Evaluation of three serological tests for brucellosis in naturally infected cattle using latent class analysis

Serological methods are traditionally used in diagnosis of brucellosis. However, the comparative performance of these tests and their accuracy under the local environment in Zambia has not been assessed. Thus, the objective of our study was to evaluate the diagnostic performance of three serological tests for brucellosis; Rose Bengal Test (RBT), competitive ELISA (c-ELISA) and Fluorescence Polarisation Assay (FPA) in naturally infected cattle in Zambia without an appropriate reference test to classify animals into truly infected and non-infected. Serological test results from a study to determine sero-prevalence were used to compare the performance of RBT, c-ELISA and FPA in diagnosing brucellosis in traditional cattle. Since none of the tests can be seen as a perfect reference test or gold standard, their performance in a population of naturally infected cattle was evaluated using latent class analysis which allows the sensitivity (Se) and specificity (Sp) to be estimated in the absence of a gold standard. The highest Se was achieved by the c-ELISA (97%; Credible Posterior Interval (CPI)=93-100%) and the highest Sp by the FPA (93%; CPI=85-99%), conversely these tests also had the lowest Sp and Se, respectively, with the RBT performing well in both the Se (93%; CPI=84-98%) and Sp (81%; CPI=61-97).

A comparative study of the cellular immune response in patients with stage IB cervical squamous cell carcinoma. Low numbers of several immune cell subtypes are strongly associated with relapse of disease within 5 years

OBJECTIVE

The purpose of this study was to investigate possible differences in the primary in situ cellular immune response between patients with and without relapse of Stage IB cervical squamous cell carcinoma.

METHOD

Paraffin-embedded tissue from 40 patients (20 with and 20 without relapse) was evaluated. Sections were immunostained for CD1a+, CD3+, CD4+, CD8+, CD20+, CD45RA+, CD45RO+, CD57+, CD68+ and GrB+ cells. Immune cell profile densities were estimated using stereology.

RESULTS

We found significantly lower densities of CD3+, CD4+, CD8+ and CD57+ cells (both intra- and peritumoral) in tissue from patients who had relapse. Also densities of intratumoral CD1a+ cells and peritumoral CD20+, CD45RA+ and CD45RO+ cells were significantly lower among patients with relapse.

CONCLUSION

This study demonstrates striking differences in the cellular immune response between patients with and without relapse within 5 years. The results are of potential value in adjuvant immunotherapy and prediction of prognosis.

Salmonella enterica Serotype Urbana Interference with Brucellosis Serology

Sheep were immunized with killed Salmonella enterica serotype Urbana cells and their sera were tested in various serological tests for antibody to Brucella sp., Yersinia enterocolitica O:9 and Escherichia coli O:157 H:7. Of the eight sheep, all gave a positive agglutination reaction in the brucellosis buffered antigen plate agglutination test (BPAT), seven gave positive brucellosis standard tube agglutination test (TAT) and complement fixation test (CFT) results and four gave slightly positive reactions in a competitive enzyme immunoassay (CELISA). Seven sera were negative in an indirect enzyme immunoassay (IELISA-SLPS) using B. abortus smooth lipopolysaccharide (SLPS) antigen and all were negative in a fluorescence polarization assay (FPA-OPS) using B. abortus O-polysaccharide antigen. Two sheep gave a slight positive reaction in an IELISA using Brucella rough lipopolysaccharide antigen (IELISA-RLPS) and four sheep were slightly positive in an FPA using Brucella LPS core antigen (FPA-CORE). All sheep had high antibody responses to S. enterica serotype Urbana, Y. and E. coli O:157 and 7 were positive for antibody to Y. enterocolitica O:9 when tested by IELISA. The sheep were negative when tested in the FPA using OPS from Y. enterocolitica O:9 but all were strongly positive in the FPA using OPS from E. coli O:157 while seven sheep had titers to S. enterica serotype Urbana. The impact on diagnostic serology for brucellosis is discussed.

