

A passive microcapsule agglutination test for the diagnosis of leptospirosis was developed by utilizing chemically stable microcapsules instead of sheep erythrocytes. In the test, sonically disrupted antigens of leptospira were sensitized to microcapsules treated with glutaraldehyde. Compared with the microscopic agglutination test, the passive microcapsule agglutination test showed a relatively genus-specific tendency and a 4- to 32-fold-higher sensitivity. The sensitized microcapsule antigens were stable for at least 1 year. The microcapsules coupled with mixed antigens can be used as a serodiagnostic screening test for diseases caused by various types of leptospira. The test, which is very simple and reproducible and requiring no specific training, can be employed easily as a routine test in diagnostic laboratories.

Agglutination Tests↗

Comparison of slide agglutination test and direct immunofluorescence assay for identification of Legionella isolates.

It is technically impractical for many clinical laboratories to use the direct immunofluorescence assay for identifying and serogrouping clinical isolates of Legionella. We compared the results obtained with the direct immunofluorescence assay with the results of a simple and less-demanding slide agglutination test for identifying 15 serogroups representing seven Legionella species. The slide agglutination test was in complete agreement with the direct immunofluorescence assay, and the serogroup to which 64 clinical isolates of Legionella belonged was correctly identified. With polyvalent, pooled antisera and absorbed, serogroup-specific antisera, the slide agglutination test is a useful alternative to the direct immunofluorescence assay in the diagnosis of Legionella infections and for studying the serological relationships of Legionella-like organisms.

Agglutination Tests↗

Evaluation of passive bacterial agglutination for the diagnosis of typhoid fever.

We evaluated the reliability of a passive bacterial agglutination test to detect Salmonella typhi somatic antigen(s) in the sera of patients with typhoid fever. It was positive in 32 of 33 bacteriologically proven typhoid fever cases. Among 13 patients with a presumptive diagnosis of typhoid fever, 11 were positive by passive bacterial agglutination. The serum of one patient with paratyphoid A was also positive. Among 50 febrile patients without typhoid fever, one was persistently positive during the course of illness; 49 were negative. The sensitivity, specificity, and accuracy indices of the passive bacterial agglutination test were over 95%. The positive and negative predictive values were 94 and 98%, respectively.

Agglutination Tests↗

Serogrouping of Clostridium difficile strains by slide agglutination.

Six different agglutinating antisera were obtained by immunizing rabbits with Formol-treated strains of Clostridium difficile. After appropriate absorption, these antisera were used to define six serogroups designated by the letters A, B, C, D, F, and G. Altogether, 315 strains of C. difficile from various origins were tested for slide agglutination by these antisera; 312 (99%) of them were agglutinated by one of these antisera. A and C were the most common serogroups. An excellent correlation, ranging from 85 to 100%, was found between the serogroup and the toxigenicity of the strains. The correlation between serogroup and sorbitol fermentation was higher, ranging from 89 to 100%. The results of this typing were compared with the clinical origin of the strains. Only strains of serogroups A, C, and D were isolated in 153 cases of antibiotic-associated diarrhea. This series included strains from three outbreaks; all the strains in two of the outbreaks belonged to serogroup C, and in the third, all the strains belonged to serogroup A. Strains of serogroups B, F, and G were only found in the stools of asymptomatic neonates or young children. In the latter samples, strains of serogroups A and D were found in the same ratio as in adults with antibiotic-associated diarrhea, but strains of serogroup C were seldom isolated. In patients treated with antineoplastic drugs and suffering from diarrhea, the distribution of the strains was the same as in cases of antibiotic-associated diarrhea.

Agglutination↗

Production and characterization of agglutinating monoclonal antibodies against predominant antigenic factors for Candida albicans.

Two clones, CA4-2 and CA5-4, which produced agglutinating monoclonal immunoglobulin M (IgM) antibodies (MAbs) against mannan antigens of Candida albicans serotype A, were established. The specificity of each MAb was determined by slide agglutination tests for cross-reactivity patterns against the homologous and six other strains of Candida and a strain of Torulopsis: C. albicans serotype B, C. tropicalis, C. guilliermondii, C. krusei, C. parapsilosis, C. pseudotropicalis, and Torulopsis glabrata. The MAb produced by CA4-2 reacted with the homologous, C. tropicalis, and T. glabrata strains, whereas the MAb produced by CA5-4 reacted with the homologous, C. albicans serotype B, and C. tropicalis strains. These results are consistent with results obtained by comparative experiments with several strains of each serotype or species. Specificity of these two MAbs by agglutination was also consistent with the cross-reactivity patterns demonstrated by indirect immunofluorescence staining. The competitive binding experiments by immunofluorescence staining with two MAbs and polyclonal factor sera (PAb factors) 5 and 6 suggested that the MAb from clone CA4-2 did not completely correspond to PAb factor 6 and that the MAb from CA5-4 was distinct from PAb factor 5 in its manner of binding to determinants (the latter was designated 5b), Cross-reactivity patterns, however, furnished evidence that these two MAbs could replace the known PAb factors 6 and 5, respectively, as reagents for aid in the identification of the strains of C. albicans and their serotypes.

