Development of an indirect ELISA for the serodiagnosis of canine infection by Onchocerca lupi.

Onchocerca lupi is a zoonotic filarioid parasite of dogs and cats with widespread distribution. A specific non-invasive diagnostic assay for the detection of O. lupi infections remains unavailable. This study aimed to assess the accuracy, specificity, and sensitivity of an ELISA test designed using nine peptides from two O. lupi proteins. Sera (n = 54) collected from O. lupi infected dogs from endemic areas (Portugal and USA), alongside sera from dogs positive for Dirofilaria immitis, D. repens, Cercopithifilaria bainae, and Acanthocheilonema reconditum (n = 53) from a non-endemic area for O. lupi, as well as from helminth-free dogs (n = 60), were tested. The checkerboard titration method was applied for the optimization of peptide concentrations and conjugate anti-dog dilutions. Sensitivity, specificity, and optimal cut-off values were calculated using ROC curve analysis. All peptides reacted against sera of O. lupi, with no correlation between optic density (OD) values and microfilariae (mfs) loads. Sensitivity and specificity values ranging from 85.45 to 100%, and 88.89% to 100%, respectively, were recorded for all peptides examined, with 100% specificity and sensitivity observed for peptides 40_3, 40_5, 130_3, 120_3 and 40_1, 130_5, respectively. The maximum cut-off value was observed for peptides 40_5 (0.765) and 40_3 (0.708). Testing of sera from dogs positive for other filarioids resulted in lower OD values (up to 1.565) for peptides 40_3 and 40_5 when compared with O. lupi (up to 2.929). The availability of this assay will be of value in epidemiological studies of canine O. lupi infection in both endemic and non-endemic areas, and in assessing the risk for zoonotic transmission.

A double-strain TM (gp45) polypeptide antigen and its application in the serodiagnosis of equine infectious anemia.

Lentiviruses, including equine infectious anemia virus (EIAV), are considered viral quasispecies because of their intrinsic genetic, structural and phenotypic variability. Immunoenzymatic tests (ELISA) for EIAV reported in the literature were obtained mainly by using the capsid protein p26, which is derived almost exclusively from a single strain (Wyoming), and do not reflect the great potential epitopic variability of the EIAV quasispecies. In this investigation, the GenBank database was exploited in a systematic approach to design a set of representative protein antigens useful for EIAV serodiagnosis. The main bioinformatic tools used were clustering, molecular modelling, epitope predictions and aggregative/ solubility predictions. This approach led to the design of two antigenic proteins, i.e. a full sequence p26 capsid protein and a doublestrain polypeptide derived from the gp45 transmembrane protein fused to Maltose Binding Protein (MBP) that were expressed by recombinant DNA technology starting from synthetic genes, and analyzed by circular dichroism (CD) spectroscopy. Both proteins were used in an indirect ELISA test that can address some of the high variability of EIAV. The novel addition of the gp45 double-strain antigen contributed to enhance the diagnostic sensitivity and could be also useful for immunoblotting application.

Multi-event capture-recapture models estimate the diagnostic performance of serological tests for myxoma and rabbit haemorrhagic disease viruses in the absence of reference samples.

Estimation of the diagnostic performance of serological tests often relies on another test assumed as a reference or on samples of known infection status, yet both are seldom available for emerging pathogens in wildlife. Longitudinal disease serological data can be analysed through multi-event capture-mark-recapture (MECMR) models accounting for the uncertainty in state assignment, allowing us to estimate epidemiological parameters such as incidence and mortality. We hypothesized that by estimating the uncertainty in state assignment, MECMR models estimate the diagnostic performance of serological tests for rabbit haemorrhagic disease virus (RHDV) and myxoma virus (MYXV). We evaluated this hypothesis on longitudinal serological data of three tests of RHDV and one test of MYXV in two populations of the European rabbit (Oryctolagus cuniculus algirus). First, we selected the optimal cut-off threshold for each test using finite mixture models, a reference method not relying on reference tests or samples. Second, we used MECMR models to compare the diagnostic sensitivity (Se) and specificity (Sp) of the three tests for RHDV. Third, we compared the estimates of diagnostic performance by MECMR and finite mixture models across a range of cut-off values. The MECMR models showed that the RHDV test employing GI.2 antigens (Se: 100%) outperformed two tests employing GI.1 antigens (Se: 21.7% ± 8.6% and 8.7% ± 5.9%). At their selected cut-offs (2.0 for RHDV GI.2 and 2.4 for MYXV), the estimates of Se and Sp were concordant between the MECMR and finite mixture models. Over the duration of the study (May 2018 to September 2020), the monthly survival of European rabbits seropositive for MYXV was significantly higher than that of seronegative rabbits (82.7% ± 4.9% versus 61.5% ± 12.7%) at the non-fenced site. We conclude that MECMR models can reliably estimate the diagnostic performance of serological tests for RHDV and MYXV in European rabbits. This conclusion could extend to other diagnostic tests and host-pathogen systems. Longitudinal disease surveillance data analysed through MECMR models allow the validation of diagnostic tests for emerging pathogens in novel host species while simultaneously estimating epidemiological parameters.

