Comparison of a commercial ELISA with the modified agglutination test for the detection of Toxoplasma gondii infection in naturally exposed sheep

Surprisingly few commercial ELISAs are available for the detection of Toxoplasma gondii infection in animals, and none for use in sheep have been evaluated. We thus compared the Bommeli Diagnostics ELISA Toxotest for the detection of T. gondii antibodies in ruminants with the reference modified agglutination test (MAT) in a series of 180 sheep sera. ELISA results were analysed at two cut-off levels (30%, comprising both weakly positive and positive results, and 100%, comprising only positive results), and compared with MAT at three cut-off levels (titre of 1 : 25, 1 : 50 and 1 : 100). The results showed a moderate agreement of ELISA at both cut-offs (kappa = 0.46 and 0.51) with MAT at a cut-off titre of 1 : 100. However, the specificity and positive predictive value were above 95% only at an ELISA cut-off of 100%, indicating its potential as a diagnostic test, particularly in areas with a high prevalence of infection. On the other hand, lower sensitivity and negative predictive value limit its value as a screening test. Thus, the ELISA Toxotest may be used for quick diagnosis of T. gondii infection in sheep in the field, i.e. for the differential diagnosis of ovine abortion storms.     

Influence of age and purpose for testing on the cut-off selection of serological methods in bovine neosporosis

The aim of this study was to investigate the need for different cut-off points, according to animal age and the purpose of testing, for two of the most widely used serological techniques in bovine neosporosis, IFAT and a crude antigen ELISA (Civtest, HIPRA). Therefore, the population reference sera used were defined using a combination of multiple criteria such as epidemiological/clinical and histopathological parameters and an immunoblot test. Firstly, foetuses and breeding cattle (heifers and cows) were considered as separate subpopulations for serological evaluation. Secondly, cut-off points for each serological technique (IFAT and ELISA) according to age group (foetuses and breeding cattle) and the different practical applications (detection of infection and abortion) were calculated following the receiver operating characteristics (ROC) analysis. Cut-off points were defined, for IFAT and ELISA for aborted breeding cattle and for IFAT alone in the case of the foetuses, assuming an equivalent cost of false positive and negative results. In infected breeding cattle, for IFAT and ELISA and in foetuses for ELISA, two possible cut-off values were obtained, one for a maximum sensitivity and one for a maximum specificity and the intervals of unclear results were defined. In this case, a cut-off value for equal sensitivity and specificity was also estimated. When cut-off points for infected breeding cattle, 1:100-1:250 for IFAT and 0.306-0.451 for ELISA were applied to a target population, optimal and similar negative and positive predictive values together with similar apparent and true prevalence results were observed suggesting the possibility of using both tests interchangeably.     

Evaluation of ELISA for the detection of Toxoplasma antibodies in swine sera

Enzyme-linked immunosorbent assay (ELISA) is compared with the indirect fluorescent antibody test (IFAT), the indirect haemagglutination test (IHAT) and the latex agglutination (LA) test for the detection of toxoplasma antibodies in swine sera. The 100 swine sera examined represent ELISA values from greater than 0 to 154 EIU. The agreement was highest (0.67) between ELISA and IFAT with an ELISA cut-off value of 30 EIU, and between ELISA and the LA test with an ELISA cut-off value of 50 EIU (0.74). All sera giving less than 10 EIU were negative in the other tests, and all those with greater than 70 EIU were positive in 1, 2 or all of the reference tests. In order to avoid false positive results with ELISA, all sera giving 10-70 EIU should be confirmed with a test which has a good specificity, e.g. IFAT. ELISA is a sensitive test and is highly suitable for the screening of large amounts of samples, but it may be too complicated for screening toxoplasma antibodies in the laboratories of abattoirs.     

