Indirect Enzyme-linked Immunosorbent Assay Test Research Articles

Development and use of indirect liquid-phase ELISA test system for detection of PRRS virus antigen during in-process control of raw materials intended for vaccine production

Porcine reproductive and respiratory syndrome (PRRS) being endemic and reported in the most countries in the world remains one of the most challenging diseases in pig industry. The main disease control measures include preventive vaccination and animal movement control within and outside the country as well as diagnostic testing of pigs in the population. Live and inactivated vaccines are used for specific prevention of porcine reproductive and respiratory syndrome. Complete and irreversible infectious agent inactivation with maximum epitope preservation and protective immunity in immunized animals are the main requirements for inactivated vaccines. Therefore, continuous improvement of methods for vaccine quality control at various vaccine production stages is of current importance. Results of development of the test system based on indirect liquid-phase enzyme-linked immunosorbent assay (ELISA) for PRRS virus antigen detection and activity testing in infectious and inactivated virus-containing cell cultures at intermediate stages of the vaccine production process are described in the paper. The test-system development process included purified and concentrated virus antigen as well as hyperimmune rabbit sera preparation. Specificity of purified and concentrated virus antigen was confirmed with real-time polymerase chain reaction. The developed test-system was shown to detect the virus antigen at initial infectivity titre of 4.87–7.21 lg TCID50/cm3 corresponding to ELISA titre (dilution) of 1:4 up to 1:64. Methodical Guidelines for detection of porcine reproductive and respiratory syndrome virus antigen with indirect liquid-phase enzyme-linked immunosorbent assay (ELISA) (2019) were developed based on the work results, commissioned and approved by the FGBI “ARRIAH” Scientific Board.

Specific antibodies reacting to JC polyomavirus capsid protein mimotopes in sera from multiple sclerosis and other neurological diseases-affected patients.

Published data support the hypothesis that viruses could be trigger agents of multiple sclerosis onset. This link is based on evidence of early exposure to viral agents in patients affected by this neurologic disease. JC (JC polyomavirus [JCPyV]), BK (BKPyV), and simian virus 40 (SV40) neurotropic polyomavirus footprints have been detected in brain tissue specimens and samples from patients affected by different neurological diseases. In this investigation, serum samples from patients affected by multiple sclerosis and other inflammatory and noninflammatory neurologic diseases, as well as healthy subjects representing the control, were investigated for immunoglobulin G (IgG) antibodies against JCPyV. To this end, an immunologic approach was employed, which consists of employing indirect enzyme-linked immunosorbent assay testing with synthetic peptides mimicking viral capsid protein 1 antigens. A significantly lower prevalence of IgG antibodies against JCPyV VP1 epitopes, with a low titer, was detected in serum samples from patients with multiple sclerosis (MS) and other neurologic diseases than in healthy subjects. Our study indicates that the prevalence of JCPyV antibodies from patients with multiple sclerosis is 50% lower than in healthy subjects, suggesting specific immune impairments. These results indicate that patients affected by neurological diseases, including MS, respond poorly to JCPyV VP1 antigens, suggesting specific immunologic dysfunctions.

Development and Potential Application of Ras Domain Containing Protein from Haemonchus contortus for Diagnosis of Goat Infection.