Enzyme-linked immunosorbent assay (ELISA) for detection of IgY Anti-Borrelia anserina antibodies in Gallus gallus domesticus / Ensaio de imunoadsorção enzimático (ELISA) indireto para detecção de anticorpos IgY Anti-Borreliaanserina em Gallus gallus domesticus

This study aimed to promote the standardization of an indirect, enzyme-linked immunosorbent assay (ELISA) for the serological detection of B. anserina in Gallus gallusdomesticus. An aliquoted sera from vaccinated chicken with B. anserina antigen (GI), experimental infected chickens with B. anserina (GII) and rustic poultry rearing of G. gallus (GIII) were tested with in-house ELISA developed to detect serum antibodies against B. anserina in G. gallus domesticus. On average, the experimentally infected chickens became positive at 9 DPI a mean ± standard deviation (SD) ODI value of 163.11 ± 70.65. The highest observed Optical Density Index (ODI) was 372.54 ± 132.39, at 26 DPI, and the highest overall ODI value was 626.51. The vaccinated chickens became positive between 8 and 10 DPV, with an ODI of 245.59 at 10 DPV, with an overall maximum ODI of 543.13. A total of 108 blood samples were collected from poultry raised on rustic farms. Of the total samples collected, 58.33% (63/108) were considered positive for B. anserina. The maximum ODI found among these rustic chickens was 283.24. This stardardization provided a sensitivity and specificity of 100%.

Este estudo teve como objetivo promover a padronização de um ensaio imunoenzimático indireto (ELISA) para a detecção sorológica de Borrelia anserina em Gallus gallus domesticus. Um frango vacinado com antígeno de B. anserina (GI), frangos infectados experimentalmente com B. anserina (GII) e frangos criados de forma rústica (GIII) foram testados com ELISA indireto in house desenvolvido para a detecção sorológica contra B. anserina em G. gallus domesticus. Em média, os frangos infectados experimentalmente tornaram-se positivos aos 9º dia pós-inoculação (DPI), um valor do índice de densidade óptica (ODI) médio ± desvio padrão (SD) de 163,11 ± 70,65. O maior ODI observado foi 372,54 ± 132,39, em 26ºDPI, e o maior valor geral de ODI foi 626,51. Os frangos vacinados tornaram-se positivos entre 8º e 10° DPV, com um ODI de 245,59 a 10 DPV, com um ODI máximo geral de 543,13. Um total de 108 amostras de sangue foram coletadas de aves criadas em fazendas rústicas. Do total de amostras coletadas, 58,33% (63/108) foram consideradas positivas para B. anserina. O ODI máximo encontrado entre essas galinhas rústicas foi 283,24. Essa padronização proporcionou sensibilidade e especificidade de 100%.

Novel polyprotein antigens designed for improved serodiagnosis of bovine tuberculosis.

Recent studies have demonstrated potential for serologic assays to improve surveillance and control programs for bovine tuberculosis. Due to the animal-to-animal variation of the individual antibody repertoires observed in bovine tuberculosis, it has been suggested that serodiagnostic sensitivity can be maximized by use of multi-antigen cocktails or genetically engineered polyproteins expressing immunodominant B-cell epitopes. In the present study, we designed three novel multiepitope polyproteins named BID109, TB1f, and TB2f, with each construct representing a unique combination of four full-length peptides of Mycobacterium bovis predominantly recognized in bovine tuberculosis. Functional performance of the fusion antigens was evaluated using multi-antigen print immunoassay (MAPIA) and Dual Path Platform (DPP) technology with panels of monoclonal and polyclonal antibodies generated against individual proteins included in the fusion constructs as well as with serum samples from M. bovis-infected and non-infected cattle, American bison, and domestic pigs. It was shown that epitopes of each individual protein were expressed in the fusion antigens and accessible for efficient binding by the respective antibodies. The three fusion antigens demonstrated stronger immunoreactivity in MAPIA than that of single protein antigens. Evaluation of the fusion antigens in DPP assay using serum samples from 125 M. bovis-infected and 57 non-infected cattle showed the best accuracy (∼84 %) for TB2f antigen composed of MPB70, MPB83, CFP10, and Rv2650c proteins. Thus, the study results suggest a potential for the multiepitope polyproteins to improve diagnostic sensitivity of serologic assays for bovine tuberculosis.

Serological and molecular detection of Theileria equi in horses from Sinop, Mato Grosso state, Brazil / Detecção sorológica e molecular de Theileria equi em equinos oriundos de Sinop, Mato Grosso, Brasil

Equine piroplasmosis is the most important tick-borne disease to affect horses in Brazil. Theileria equi is one of the causative agents of equine piroplasmosis. Chronic cases are expected, in which the animals show no apparent signs of infection and remain asymptomatic but constitute a source of the infectious agent that ticks can spread. This study was conducted across 81 ranches located in the municipality of Sinop, State of Mato Grosso, Brazil. A sample calculation was performed to estimate the apparent prevalence of T. equi among horses. A total of 1,853 animals were included in the sampling analysis based on the information available from the Institute of Agricultural and Livestock Defense of Mato Grosso State. The serological analysis of 367 serum samples using an indirect enzyme-linked immunosorbent assay (ELISA) to detect anti-T. equi antibodies revealed that 337 animals were positive, representing a frequency of 90.70%. The molecular analysis to amplify the EMA-1 gene showed positivity in 20 of 89 tested samples. The fragments of four samples were sequenced and analyzed to determine their similarities to sequences from other species, based on sequences deposited at GenBank. All showed 100% similarity with T. equi. Our study represents the first report of T. equi antibodies among the equids in north-central region of Mato Grosso, revealing the widespread distribution of seropositive animals.

