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Species in four genera of yeasts produce mating types that clump when brought together in liquid or on solid media. All species of a phylogenetic line of Saccharomyces are sexually agglutinative. Unisexuals of the latter species are believed to have from one to four sets of chromosomes, whereas bisexuals are believed to have from two to eight sets.
The sensitivity of transformed 3T3 fibroblasts to agglutination by concanavalin A is reduced by alkaloids that bind specifically to protein subunits of microtubules.
The temperature of incubation affected the typability of beta-hemolytic group A streptococci by T-agglutination tests. When strains could not be typed after routine incubation at 30 C, they were incubated at 22 to 25 C, and nearly a 10% increase in typability was achieved. The clinical source of the strains was related to their typability. Incubation at the lower temperature was required for successful typing of higher percentages of strains from the skin and other clinical sources than from the throat. Sixty per cent of the skin strains were represented by six serotypes. Of these, 53% of the strains required incubation at 22 to 25 C before they could be typed.
Cross-reactivity between Candida albicans and representative Enterobacteriaceae was investigated by agglutination methods. It was observed that anti-Candida serum reacted to certain groups of salmonellae and shigellae. The only antiserum against the enteric bacilli that reacted with Candida was Salmonella C(1). When anti-Candida serum was adsorbed with C. albicans or S. montevideo, all the activity was removed. However, when the anti-Salmonella serum was adsorbed with the antigens, Salmonella adsorbed the whole antibody activity, whereas Candida removed only its corresponding antibody.
The serological response in burros and horses to the viable LVS strain of Pasteurella tularensis was studied. High-titered agglutinating antisera and fluorescent-antibody conjugates were obtained in both groups of animals. Maximum titers were obtained in horses 14 to 21 days after the start of vaccination and in burros 21 to 28 days after the start of vaccination. The use of Woodhour's adjuvants or booster inoculations did not result in increased titers.
O antigens of Vibrio parahaemolyticus can be detected by a slide agglutination test.
A newly developed latex agglutination (LA) test and a modified immunodiffusion (ID) test were evaluated. The antigen used was a homogenate of Candida albicans. A total of 167 antisera were employed in the evaluation. They included 36 sera from clinically well persons; 78 from patients with various clinical forms of candidiasis; 52 from patients with proven cases of aspergillosis, blastomycosis, coccidioidomycosis, cryptococcosis, histoplasmosis, nocardiosis, paracoccidioidomycosis, sporotrichosis, and tuberculosis; and one serum from a patient with toruloposis. Use of the LA test in conjunction with the ID test permitted the detection of more than 90% of 43 proven candidiasis cases. Of all the heterologous cases and normal human sera tested, LA reactions were noted with 3 of 10 cryptococcosis case specimens, 1 of 9 tuberculosis case specimens, and with the torulopsemia case serum. In contrast, the only heterologous serum reactive in the ID test was that from the patient with torulopsemia. Torulopsis glabrata and C. albicans antisera gave identical reactions in LA and ID tests with T. glabrata or C. albicans antigens. ID tests with selected antigens, however, permitted differentiation of rabbit and human T. glabrata antibody from that of C. albicans antibody. Six different precipitins were recognized with the C. albicans antigens. The occurrence of multiple precipitin lines and high LA titers was suggestive of severe candidiasis. The LA test, in contrast to the ID test, appeared to have prognostic value. Together, the LA and ID tests provided a simple, rapid, and accurate means of detecting and monitoring infections by species of Candida.
A method for improving the original Galton microtechnique for detecting leptospiral antibodies has been developed. Simultaneous titrations were performed on 281 animal and human sera and 17 hyperimmune sera with the microscopic agglutination (MA) test and the improved microtechnique. Reproducibility of the improved microtechnique was determined independently on 65 animal sera by two laboratory sections. The results obtained by comparing positive test data from human and animal sera indicated that agreement between the original MA test and this new method exceeded 94%, whereas the original Galton microtechnique and the original MA test agreed in a maximum of 77% of the tests. This study indicates that the results obtained with the improved microtechnique are much more comparable to results obtained with the original MA test than are those obtained with the original Galton microtechnique.