Simple SummaryThe early diagnosis of Haemonchosis is important for the control and effective treatment of the disease. Early stage detection of Haemonchus contortus infection has not been attempted in goats, even though the immature worms are blood-sucking. This study was carried out to detect H. contortus infection during the early and late stages in goats. The results of this study assessed that recombinant H. contortus Ras domain-containing protein (rHcRas) could detect the antibody in H. contortus-infected goat sera during the prepatent and postpatent periods with high sensitivity and specificity using immunodiagnostic techniques. Our findings illustrated that indirect ELISA based on rHcRas also had the potential to detect H. contortus infection from field samples.Haemonchus contortus is an important gastrointestinal nematode of small ruminants that causes significant mortality in goats worldwide. Diagnosis of this infection mainly depends on the evaluation of clinical signs and fecal examination. However, limitations often occur in early or mild infections. For this purpose, serological diagnosis seems to be more accurate and reliable. Ras domain-containing protein (Ras) is one of H. contortus’s excretory and secretory products (ESPs) that can be isolated from different larval stages of the nematode. In this study, the recombinant H. contortus Ras domain-containing protein (rHcRas) was expressed and purified and its diagnostic potential was evaluated. Reactions between rHcRas and goat sera were tested using Western blotting (WB). The results showed that rHcRas could be recognized by sera as early as 14 days post infection (DPI), and antibodies against rHcRas in infected goats could be maintained for over 89 days. No reaction was found between rHcRas and antibodies against Trichinella spiralis, Fasciola hepatica, or Toxoplasma gondii. An indirect enzyme-linked immunosorbent assay (ELISA) was produced based on rHcRas. The optimal coating antigen (157 ng of rHcRas/well) and serum dilutions (1:50) were determined via checkerboard titration. Indirect ELISA based on rHcRas showed 87.5% sensitivity and 90.6% specificity. The cut-off values for this experiment were determined to be 0.324 (positive) and 0.273 (negative), respectively, and the variation coefficient (CV) was less than 15%. The results of the indirect ELISA in-field examination showed that 17.6% (9/51) of the goats were infected with H. contortus, higher than the fecal examination results (15.7%, 8/51). When compared the results of the indirect ELISA and necropsy testing, 98.0% (50/51) consistency was found. These results indicated that rHcRas was a potential antigen for the diagnosis of H. contortus infection in goats.

Seroprevalence of ovine brucellosis in the microregion of Teresina, Piauí, Brazil

ABSTRACT: Among the diseases that affect the reproductive system of domestic animals, brucellosis in the sheep species is important because it generates significant economic losses to sheep rearing. Thus, it is a threat to the growth and productivity of sheep herds. In the face of this problem, the objective of the present research was to identify the prevalence of ovine brucellosis in herds in municipalities of the Teresina, Piauí, Brazil microregion by using the agar gel immunodiffusion assay (AGID) and indirect enzyme-linked immunosorbent assay (ELISA) serological tests. Fourteen municipalities were included in the research. Blood samples were collected from 521 pubescent animals by puncturing the jugular vein. After collection, the samples were submitted to the serological techniques, AGID and indirect ELISA, to detect anti B. ovis antibody. Of the 521 samples submitted to the AGIDtest, 23 (4.41%) were sera reagent and 498 (95.58%) negative. The indirect ELISA tests, 24 (4.61%) suspect samples and 497 (95.39%) negative samples were obtained, and there were no reagent animals in this test, only suspect. The seroprevalence of ovine brucellosis in the Teresina, Piauí microregion was 4.41%. Thus, it is possible to identify sheep with reagent serology to infection by B. ovis, that is present in municipalities in the state of Piauí, Brazil. Furthermore, AGIDwas shown to be more sensitive in detecting animals that had had contact with the etiological agent of the disease.

Development of indirect ELISA for the detection of canine adenovirus type 2 antibodies in dog sera.

BackgroundCanine adenovirus type 2 (CAV-2) induces infectious laryngotracheitis in members of the family Canidae, including dogs. To date, no ELISA kits specific for CAV-2 antibody have been commercialized for dogs in Korea.ObjectivesWe aimed to develop new indirect enzyme-linked immunosorbent assay (I-ELISA) to perform rapid, accurate serological surveys of CAV-2 in dog serum samples.MethodsIn total, 165 serum samples were collected from dogs residing in Chungbuk and Gyeongbuk provinces between 2016 and 2018. The Korean CAV-2, named the APQA1701-40P strain, was propagated in Madin–Darby canine kidney cells and purified in an anion-exchange chromatography column for use as an antigen for I-ELISA. The virus-neutralizing antibody titers of CAV-2 in the dog sera were measured by virus neutralization (VN) test.ResultsWe compared the results obtained between the VN and new I-ELISA tests. The sensitivity, specificity, and accuracy of new I-ELISA were 98.6%, 86.4% and 97.0% compared with VN test, respectively. New I-ELISA was significantly correlated with VN (r = 0.91).ConclusionsThese results indicate that new I-ELISA is useful for sero-surveillance of CAV-2 in dog serum.