A piroplasmose equina é a doença transmitida por carrapatos mais importante em cavalos no Brasil. Theileria equi é um dos agentes causadores da piroplasmose equina. São esperados casos crônicos, nos quais os animais não apresentam sinais aparentes de infecção e permanecem assintomáticos, mas constituem uma fonte de infecção e disseminação por carrapatos. Este estudo foi realizado em 81 fazendas localizadas no município de Sinop, Estado de Mato Grosso, Brasil. Um cálculo amostral foi realizado para estimar a prevalência aparente de T. equi entre cavalos. No total, 1.853 animais foram incluídos na análise amostral com base nas informações disponíveis no Instituto de Defesa Agropecuária do Estado de Mato Grosso. A análise sorológica de 367 amostras de soro por meio de ensaio imunoenzimático indireto (ELISA) para detecção de anticorpos anti-T. equi revelou que 337 animais eram positivos, representando uma frequência de 90,70%. A análise molecular para o gene EMA-1 mostrou positividade em 20 das 89 amostras testadas. Os fragmentos de quatro amostras foram sequenciados e analisados para determinar suas semelhanças com sequências de outras espécies, a partir das sequências depositadas no GenBank. Todos mostraram 100% de similaridade com T. equi. Nosso estudo representa o primeiro relato de anticorpos contra T. equi entre os equídeos na região centro norte de Mato Grosso, revelando a ampla distribuição de animais soropositivos.

Comparison of hemagglutination inhibition tests, immunoperoxidase monolayer assays, and serum neutralizing tests in detecting antibodies against blue eye disease in pigs.

Blue eye disease (BED) of pigs was identified in the early 1980s in La Piedad, Michoacan, Mexico. The causal agent is Porcine orthorubulavirus (PRV), which affects pigs of all ages, producing nervous, respiratory, and reproductive disorders. BED is geographically endemic to the center of Mexico, where 75% of the country's swine industry is concentrated. Due to its adverse effects on the swine industry and the risk of dissemination to other countries, it is essential to have reliable diagnostic methods for BED. The objective of this study was to establish the optimal conditions for three serological tests, hemagglutination inhibition (HI), immunoperoxidase monolayer assay (IPMA), and serum neutralization (SN), and to compare their sensitivity, specificity, kappa coefficient, and predictive values. Twelve different HI protocols (9408 tests), one SN protocol and one IPMA protocol (784 tests, each) were evaluated. Forty-nine sera were analyzed, and thirty-seven sera showed true positive results, while twelve showed true negative results. The kappa coefficient was used to assess the variation in each test. The best HI protocol registered a sensitivity and specificity of 89 and 100%, respectively, the IPMA test showed values of 85 and 100%, and the SN test registered a sensitivity of 91% and a specificity of 96%. One of the disadvantages of the HI test is that when chicken red blood cells (RBCs) are used, elution occurs in a short incubation time, which would decrease the specificity. The use of bovine RBCs increases the specificity of the testy and makes it more stable, but it decreases the sensitivity. The results of HI and SN revealed the importance of eliminating the complement system of the serum and removing other inhibitors to avoid test nonspecificity. The IPMA test does not use an active virus; hence, it is considered safe and does not present any risk of disseminating PRV.

Inquérito sorológico de brucelose em machos e fêmeas bovinas em fazendas do Estado de Mato Grosso do Sul / Serological survey of brucellosis in males and females of cattle in the State of Mato Grosso do Sul

Objetivou-se avaliar a ocorrência de animais soro reagentes à brucelose bovina em fazendas localizadas no Estado de Mato Grosso do Sul, por meio de exame sorológico utilizando o Antígeno Acidificado Tamponado (AAT) e discutir as possíveis diferenças entre as soroprevalências de fêmeas e machos. Foram avaliados, a partir do teste de triagem com Antígeno Acidificado Tamponado (AAT), 724 bovinos da raça Nelore, sendo 274 machos e 450 fêmeas, provenientes de oito propriedades com histórico de problemas reprodutivos. O teste foi procedido conforme o protocolo determinado pelo Ministério da Agricultura, Pecuária e Abastecimento (MAPA). Os resultados demonstraram baixa soroprevalência da doença nos bovinos testados, sendo detectada prevalência para a doença de 1,10% nos machos e 2,88% nas fêmeas.Quando se considera o touro isoladamente nos rebanhos, pode-se perceber que a fertilidade é muito mais importante nos machos do que nas fêmeas individualmente, uma vez que os touros podem se acasalar com um número muito maior de fêmeas, seja na monta natural ou na inseminação artificial, demonstrando a importância do inquérito epidemiológico na população geral, principalmente nos machos. A maior frequência da doença foi encontrada nas fêmeas podendo estar relacionada à infecção por Brucella spp. no ambiente decorrente de parto ou aborto tornando as fêmeas transmissoras permanentes da doença.

