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PubMed1990

Microagglutination test for early and specific serodiagnosis of tularemia.

A microagglutination test with safranin-stained Francisella tularensis antigen was compared with a conventional tube agglutination test for the serodiagnosis of tularemia. The microagglutination test was performed in round-bottom microtiter plates by using 0.025 ml of the antisera and of the antigen. The antibody titers obtained by using the microagglutination test were 8 to 64 times higher than those seen with the tube agglutination. By the microagglutination test, the serum agglutinins were detected 3 days earlier in rabbits and 9 days earlier in humans than by the tube agglutination test. The microagglutination test also detected residual circulating antibodies in humans more than 20 years after recovery from infection. These early agglutinins were shown to be in the immunoglobulin M class because of their sensitivities to 2-mercaptoethanol. No significant group agglutination reaction with Brucella abortus was observed. These observations indicate that the microagglutination test is a useful tool for the early and specific serodiagnosis of tularemia.

Agglutination Tests↗
PubMed1978

Surface modification of guinea pig sperm during in vitro capacitation: an assessment using lectin-induced agglutination of living sperm.

Plant lectins have been used to advantage to study carbohydrate-containing cell surface receptors in numerous systems. In this study, a simple, reliable assay was developed to quantitate lectin-induced agglutinability of sperm. This assay was used successfully to compare some of the surface properties of uncapacitated and capacitated guinea pig sperm. Capacitation was induced by incubating sperm in minimum capacitation medium (MCM) or modified Tyrodes solution (T-PL). Control incubations were done in Ham's F-10 or Hank's balanced salt solution which do not support capacitation. At timed intervals during incubation, sperm samples were assessed for pattern and degree of lectin-induced agglutination. Results establish that: (1) soybean agglutinin (SBA) and to a lesser extent concanavalin A (Con A) induced agglutinability of guinea pig sperm increase during in vitro capacitation in MCM; (2) a similar increase in SBA induced agglutinability occurs during capacitation in T-PL, but not in the non-capacitating media; and (3) for sperm incubated in MCM or T-PL, there is a significant increase in tail to tail agglutination after capacitation. The results with SBA demonstrate that D-galactose and/or N-acetyl-D-galactosamine containing receptor sites or the guinea pig sperm surface are affected by capacitation, and this effect occurs, at least in part, in the sperm tail. Possible explanations for the observed increase in agglutinability are discussed. The agglutination assay may prove useful as a direct test for the occurrence of capacitation and may be especially valuable for species having a small acrosome or limited number of eggs.

Acrosome↗
PubMed1990

Leptospiral antibodies in patients from a Barbadian general practice.

Sera from 1,419 patients who attended a Barbadian general practice for a variety of complaints between 1 April 1984 and 30 April 1988 were examined for leptospiral agglutinins by the microscopic agglutination test (MAT). Sera from the 42 patients with pyrexia of unknown origin, jaundice or kidney involvement, and the 26 patients with titres greater than or equal to 1:400 in the MAT, were also examined by the ELISA for IgM and IgG antibodies. Current or recent mild leptospiral infection was diagnosed in four of the patients, but some mild cases may have been missed. Two further cases of leptospirosis were recorded after the study period ended; both were very ill but responded well to doxycycline therapy. Altogether 177 of the 1,419 patients (12.5%) had agglutination titres greater than or equal to 1:50. These were 104/739 males (14%) and 73/680 females (11%). Seropositivity tended to increase with age (p less than 0.01), and the highest rates were in agricultural workers (35%), labourers (24%) and non-manual outdoor workers (19%). The difference in seropositivity between the main occupational groups was highly significant (p less than 0.001). The serogroups most commonly recorded among the seropositive patients were Autumnalis (31%), Panama (26%), Australis (24%) and Pyrogenes (20%). Autumnalis predominated in each of the main occupational groups except indoor non-manual workers where Panama, Pyrogenes and Australis occurred more frequently. 95% of the positive titres ranged between 1:50 and 1:400. Titres tended to increase with age, but there was no obvious association between higher titres and particular occupations.(ABSTRACT TRUNCATED AT 250 WORDS)

Agglutination Tests↗
PubMed1987

Selective lectin reactions of two stocks of Leishmania enriettii with differing pathogenicity.