Development and validation of an ELISA for the detection of leptospire-specific antibodies in rodents

An enzyme-linked immunosorbent assay (ELISA) for the detection of IgG antibodies in rodents was developed and validated with the microscopic agglutination test (MAT) and leptospiral cultures. Sonicated antigen from cultures of serovars tarassovi and pyrogenes was used. As conjugate, a combination of anti-rat and anti-hamster IgG labeled with peroxidase was used. The optimal cut-off point was determined by plotting the sensitivity and specificity for various cut-off point values by means of receiver operating characteristic (ROC) curve. Concordance between ELISA and each of the MAT titers was measured by kappa (kappa). Proportions of positive results were compared by means of McNemar's test. Total 214 rodents were trapped, but only 117 could be processed by the three techniques (culture, ELISA, MAT; 1:20, 1:40, 1:50) and used for statistical analysis. Although, MAT titers in rodents infected with the serogroup Ballum tended to be lower than those infected with the serogroup Icterohaemorrhagiae, all (20/20) were ELISA-positive and almost all (19/20) were MAT-positive.The percentage of positive results obtained by ELISA, 47.0% exceeded significantly the 40.2% obtained by MAT (1:50). Difference between ELISA and MAT (1:40) was not significant and no differences were observed between ELISA and MAT (1:20). Agreement, specificity, sensitivity and the consequent area under the ROC curve between ELISA and MAT were higher as MAT cut-off points were lowered, being optimal at 1:20. The fact that differences between ELISA and MAT were significant at 1:50, but not at 1:40 or 1:20, supports the suggestion that lower MAT titers should be considered positive in rodents. The ELISA developed to detect leptospire-specific antibodies had optimal sensitivity and specificity in relation to MAT and it is concluded that it may constitute a very useful indicator for epidemiological purposes of past or present leptospiral infection in rodents.     

Fluorescence polarization assay for the diagnosis of bovine brucellosis: adaptation to field use

A fluorescence polarization assay (FPA) was used to test whole blood samples prepared by mixing blood cells from cattle without exposure to Brucella abortus (B. abortus) with sera from animals with confirmed (bacteriologically) infection. A cut-off value between negative and positive values was initially established to be 87.2mP. This value was changed to 95mP to increase assay specificity without loss of sensitivity when testing blood samples from negative animals. The FPA technology was applied to whole blood samples in the field and to stored whole blood samples using two diluent buffers. Relative sensitivity and specificity values for the FPA performed in the field, based on buffered antigen plate agglutination test and competitive enzyme immunoassay results were 95.3 and 97.3%, respectively. However, to obtain maximum sensitivity and specificity, a cut-off value of 105mP was determined for fresh whole blood samples. The relative sensitivity and specificity values of the FPA when testing stored whole blood samples were 100% each using a 95mP cut-off.The usefulness of the FPA for testing whole blood samples in the field was demonstrated.     

Serologic immunoreactivity to Neospora caninum antigens in dogs determined by indirect immunofluorescence, western blotting and dot-ELISA

Neospora caninum, is a coccidian protozoan known as a major cause of bovine abortion and canine neuropathies. The aim of the present study was to develop a reliable and quick test to detect antibodies to N. caninum in dog sera. Sixty-five serum samples from dogs, including 35 positive and 30 negative for N. caninum antibodies were used for standardization of the test. In parallel, immunoreactivity of the sera to Toxoplasma gondii antigens was investigated using a passive agglutination test. A dot-ELISA test, using soluble extract of N. caninum tachyzoites on nitrocellulose ester membranes, was developed and standardized. SDS-PAGE and complementary analysis of reactivity by Western blotting were used for the characterization of the immunoreactive fractions of all tested sera. The sensitivity and specificity of the dot-ELISA were 94 and 73%, respectively, compared to IFAT at a cut-off of 1:50, and 87 and 100% compared to IFAT at a cut-off of 1:25. Among the sera that tested positively for both IFAT and dot-ELISA, only 8.6% were reactive to T. gondii. The most immunoreactive fractions in Western blots were the 14-, 33-, 42- and 55 kDa bands, with percentages of 42, 60, 42 and 37%, respectively. The 60 kDa band showed a non-specific reaction in 43% of neosporosis-negative animals by both dot-ELISA and IFAT. These results indicate that the dot-ELISA using N. caninum antigen present good sensitivity and specificity, and might be used as a screening test to detect antibodies to N. caninum in dogs.     