Mother-to-Child Transfer of Reactivated Varicella-Zoster Virus DNA and Varicella-Zoster IgG in Pregnancy.

Stress-induced subclinical reactivation of varicella-zoster virus (VZV) has been studied previously. However, subclinical reactivation of VZV induced by the stress of pregnancy has not been investigated. The objective was to study varicella DNA and varicella antibody levels in mothers and their newborn babies. VZV immunoglobulin G (IgG) levels in 350 mother-newborn dyads were studied using indirect enzyme-linked immunosorbent assay testing. A subset of 73 dyads was selected, DNA was isolated from the serum samples, and quantitative polymerase chain reaction (qPCR) was performed. Nearly 15% (14.6%) mothers tested were positive for varicella antibodies (>100 mIU/dL) and 16% were borderline (<100 and >50 mIU/dL). Approximately 16.9% of the babies were positive, and 18% were in borderline. Among those tested for VZV-DNA, 70% of mothers with low VZ-IgG (<100 mIU/dL) and 11.32% of those with high VZ-IgG (>100 mIU/dL) were positive for DNA. Among the newborns, 60% of those with low VZ-IgG and 15% of those with high VZ-IgG were positive for DNA. Mothers who have had VZV infection in the past can transmit VZV DNA to their babies.

Development of an Indirect Enzyme-linked Immunosorbent Assay to Detect Antibodies against Serotype A2013 of Foot and Mouth Disease Virus in Cattle.

Foot and mouth disease (FMD) is a contagious animal disease that causes irreparable damage to the economy of countries, including Iran in which this disease is a native one. Among the ways to combat FMD are vaccination and slaughter. Due to the specific situation of Iran, it is not possible to kill infected animals. Therefore, vaccination is the most important way to fight this disease. Serum neutralization test (SNT) and enzyme-linked immunosorbent assay (ELISA) are two main methods to evaluate the safety and calculate antibody titer. In this study, an indirect ELISA test was developed based on the coating of a complete viral particle (140s) which made it possible to determine antibody. In addition, serotype and viral type were determined without the need for time-consuming and complex molecular tasks, including gene expression. Moreover, in case of a new epidemic, a new epidemic condition can be detected using a serum antibody method. However, the coating of the complete viral particle leads to virus purification as well as the conjugated anti-immunoglobulin antibody testing of the same animal. In this study, the SNT was used as a gold standard test to determine the serum antibody level and compare its results with indirect ELISA method to determine the sensitivity and specificity of the indirect ELISA. To measure the anti-virus antibody rate of FMD (type A2013) through receiver operating characteristic analysis with 100% sensitivity and the specificity of 90%, the routine formulas were utilized using 100 % and 82%sensitivity and specificity, respectively. In this study, the cutoff value for the optical density was obtained at 0.3 and there was a significant difference between the vaccinated animals and the unvaccinated ones in terms of antibody level against the A2013 type. This indicates the correctness of the test and the accurate and proportional antibody detection against the understudy viral types of FMD.

Indirect Enzyme Linked Immunosorbent Assay Sebagai Metode untuk Melacak Bruselosis pada Sapi Perah (INDIRECT ENZYME IMMUNOSORBENT ASSAY (I-ELISA) AS METHOD FOR DETECT BRUCELLOSIS IN DAIRY COW)

