Serological Diagnosis of Human Melioidosis with Indirect Hemagglutination and Complement Fixation Tests

An indirect hemagglutination (IHA) test and a complement fixation (CF) test were evaluated from test results on sera from 212 human melioidosis patients of which 119 were culturally proved cases. Significant antibody titers (IHA titers of 1:40 or greater and CF titers of 1:4 or greater) were demonstrated with either test in all except five patients. IHA and CF titers ranged as high as 1:20,480 and 1:1,024, respectively. Antibodies were usually demonstrated by both tests 1 week after onset of disease. Transient seronegative reactions during the course of disease were seen in sera of approximately 19% of the patients with either IHA and CF but rarely with both tests. High titers in either test were obtained by the third week of disease and reached maximum levels in 4 to 5 months. Titers usually were detectable for 9 or more months. Antibodies were detected by IHA and CF tests in 80 to 100% of the sera obtained at various time intervals from 9 months to 2 or more years after disease onset. Antibody persistence occurred in patients who had a short disease course, as well as in patients with prolonged, complicated infections. The IHA test had excellent specificity when evaluated with normal human sera and diverse antimicrobial sera from hyperimmunized rabbits and human patients. The CF antigen appeared to contain common antigens with some but not all types of Pseudomonas aeruginosa. The specificity of the CF antigen could be enhanced without appreciable effect on its sensitivity by use of a titer of 1:8 in lieu of 1:4 as a criterion for a significant reaction. Either test could be used advantageously for the laboratory diagnosis of melioidosis.     

Effects of a Single Histoplasmin Skin Test on the Serological Diagnosis of Histoplasmosis

Numerous reports have indicated that a single histoplasmin skin test may stimulate humoral antibodies to Histoplasma capsulatum antigens in histoplasmin-hypersensitive individuals. Although these investigations concur that antibody elevations are evoked, they vary in the reported degree of incidence and response induced, and they cast doubt on the interpretation of serological tests in the diagnosis of histoplasmosis. Histoplasmin-hypersensitive subjects (114) were bled prior to administration of the skin test, 2 days later, at the time this test was read, and 15 and 30 days after testing. No significant antibody titers were observed at 2 days. At 15- and 30-day intervals, only 17 (15%) of the subjects demonstrated circulating antibodies. All 17 showed agar gel bands; 5 demonstrated no complement-fixation (CF) titers, 10 produced CF antibodies ranging from 1:8 to 1:16, and 2 demonstrated titers of 1:32. The data suggest that skin testing does not interfere significantly with antibody levels in sera drawn approximately 2 days after administration of antigen. However, since titers as high as 1:32 were obtained at later intervals, such reactions should be evaluated cautiously and only after consideration of clinical findings.     

Detection of Coronavirus 229E Antibody by Indirect Hemagglutination

Tannic-acid treated sheep erythrocytes (fresh or glutaraldehyde preserved) were sensitized with 229E antigens from human embryonic lung (RU-1) cell cultures. Indirect hemagglutination (IHA) antigen titers in 229E-infected cell cultures paralleled virus infectivity and complement fixation (CF) antigen titers. The identity of the IHA antigen was confirmed by testing extracts from inoculated and control cell cultures for ability to inhibit IHA. Also, significant increases in IHA antibody were demonstrated with acute and convalescent serum pairs from patients with proven 229E infections. A comparison of IHA, neutralization and CF titers for 229E antibodies was made on human sera drawn from different populations. The IHA and neutralization results were in agreement on 93% of the 129 sera found to be positive by at least one of three tests. The number of antibody titers detected by the CF test was insufficient to permit comparison. Hyperimmune sera from animals immunized with OC 43 did not react with 229E by IHA. Also no increase in IHA antibody was demonstrated with acute and convalescent serum pairs from patients with seroconversions to OC 43. These findings suggest that the IHA test provides (i) a rapid and sensitive method for serodiagnosis of 229E infections and (ii) a simple and inexpensive method for seroepidemiological studies.     

Serologic distribution of antibodies against adenoviruses in sheep of large-scale farms.