Second generation competitive enzyme immunoassay for detection of bovine antibody to Brucella abortus

A second generation competitive enzyme immunoassay (CELISA) for detection of bovine antibody to Brucella abortus was developed. This assay was different from previously developed CELISAs in that the detection reagent used was a recombinant combination of the receptor portions of protein A and protein G, labelled with horseradish peroxidase. This eliminates the need for polyclonal anti-mouse-enzyme conjugate reagents for detection thus allowing for true standardization. The assay utilized a monoclonal antibody specific for a common epitope of the O-polysaccharide (OPS) of smooth lipopolysaccharide (SLPS) derived from B. abortus S1119.3 but which did not react with protein A/G. This monoclonal antibody was used to compete with antibody in the bovine test serum. Binding of bovine antibody to the smooth lipopolysaccharide antigen was then measured directly with the protein A/G enzyme conjugate. In this case, development of colour in the reaction was indicative of the presence of bovine antibody. The performance characteristics, sensitivity, specificity and exclusion of B. abortus S19 vaccinated animals, of the assay were very similar to those of the classical CELISA.

Detection ofEschericia coliO157:H7 by Fluorescence Polarization Assay and Polymerase Chain Reaction

It is recognized that cattle and other domestic animals can be a reservoir of pathogenic Escherichia coli, including serotype O157:H7. To contain this potential health hazard, the first step is the identification of the carrier animals. For these purposes, a rapid serological screening test, a fluorescence polarization assay (FPA) was developed and results obtained from a randomly selected cattle population as well as cattle immunized with E. coli O157:H7 were compared to those obtained with an indirect enzyme immunoassay (IELISA). To identify pathogenic strains in carrier animals, polymerase chain reactions (PCR) for Shiga-like toxins I and II were implemented using agarose electrophoresis. The sensitivity of the fecal extracted E. coli for Shiga-like toxin I and II was approximately 200 CFU per reaction using multiplex hot-start nested PCR. The sensitivity of the fecal extracted E. coli varied from approximately 5x10(2) to 2.5x10(3) CFU per reaction depending on the commercial kits used. The combination of the serological screening FPA and hot-start nested PCR confirmatory assays provided rapid identification of the pathogen.

Detection of Ovine Antibody toBrucella ovisby Indirect Enzyme Immunoassay

Because some batch-to-batch variation in the preparation of rough lipopolysaccharide (RLPS) from Brucella ovis has been experienced, several protocols were tested to establish the most reliable method for detection of antibody in indirect enzyme immunoassay. An early version of the assay gave a performance index (PI=sum of optimum percent sensitivity and percent specificity, determined by receiver operator characteristic analysis) of 198.6. This assay used RLPS from B. ovis as the antigen and a monoclonal antibody specific for bovine IgG(1) heavy chain-enzyme conjugate for detection. This was not repeatable using other batches of antigen. Newer versions of the assay generally had decreased sensitivity values, giving PIs of 193. Use of a recombinant protein A/G-enzyme conjugate did not improve the PI (PI=190), giving reduced specificity and higher sensitivity. The final version used B. abortus RB51 RLPS as the antigen and protein A/G-enzyme conjugate for detection, giving a PI of 197. Because of the batch uniformity of the B. abortus RB51 RLPS and the versatility of the protein A/G-enzyme conjugate, the latter version appears to be the most useful for diagnostic serology.

Application of the fluorescence polarization assay for detection of caprine antibodies to Brucella melitensis in areas of high prevalence and widespread vaccination

The screening Rose Bengal test (RBT), the buffered plate agglutination test (BPAT), and the confirmatory complement fixation test (CFT) are currently approved by the World Organization for Animal Health (OIE) for diagnosis of goat brucellosis. However, RBT (at 3% or 8% cell concentration) is known to be affected by vaccinal antibodies. In the present study, Mexican and Canadian OIE tests were compared with the fluorescence polarization assay (FPA), alone or in combination, using indirect and competitive enzyme-linked immunosorbent assays as classification variables for goat sera obtained from an area of high prevalence and widespread vaccination. The relative sensitivities and specificities were, respectively, 99.7% and 32.5% for RBT3, 92.8% and 68.8% for RBT8, 98.4% and 84.8% for Canadian CFT, 83.7% and 65.5% for Mexican CFT, and 78.1% and 89.3% for FPA. The use of FPA as the confirmatory test in combination with other tests significantly increased the final specificities of the screening tests alone; BPAT, RBT3, and RBT8 plus FPA resulted in final specificities of 90%, 91.2%, and 91.3%, respectively, whereas for the combinations RBT3 plus Mexican CFT, RBT8 plus Mexican CFT, and BPAT plus Canadian CFT, specificities were 65.5%, 63.2%, and 91.7%, respectively. We suggest that FPA may be routinely applied as an adaptable screening test for diagnosis of goat brucellosis and as a confirmatory test for screening test series. Some advantages of FPA are that its cutoff can be adjusted to improve its sensitivity or specificity, it is a low-cost and easy-to-perform test of choice when specificity is relevant or when an alternative confirmatory test is not available, and it is not affected by vaccination, thus reducing the number of misdiagnosed and killed goats.