Brucellosis has become a zoonotic disease that received attention in efforts to prevent and eradicate strategic infectious animal diseases in Indonesia. Brucellosis can be detected early by the rose bengal test (RBT), followed by complement fixation test (CFT) and by enzyme linked immunosorbent assay (ELISA). The aims of this research was to study the indirect enzyme linked immunosorbent assay test (I-ELISA) as an alternative test for detecting brucellosis in dairy cattle. The method was used by conducting tests of RBT, CFT, I-ELISA and commercial I-ELISA to test brucellosis. The test results were calculated sensitivity and specificity, as well as analyzed by calculating the kappa value. The method was used by conducting tests of RBT, CFT, I-ELISA and commercial I-ELISA to test brucellosis. The test results were calculated for sensitivity and specificity, as well as analyzed by calculating the Kappa statistical value. The results of the sensitivity and specificity calculation showed that the indirect enzyme linked immunosorbent assay (I-ELISA) test developed a higher sensitivity (100%) compared to RBT test (93.75%) and commercial I-ELISA (93.75%). The developed I-ELISA specificity (74.68%) was still lower than RBT (89.87%), but higher than commercial I-ELISA (70.52%). The calculation of the statistical value of kappa RBT with CFT showed the kappa value 0.7120 which meaned it had a good agreement, commercial I-ELISA with CFT showed kappa value 0.6165 which meaned it had good suitability, whereas I-ELISA developed with CFT showed kappa value 0.4984 which meaned having a moderate agreement.In conclusion, the indirect enzyme linked immunosorbent assay (I-ELISA) which had been developed had low specificity, but the sensitivity was the highest compared to the commercial I-ELISA test and RBT, so this test was appropriate to be used as a screening test, especially in dairy cows movement into brucellosis-free areas or regions.

Decline of antibody response in indirect ELISA tests during the periparturient period caused diagnostic gaps in Coxiella burnetii and BVDV serology in pluriparous cows within a Holstein dairy herd

In cattle, indirect enzyme-linked immunosorbent assay (ELISA) tests are commonly used in serological routine diagnostics. In a longitudinal study design, changes in relative optical density (OD) from drying-off until week 11 after calving were analyzed in blood and milk samples from pluriparous dairy cows (n=21) using a commercial indirect anti-C. burnetii ELISA test. In a second part of this study, changes over time were evaluated in blood and milk samples of 11 of these cows in an indirect ELISA detecting anti-Bovine viral diarrhea virus (BVDV) antibodies. Regarding the cows which were still in the herd at the time of calving, blood serological qualitative changes from positive to negative or indeterminate were demonstrated in 7/20 cows (35%) for the anti-C. burnetii indirect ELISA and in 2/10 cows (20%) for the anti-BVDV indirect ELISA, respectively, during the period from 14days ante partum to calving. Relative OD in the anti-C. burnetii and the anti-BVDV indirect ELISA tests followed basically similar courses over time. In blood serum, relative OD initially increased after drying-off, before a drop around calving was observed. After the colostrum period, relative OD in blood serum showed an increase until week 11 of lactation. In colostrum samples, relative OD levels were higher than in milk samples obtained one day before drying-off. After parturition, relative OD in milk decreased until week 6 of lactation in the anti-C. burnetii indirect ELISA and until week 11 in the anti-BVDV indirect ELISA, respectively. In conclusion, blood serological investigations in periparturient dairy cows using indirect ELISA kits should be avoided.

Prevalence of Chlamydia abortus Antibodies in Horses From the Northern State of Mexico and Its Relationship With Domestic Animals

Abstract Chlamydia abortus is obligate intracellular bacteria that cause a wide range of reproductive and respiratory diseases in animals and humans. Serologic and molecular evidences of C. abortus in Mexico have been reported in sheep and goats. The presence of C. abortus antibodies in horses (n = 301) was detected by a commercial indirect enzyme-linked immunosorbent assay test. Additionally, C. abortus antibodies in bovines (n = 25), goats (n = 8), and sheep (n = 94) reared with horses were detected to identify probable animal species that could infect horses. The prevalence obtained was 1.32% for horses, 48% for bovines, 12.5% for goats, and 29.7% for sheep. The 75% of horses seropositive to C. abortus were obtained from farms with the presence of sheep seropositive to C. abortus . These results suggest that the presence of C. abortus in horses from Mexico exist and can be related with the presence of sheep positive to C. abortus .