The common soluble antigen of the first subgroup of bovine adenoviruses was used for assaying 793 sheep sera by the agar gel diffusion test. Of the 50 farms included in the study 43 were found infected. The ratio of reacting samples was 73.7% of the sera obtained from infected farms. Virus neutralization tests revealed that a considerable number of sera reacted specifically with all types of ovine adenoviruses, even with serotypes which had never been isolated in Hungary. The results yielded by the agar gel diffusion tests were compared with the results of virus neutralization tests. Of 850 cattle serum samples, agar gel diffusion tests gave positive results in 33.4%. Virus neutralization test was done only with the bovine and adenovirus type 2. No differences could be detected in antibody titres when the prototype strains (No. 19) and the strain isolated from sheep (ORT/111) were compared in parallel titrations. Both ruminant species were found to be infected with hovine adenovirus type 2. Neverthless, inapparent infection with these strains seemed to be less frequent among cattle than in sheep flocks.     

Sensitive Matrix Gel Diffusion Test for the Detection of Australia Antigen

A matrix gel diffusion (MGD) procedure with a sensitivity comparable to the complement fixation test (CF) has been developed for detecting Australia antigen in serum. The test utilizes a thin layer of agar (0.1 mm) with an applied plastic matrix. Reactants are introduced directly onto the surface of the agar through wells in the plastic matrix. End points obtained by CF with a panel of 11 sera varied from 1:8 to 1:512. When these sera were tested by MGD, end points for detection of antigen were within one dilution of that obtained by CF.     

Humoral antibody response and Ig characterization of the specific agglutinins in rabbits during experimental American trypanosomiasis

A comparative follow up study of the specific agglutinins detected by direct agglutination (DA) test and the immune response detected by specific lysis (SL), indirect immunofluorescence (IFA), indirect hemagglutination (IHA) and complement fixation (CF) tests in rabbits inoculated with trypomastigotes of T. cruzi is reported here.The specific antibody response was detected first by DA test. Reductive cleavage of sera with 2-mercaptoethanol produced a drop in the agglutinin titer of the sera during the first 30 days of infection.The next test to become positive was SL and later on the IFA, IHA and CF tests became positive simultaneously.When fractions obtained by column chromatography in Sephadex G-200 were tested serologically it was demonstrated that specific antibodies were detected mainly in fraction I (IgM) of the pooled rabbit sera obtained 15 days after inoculation (acute stage), and in fraction II (IgG) of the pooled sera obtained from rabbits 90 days after inoculation (chronic stage).Antigens prepared with trypsinized and formolized epimastigotes of three T. cruzi strains, belonging to each one of the different immunological groups described, worked similarly in the detection of specific agglutinin antibodies.Trypanosoma cruzi agglutinins were highly specific in their reaction with their homologous T. cruzi antigens as was proved by the low agglutinin titer obtained in sera from infected rabbits when, instead of T. cruzi epimastigotes, promastigotes of L. donovani were used as antigen, and by the incapacity of this parasite to absorb the T. cruzi agglutinins.     

An indirect hemagglutination antibody test to detect antibodies to Borrelia burgdorferi in patients with Lyme disease

An indirect hemagglutination antibody (IHA) test was evaluated for its ability to detect borrelial antibodies in serum samples from patients with Lyme disease. The key test reagent developed for this antibody detection system was tannic acid-treated and glutaraldehyde-fixed sheep red blood cells (SRBC) containing Borrelia burgdorferi (Bb) antigens attached to the outer surface of the SRBC. In order to establish suitable cut-off titers, initial specificity and sensitivity measurements were made using sera from 100 anonymous healthy volunteers and 30 additional pre-determined samples known to be non-reactive or reactive for Lyme disease or syphilis. These results were compared with those obtained using a commercially available ELISA. At titers >/=64, the IHA test had a combined 98% specificity and 100% sensitivity for these 130 serum samples, 30 of which were known positives or negatives, whereas the ELISA was less specific (93%) and much less sensitive (80%). Subsequent testing was performed on sera from 65 patients with the erythema migrans (EM) rash and 20 patients with early disseminated (cardiac/neurologic) symptoms or with Lyme arthritis. At initial presentation, 46-48% of the EM patients had IHA reactivity, with titers >/=128, while 42% were positive in the ELISA. Follow-up testing performed on these EM patients, 8-12 days after receiving antibiotic treatment, revealed that Bb antibodies were detected best by the IHA test (83-86% reactive) relative to the ELISA (81% reactive). Bb antibodies were readily detectable on all of the serum samples from the early disseminated and late stage Lyme disease cases in both assay systems. Based on these results and because of its technical and interpretive simplicity, the IHA test should be considered as a useful and convenient alternative for the serological analysis of Bb infections.     