Agglutination↗

Staphylococcus aureus strains which are not identified by rapid agglutination methods are of capsular serotype 5.

A total of 183 recent Staphylococcus aureus clinical isolates were tested with three commercially available rapid agglutination methods. The capsular polysaccharide type and resistance to oxacillin of these isolates were also determined. Seven isolates were not identified correctly by agglutination methods. All isolates not identified by the rapid methods were of capsular serotype 5, and of these isolates, six were resistant to oxacillin. The results suggest that these agglutination kits can be improved by the use of antibodies reactive with S. aureus capsular polysaccharide.

Agglutination Tests↗

Comparison of crossed immunoelectrophoresis, enzyme-linked immunosorbent assays, and tube agglutination for serodiagnosis of Yersinia enterocolitica serotype O:3 infection.

Antibodies against Yersinia enterocolitica serotype O:3 were measured by crossed immunoelectrophoresis (XIE) using whole-cell sonic extract as antigen and by enzyme-linked immunosorbent assays (ELISAs) using either purified lipopolysaccharide or whole formalinized cells expressing virulence plasmid-encoded surface antigens (pYV+ cells). The results were compared with those obtained with the standard tube agglutination method. Sera from three groups of people were examined by using these assays. The first group consisted of healthy blood donors, the second consisted of patients with recent infection due to microorganisms other than Y. enterocolitica O:3, and the third consisted of patients with recent Y. enterocolitica O:3 infection. Sera from the last group were also obtained at regular intervals for 12 months postinfection. Results obtained with XIE and the ELISAs were in good agreement with those obtained with tube agglutination. Variation, diagnostic sensitivity, and diagnostic specificity were satisfactory for all the assays studied. However, the lipopolysaccharide ELISA was less laborious than tube agglutination and XIE and carried a somewhat greater diagnostic specificity than the pYV+ ELISA. XIE and the pYV+ ELISA, on the other hand, also had advantages. XIE enabled simultaneous examination of the individual antibody response against a wide range of chromosome-encoded antigens, and the pYV+ ELISA enabled detection of specific pYV antibodies when sera were adsorbed with formalinized pYV-cured Y. enterocolitica O:3 cells prior to the assay.

Adolescent↗

Salmonella serogroups C2 and C3 identified by agglutination using an immunoglobulin G3(kappa) monoclonal antibody (32-1-E3) reactive with a somatic factor 8-like polysaccharide antigen.

An immunoglobulin G3(kappa) monoclonal antibody (MAb), MAb 32-1-E3, which was prepared in BALB/c mice by using a heated, alcohol-acetone-extracted Salmonella newport CDC 50 antigen, reacted with protein-free lipopolysaccharides from Salmonella groups C2 (O:6,8) and C3 (O:-,8) but not with those from any other serogroup tested. Sodium periodate did not inhibit antigen reactivity, which was consistent with its identity as the abequose-containing disaccharide O:8 antigen. Reactivity was inhibited by competition with serogroup C2 (O:6,8) and C3 (O:-,8) antigens but not with non-O:8 antigens. Reactivity was also inhibited by preincubation of the antigen with polyclonal rabbit antiserogroup C2 or C3 antibodies but not with antisera to serogroup C1 or other Salmonella serogroups. The MAb agglutinated with all strains of Salmonella serogroups C2 and C3 tested but not with other bacteria. Agglutination was inhibited by preabsorbing the MAb with either of two serogroup C3 Salmonella strains, S. virginia CDC 189 or S. haardt MDL 83A4545, which contain only O:8, but not by preabsortion with O:8-negative S. cholerasuis MDL 81A7623 (group C1; O:6,7), S. paratyphi type B CDC 157 (group B; O:1,[4],5,12), or Escherichia coli (O:157) (which contains no Salmonella serogroup antigens). The MAb reacted strongly (4+ agglutination) with all 140 wild-type strains of group C2 and C3 Salmonella spp. tested and showed no reaction with any of 1,324 wild-type strains of non-C2 or non-C3 Salmonella spp. tested. The MAb is useful as a replacement for absorbed, polyclonal, single-factor O:8 antiserum to discriminate Salmonella serogroups C2 and C3 from serogroup C1.