AN EVALUATION OF ELISA USING RECOMBINANT P17 ANTIGEN FOR CATTLE BRUCELLOSIS

Brucellae are Gram-negative cocccobacilli, facultative intracellular bacterial pathogens of both humans and animals. Brucellosis is an important disease that is difficult to diagnose and treat that causes heavy economic losses and human suffering. Diagnosis of brucellosis plays a vital role for control and prevention of the disease. Lipopolysaccharide (LPS) based Enzyme Linked Immuno Sorbent Assay (ELISA) shows false positivity due to cross-reactivity with other gram-negative bacteria LPS. The present investigation was undertaken to assess the diagnostic potential of the recombinant P17 protein of Brucella. P17 gene of Brucella abortus (B. abortus) was amplified, cloned and subcloned into pQE 30 vector yielding high levels of protein expression. The purified recombinant P17 (rP17) protein was used to develop an indirect ELISA (i-ELISA) test for brucellosis. The rP17-ELISA was compared with RBPT (Rose Bengal Precipitation Test) and LPS-ELISA using 530 cattle sera. The concordance percentage and kappa statistics of P17-ELISA is greater in compression with LPS-ELISA. Relative sensitivity and relative specificity of P17-ELISA shows a positive trend with RBPT. The data suggest that P17-ELISA can be a useful method for Brucella diagnosis and recombinant P17 protein is a potential antigen for diagnosis of cattle brucellosis.

Enzyme-Linked Immunosorbent Assays Using the Recombinant gp51 and p24 of Bovine Leukemia Virus for Immunodetection of the Disease

Enzyme-linked immunosorbent assay (ELISA) is often used to test bovine leukemia virus (BLV) infection. However, commercially available kits test in South America detect only antibodies against the gp51 protein. With the aim to improve the sensitivity of the test, we developed here a two-step indirect dual ELISA test that included both proteins p24 and gp51, expressed and produced in E. coli and baculovirus expression system respectively. Two hundred ten BLV sera, stated as double positive or double negative by the combination of commercial agar gel immunodiffusion (AGID) assay and a gp51-ELISA test, were tested with our in house dual rp24/rgp51 ELISA. Firstly, we checked the purified, optimized and standardized proteins as antigen by the checkerboard technique, and set up our in house ELISA test. The concordance correlation coefficient (CCC) and coefficient of variation (CV) intraplate repeatability levels were within the values established by the international standards. The statistical analysis demonstrated the value of sera correctly ranked highest (93.48%), and for 0.3 cutoff, the sensitivity was 95.65% and the specificity 91.30%. In conclusion, the rp24/rgp51 ELISA developed and standardized here demonstrated to have good analytical characteristics to be considered for screening of BLV.

Development of an indirect enzyme-linked immunosorbent assay test for detecting antibodies to chicken astrovirus in chicken sera

The development of an indirect enzyme-linked immunosorbent assay (ELISA) for the serological diagnosis of Group B chicken astrovirus (CAstV) infections is described. The test was based on the use of an affinity-purified capsid antigen, specific to CAstV isolate 11672, produced as a glutathione-S-transferase N-terminal fusion protein by a recombinant baculovirus. Strongly positive ELISA signals were elicited against experimentally produced antisera raised to CAstVs from Group B (subgroups i and ii) but were negative for antisera raised to a Group A CAstV. Using a panel of 240 selected serum samples, 99% agreement was observed when the results obtained by ELISA were compared to those from an indirect immunofluorescence test for CAstV 11672. The ELISA test was applied to 68 serum sets comprising 1864 samples, which were obtained from parent and grandparent flocks originating mainly in the UK. Of the 52 sets containing ELISA-positive samples, 24 sets had >75% samples positive and nine sets had <25% samples positive and were regarded as having high and low seropositivities, respectively. Of the 1864 serum samples tested 1090 (58.5%) were ELISA positive and of these, 234 sera (21.5%) produced strongly positive signals, whereas moderately positive and weakly positive signals were produced by 562 (51.5%) and 294 (27%) sera. When used for flock screening purposes, this ELISA test can be used to (i) investigate the occurrence of first-time CAstV infections of parent flocks during lay and the possible adverse effects caused by vertically transmitted CAstV infections on broiler hatchability and performance and (ii) diagnose Group B CAstV infections within specific pathogen free flocks.