The objective of this study was to evaluate the occurrence of seroreactive animals to bovine brucellosis in farms located in the State of Mato Grosso do Sul, by means of a serological examination using the Acidified Buffered Antigen (AAT) and to discuss the possible differences between the seroprevalence of females and males. A total of 724 Nellore cattle, 274 males and 450 females, from eight farms with a history of reproductive problems, were evaluated using the screening test with Acidified Buffered Antigen (AAT). The test was carried out according to the protocol determined by the Ministry of Agriculture, Livestock and Food Supply (MAPA).The results showed a low seroprevalence of the disease in the tested cattle, with a prevalence of 1.10% in males and 2.88% in females.When considered the bull alone in herds, it can be shown that fertility is much more important in males than in females individually, since bulls can mate with a much larger number of females, either in natural mating or in artificial insemination, demonstrating the importance of epidemiological survey in the general population, especially in males. The highest frequency of the disease was found in females and may be related to infection by Brucella spp. in the environment from childbirth or abortion making females permanent transmitters of the disease.

Inquérito sorológico de brucelose em machos e fêmeas bovinas em fazendas do Estado de Mato Grosso do Sul / Serological survey of brucellosis in males and females of cattle in the State of Mato Grosso do Sul

Objetivou-se avaliar a ocorrência de animais soro reagentes à brucelose bovina em fazendas localizadas no Estado de Mato Grosso do Sul, por meio de exame sorológico utilizando o Antígeno Acidificado Tamponado (AAT) e discutir as possíveis diferenças entre as soroprevalências de fêmeas e machos. Foram avaliados, a partir do teste de triagem com Antígeno Acidificado Tamponado (AAT), 724 bovinos da raça Nelore, sendo 274 machos e 450 fêmeas, provenientes de oito propriedades com histórico de problemas reprodutivos. O teste foi procedido conforme o protocolo determinado pelo Ministério da Agricultura, Pecuária e Abastecimento (MAPA). Os resultados demonstraram baixa soroprevalência da doença nos bovinos testados, sendo detectada prevalência para a doença de 1,10% nos machos e 2,88% nas fêmeas.Quando se considera o touro isoladamente nos rebanhos, pode-se perceber que a fertilidade é muito mais importante nos machos do que nas fêmeas individualmente, uma vez que os touros podem se acasalar com um número muito maior de fêmeas, seja na monta natural ou na inseminação artificial, demonstrando a importância do inquérito epidemiológico na população geral, principalmente nos machos. A maior frequência da doença foi encontrada nas fêmeas podendo estar relacionada à infecção por Brucella spp. no ambiente decorrente de parto ou aborto tornando as fêmeas transmissoras permanentes da doença.

The objective of this study was to evaluate the occurrence of seroreactive animals to bovine brucellosis in farms located in the State of Mato Grosso do Sul, by means of a serological examination using the Acidified Buffered Antigen (AAT) and to discuss the possible differences between the seroprevalence of females and males. A total of 724 Nellore cattle, 274 males and 450 females, from eight farms with a history of reproductive problems, were evaluated using the screening test with Acidified Buffered Antigen (AAT). The test was carried out according to the protocol determined by the Ministry of Agriculture, Livestock and Food Supply (MAPA).The results showed a low seroprevalence of the disease in the tested cattle, with a prevalence of 1.10% in males and 2.88% in females.When considered the bull alone in herds, it can be shown that fertility is much more important in males than in females individually, since bulls can mate with a much larger number of females, either in natural mating or in artificial insemination, demonstrating the importance of epidemiological survey in the general population, especially in males. The highest frequency of the disease was found in females and may be related to infection by Brucella spp. in the environment from childbirth or abortion making females permanent transmitters of the disease.

Evaluation of a cystatin-like protein of Trichinella spiralis for serodiagnosis and identification of immunodominant epitopes using monoclonal antibodies.

An antigenic cystatin-like protein (Ts-CLP) selected from cDNA library of intestinal infective larvae at 6 h post-infection, was expressed by prokaryotes in the form of a histidine-tagged protein (rTs-CLP). The fusion protein was purified by an on-column refolding procedure using Ni-NTA affinity chromatography. An indirect rTs-CLP ELISA was developed using 270 known negative serum samples from commercial swine maintained under non-special pathogen free conditions. Based on the distribution of the signal-to-positive (S/P) ratio, a cut-off value was set at 0.30. Using this cut-off value, rTs-CLP ELISA was evaluated using sera from swine experimentally infected with 1000 and 50,000 muscle larvae of Trichinella spiralis. Specific IgG antibodies were detectable by rTs-CLP ELISA as soon as 17 days post-infection (dpi), but the commercial ELISA kit based on excretory-secretory (ES) antigens did not permit detection before 21 dpi. Three monoclonal antibodies (McAbs) against Ts-CLP (designated 1H9, 6B5 and 7F8) were obtained by screening with both rTs-CLP ELISA and ES ELISA methods. Two dominant epitopes recognized by McAbs were determined by analysis with overlapping fusion peptides and synthetic peptides. One epitope 39 HEALFSSDLKQESGV 53 was recognized by 1H9 and 6B5, and the other epitope 178 REALFSSDSKEQSGV 192 was recognized by 7F8. The generation of McAbs against Ts-CLP and the characterization of the two dominant epitopes provide a foundation for the development of a specific early serodiagnostic strategy for T. spiralis infection.