Nonspecific inhibitors of rubella hemagglutination can be removed by treatment of sera with heparin-manganous chloride for use in the hemagglutination-inhibition test. After removal of nonspecific inhibitors by this procedure, an excess of manganous chloride may remain. This may cause the cells to agglutinate, thus obscuring the reading at low serum dilutions. This disadvantage can be overcome by the addition of sodium carbonate, which forms an insoluble compound with manganous chloride and does not interfere with antibody determination. The procedure presents a further refinement of the hemagglutination inhibition test for rubella by increasing specificity and sensitivity; it permits detection of antibody levels as low as 1:4 in sera.
Human leishmaniasis is a severe health problem in many countries around the world. Hence, a cheap, reliable, and accurate diagnostic test is required to fight this disease. Perhaps the direct agglutination test (DAT) meets these criteria, but antigen elaboration involves many difficulties. We have developed a new antigen elaboration method, the EasyDAT method, that avoids the problems associated with the DAT. In this study, we compared the traditional DAT antigen method with our EasyDAT antigen method by using canine sera. The sensitivities (100%) and specificities (98.7%) were the same for both methods; we therefore concluded that the EasyDAT Leishmania antigen method simplifies serologic diagnosis, making this method easier and cheaper to use.
Post-kala-azar dermal leishmaniasis (PKDL) is a dermal complication, a sequel to kala-azar. Diagnosis of PKDL presents a challenge due to the low parasite burden in the lesions. The direct agglutination test (DAT) based on promastigote and amastigote antigens of Leishmania donovani of indigenous isolates was developed to diagnose PKDL, and the results were compared with those of the rk39 strip test. The sensitivities of DAT for antileishmanial antibody detection, based on promastigote and amastigote antigens at a cutoff titer of 1:800 were 98.5% and 100%, respectively, with corresponding specificities of 96.5% and 100%. DAT could correctly detect 100% polymorphic cases and 95.4% macular PKDL cases. In comparison, the rk39 strip test was able to correctly diagnose 95.6% of polymorphic and 86.0% macular PKDL cases. DAT based on axenic amastigote antigen provided 100% sensitivity and specificity, making it particularly useful for macular PKDL cases, which are often missed by the rk39 strip test. Thus, DAT provides a simple, reliable, and inexpensive test for PKDL diagnosis with potential applicability in field conditions.
The usefulness of the high-density particle agglutination (HDPA) test as a potential tool for the detection of anti-Coxiella burnetii antibodies in animal sera was studied by using 619 cow, 589 dog, and 150 cat serum samples and antisera from rabbits, guinea pigs, and mice. The sensitivity and specificity of the test versus those of the reference microimmunofluorescence test were determined at two different threshold titer values. At the cutoff value of 1:16, the sensitivities of the HDPA test for cow, dog, and cat sera were 94.3, 95, and 91.3%, respectively, and the specificities were 95.5, 95.3, and 91.3%, respectively. At the cutoff value of 1:32, the sensitivities were 86.7, 88.3, and 82.6%, respectively, and the specificities were 99, 99.2, and 98.4%, respectively. For the group of immune laboratory animals all samples from rabbits, guinea pigs, and mice were positive by the HDPA test. The erythrocyte-sensitizing substance from phase II C. burnetii was found to contain protein and carbohydrate, and both fractions are immunoreactive. The study results show that the HDPA test is a useful tool in the epizootiological survey of Coxiella infection in animals.
Seven strains of Mycoplasma hominis from human genital tracts were selected to produce antisera. The complement-dependent mycoplasmacidal (MC) activity and two complement-independent activities, metabolic inhibition (MI) and agglutination during growth (GA), of these sera were compared. The GA and MI tests were equivalent in titer and generally not affected by concentration of antigen; they revealed specific cross-reacting patterns among the seven strains. There was little if any cross-reactivity with antisera to other human mycoplasmas or to Mycoplasma arthritidis. Control sera from unimmunized rabbits and sera against concentrated uninoculated culture media were also nonreactive. On the other hand, the sensitivity and specificity of the MC test were affected by the concentration of antigen: at about 10(2) color-changing units (CCU) of antigen, all strains were equivalently cross-reactive against the seven antisera, but at 10(2) to 10(4) CCU the individual strain specificity appeared, whereas at about 10(5) CCU little or no antibody was detectable by MC. The MC tests with the lowest concentrations of antigen gave the highest titers of antibody, but at such low concentrations of antigen there was not only loss of individual strain specificity but also some cross-reactivity against other human mycoplasmas, M. arthritidis, or control rabbit sera. Studies with paired human sera also indicate that the MC test with small amounts of antigen is more sensitive than GA-MI.