First report of Toxoplasma gondii in camels (Camelus dromedarius) in Ethiopia: bioassay and seroepidemiological investigation.

BackgroundToxoplasmosis is a major public health concern in many countries of the world. A cross-sectional and follow up experimental study designs were used for seroepidemiological and bioassay studies, respectively from November 2012 to April 2013. The objectives were to estimate the seroprevalence of T. gondii infection, to assess risk factors and to isolate the parasite from camels in the Fentale district, Ethiopia. A direct agglutination test (DAT) and indirect enzyme linked immunosorbent assay (ELISA) kits were used to test camel sera. Hearts and tongues (each 25 g) from 31 seropositive camels were bioassayed in mice. Associations between seroprevalence and potential risk factors (collected using a questionnaire survey) were analyzed using logistic regression.ResultsAn overall T. gondii prevalence of 49.62% (220/455) by DAT and 40.49% (179/451) by indirect ELISA test were detected. Herd level seroprevalence of 96.77% (30/31) (95% CI: 83.30– 99.92) by DAT was recorded and it was significantly higher in areas where wild felids are present (P = 0.038). Multivariable logistic regression showed that the likelihood of acquiring T. gondii infection was significantly higher in camels in the Ilala pastoral association [PA] (82.26%) (Adjusted Odds ratio [aOR] = 10.8; P < 0.001) than camels in the Galcha PA (31.43%), in camels of ≥ 8 years old (56.52%; aOR = 1.88; P = 0,033) than camels of ≤ 4 years old (34.26%) and in areas where domestic cats are present (aOR = 4.16; P = 0.006). All camel owners were uneducated, handle aborted fetus with bare hands, and drink raw camel milk. DAT and ELISA tests had moderate agreement (Kappa = 0.41). Viable T. gondii were isolated from 16.13% (5/31) of DAT positive camels. One DAT positive but ELISA negative camel sample gave a cyst positive result.ConclusionsT. gondii infection of camels in the study district is widespread. Age, presence of domestic cats and study PA are independent predictors of T. gondii seropositivity. Isolation of viable parasites from edible tissues of camels and the very poor knowledge of pastoralists about toxoplasmosis suggest the need for prevention of toxoplasmosis through bio-security measures, education and further investigation to unravel the impact of camel toxoplasmosis deserves consideration.Electronic supplementary materialThe online version of this article (doi:10.1186/s12917-014-0222-7) contains supplementary material, which is available to authorized users.

Identification and In Vitro Characterization of Phage-Displayed VHHs Targeting VEGF

Vascular endothelial growth factor (VEGF) is a potential target for cancer treatment because of its role in angiogenesis and its overexpression in most human cancers. Currently, anti-VEGF antibodies have been shown to be promising tools for therapeutic applications. However, large size, poor tumor penetration, immunogenicity, and production in cost- and labor-intensive conditions are major drawbacks of such agents. The antigen-binding regions of camelid single-chain antibodies (VHHs), due to their unique biophysical characteristics, offer an alternative to conventional antibodies for tumor-targeting purposes. The present study was undertaken to generate and characterize anti-VEGF VHHs from an immune VHH library using phage display. Four rounds of panning were performed, and selected VHHs were characterized using various immunological techniques. Assessment of the antigenic profile of VHHs was done using competition enzyme-linked immunosorbent assay (ELISA). Selected VHHs reacted strongly to VEGF in indirect ELISA and cross-reactivity ELISA tests. The binding affinity of three VHHs, ZFR-1, ZFR-2, and ZFR-5, ranged from 2.5 to 80 nM, and among them, ZFR-5, which was selected for proliferation assay, significantly inhibited the endothelial cell growth in a dose-dependent manner. Taken together, our results indicate that ZFR-5 and other VHHs may be promising tools in cancer research and treatment.