True prevalence and spatial distribution of equine infectious anemia virus (EIAV) in horses from northeast region of Brazil

Equine infectious anemia (EIA) is a viral infection, caused by a lentivirus of the Retroviridae family, Orthoretrovirinael subfamily and its occurrence generates significant economic losses due to culling of positive animals as a measure of infection control. The objective of this work was to determine the prevalence of horses positive for equine infectious anemia virus (EIAV) and to identify the occurrence of areas with higher densities of cases in the states of Paraíba (PB), Pernambuco (PE), Rio Grande do Norte (RN) and Ceará (CE), Northeast region of Brazil, during the rainy (May and June) and dry (October and November) periods of 2017 and 2018. Serum samples from 6,566 horses from the states of PB, PE, RN and CE, Brazil, provided by the Laboratório Veterinária Diagnóstico - Ltda., were used. Serological diagnosis of EIA was performed using indirect enzyme-linked immunosorbent assay (ELISA) as a screening test and agar gel immunodiffusion test (AGID) as a confirmatory test. The apparent prevalence was obtained by dividing the number of seroreactive animals by the total number of animals, while the true prevalence was estimated by adjusting the apparent prevalence, considering the sensitivity (100%) and specificity (98.6%) of the diagnostic protocol used. For the construction of Kernel estimates, the Quartic function was used. In the dry season, of the 1,564 animals sampled, 28 were serologically positive, of which 19 belonged to the state of Ceará, 7 to Paraíba and 2 to Rio Grande do Norte. In 2018, it was observed that, during the rainy season, 26 of the 1,635 horses were seroreactive, with 19 cases resulting from Ceará, 4 from Paraíba and 3 from Pernambuco. In the dry season, 32 of the 1,526 animals were seroreactive to EIAV, of which 26 were from Ceará, 3 from Paraíba, 1 from Rio Grande do Norte and 2 from Pernambuco. In the dry period of 2017, the CE had a real prevalence of 1.22% (95% CI = 0.05 - 2.99%). In 2018, during the rainy season, prevalences of 0.03% (95% CI = 0 - 1.18%) were identified in CE and 1.69% (95% CI = 0 - 8.38%) in PE. Regarding the 2018 dry period, a prevalence of 1.32% (95% CI = 0.26 - 2.84%) was found in the state of CE. In both dry and rainy periods of 2017, the presence of spatial clusters of animals positive for EIA was observed, mainly in the border areas among the states of CE, PE, PB and RN. In 2018, there was a variation in the distribution of areas with higher densities of cases between the rainy and dry periods. The state of CE had the highest prevalence of positive animals and the presence of areas with higher densities of EIA cases in both climatic periods, in the years 2017 and 2018. In some municipalities of the CE, important sporting events of agglomeration of animals take place, which can favor the transmission of EIAV by facilitating the contact of infected and susceptible animals. Population density may be a factor associated with the higher prevalence observed in this region, as it has the second largest herd among the states studied. Higher densities indirectly contribute to the occurrence of infectious diseases, as they favor the contact of infected and susceptible animals. The occurrence of higher densities of cases in the border areas of the states of PE, RN, CE, and PB may be related to the greater movement of animals in these regions, favoring the indirect contact of infected horses with susceptible ones. The observed results demonstrate the circulation of the EIAV in four states in the Northeast region of Brazil.(AU)

Performance of Ag-ELISA in the diagnosis of Taenia solium cysticercosis in naturally infected pigs in Tanzania.

BACKGROUND: Taenia solium is a zoonotic parasite responsible for neurocysticercosis-a major cause of late-onset acquired epilepsy in humans. Lack of affordable, specific and sensitive diagnostic tools hampers control of the parasite. This study assessed the performance of an antigen detection enzyme-linked immunosorbent assay (Ag-ELISA) in the diagnosis of viable T. solium cysticercosis in naturally infected slaughter-age pigs in an endemic area in Tanzania. METHODS: A total of 350 pigs were bled before they were slaughtered and their carcases examined. Serum was analyzed for circulating antigens by using a monoclonal antibody-based B158/B60 Ag-ELISA. Each carcase was examined for the presence of Taenia hydatigena cysticerci and half carcase musculature together with the whole brain, head muscles, tongue, heart and diaphragm were sliced with fine cuts (< 0.5 cm) to reveal and enumerate T. solium cysticerci. Half carcase dissection can detect at least 84% of infected pigs. Prevalence and their 95% confidence intervals (CI) were calculated in Stata 12. Sensitivity, specificity, predictive values and likelihood ratios were determined. RESULTS: Twenty-nine pigs (8.3%, 95% CI: 5.6-11.7%) had viable T. solium cysticerci while 11 pigs had T. hydatigena cysticerci (3.1%, 95% CI: 1.6-5.5%). No co-infection was observed. Sixty-eight pigs (19.4%, 95% CI: 15.4-20%) tested positive on Ag-ELISA; of these, 24 had T. solium cysticerci and 7 had T. hydatigena cysticerci. Sensitivity and specificity were determined to be 82.7% and 86.3%, respectively. Positive and negative predictive values were 35.2% and 98.2%, respectively. Likelihood ratios for positive and negative Ag-ELISA test results were 6.0 and 0.2, respectively. There was a significant positive correlation between the titre of circulating antigens and intensity of T. solium cysticerci (r(348) = 0.63, P < 0.001). CONCLUSIONS: The Ag-ELISA test characteristics reported in this study indicate that the test is more reliable in ruling out T. solium cysticercosis in pigs, than in confirming it. Hence, a negative result will almost certainly indicate that a pig has no infection, but a positive result should always be interpreted with caution. Estimates of T. solium prevalence based on Ag-ELISA results should, therefore, be adjusted for test performance characteristics and occurrence of T. hydatigena.