Canine Dirofilaria immitis infection in a hyperenzootic area: examination by parasitologic findings at necropsy and by two serodiagnostic methods

A total of 174 dogs from an area hyperenzootic for Dirofilaria immitis were grouped into 4 age categories and necropsied; information was obtained on adult D immitis infections and on the presence of microfilariae. Serum samples from these dogs were examined by an enzyme-linked immunosorbent assay (ELISA) for antibody to adult D immitis and by an indirect fluorescent antibody test (IFAT) for antibody to microfilarial surface antigens. In dogs less than or equal to 5 months of age, necropsy demonstrated no evidence of infection; however, positive serologic results indicated that some of these dogs had prepatent infections. The percentage of dogs with ELISA titers (positive) increased with age, as did the percentage of dogs with adult D immitis infections. The IFAT results were positive in some dogs in each age category. Sera from all 29 dogs with occult infections were positive by ELISA. Sera from 6 of 20 dogs with occult dual-sex heartworm infections and 1 of 9 dogs with occult single-sex heartworm infections were positive by IFAT. For diagnosing occult dirofilariasis, the ELISA had a positive predictive value which increased with age of the dog to a maximum of 65.0% in dogs greater than or equal to 12 months of age; ELISA had a negative predictive value of 100% in all age groups. In contrast, positive and negative predictive values for the IFAT decreased with age of the dog to 60% and 37.5%, respectively, in dogs greater than or equal to 12 months of age.     

Diagnostic performance of the Pourquier ELISA for detection of antibodies against Mycobacterium avium subspecies paratuberculosis in individual milk and bulk milk samples of dairy herds

The objective of the study was to determine the diagnostic performance of the Pourquier ELISA for detection of antibodies against Mycobacterium avium subsp. paratuberculosis (Map) in individual milk samples and in bulk milk samples. For individual milk samples the specificity of the Pourquier ELISA was estimated by testing a panel of individual milk samples from certified Map-free herds. The relative sensitivity of the assay in individual milk samples and agreement of the results with those of serum samples was estimated by testing panels of paired serum-milk samples from seropositive cattle, whole-herd investigations, and moderate or heavy shedders. The specificity of the ELISA for individual milk samples was still 99.8% at a cut-off of 20% sample to positive (S/P) value, clearly lower than the cut-off defined by the manufacturer (30% S/P). The relative sensitivity for individual milk samples as compared with positive serum samples was 87% for a cut-off of 20% S/P, and 80% for a cut-off of 30% S/P. The sensitivity of this ELISA for detection of high shedders was >90% both for individual milk and serum samples, also agreement was very good (kappa=0.91 for all paired samples). The specificity of the Pourquier ELISA in bulk milk samples was investigated by testing bulk milk samples from certified Map-free herds. Feasibility of bulk milk testing was investigated by titrating ELISA positive individual milk samples in negative milk. In addition, 383 bulk milk samples from herds with a known within-herd seroprevalence were tested. The specificity of the ELISA for bulk milk samples was 100% at a cut-off of 12.5% S/P. At the cut-off recommended by the manufacturer (30% S/P) performance of the bulk milk ELISA related to herd status (> or =2 seropositive cows) was rather poor, corresponding with a sensitivity of 24% and a specificity of 99% relative to serology. However, at the revised cut-off for bulk milk of 12.5% S/P and a within-herd seroprevalence of > or =3%, sensitivity and specificity relative to serology were 85% and 96%, respectively. Given the current herd-level seroprevalence in The Netherlands, these test characteristics corresponded with positive and negative predictive values for bulk milk of 67% and 94%, respectively. In conclusion, the diagnostic performance of the Pourquier ELISA for individual milk samples creates opportunities for a cheaper and more feasible testing scheme, while the diagnostic performance for bulk milk samples warrants further consideration.     