Teste de ELISA indireto para diagnóstico sorológico de leishmaniose visceral em canídeos silvestres

Na América do Sul, alguns canídeos silvestres são considerados reservatórios naturais da Leishmania chagasi. A resposta imunológica desses animais à Leishmania é pouco conhecida, havendo a necessidade de métodos diagnósticos adequados para esse fim. No presente estudo, é descrita a padronização do ensaio imunoenzimático indireto (ELISA) para o diagnóstico sorológico de leishmaniose visceral em canídeos silvestres brasileiros. Foram estudadas amostras de soro e plasma de 12 canídeos cativos: sete lobos-guará (Chrysocyon brachyurus), três raposinhas (Lycalopex vetulus) e dois cachorros-do-mato (Cerdocyon thous). As amostras de um C. brachyurus e uma L. vetulus, cativos em área endêmica para LV, que apresentavam doença clínica e positividade em testes de Imunofluorescência Indireta e Reação em Cadeia de Polimerase, foram utilizadas como controles positivos. Foram comparados os conjugados anti-IgG de cão e proteína A, ambos ligados a peroxidase, cujos testes detectaram quatro (04/12) e três (03/12) C. brachyurus soropositivos para anticorpos anti-Leishmania sp., respectivamente. As médias das densidades ópticas (DOs) das amostras negativas foram nitidamente mais baixas do que as médias das DOs dos positivos tanto no ELISA com anti-IgG de cão (4,8 vezes) como com proteína A (15,5 vezes). Os soros de três C. brachyurus positivos no ELISA indireto foram avaliados por Western blotting e identificaram 22 bandas, sendo imunodominantes as de peso molecular de 19, 22, 24, 45 e 66 kDa. Os testes ELISA com a proteína A e o conjugado anti-IgG de cão apresentaram respectivamente concordância excelente (Kappa = 1; p&lt;0,001) e moderada (Kappa = 0,8; p&lt;0,0015), com o Western blotting. Ambos foram, portanto, considerados adequados a avaliações de triagem de animais cuja resposta humoral de anticorpos indica contato com o parasito, úteis para subsidiar estudos para adequação de metodologias específicas para os canídeos silvestres.

Subclinical Diagnosis of Caseous Lymphadenitis Based on ELISA in Sheep from Brazil

Caseous lymphadenitis (CLA), caused by Corynebacterium pseudotuberculosis, is a chronic contagious disease that affects small ruminants and still remains an important problem for many lamb-producing countries. Animals are considered clinically infected when occurs abscesses in superficial lymph nodes. Visceral or internal form can coexist which no apparent clinical signs of infection are seen. The best procedure to avoid spread of the disease is elimination of infected animals. However, as the chronic and subclinical nature of the infection of CLA alternative methods are required for detection and screening. In this study, we described the performance of indirect Enzyme-Linked Immunosorbent Assay (ELISA) for diagnosis of CLA in asymptomatics sheep. Also, test culture and biochemical identification were achieved to confirm CLA infection. The serological diagnostic was performed in sheep symptomatics (n=50) and asymptomatics (n=374) from nine flocks. Analysis reported high positivity of 71% for ELISA in 85% of asymptomatic animal for CLA with a sensitivity of 88% and specificity of 31%. Results from ELISA test in asymptomatic animals against culture for caseous lymphadenitis were more specific (97%) and permitted to exclude healthy animals without symptoms. This study concluded that C. pseudotuberculosis infection could be widely disseminated in sheep flocks in Northwestern region of the state of Sao Paulo, Brazil and only one screening test is not enough. The association with indirect ELISA test and culture could better indicate the real problem of CLA in sheep flocks.