Performance of the Dot-blot test method for detecting antibodies to Sarcocystis spp. in cattle / Desempenho do teste Dot-blot para detecção de anticorpos para Sarcocystis spp. em bovinos

Serological techniques can detect antibodies against Sarcocystis spp., Neospora caninum and Toxoplasma gondii antigens in single or mixed infections. Immunofluorescent antibody tests (IFAT) is considered the gold standard technique for Sarcocystosis diagnostic in cattle serum and a positive IFAT result reflects Sarcocystis spp. infection. Therefore, the aims of the present study were to compare IFAT and Dot-blot for sarcocystosis diagnostic in experimentally infected mice and to investigate serological cross-reactions with N. caninum and T. gondii in these methods. Mice (Mus musculus) were inoculated intraperitoneally with bradizoites of Sarcocystis spp. or tachyzoites of N. caninum or T. gondii. Serum samples were obtained and analyzed by IFAT and Dot-blot for the three protozoa. Serum from N. caninum and T. gondii experimentally infected mice were tested by IFAT and reacted only to N. caninum or T. gondii antigens, respectively. Specific antibodies against Sarcocystis spp. were present in all animals experimentally infected with this protozoan, with IFAT titers from 10 to 800. Serum samples from mice experimentally infected with Sarcocystis spp., N. caninum and T. gondii and tested by Dot-blot demonstrated no cross reaction between protozoa. A Dot-blot using Sarcocystis spp. antigen appears to be a good alternative to IFAT in the serological diagnosis of Sarcocystosis.(AU)

As técnicas sorológicas podem detectar anticorpos contra os antígenos de Sarcocystis spp., Neospora caninum e Toxoplasma gondii em infecções únicas ou mistas. O teste de anticorpos imunofluorescentes (IFAT) é considerado a técnica padrão-ouro para o diagnóstico de sarcocistose no soro de bovinos e um resultado positivo de IFAT reflete Sarcocystis spp. infecção. Portanto, os objetivos do presente estudo foram comparar IFAT e Dot-blot para diagnóstico de sarcocistose em camundongos infectados experimentalmente e investigar reações cruzadas sorológicas com N. caninum e T. gondii nesses métodos. Os camundongos (Mus musculus) foram inoculados intraperitonealmente com bradizoítos de Sarcocystis spp. ou taquizoítos de N. caninum ou T. gondii. As amostras de soro foram obtidas e analisadas por IFAT e Dot-blot para os três protozoários. O soro de N. caninum e T. gondii infectados experimentalmente foram testados por IFAT e reagiram apenas aos antígenos de N. caninum ou T. gondii, respectivamente. Anticorpos específicos contra Sarcocystis spp. estavam presentes em todos os animais experimentalmente infectados com este protozoário, com títulos de IFAT de 10 a 800. Amostras de soro de camundongos infectados experimentalmente com Sarcocystis spp., N. caninum e T. gondii e testadas por Dot-blot não demonstraram reação cruzada entre protozoários. Um Dot-blot usando Sarcocystis spp. O antígeno parece ser uma boa alternativa ao IFAT no diagnóstico sorológico da sarcocistose.(AU)

An efficient fiber-based ELISA for detection of antibody against fowl adenovirus serotypes 7 and 8.

An outbreak of inclusion body hepatitis caused by fowl adenovirus serotype 8 (FAdV-8) has caused significant economic losses in the poultry industry worldwide. However, a rapid serology test kit specific to FAdV-8 is not available to date. We developed a fiber-based ELISA using the purified GST-fiber of FAdV-8 as coating antigen to measure antibodies against FAdV-8. Specificity analysis showed that our ELISA could react with sera against FAdV-7, -8a, and -8b, but not with sera against the other pathogens tested. Moreover, detection of positive sera with our ELISA had 83% and 94% agreement with an indirect immunofluorescence assay (IFA) and a commercial ELISA from BioChek, respectively. Our ELISA was also effective in the detection of antibodies against FAdV-8 in sera from both experimentally infected and clinically vaccinated chickens. Our FAdV-8 fiber-based ELISA can be a valuable tool to specifically and sensitively detect antibodies against FAdV-7 and/or -8 in infected or vaccinated chickens.