Comparison of a commercial ELISA with the modified agglutination test for detection of Toxoplasma infection in the domestic pig

The modified agglutination test (MAT) and a commercially available enzyme-linked immunosorbent assay (ELISA) were compared for detection of antibodies to Toxoplasma gondii in naturally-infected market-aged pigs. Infected pigs were obtained from commercial slaughter facilities and from farms where infection had previously been detected. Infection was confirmed by bioassay in cats. For 70 bioassay positive pigs, 60 were positive by MAT (85.7% sensitivity) and 62 were positive by ELISA (88.6% sensitivity). Of 204 bioassay negative samples 193 were negative by MAT (94.6% specificity) and 200 were negative by ELISA (98.0% specificity). Good correlation was seen between MAT and ELISA results. The results suggest that the ELISA may be a good tool for epidemiological studies of Toxoplasma infection on pig farms.     

Development of an indirect ELISA-NcSRS2 for detection of Neospora caninum antibodies in cattle

Neosporosis is of alarming economic concern in the cattle industry. The effectiveness of diagnostic tests for detecting specific antibodies against Neospora caninum is hampered by potential cross-reaction with other coccidia. Use of a single specific antigen might improve test specificity. An indirect enzyme-linked immunosorbent assay (ELISA) was developed using the truncated protein NcSRS2 expressed in Escherichia coli. The ELISA results were compared with those of the indirect fluorescence antibody test (IFAT). Receiver Operating Characteristic (ROC) and Tests in the Absence of a Gold Standard (TAGS) analysis revealed an assay having 96% specificity and 95% sensitivity when applied to 145 positive and 352 negative sera from two distinct cattle populations. Using OD ≤ 0.095 as the cut-off point, the assay's negative and positive predictive values ranged from 98.8% to 50.8% and from 58.8% to 99.1%, respectively, depending on neosporosis prevalence in a given area. The novel ELISA-NcSRS2 format described in the present report constitutes a specific and sensitive method for detecting N. caninum in cattle.     

Application of repeated bulk milk testing for identification of infection dynamics of Neospora caninum in Thai dairy herds

In this prospective study, repeated bulk milk tests were evaluated to establish the Neospora caninum antibody status and to describe infection dynamics and changes in prevalence of N. caninum in Thai dairy herds. Bulk milk from 418 herds in northeast Thailand were collected at three consecutive samplings, in December 2002 (sampling 1), April (sampling 2) and December 2003 (sampling 3). All samples were analysed for presence of N. caninum antibodies by iscom ELISA, and the optical density values were dichotomized at three different cut-offs. Herd status at either sampling 1 or sampling 2 was used to predict herd status at sampling 3. Changes in both sensitivity and specificity at the first samplings at all cut-offs were consistent with commonly seen patterns when evaluating performance of diagnostic tests. In addition, the predictive positive values (PPV) of herd status at each of the two samplings were more affected by time of sampling than choice of cut-off, whereas the predictive negative values (PNV) increased with increasing cut-off. Herd status at the first samplings was also interpreted in combination, i.e. herds that were negative at both samplings were considered negative and positive otherwise in Combination A, while herds positive at both samplings were considered positive in Combination B. When using these combinations, Combination A gave higher PNV but lower PPV than Combination B at all cut-offs. Using the optical density value 0.20 as cut-off to establish the herd N. caninum antibody status, 270 herds (65%) kept their status throughout the study period, but 148 herds converted their status at least once. Interestingly, 136 (86%) of the 158 herds that were considered negative at sampling 1 and sampling 2 remained negative at sampling 3. In addition of the 159 herds considered positive at the first two samplings, 134 (84%) were still positive at sampling 3. We concluded that repeated bulk milk testing at regular intervals provided better information about herd N. caninum status than a single test. Further, our results showed that the infection is prevalent in northeast Thailand, but that a herd can keep a negative infection status despite the frequent presence of dogs.     