Agglutination Tests↗

Evaluation of new agglutination test for identification of oxacillin-susceptible and oxacillin-resistant Staphylococcus aureus.

A new agglutination test (Monostaph +; Bionor, Skien, Norway) has been developed. This new agglutination test has been compared with two other agglutination tests for the identification of 128 isolates of Staphylococcus aureus and 82 coagulase-negative staphylococci. The sensitivities of both Monostaph + and Pastorex Staph-Plus were excellent (98.7 and 97.4%, respectively) in detection of oxacillin-resistant Staphylococcus aureus. The specificity was 96.4% (two Staphylococcus epidermidis isolates and one Staphylococcus hominis isolate were false positive).

Agglutination Tests↗

Single-tube mixed agglutination test for the detection of staphylococcal protein A.

A simple, rapid mixed agglutination test using sheep erythrocytes (SRBC) sensitized with rabbit hemolysin and intact viable staphylococci is described for the detection of bound staphylococcal protein A. Soluble protein A was heat extracted from 50 clinical isolates as well as the Cowan I and Wood 46 strains of Staphylococcus aureus and titered by a hemagglutination test using sensitized SRBC and dilutions of soluble protein A. Protein A could be detected in all of these supernatants including that of S. aureus Wood 46, a strain generally considered to be protein A negative. These organisms were later retested by the mixed agglutination test and even those staphylococcal isolates expressing very low heat-extractable soluble protein A concentrations (1:2 titers) were positive, confirming the sensitivity of the test. In a screen of clinical isolates, only 4 of 235 (1.8%) coagulase-positive isolates were negative in the mixed agglutination test. Of 25 coagulase-negative isolates, none yielded a positive reaction.

Agglutination Tests↗

Detection of heat-stable antigens of Campylobacter jejuni and C. coli by direct agglutination and passive hemagglutination.

The two serotyping schemes for the detection of heat-stable antigens of Campylobacter jejuni and Campylobacter coli use the same strains for antiserum production but differ in the detection systems used for identifying agglutination. The Penner method uses passive hemagglutination (PHA) while the Laboratory of Enteric Pathogens method uses the same antisera but in a whole-bacterial-cell direct agglutination (DA) protocol. C. jejuni produces a polysaccharide capsule, which is antigenic, and is the main component detected by the PHA method. The DA method will detect both capsule antigens and lipopolysaccharide (LPS) or lipooligosaccharide (LOS) surface antigens. Comparison of both methods by using a selection of isolates from human infection has shown a range of variation in agglutination specificity, reflecting the differences in antigens detected by the two methods. While 27.4% of the 416 C. jejuni isolates reacted with the antisera raised against the same type strains by either method, the majority showed a range of more complex relationships. None of the 37 C. coli isolates reacted with the same antiserum by both methods. Together the two schemes gave a total of 102 distinct combined serogroups for C. jejuni and 16 for C. coli. Thus, while some clonally related isolates share the same capsule and LOS or LPS antigens, other strains appear to have a common capsule antigen but differ in their LPS or LOS structures or vice versa.

Agglutination Tests↗

Microtitration agglutination for detection of Treponema hyodysenteriae antibody.

A microtitration agglutination test for the detection of Treponema hyodysenteriae antibody in swine and rabbit sera is described. The following methods provided the best test results: antigen produced from the spirochete after a culturing period of 36 to 44 h at 38 degrees C, washed antigen inactivated with 0.01% Merthiolate at 4 degrees C for 24 to 36 h, sera heated at 56 degrees C for 30 min, a diluent of phosphate-buffered saline (0.01 M, pH 7.2), and test results read macroscopically after 18 to 24 h of incubation at 38 degrees C. The test enabled detection of antibody against pathogenic T. hyodysenteriae with a high level of consistency and sensitivity. Sera against nonpathogenic T. hyodysenteriae produced low agglutinating titers (less than or equal to 1:8) when reacted against antigen from pathogenic isolates. Inactivated antigen remained stable for 7 to 10 days. Specificity of the reaction in the agglutination test was shown by absorption studies.

Agglutination Tests↗

Activation of the murine sarcoma virus genome after infection with the murine leukemia virus as determined by cell agglutination.

Non-virus-producing NIH/3T3 cells transformed by the murine sarcoma virus are agglutinated by conconavalin A to the same low level as normal NIH/3T3 cells. Infection with the murine leukemia virus greatly increases the agglutination of transformed cells but not that of normal cells. These data suggest that the morphological expression of cell transformation and the surface alterations associated with increased cell agglutination are controlled by the expressions of different sarcoma virus genes.

Agglutination↗