Serological survey of bluetongue virus in sheep from Minas Gerais / Inquérito sorológico do vírus da língua azul em ovinos de Minas Gerais

Bluetongue is an infectious, non-contagious disease that affects domestic and wild ruminants, caused by a virus from the Orbivirus genus, Reoviridae family, transmitted by arthropod vectors of the Culicoides genus. This paper aims to be the first serological survey of bluetongue in sheep from the Meso-regions of Campo das Vertentes and South and Southeast of Minas Gerais. Samples were collected from sheep from different properties. The serum samples were submitted to Agar Gel Immunodiffusion (AGID) and competitive Enzyme-Linked Immunosorbent Assay (cELISA). 303 serum samples were submitted to AGID and cELISA. In these samples, 164 (54.13%) were positive in the AGID technique, and 171 (56.44%) positive in the cELISA technique, with an almost perfect agreement between the techniques (kappa index = 0.887). In all visited properties, positive animals have been found in the herd. Animals acquired from properties of the studied mesoregions were more likely to be positive in IDGA and cELISA tests than animals acquired from properties in other regions of Brazil (p<0.001). These results suggest that bluetongue virus (BTV) is widespread in the mesoregions of Campo das Vertentes and South and Southeast of Minas Gerais.(AU)

A língua azul (LA) é uma doença infecciosa, não contagiosa, que acomete ruminantes domésticos e silvestres, causada por um vírus do gênero Orbivirus da família Reoviridae, transmitida por vetores artrópodes do gênero Culicoides. O presente estudo representa o primeiro trabalho a realizar um inquérito sorológico da língua azul em rebanhos ovinos nas Mesorregiões de Campo das Vertentes e Sul e Sudoeste de Minas Gerais. Foram coletadas amostras de soro de ovinos de diferentes propriedades. As amostras de soro foram submetidas aos testes de imunodifusão em gel de ágar (IDGA) e ensaio de imunoadsorção enzimática por competição (cELISA). Ao todo 303 amostras de soro foram submetidas ao IDGA e cELISA. Dessas amostras, 164 (54,13%) foram positivas na técnica de IDGA e 171 (56,44%) positivas na técnica de cELISA, havendo concordância quase perfeita entre as técnicas (índice kappa = 0,887). Em todas as propriedades visitadas, foram encontrados animais positivos no rebanho. Animais adquiridos de propriedades das Mesorregiões estudadas, tiveram mais chances de serem positivos nos testes de IDGA e cELISA do que animais adquiridos de propriedades de outras Regiões do Brasil (p<0,001). Esses resultados sugerem que o vírus da língua azul encontra-se disseminado em ovinos nas Mesorregiões de Campo das Vertentes e Sul e Sudoeste de Minas Gerais.(AU)

Detection of antibodies against Toxoplasma gondii in cats using an immunochromatographic test based on GRA7 antigen.

Toxoplasmosis, caused by Toxoplasma gondii, is one of the most common parasitic diseases worldwide. The GRA7 of T. gondii (TgGRA7) is an essential component of the parasitophorous vacuole (PV) and PV membrane surrounding the tachyzoites and the cyst wall of the bradyzoites. While it has been widely employed as antigen for ELISA, there is only one study that has reported its potential as antigen for immunochromatographic test (ICT) in pigs. There is no study yet documenting its potential for ICT serodiagnosis of T. gondii infection in cats. In this study, we assessed the efficacy of an ICT using TgGRA7 in the detection of Toxoplasma infections in 100 cats and compared the results with iELISAs using TgGRA7 and lysate antigens of T. gondii strains, RH, PLK, and VEG. Our results revealed that TgGRA7-ICT is a reliable test for the diagnosis of anti-T. gondii antibodies in cats, producing comparable results as conventional serological methods. This study is the first report on the use of TgGRA7 as ICT antigen for the serodiagnosis of T. gondii infection in cats.

Comparative evaluation of fluorescence polarization assay and competitive ELISA for the diagnosis of bovine brucellosis vis-a-vis sero-monitoring.

Brucellosis is an important zoonosis that constitutes a serious public health hazard which is caused by a bacterium belonging to the genus Brucella. In the present study, two highly specific serological tests for brucellosis diagnosis, fluorescence polarization assay (FPA) and competitive ELISA (cELISA) were standardized in the laboratory, evaluated and compared with rose bengal plate test (RBPT), indirect ELISA (iELISA) and commercial cELISA kit. For test evaluation, 1386 serum samples [apparently healthy animals (n = 260), samples from Brucella infected farms (n = 701) and B. abortus S19 vaccinated animals (n = 425)] were analyzed to assess suitable diagnostic test in B. abortus S19 post vaccinated bovine population. In apparently healthy brucellosis free farms, RBPT, iELISA, in-house FPA and cELISA were found to be highly specific than commercial cELISA. Commercial cELISA kit was comparatively more sensitive than other serological tests in samples collected from infected farms. The FPA showed sensitivity nearly equal to RBPT and in-house cELISA showed greater sensitivity than RBPT in infected farms. In animals with persistent vaccinal antibodies, only in-house FPA and cELISA recorded higher specificity of 87.64 and 90.27%, respectively. The other tests, RBPT and iELISA displayed similar reactivity with vaccine antibodies to that of infection antibodies whereas commercial cELISA kit showed an intermediate specificity of 47.69%. With these findings, RBPT, iELISA and cELISA are suggested for screening infected herds, and in-house developed FPA and cELISA tests with a proven specificity can be used for confirmatory diagnosis of brucellosis in B. abortus S19 post vaccinated animal populations.