Characterization of antigen purified from type 3 strains of Pasteurella multocida and its use for an enzyme-linked immunosorbent assay

Surface antigens were purified from a type 3, 4 rabbit isolate of Pasteurella multocida designated as R11146. Two protein peaks were obtained by gel filtration with Sephadex G-200 from crude saline extract. Major antigenic activity was detected in the first peak. The first peak was absorbed onto DEAE-cellulose and eluted by a linear gradient of NaCl. Four fractions eluted from the column contained a single antigen which was identical to an antigen purified from another type 3 strain, P-1059. Also, they uniformly contained two protein species of molecular weights of 44,000 and 25,500. Six Pasteurella-free rabbits were infected intranasally with R11146 isolate and antibody response was determined by an enzyme-linked immunosorbent assay (ELISA) with the use of an antigen purified from P-1059 strain. Serum samples from the infected rabbits showed ELISA titers at the plateau stage by 21 or 28 days post-inoculation. Highest titers ranged from 1:15,000 to 1:16,000, while all the preinoculation sera had titers lower than 1:10. The high titers generally persisted for longer than 98 days after the infection. These results indicate that ELISA using a purified type 3 antigen is useful to detect P. multocida infection in rabbits by a type 3-related strain.     

Candida albicans antigens studied in complement fixation test and agar gel diffusion test

Summary The antigens prepared simultaneously from seven type ACandida albicans strains by cell disintegration by means of sonic vibrations, grinding with the sea-sand, autolysis and the antigens precipitated with acetone from fluid cultures were studied in complement fixation test and agar gel diffusion test against selected rabbit immune sera. The complement fixation test was performed in plexiglass plates as chessboard titration. The agar gel diffusion test was performed in petri dishes according toOuchterlony and according toBjörklund's specific inhibition of precipitation. The activity of studied antigens determined in complement fixation test was high. The antigen titers were ranging from 1/512 to 1/8192. The reaction observed in agar gel diffusion test were also strong and precipitation spectra consisted of 1–3 lines. The reaction pattern obtained in both tests depended on the character of the analysed reagents. TheBjörklund's modification was successfully applied to serological grouping of the strains under study. Sixteen human sera collected from patients with symptoms of Asthma bronchiale and Bronchitis chronica, from whose sputumCandida albicans was isolated, were tested in both tests. The researches made on human sera were intended as preliminary tests.Head of the department: Prof. Dr.Z. Przybylkiewicz.     

An enzyme-linked immunosorbent assay to detect serum IgG to Pasteurella multocida in naturally and experimentally infected rabbits

An enzyme-linked immunosorbent assay (ELISA) was evaluated for efficacy in detecting serum IgG against Pasteurella multocida in both naturally and experimentally infected rabbits. Blood samples and nasal cultures were taken concurrently from 58 rabbits from four conventional rabbitries. Nine rabbits from a pasteurella-free colony served as negative controls. Fifty-six rabbits were ELISA positive. Of these, 46 were P. multocida culture positive, 10 were culture negative. Two rabbits were ELISA negative, culture negative. There were no ELISA negative, culture positive animals. Serotyping by the gel diffusion precipitin test demonstrated that of the 44 typed P. multocida isolates, 57% were serotype 4, 27% were serotype 12 and 16% were serotype 3. In rabbits experimentally infected intranasally with P. multocida, serum IgG against P. multocida began to rise 21 to 33 days after infection and remained elevated until the animals were euthanized 90 days post infection. Two enzyme-linked immunosorbent assays were compared which used potassium thiocyanate extracts of different serotypes of P. multocida as antigen. The results obtained were similar, suggesting the presence of antigens common to both serotypes.     