Detection of Anti‐BrucellaAntibodies in Llama (Lama glama)

Seven llamas were immunized with killed Brucella abortus S1119.3 cells and bled sequentially, resulting in 64 samples. An eighth llama was kept as a negative control. In addition, 299 llama and 2075 alpaca sera, submitted for diagnostic testing, were included. Sera from all llamas were tested by the buffered antigen plate agglutination test, the complement fixation test, and the indirect enzyme immunoassays using smooth and rough lipopolysaccharides. A competitive enzyme immunoassay and fluorescence polarization assays were also performed. The sensitivity values for llama sera ranged from 92.2% to 100% and the specificity values from 89.6% to 100%. No alpacas were immunized. The specificity values for alpaca sera ranged from 94.8% to 100% specific although some sera gave an 'agglutination like' reaction after about 10 minutes of incubation. The complement fixation test could not be used, as 31% of the sera were anticomplementary and 4% were false positive.

Development of an indirect enzyme-linked immunosorbent assay for detecting equine serum antibodies to the lipopolysaccharide of Salmonella abortusequi

An indirect enzyme-linked immunosorbent assay (IELISA) was developed for the detection of equine serum antibodies to lipopolysaccharide of Salmonella enterica subsp. enterica serovar Abortusequi (LPS), a causative organism of Equine Paratyphoid. The data presented demonstrates that horses immunized with S. abortusequi LPS developed antibodies detectable by the IELISA. By comparison, the tube agglutination test (TAT) did not detect antibody to S. abortusequi LPS as consistently as the IELISA. The data suggests that the IELISA may be a more suitable test for the detection of serum antibodies to S. abortusequi than the TAT.

Rapid, field-adapted indirect enzyme-linked immunosorbent assay for detection of antibodies in bovine whole blood and serum to Brucella abortus

A simple, rapid, field-adapted indirect enzyme-linked immunoassay (FldELISA) for the detection of antibodies to Brucella abortus in whole blood and serum has been developed. This assay detects antibodies to B. abortus in approximately 15 min or less. Over a 3-month period, this assay has consistently identified immunized and nonimmunized animals, while the percent coefficient of variation for each immunized animal has been less than 20%. As with any indirect enzyme-linked immunoassay, quality control can be established and maintained. Using defined positive and negative sera, the sensitivity and specificity of the FldELISA was 100% and 94.2%, respectively. As a model, this test can be readily extended to other disease applications that use lipopolysaccharide or other stable antigens for the detection of antibodies, such as those to Salmonella spp., Escherichia coli, or Yersinia spp.

Is the quality and cost of food affected if industrially produced trans fatty acids are removed?

Since the start in Italy and Denmark more than 10 years ago the application of fats and oils without trans fatty acids (TFA) has increased all over the world. Today the food industry uses enormous resources to decrease the content of TFA in existing and new products. The food industry has in most cases succeeded in making consumer accepted products without TFA-most of the quality issues have been related to the technological properties of the fat- and oil-based ingredients. The change from the traditional process of selective hydrogenation to fractionation and interesterification has caused a change in the demand of vegetable oils and process capacities in the market, but until now most of these changes has been absorbed by the market without significant changes in the cost of the raw materials.

Phi c31 integrase induces chromosomal aberrations in primary human fibroblasts

Phi c31 integrase is investigated as a novel tool for nonviral gene therapy as the enzyme can direct site-specific integration into a host chromosome. In order to investigate effects of phi c31 integrase expression in normal human cells, we have generated stably transfected primary human fibroblasts expressing the enzyme. All control cells were cytogenetically normal, but in cells expressing phi c31 integrase, numerous chromosomal abnormalities including various translocations were found, suggesting that the enzyme itself acts as a mutagen.