Sensitivity and specificity of various serological tests for the detection of Toxoplasma gondii infection in naturally infected sheep

Comparative serological examination of 300 serum samples from sheep slaughtered in the main abattoir in Cairo, Egypt revealed a higher prevalence of toxoplasmosis (43.7%) with the modified agglutination test (MAT), followed by the enzyme linked immune-sorbant assay (ELISA) (41.7%) and the indirect fluorescent antibody test (IFAT) (37%), while the lowest prevalence was detected with the dye test (DT) (34%). When the data from the first three serological tests were compared with that of the DT test, which was used as a reference test for toxoplasmosis, MAT had the highest sensitivity (96%), followed by ELISA (90.1%) and IFAT, which demonstrated the lowest sensitivity (80.4%). Conversely, IFAT had the highest specificity (91.4%), followed by MAT (88.9%) and ELISA (85.9%).     

Evaluation of a new in‐clinic test system to detect feline immunodeficiency virus and feline leukemia virus infection

Background: Many in‐house tests for the diagnosis of feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) infection are licensed for use in veterinary practice. A new test with unknown performance has recently appeared on the market. Objectives: The aims of this study were to define the efficacy of a new in‐clinic test system, the Anigen Rapid FIV Ab/FeLV Ag Test, and to compare it with the current leading in‐clinic test, the SNAP Kombi Plus FeLV Antigen/FIB Antibody Test. Methods: Three‐hundred serum samples from randomly selected healthy and diseased cats presented to the Clinic of Small Animal Medicine at Ludwig Maximilian University were tested using both the Anigen Rapid Test and the SNAP Kombi Plus Test. Diagnostic sensitivity, specificity, and positive and negative predictive values were calculated for both tests using Western blot as the gold standard for verification of FIV infection and PCR as the gold standard for FeLV infection. Results: The presence of antibodies against FIV was confirmed by Western blot in 9/300 samples (prevalence 3%). FeLV DNA was detected by PCR in 15/300 samples (prevalence 5%). For FIV infection the Anigen Rapid Test had a sensitivity of 88.9%, specificity of 99.7%, positive predictive value of 88.9%, and negative predictive value of 99.7%. For FeLV infection, the Anigen Rapid Test had a sensitivity of 40.0%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 96.9%. Diagnostic accuracy was similar to that of the SNAP Kombi Plus Test. Conclusion: The new Anigen Rapid FIV Ab/FeLV Ag Test performed very well and can be recommended for use in veterinary practice.     

Evaluation of an ELISA for detection of antibodies to Babesia bovis in cattle in Australia and Zimbabwe

An enzyme-linked immunosorbent assay (ELISA) for antibodies to Babesia bovis was evaluated in comparison with the indirect fluorescent antibody test (IFAT) in Australia and Zimbabwe. Positive and negative threshold values for the ELISA were set using sera from cattle of known infection status. Sensitivity and specificity estimates for the ELISA based on 158 positive sera from cattle experimentally infected with Australian isolates of B. bovis and 318 negative sera collected from B. bovis-free herds in Australia were 100% and 99.4%, respectively. The specificity of the assay in Africa, based on 328 sera from B. bovis-free herds in Kenya and South Africa, was 99.7%. The ELISA was compared with the IFAT using sequential sera from 16 calves experiencing primary B. bovis infections, and a total of 777 field sera collected from B. bovis-endemic herds in Australia and Zimbabwe. In primary infections, the ELISA and IFAT detected antibodies at or about the same time. With sera from endemic herds, the performance of the ELISA was at least comparable with that of the IFAT. Two hundred and fourteen of 221 sera that were negative by IFAT, were negative by ELISA, and 428 of 439 sera that were clearly positive by IFAT were positive by ELISA. Of 117 sera that gave equivocal (suspect or weak positive) results in the IFAT, 20 were positive by ELISA, 7 were suspect and 90 were negative. We conclude that the ELISA will be useful for epidemiological studies on B. bovis in Australia and Zimbabwe, and probably elsewhere.     