Serosurveillance for Pseudomonas pseudomallei infection in Thailand.

A nation-wide survey was conducted to see the prevalence of serosensitivity to Pseudomonas pseudomallei antigens by indirect hemagglutination (IHA) and indirect immunofluorescent assay (IFA) for IgG and IgM. Serum samples were collected from blood donors in eight selected areas and bacteriologically confirmed melioidosis patients in Ubon Ratchathani province. The distribution patterns of antibody titers were compared among the survey areas with cut-off points set at 1:160 for IHA, 1:4 for IFA-IgM and 1:32 for IFA-IgG. These cut-off points were decided by ROC (Receiver Operating Characteristics) analysis. The specificity (% true negative reactions) of each serological test in the general population differed significantly among survey areas, possibly reflecting the extent of inapparent infection in each community. IFA was more successful than IHA in differentiating between negative from positive reactions. The survey classified the areas into endemic (Khon Kaen, Ubon Ratchathani), transported (Bangkok), and non-endemic (other provinces) types.     

Indirect Hemagglutinating Antibody Response to Herpesvirus hominis Types 1 and 2 in Immunized Laboratory Animals and in Natural Infections of Man

Indirect hemagglutinating (IHA) antibody responses to Herpesvirus hominis types 1 and 2 (HVH-1 and HVH-2) were compared to complement-fixing and neutralizing antibody responses in immunized laboratory animals (rabbits, guinea pigs, and hamsters) and in natural infections of man. With the immunized animals, type specificity was seen only in the IHA test and only with antisera produced in hamsters and in the rabbits immunized with HVH-2. In human nongenital infections (considered to be caused predominately by HVH-1), IHA and neutralizing antibodies developed at about the same rate and reached approximately the same levels for HVH-1 and HVH-2. IHA titers tended to be higher than neutralizing antibody titers for both virus types. In genital infections (considered to be caused predominately by HVH-2), there was a rapid IHA antibody response to HVH-2, and the early HVH-2 antibody demonstrable by IHA, but not by neutralization tests, was found to be immunoglobulin M in nature. In genital infections, IHA titers for HVH-2 were markedly higher than neutralization titers, but there was no pronounced difference in neutralizing the IHA antibody titers for HVH-1. Several patients with genital infections fialed to develop IHA antibody for HVH-1. The IHA test possessed no greater sensitivity than did complement fixation or neutralization tests for serodiagnosis of HVH infections. Despite the fact that a number of patients with genital infections produced IHA antibody only for HVH-2, the test was no more effective than the neutralization test in providing a type-specific serodiagnosis of infection, due largely to the fact that the rapid IHA antibody response to HVH-2 prevented demonstration of a further, significant antibody titer increase in a number of cases.     

A sero-epidemiological study of onchocerciasis with the indirect hemagglutination test

A sero-epidemiological study of onchocerciasis was carried out with the IHA test in Guatemala. In the endemic area, 94.8% of 191 subjects with microfilariae, 82.1% of 172 cases with onchocercal nodules, and 22.5% of 236 cases without either microfilariae or nodules gave positive reactions in the IHA test. On the other hand, the positive rate was 3.4% and 2.0% in each of 2 nonendemic populations. A follow-up study of reactors in the IHA with neither microfilariae nor nodules showed that 11 (42%) of 26 cases were microfilaria positive 6--7 mo after the first examination. A clear correlation was found between the results of the IHA test and skin biopsy in surveyed communities. The age distribution curve of the IHA test was closely associated with skin biopsy although the former was higher. IHA titers rose in proportion to microfilarial density. A sex-related difference was evident in the IHA positive rate in the subjects from medium and low endemic areas, but little difference was shown in individuals from a higher endemic area.     