Antiserum to Staphylococcus aureus strain 17 was treated with S. aureus strain 61218 until the antibodies against thermostable agglutinogen were removed. The absorbed serum agglutinated phage-typable as well as phageuntypable staphylococci of human biotype, whether recovered from people or from dogs.
The common antigen of calf enterotoxigenic strains of Escherichia coli, recently established as the K99 antigen, was studied by means of the slide agglutination test and immunoelectrophoresis. Specific antisera were obtained by absorption of crude antisera with ultrasonicates of autologous cells grown at 18C or by injection into rabbits of the purifies K99 antigen obtained by preparative electrophoresis. The K99 antigen was usually undetectable in calf enterotoxigenic E. coli cultures with capsular K antigens of the A variety grown at 37C on commercially available nutrient agar plates designed for the isolation of Enterobacteriaceae, but was rapidly detectable when grown on a buffered semi-synthetic medium at pH 7.5 (Minca medium). An alternative procedure for the isolation and identification of calf entertosigenic E. coli strains from feces, using the Minca medium, is proposed. K99 was found in 70 of 74 strains of E. coli, the enterotixigenicity of which was established in the ligated gut test in calves. None of the 20 cultures negative in the ligated gut test possessed K99 antigen. The K99 antigen is therefore probably a useful diagnostic tool for the identification of calf enterotixigenic E. coli strains, taking into account that K99 and enterotoxigenicity are controlled by different plasmids.
Serum from healthy, nonimmune humans contained immunoglobulin M (IgM) antibodies that agglutinated Leishmania donovani promastigotes, activated complement, and enhanced promastigote ingestion by human monocytes. The findings indicate that IgM antibodies have the capacity to affect the initial interaction of L. donovani promastigotes with human host defenses.
Monoclonal antibodies (MAbs) were generated against lysates of clinical Mycoplasma hominis isolates. Three of these, designated BG2, BA10, and FE6, recognized an integral membrane protein of M. hominis with an apparent molecular weight of 50,000 (p50). Electron microscopy studies demonstrated that this protein is distributed evenly over the cell surface. These anti-p50 MAbs were species specific for M. hominis; they reacted with 42% of 126 tested clinical M. hominis isolates and showed no reactivity to heterologous mycoplasma species. Immunoblot analysis after limited proteolysis of purified p50 demonstrated that the three MAbs reacted with different epitopes of the protein. Unlike BA10 and FE6, MAb BG2 induced a decrease in arginine metabolism and a reduction of CFU in metabolic inhibition tests. F(ab)2 fragments of MAb BG2 showed the same inhibitory effect as the intact MAb molecule, while Fab and Fc fragments had no influence on vital functions. Preincubation of the mycoplasmas with MAb BG2 followed by trypsin treatment yielded the same amount of CFU as the control without antibodies. In conclusion, the cell aggregates were resolved by the trypsin treatment. These experiments and tests with the antibody fragments led to the conclusion that only the intact MAb structure or the F(ab)2 structure had metabolic inhibition potential and that the observed metabolism inhibition as well as the apparent decrease in viability were a result of agglutination by MAb BG2.
The serine repeat antigen (SERA) is a vaccine candidate antigen of Plasmodium falciparum. Immunization of mice with Escherichia coli-produced recombinant protein of the SERA N-terminal domain (SE47') induced an antiserum that was inhibitory to parasite growth in vitro. Affinity-purified mouse antibodies specific to the recombinant protein inhibited parasite growth between the schizont and ring stages but not between the ring and schizont stages. When Percoll-purified schizonts were cultured with the affinity-purified SE47'-specific antibodies, schizonts and merozoites were agglutinated. Indirect-immunofluorescence assays with unfixed parasite cells showed that SE47'-specific immunoglobulin G (IgG) bound to SERA molecules on rupturing schizonts and merozoites but the IgG did not react with the schizont-infected erythrocytes (RBC). Furthermore, double-fluorescence staining against SE47'-specific IgG and anti-human RBC membrane IgG showed that the RBC membrane disappeared from SE47'-specific-IgG-bound schizonts after cultivation. These observations suggest that the SE47'-specific antibodies inhibit parasite growth by cross-linking SERA molecules that are associated with merozoites in rupturing schizonts with partly broken RBC and parasitophorous vacuole membranes, blocking merozoite release.