Five days old promastigote culture forms of two stocks of Leishmania enriettii pathogenic and non-infective for Cavia procellus, were tested with the lectins of Canavalia ensiformis, Ricinus communis-120, Soja hispida (Glycine maxima), Arachis hypogaea, Ulex europaeus, Ulex europaeus I, Ulex europaeus II, Laburnum alpinum, Lotus tetragonolobus, Euonymus europaeus and with a monoclonal antibody against blood group H. The pathogenic stock reacted with the anti-H lectin of Lotus tetragonolobus and the monoclonal anti-H and the monoclonal anti-H but not with anti-H of U. europaeus I and E. europaeus. The non-infective stock reacted with none of these anti-H specific agglutinins. They had strong agglutination reactions to C. ensiformis (500 micrograms/ml, 1,000 micrograms/ml, 10 mg/ml) R. communis-120 (1:10), S. hispida (1,000 micrograms/ml) and A. hypogaea (500 micrograms/ml, 1,000 micrograms/ml, 2,000 micrograms/ml). They showed moderate agglutinations to U. europaeus, L. alpinum and U. europaeus II. The non-infective stock showed only moderate reactions to C. ensiformis (10 mg/ml), R. communis-120 (1:10), A. hypogaea (2,000 micrograms/ml) and S. hispida (1,000 micrograms/ml). Neither N-acetylneuraminic acid nor neuraminidase was detected on the cell surface of both stocks. This result demonstrates clearly that both stocks of L. enriettii differ in their cell surface carbohydrates. The agglutination reactions with lectins of the non-infective stock of L. enriettii are very similar to L.t. major.

Agglutination↗
PubMed1975

Social interactions and antibody titres in young male chickens (Gallus domesticus).

The influence of social interactions on established antibody titres to a Salmonella pullorum antigen was determined in several Athens Randombred families. In two experiments, a large-bodied, aggresive family and a small-bodied, relatively non-aggressive family were placed in three social environments: (1) Four-bird control groups with no changes in membership once formed; (2) three-bird resident groups to which a new fourth bird was introduced daily; (3) the single bird that had been moved to a new group each day. The normal rate of decline in antibody titres was significantly accelerated in birds that were introduced as new members daily (group 3), but only in members of the small non-aggressive family. In a third experiment, using families relatively close in size and aggressiveness, the effects of social grouping on antibody titres were not significant.

Agglutination Tests↗
PubMed1981

Lectins as biochemical agents for the isolation of sealed membrane vesicles of defined polarity.

The asymmetric distribution of carbohydrate on biological membranes has provided the basis for the development of lectin-affinity methodology which permits the isolation of sealed, inside-out membrane fractions from heterogeneous populations of vesicles. Optimal conditions for these separations have been assessed employing purified right-side-out and inside-out vesicles derived from the plasma membrane of human erythrocytes as a model system. In this special case, homogeneous populations of defined polarity can be produced by varying the ionic conditions during formation of the vesicles. Surface-specific enzymic markers exist also for monitoring the integrity and orientation of a given population. Multivalent lectins such as wheat germ agglutinin and soya bean agglutinin which induce direct agglutination of erythrocyte membrane fragments containing accessible carbohydrate residues, selectively remove more than 90% of right-side-out and non-sealed membrane from a mixed population, a reaction which is inhibited by GluNAc or GalNAc, respectively. Non-agglutinating lectins, e.g. concanavalin A, immobilized on an inert matrix such as Sepharose 4B, may be employed to adsorb out specifically vesicles with exposed glycopeptides on their surface. In this technique, it is necessary normally to remove the non-sealed membranes on Dextran density gradients prior to the final preparation of inside-out vesicles on Con A-Sepharose. Finally, selective immunoprecipitation of fragments with accessible sugars may also be achieved after treatment with a non-agglutinating lectin (concanavalin A) followed by incubation with anti-concanavalin A IgG which promotes rapid aggregation of membrane containing exposed receptors for the lectin. These procedures should prove generally suitable for the isolation of tightly-sealed, inside-out membrane populations in a variety of biological systems. Pure populations of vesicles, exhibiting reversed polarity, are valuable in surface-labelling studies for investigating the structure, function and transmembrane distribution of integral membrane proteins/glycoproteins.