Evaluation of a recombinant LigB protein of Leptospira interrogans serovar Canicola in an enzyme-linked immunosorbent assay for the serodiagnosis of bovine leptospirosis

A recombinant leptospiral lipoprotein, LigB, was evaluated for use in the diagnosis of bovine leptospirosis by enzyme-linked immunosorbent assay (rLigB IgG ELISA). The standard reference test (Microscopic agglutination test, MAT) of 200 serum samples from cattle suspected of leptospirosis showed that 95 (47.5%) samples had positive agglutination titres, which ranged from 100 to 1600. In rLigB IgG ELISA, 49% of the samples were positive. Sensitivity of IgG ELISA for 95 bovine sera, which had MAT titres of greater than or equal to 100, were 100%. ELISA showed a specificity of 97.1% with 105 bovine sera, which were negative at a 1:50 dilution in MAT for Leptospira interrogans serovars. The results of ELISA and MAT correspond very good. When analytical specificity of IgG ELISA was evaluated using bovine serum samples from animals showing the serum antibodies to other pathogens, no cross-reaction was observed. Thus the recombinant LigB IgG ELISA can be used instead of the MAT as an aid to the diagnosis of bovine leptospirosis.     

Use of a water hardness test kit to measure serum calcium concentration in cattle

OBJECTIVE: To determine whether a commercially available water hardness test kit could be used to measure total serum calcium concentration and diagnose hypocalcemia in dairy cows. DESIGN: Prospective study. ANIMALS: 30 dairy cows from 19 commercial herds. PROCEDURE: Serum calcium concentration was determined using a water hardness test kit and a standard, laboratory-based method. Simple linear regression was used to determine whether there was a linear relationship between results of the 2 methods, and Spearman's rank correlation was used to calculate correlation between measurements. Sensitivity, specificity, and predictive values of using test kit-derived values for diagnosis of hypocalcemia (laboratory value < 8 mg/dl) were calculated. RESULTS: There was a high correlation and significant linear relationship between results of the 2 methods. Sensitivity, specificity, predictive value of a positive test result, and predictive value of a negative test result were 100, 73, 86, and 100%, respectively. Accuracy was improved by using a test kit-derived calcium concentration of 7 mg/dl as the cut-off for determining hypocalcemia. CLINICAL IMPLICATIONS: Results indicate that a commercially available water hardness test kit can be used as a rapid, inexpensive method of estimating serum calcium concentrations and diagnosing hypocalcemia in dairy cattle. However, the test is not practical for cow-side use, because blood samples must be centrifuged to obtain serum for use in the test kit.     

Evaluation of a new early pregnancy test in mares

The goal of this study was to evaluate the accuracy of the early conception factor (ECF) assay test to answer the following questions: (1) Can the test be used reliably to make a decision to flush an embryo donor mare? (2) Can the test be used to detect early embryo loss before day 17 in the mare? (3) Can the test accurately diagnose non-pregnancy?The performance of the test (sensitivity, specificity, positive predictive value [PPV], and negative predictive value [NPV]) was measured against the results of embryo flushing (n = 28) in 1 group and against ultrasound pregnancy diagnosis in another group (n = 17). Serum samples were taken from embryo donor mares on day 8 post-ovulation (day of embryo flushing) and from the embryo transfer recipient mares on days 6 to 8 after embryo transfer (day of pregnancy diagnosis by ultrasound). The tests were set up and read on the same day by 3 blinded observers. The kappa (κ) value, for agreement among the 3 blinded readers of the test, was 0.64.The sensitivity, specificity, PPV, NPV, and accuracy were, respectively, 42.6%, 51.9%, 63.8%, 31.1%, and 46.8%.Under the conditions of the current study, the test proved to be unreliable for detection of the presence of an embryo.     