Evaluation of four serological tests to detect prevalence of bovine brucellosis in Khartoum State

To estimate the prevalence rate of bovine brucellosis in Khartoum State of Sudan and to compare the different serological tests, 636 stratified random samples of milk from farms and markets in the state were collected. Individual milk and blood samples were also collected from farms which showed positive reaction to the bulk milk ring test. All these samples were tested for Brucella antibodies using the milk ring test (MRT), Rose Bengal plate test (RBPT) and indirect ELISA test on milk and serum. The prevalence of Brucella antibodies was higher in milk compared with serum samples. In Enzyme-linked Immuno Sorbent Assay (ELISA) test using milk samples, it was 34.7%, followed by Milk Ring Test 32.5%, while the prevalence when using the serum was 27% with the Rose Bengal Plate Test and 24.4% when using serum-ELISA. The sensitivity and specificity of MRT were 85 and 95% and for RBPT were 92 and 94%, respectively. There were association between the MRT and milk-ELISA (p < 0.01) and between RBPT and serum-ELISA (p < 0.05). The percentage agreement among MRT and milk- ELISA was 83% Kappa (p < 0.01), while the percentage agreement between RBPT and serum-ELISA was 86% Kappa (p < 0.01). When comparing the sensitivity, specificity and percentage agreement between milk-ELISA and serum-ELISA for the same cows, sensitivity for milk-ELISA was 92.8% and the specificity was 98.8%. The percentage agreement between milk-ELISA and serum-ELISA was 79% Kappa (p < 0.01). Milk-ELISA will provide an easy and significant contribution to detect brucellosis compared to other serological tests. Key words: Sudan, milk, ELISA, serology, serum-ELISA, brucellosis.

The Value of BP230 Enzyme-Linked Immunosorbent Assay in the Diagnosis and Immunological Follow-Up of Bullous Pemphigoid

Background: The value of 230-kDa bullous pemphigoid antibody (BP230) enzyme-linked immunosorbent assay (ELISA) for the diagnosis of bullous pemphigoid (BP) was investigated, but in the immunological follow-up of the disease remains unknown. Objective: Evaluation of BP230 ELISA for diagnosis, follow-up and prediction of relapse in BP. Methods: Monocenter retrospective and prospective study. Patients with typical BP. Detection of autoantibodies by indirect immunofluorescence (IIF), BP180 and BP230 ELISA tests at diagnosis, during the treatment (disease control or failure) and at treatment stop (relapse or not 3 months after). Results: 74 patients were included. At diagnosis, BP230 ELISA sensitivity was lower than IIF and BP180 ELISA. Combining both ELISA added a weak gain of sensitivity. Both tests paralleled the clinical evolution, especially in case of disease control. At the end of the treatment, BP230 ELISA was not different in patients with or without relapse. Conclusion: In routine practice, BP230 ELISA does not seem to be a useful additional test in typical BP.

Seroprevalence of Neospora caninum Infection on Dairy Cattle in Farms from Southern Romania

Neospora caninum, a coccidian parasite closely related to Toxoplasma gondii, is one of the major causes of abortion in cattle worldwide. Conventional serological techniques, such as the indirect fluorescent antibody test and enzyme-linked immunosorbent assay (ELISA), are routinely used in adult animals and aborted fetuses for the detection of anti- N. caninum antibodies. In Romania, infection with N. caninum in cattle has been reported recently, but only in limited areas from the north and central parts of the country. Therefore, the aim of this study was to obtain additional seroepidemiological data on infection with N. caninum on dairy farms from the south of Romania. A total of 258 blood samples was analyzed from 230 dairy cows and 28 calves from 9 dairy farms in southern Romania; the presence of specific IgG antibodies against N. caninum was determined using an indirect ELISA test. The average seroprevalence was 40.3%, but the within-herd prevalence ranged between 11.5 and 80.0%; the seroprevalence in dairy cows was 41.7%, while in calves it was 28.6%. Of the positive samples, 74.0% (77/104) had a high positive reaction (S/P ratio more than 1.0), while 26.0% (27/104) had a low positive reaction (S/P ratio between 0.5 and 1.0). This study indicates that N. caninum infection is widespread in the south of Romania, which could explain the causes of abortions registered in some herds in the studied area. However, a serological screening across the country is planned in order to assess the actual national prevalence of N. caninum infection, followed by implementation of a prevention and control program.