Seroprevalence of Toxoplasma gondii infection in goats by the indirect haemagglutination, immunofluorescence and immunoenzymatic tests in the region of Uberlândia, Brazil

A comparative study of the indirect haemagglutination (IHA), immunofluorescence (IFAT) and immunoenzymatic (ELISA) tests was carried out to determine the prevalence of Toxoplasma gondii antibodies in goats. One hundred seventy-four serum samples were obtained from four goat herds from the region of Uberlandia, State of Minas Gerais. The distribution of the animals, according to their origin, was as follow: 71 from herd I; 39 from herd II; 37 from herd III; and 27 from herd IV. Serum samples were analyzed by IHA, IFAT and ELISA, considering the reactivity of the serum samples at dilution > or = 1:64 as cut off titer for the three tests. A global seroprevalence of 18.4% was observed, with significantly higher positivity rate in the herd II (66.7%) and older animals (> 36 months). A high and significant positive correlation was found between the titers obtained by the IHA versus IFAT, IHA versus ELISA, and ELISA versus IFAT. Therefore, it can be concluded that the three analyzed tests have shown to be highly concordant and appropriate for epidemiological surveys of Toxoplasma infection in goats. Although the seroprevalence of T. gondii infection in goats is relatively low in this region as compared to other regions of the country, adequate management might be useful and essential to control the infection in the goat herds.     

Preparation and Standardization of an Australia Antigen Antibody of Equine Origin

A horse has been immunized with Australia antigen (Au/SH) purified 20-fold by a procedure employing gel filtration of Cohn fraction IV derived from an Au/SH-positive human plasma pool. Hyperimmunization was initiated by the intramuscular injection of 20 ml of a mixture of equal parts of purified Au/SH and complete Freund's adjuvant. The 20-ml volume was divided into four 5-ml doses, two of which were administered on each side of the horse's neck. Booster doses of antigen alone were given as follows: 10 ml intravenously 30 days later and 5 ml intramuscularly on each of days 77 and 205. Au/SH antibody formed readily, beginning on day 17, and was demonstrated by the agar gel double-diffusion technique and the complement fixation test during the subsequent 6 months. Antihuman plasma protein antibodies were effectively removed from the horse serum by one absorption with 1 to 3 volumes of normal human plasma. Abrupt rises in anticomplementary activity observed shortly after the third and fourth antigen injections, when the horse had developed elevated and steady levels of Au/SH antibody, could possibly be due to formation of antigen-antibody complexes. After optimal conditions were determined, an Au/SH antibody reagent pool which met official requirements was prepared. It was found equally suitable for the agar gel double-diffusion, complement fixation, and counterimmunoelectrophoresis test procedures.     

Use of the agar diffusion precipitation test in the diagnosis of hog cholera

The application of the agar diffusion precipitation (ADP) test for diagnosing hog cholera was investigated. The test used as antigen, pancreatic tissue from 272 pigs that had been inoculated with hog cholera virus. The test was positive for 13.5% of the animals that were sick for 4 days or less, 40% of those sick for 5 days, and 77% of those sick for 6 days or more. The test was positive for 13.5% of all animals that had been vaccinated with crystal violet-glycerol hog cholera vaccine and had been sick for at least 6 days after challenge inoculation. Titration of the virus in ADP-test-negative and ADP-test-positive pancreatic suspensions did not show a direct correlation between the infective virus particle and the precipitating antigen.     

Effects of frozen storage on the structure of sarcocysts in pig muscle and implications in taxonomic studies

The morphology of the cyst wall of Sarcocystis has unique characteristics that can be used in species identification. To find a suitable way to preserve Sarcocystis cyst samples for species identification, by light microscopy and electron microscopy, we recorded the morphological changes in the cysts of Sarcocystis suihominis and Sarcocystis miescheriana from pig muscle, induced by storage at -20 degrees C. Comparisons were made between fresh cysts and those subjected to frozen storage for periods of 3 days, 20 days and 30 days. Results: cyst wall of the two Sarcocystis species appeared unaffected by storage. There was no obvious change in the length, nor in the width of the protrusions after storage (P>0.05), but the structure of the bradyzoite in the sarcocyst was in many cases disintegrated at -20 degrees C in 20 days for S. miescheriana and 30 days for S. suihominis. To our knowledge this is the first report that Sarcocystis cyst in muscle can be stored at -20 degrees C before and remain suitable for ultrastructural morphological study. Consequently, this paper proposes freezing as a convenient storage method for samples used in taxonomic studies of Sarcocystis.     