A modified agglutination test for the diagnosis of Besnoitia besnoiti infection

Bovine besnoitiosis is caused by Besnoitia besnoiti, an obligate intracellular apicomplexan parasite. Affected animals present cutaneous and systemic manifestations and the disease may lead to considerable economic losses. Although generally associated to tropical and subtropical areas, bovine besnoitiosis is now considered an emergent disease in Europe, due to the increasing number of new cases and apparent geographical expansion. In this study we evaluated the performance of a modified agglutination test (B-MAT) in the serodiagnosis of bovine besnoitiosis in comparison to the indirect immunofluorescent-antibody test (IFAT). To establish optimal protocol conditions we used bovine sera with a known infection status for B. besnoiti infection. Positive animals (n=36) presented B. besnoiti dermal cysts and anti-B. besnoiti specific antibodies, as determined by the indirect immunofluorescence test (IFAT). Negative animals (n=103) were from non-endemic areas in Portugal and negative by the IFAT. From here, we evaluated the sensitivity and specificity of the B-MAT relative to the IFAT with a panel of sera from herds with history of bovine besnoitiosis in Portugal, Spain and France (n=402), using three serum dilutions (1:80, 1:160, 1:320). Considering the positive cut-off at 1:160 serum dilution, the B-MAT showed an almost perfect test agreement with the IFAT; (κ=0.968; 95% CI: 0.941-0.996) with a relative sensitivity of 97.2% (95% CI: 94.1-100%) and a relative specificity of 99.3% (95% CI: 98.4-100%). As a simple and inexpensive technique the B-MAT represents a valuable tool for the diagnosis and study of the epidemiology of bovine besnoitiosis.     

Proteomic identification and profiling of canine lymphoma patients*

This study employed proteomic and bioinformatic approaches to identify serum biomarkers in canine lymphoma patients. Chilled serum samples derived from non‐lymphoma (n = 92) and lymphoma (n = 87) patients were shipped from first opinion veterinary practices, subjected to ion exchange chromatography and analysed by surface‐enhanced laser desorption ionization mass spectrometry. Nineteen serum protein peaks were identified between the two groups as being significantly different (P < 0.05) based upon their normalized ion intensities. Two biomarkers were identified that were capable of differentiating lymphoma and non‐lymphoma patients. Analysis of the test data provided a positive predictive value (PPV) of 82%. A clinical follow‐up study was carried out on 96 canine patients suspected of having lymphoma. Evaluation of this data gave a specificity value of 91%, sensitivity of 75%, PPV of 80% and negative predictive value of 88%. In conclusion, the expression pattern of two serum biomarkers has enabled serum samples to be classified into either lymphoma or non‐lymphoma categories.     

Evaluation of two enzyme immunoassays for detection of Clostridium difficile toxins A and B in swine

Diagnosis of Clostridium difficile-associated disease (CDAD) in neonatal pigs is accomplished, in part, by detection of toxins A (TcdA) and B (TcdB) in feces or colonic contents. Samples (n=115) were tested simultaneously with two toxin assays (Clostridium difficile Tox A/B II, TechLab, Blacksburg, VA; Gastro-tect Clostridium difficile Toxin A+B, Medical Chemical Corporation). Previous comparison of the Tox A/B II assay to the reference method (toxicity in CHO cell monolayers) revealed an overall correlation of 88%, with 91% sensitivity and 86% specificity, a positive predictive value of 86 and a negative predictive value of 84. In comparing the two EIAs, a group of nine samples were positive in both assays and a group of 92 were negative in both. However, 14 samples positive in the Tox A/B II were negative in the Gastro-tect assay. Thus, in comparison to the Tox A/B II assay, the Gastro-tect assay was 100% specific but only 39% sensitive. Its negative predictive value was 87, but its positive predictive value was 100. Thus, the Tox A/B II kit is apparently superior to the Gastro-tect Toxin A+B test for diagnosis of CDAD in neonatal pigs.