Serological discrimination by indirect enzyme immunoassay between the antibody response to Brucella sp. and Yersinia enterocolitica O:9 in cattle and pigs

A rapid, inexpensive and rugged serological test that distinguishes cattle and swine infected with Brucella sp. or Yersinia enterocolitica O:9 is described. The test protocol, which is an indirect enzyme immunoassay uses a high concentration of divalent cation chelating agents to minimize binding of Y. enterocolitica O:9 antibody to rough lipopolysaccharide antigen derived from B. abortus RB51. No false positive reactions were observed when testing 100 Canadian cattle and swine without any evidence of brucellosis. The assay detected 91.6% of cattle (n=155) and 93.5% (n=31) of swine infected with Brucella sp. Sera from 58 cattle and 38 swine exposed to Y. enterocolitica O:9 were negative while only 20 sera from 121 'false positive' reactors of unspecified origin gave low level positive reactions, eliminating 84% of the false positive reactions.

Towards single screening tests for brucellosis

This paper describes an indirect enzyme-linked immunosorbent assay (I-ELISA) and a fluorescence polarisation assay (FPA), each capable of detecting antibody in several species of hosts to smooth and rough members of the genus Brucella. The I-ELISA uses a mixture of smooth lipopolysaccharide (SLPS) and rough lipopolysaccharide (RLPS) as the antigen, and a recombinant protein A/G conjugated with horseradish peroxidase as the detection reagent. When using individually determined cutoff values, the SLPS/RLPS combined-antigen I-ELISA detected antibody in slightly more animals exposed to SLPS or to RLPS than did I-ELISA procedures using each individual antigen separately. Similarly, the assay using combined antigens detected antibody in slightly fewer animals not exposed to Brucella sp. When a universal cutoff of 10% positivity was used (relative to strongly positive control sera of each species), the overall performance index (percentage sensitivity plus percentage specificity) value decreased by 1.0 (from 199.4 to 198.4). In the FPA, it was not possible to use a universal cutoff without significant loss of performance. The overall sensitivity value for the FPA using the combined FPA antigen was 1.0% lower than using the O-polysaccharide (OPS) from SLPS and 9.1% higher than using the core antigen (CORE) from RLPS. When the combined antigen was used, the FPA specificity was slightly higher (1.2%) than from only the OPS, and considerably higher (12.6%) than the CORE. Overall, both the I-ELISA and the FPA with combined antigens were suitable as screening tests for all species of Brucella in the animal species tested.

Y-chromosome STR haplotypes in Danes

A total of 185 unrelated Danish males were typed for the Y-chromosome STRs DYS19, DYS385a/b, DYS389-I, DYS389-II, DYS390, DYS391, DYS392, DYS393, DYS437, DYS438 and DYS439 using the kits PowerPlex Y (Promega), ReliaGene Y-Plex 6 and ReliaGene Y-Plex 5 (Reliagene Technologies). A total of 163 different haplotypes were observed and among these, 144 haplotypes were unique. The gene diversity was 0.9985. In DYS392, a variant allele migrating as a 10.2 allele was observed. Sequencing of the allele showed a deletion upstream the repeated area.

Comparison of fluorescence polarization assay with card and complement fixation tests for the diagnosis of goat brucellosis in a high-prevalence area