Indirect haemagglutination (IHA) test in the serodiagnosis of amoebiasis

Among 72 patients clinically suspected of Entamoeba histolytica (E. histolytica) infections, 39 positive cases (54%) were detected serologically by the indirect hemagglutination (IHA) test. Parasitologically, microscopic examination of three consecutive stool specimens from all these patients indicated positivity for E. histolytica cysts and or trophozoites in 10 of the patients with IHA antibody titers greater than or equal to 1:128, which is of clinical significance. Another 2 patients were parasitologically positive but showed low IHA antibody titres (1:32-1:64); follow up indicated response to treatment with metronidazole. The highest serological positivity (100%) were detected in patients with liver abscess, all were clinically proven cases of extra-intestinal amoebiasis. IHA antibody levels of clinical significance were seen in all four patients with chronic dysentery with parasitological evidence of E. histolytica in their stools. In a group of patients with abdominal pain nine positives were detected serologically, four of which were positively diagnosed concurrently by parasitology; the remaining five patient's sera showed high IHA antibody titres with absence of cysts or trophozoites in stools, indicative possibly of persistence of antibodies from past infection. The serologic determination of E. histolytica IHA antibodies in a control group consisting of normal healthy school children and adults of both sexes without any clinical evidence of amoebiasis showed the absence of any positive titres of clinical significance; low titres (1:32-1:64) were detected in 5.2% of 232 sera tested. Parasitological examination of three consecutive stool specimens from all individuals in the control group showed the presence of cysts of E. histolytica in just two among 232 tested (0.9%).     

Serological Characterization of Haemophilus Pleuropneumoniae (Actinobacillus Pleuropneumoniae) Strains and Proposal of a New Serotype: Serotype 9

Ten strains of H. pleuropneumoniae isolated from 10 herd outbreaks of pleuropneumonia were studied by means of the slide agglutination test, the indirect haemaggluitiniation (IHA) test and by gel diffusion. The strains were antigenically homogeneous and serologically distinct from serotypes 1 through 8. It is therefore proposed to refer these strains to a new serotype: serotype 9, with strain CVJ 13261 as the type strain. In addition to the serotype-specific capsular antigens, capsular antigen of serotype 1 (strain 4074) could be demonstrated in the 10 strains by means of gel diffusion analyses. In cross protection studies it was shown that the antigenic determinants shared by serotypes 9 and 1 were unable to yield a sufficient protection against disease. Thus, parenteral immunization with a killed 6-h culture of serotype 9 did not afford an acceptable protection against challenge with serotype 1 since only 3 of the 5 vaccinates were protected. The reverse experiment showed that parenteral immunization with serotype 1 only protected 1 out of 4 vaccinates.     

Evaluation and comparison of an indirect fluorescent antibody test for detection of antibodies to Sarcocystis neurona, using serum and cerebrospinal fluid of naturally and experimentally infected, and vaccinated horses

The objectives of this study were to evaluate the accuracy of the indirect fluorescent antibody test (IFAT) using serum and cerebrospinal fluid (CSF) of horses naturally and experimentally infected with Sarcocystis neurona, to assess the correlation between serum and CSF titers, and to determine the effect of S. neurona vaccination on the diagnosis of infection. Using receiver-operating characteristic analysis, the areas under the curve for the IFAT were 0.97 (serum) and 0.99 (CSF). Sensitivity and specificity were 83.3 and 96.9% (serum, cutoff 80) and 100 and 99% (CSF, cutoff 5), respectively. Titer-specific likelihood ratios (LRs) ranged from 0.03 to 187.8 for titers between <10 and 640. Median time to conversion was 22-26 days postinfection (DPI) (serum) and 30 DPI (CSF). The correlation between serum and CSF titers was moderately strong (r = 0.6) at 30 DPI. Percentage of vaccinated antibody-positive horses ranged from 0 to 95% between 0 and 112 days after the second vaccination. Thus, the IFAT was reliable and accurate using serum and CSF. Use of LRs potentially improves clinical decision making. Correlation between serum and CSF titers affects the joint accuracy of the IFAT; therefore, the ratio of serum to CSF titers has potential diagnostic value. The S. neurona vaccine could possibly interfere with equine protozoal myeloencephalitis diagnosis.