Acetylcholinesterase↗
PubMed1984

A sensitive screening method of detecting anti-granulocyte antibodies employing radiolabeled staphylococcal protein A.

We describe an improved method of detecting anti-granulocyte antibodies utilizing radiolabeled staphylococcal protein A (SPA). The results of this SPA assay were compared to data obtained with leukoagglutination tests and granulocyte indirect immunofluorescence techniques. We have shown that the SPA assay is highly sensitive and reproducible. In addition, absorption studies confirmed that the assay is specific for granulocytes. The SPA assay is performed in microtiter plates, and requires significantly fewer granulocytes and less test sera than previously described techniques. Also, we have shown that granulocytes prepared for this assay can be separated and stored for up to 48 h. Therefore, the SPA assay described herein is particularly useful for screening of sera and is one of the most sensitive assays available for detecting anti-granulocyte antibodies.

Absorption↗
PubMed1975

A pattern in the development of agglutinogenic antigens of cyclically transmitted isolates of Trypanosoma gambiense.

Three isolates of T. gambiense, belonging to 2 serologically different substrains of the species, were cyclically transmitted to rabbits and monkeys by G. morsitans or G. tachinoides. Sera collected from the infected animals were tested for agglutinating antibodies to 17 different serotype antigens prepared from rodent-adapted isolates of T. gambiense. The first antibodies detected in sera from all of the animals agglutinated the same serotype antigen L2, indicating that it possibly consisted of trypanosomes bearing a basic antigen of T. gambiense. In 2 animals infected with 1 isolate the development of antibody to the common serotype L2 was accompanied by the development of antibody to a second serotype U1. Comparisons of the patterns in which antibodies were produced to other serotype antigens in different animals indicated that there were many similarities in the sequences in which they developed in different rabbits infected with (a) any 1 isolate (b) 2 different isolates of 1 substrain and (c) isolates of 2 serologically different substrains. There were also similarities in the sequences in which the antigens developed in rabbits and monkeys infected with an isolate by the same fly or by different tsetse flies. The ordered sequence in which these 3 cyclically transmitted isolates of T. gambiense, of significantly varied origin and laboratory history, produced variant antigens in hosts of different species provides further evidence to support previous suggestions that antigenic variation in trypanosomes is an adaptive process, rather than one involving selection of mutants.

Adaptation, Biological↗
PubMed1979

A study of leptospirosis among animals in Barbados W.I.

Microscopic agglutination tests performed during 1971 and 1972 on Barbadian livestock showed positive serological reactions for leptospirosis as follows: cattle 51%, pigs 13%, sheep 18%, horses 64% and goats 19%. The serogroup Autumnalis predominated in all but horses in which the reactions to the Pyrogenes group appeared slightly higher. After the isolation of a strain of Leptospira serotype fort-bragg (Barbadian strain No. 119) of the Autumnalis serogroup in 1973, and its subsequent inclusion in our test battery of leptospiral antigens, high percentages of cattle, dogs, mongooses and man showed sero-positive reactions against the strain. Attention is called to the wide dissemination of the fort-bragg serotype on the island and to the role of rodents and the mongoose in its spread. 74 clinically affected Barbadian cattle from three herds were studied during 1975-76; 60 (81%) were serologically positive and nine different serogroups were represented. Predominant sero-positive reactions to Hebdomadis, Autumnalis, Ballum and Pyrogenes antigens were recorded. The highest titres were against Autumnalis, Hebdomadis and Pomona. Hebdomadis and Pomona serogroup antibodies may be due to many importations of cattle with those infections into Barbados.

Agglutination Tests↗
PubMed1979

The problem of human leptospirosis in Barbados.

The results of a retrospective study of human leptospirosis cases occurring in Barbados during the period 19-68-74, and of serological findings among high risk occupational groups, fever cases and health centre patients monitored for the disease during 1975-77, indicate that infection by serotype fort-bragg of the Autumnalis group is widespread in this Caribbean island. The occupational groups most affected are sanitation workers and sugar-cane workers. Results of serological tests conducted at the principle hospital are comparable with the results obtained by the microscopic agglutination reference test procedure conducted at the Pan American Zoonosis Centre (CEPANZO).

Adolescent↗