An evaluation of fluorescence polarization assay (FPA) to detect antibodies against Brucella melitensis according to the Mexican Official Norm (NOM) was performed. In this study, a total of 2582 goat serum samples from a high-prevalence area in northeast Mexico where vaccination is applied, were used. Of these, 1094 were classified as NOM negatives (card test (CT) negatives or CT positives/complement fixation test (CFT) negatives) and 1488 as NOM positives (CT and CFT positives). The receiver operator characteristics (ROC) curve analysis was used to obtain the FPA sensitivity (83.5%), specificity (82.2%) and accuracy (88.2%) compared with NOM criteria, using a cut-off value of 89mP for positive samples. In addition, FPA produced 84.1% of negative results versus 65.7% of CT using 1094 CFT negative samples, which indicated that FPA performance was better than CT to detect negative samples or differentiate samples from vaccinated animals. Finally, FPA showed 95.8% sensitivity when using 702 negative non-vaccinated samples. Taken together, these results suggested that FPA might replace CT as a screening test for its better performance compared with CFT, its adjustable cut-off useful in different epidemiological situations, and for its reliability, ease of performance, comparable cost with CT regimen, and potential application in field and high-throughput laboratories. The use of FPA as screening test will help to reduce the percentage of goats wrongly slaughtered because of brucellosis misdiagnosis. More studies on FPA are required for its approval as diagnostic tool for goat brucellosis.

Comparison of serological tests for the detection of ovine and caprine antibody to Brucella melitensis

The indirect enzyme-linked immunosorbent assay (IELISA), the competitive enzyme-linked immunosorbent assay (CELISA) and the fluorescence polarisation assay (FPA) were evaluated with sera from sheep experimentally infected with Brucella melitensis and negative Canadian sheep. The sensitivity and specificity of the assays were as follows: IELISA: 91.7% and 97.6%, CELISA: 75.0% and 99.8% and FPA: 91.7% and 89.5%. Sera from the same experimental population were divided according to serological reaction in the rose bengal agglutination test (RBT) and the complement fixation test (CFT). Reactivity relative to the RBT positive and CFT positive sera were as follows: IELISA: 99.7%, CELISA: 93.2% and FPA: 99.1%. Since sera from goats with proven B. melitensis infection were not available, 699 sera from goats judged positive in the buffered antigen plate agglutination test (BPAT) and CFT and 982 BPAT/CFT negative Canadian goats were used. The sensitivity and specificity of the assays relative to the BPAT and CFT positive sera were: IELISA: 99.4% and 98.0%, CELISA: 95.4% and 97.1% and FPA: 92.7% and 99.8%.

A comparison of four serologic assays in screening for Brucella exposure in Hawaiian monk seals

A survey for Brucella spp. antibodies was undertaken on 164 serum samples from 144 Hawaiian monk seals (Monachus schauinslandi) from the northwestern Hawaiian Islands collected between 1995 and 2002. The buffered antigen plate agglutination test (BPAT), the indirect enzyme immunoassay (I-ELISA), the competitive enzyme immunoassay (C-ELISA), and the fluorescence polarization assay (FPA) were compared with regard to their ability in detecting antibodies to Brucella spp. in the serum samples. Overall, antibodies were detected in 28 (17.1%) animals, using the BPAT test, 25 (15.2%) by the C-ELISA, and 19 (11.6%) in the I-ELISA and the FPA test, using thresholds established for cattle. No evidence of gross pathology consistent with clinical brucellosis was noted in any of the seropositive animals tested. Although further work would be necessary to validate these tests for use with monk seals it appears that both the C-ELISA and the FPA tests would be appropriate as diagnostic screening tests for detection of antibodies to Brucella spp. in this species.

Combined ilioinguinal blockade and local infiltration anaesthesia for groin hernia repair—a double-blind randomized study

BACKGROUND

Local infiltration anaesthesia for inguinal hernia repair is cost-effective, but fear of intra-operative pain may hinder its widespread use. It is unknown whether a combined ilioinguinal blockade and local infiltration anaesthesia improves intra-operative analgesia.

METHODS

We performed a double-blind randomized study in 160 patients undergoing inguinal hernia mesh repair under local infiltration anaesthesia with or without additional ilioinguinal blockade. Intra-operative pain and pain at 24 and 48 h postoperatively and analgesic requirements (acetaminophen, ibuprofen, and tramadol) were assessed.

RESULTS

Median intra-operative pain scores were reduced (P=0.02) from 13 to 9 with additional ilioinguinal blockade, with no differences in requirement for sedation. There were significantly (P<0.05) more patients with intra-operative visual analogue pain scale >/=30 in the placebo group vs the ilioinguinal blockade group. Postoperative pain scores and analgesic requirements were similar.

CONCLUSION

Combined ilioinguinal blockade and local infiltration anaesthesia is recommended for groin hernia repair to reduce intra-operative pain.