High proportion of cattle and sheep seropositive and renal carriers of Leptospira sp. under semiarid conditions / Alta proporção de bovinos e ovinos soropositivos e portadores renais de Leptospira sp. em condições semiáridas

The aims of this study were to perform serological and molecular detection of Leptospira sp. infection in cattle and sheep under semiarid conditions. Based on a preliminary study performed in our research group, we selected six rural properties showing a positivity ≥ 60% for Sejroe serogroup with titer ≥ 200 measured in serological tests from cattle. In the present study, blood and urine samples were collected from 99 females of reproductive age (51 cattle and 48 sheep) for serological diagnosis, molecular detection and Leptospira sp. attempt to strain recovery. Of the 99 analyzed animals 38.4% (38/99) were positively reactive at the serological tests. Of them, 49% (25/51) were cattle and 27.1% (13/48) sheep. The serogroups detected in cattle were Sejroe (36.8%), Hebdomadis (26.3%), Australis (10.5%), Djasiman (10.5%), Ballum (5.3%), Pomona (5.3%), and Cynopteri (5.3%) with titers of 100­800. In sheep, the reactive serogroups were Australis (27.3%), Ballum (27.3%), Djasiman (18.1%), Tarassovi (9.1%), Icterohaemorrhagiae (9.1%), and Cynopteri (9.1%) with titers of 100­400.Leptospiral DNA was detected in nine urine samples, including five cattle and four sheep. Property 1 showed the highest serological positivity frequencies for both cattle (70.6%) and sheep (70.6%). Similarly, the highest frequency of DNA detection was also found (eight samples, 89%). In this property, we observed the existence of consorted rearing of cattle and sheep with close coexistence between these species. In semiarid conditions, transmission among animals of the same species seems to be the main form of Leptospira sp. dissemination in cattle and sheep herds. However, the contribution of other domestic and wild animals cannot be discarded. The practice of consorted rearing of cattle and sheep and their close coexistence may facilitate the spread of the pathogen in rural properties.

Os objetivos deste estudo foram realizar detecção sorológica e molecular da infecção por Leptospira sp. em bovinos e ovinos em condições semiáridas. Com base em estudo preliminar realizado em nosso grupo de pesquisa, foram selecionadas seis propriedades rurais com soropositividade ≥ 60% para o sorogrupo Sejroe com título ≥ 200 em bovinos. No presente estudo, amostras de sangue e urina foram coletadas de 99 fêmeas em idade reprodutiva (51 bovinos e 48 ovinos) para diagnóstico sorológico, detecção molecular e tentativa de recuperação de estirpesde Leptospira sp. Dos 99 animais analisados, 38,4% (38/99) foram sororeativos nos testes sorológicos. Destes, 49% (25/51) eram bovinos e 27,1% (13/48) ovinos. Os sorogrupos detectados em bovinos foram Sejroe (36,8%), Hebdomadis (26,3%), Australis (10,5%), Djasiman (10,5%), Ballum (5,3%), Pomona (5,3%) e Cynopteri (5,3%) com títulos de 100 a 800. Nos ovinos, os sorogrupos reativos foram Australis (27,3%), Ballum (27,3%), Djasiman (18,1%), Tarassovi (9,1%), Icterohaemorrhagiae (9,1%) e Cynopteri (9,1%) com títulos de 100-400. O DNA leptospiral foi detectado em nove amostras de urina, incluindo cinco bovinos e quatro ovinos. A propriedade 1 apresentou as maiores frequências de positividade sorológica para bovinos (70,6%) e ovinos (70,6%). Da mesma forma, a maior frequência de detecção de DNA também foi encontrada (oito amostras, 89%). Nesta propriedade observou-se a existência de criação consorciada de bovinos e ovinos com estreita convivência entre estas espécies. Em condições semiáridas, a transmissão entre animais da mesma espécie parece ser a principal forma de disseminação de Leptospira sp. em rebanhos bovinos e ovinos. No entanto, a contribuição de outros animais domésticos e selvagens não pode ser descartada. A prática de criação consorciada de bovinos e ovinos e sua estreita convivência podem facilitar a disseminação do patógeno em propriedades rurais.

Evaluation of the performance of three serological tests for diagnosis of Leishmania infantum infection in dogs using latent class analysis / Avaliação da realização de três testes sorológicos para diagnóstico de infecção por Leishmania infantum em cães utilizando análise de classe latente

Abstract Canine leishmaniasis (CanL) is a disease caused by Leishmania infantum. Serological methods are the most common diagnostic techniques used for the diagnosis of the CanL. The objective of our study was to estimate the sensitivity and specificity of one in-house ELISA kit (ELISA UNIZAR) and three commercially available serological tests (MEGACOR Diagnostik GmbH) including an immunochromatographic rapid test (FASTest LEISH®), an immunofluorescent antibody test (MegaFLUO LEISH®) and an enzyme-linked immunosorbent assay (MegaELISA LEISH®), using latent class models in a Bayesian analysis. Two hundred fifteen serum samples were included. The highest sensitivity was achieved for FASTest LEISH® (99.38%), ELISA UNIZAR (99.37%), MegaFLUO LEISH® (99.36%) followed by MegaELISA LEISH® (98.49%). The best specificity was obtained by FASTest LEISH® (98.43%), followed by ELISA UNIZAR (97.50%), whilst MegaFLUO LEISH® and MegaELISA LEISH® obtained the lower specificity (91.94% and 91.93%, respectively). The results of present study indicate that the immunochromatographic rapid test evaluated FASTest LEISH® show similar levels of sensitivity and specificity to the quantitative commercial tests. Among quantitative serological tests, sensitivity and specificity were similar considering ELISA or IFAT techniques.

Resumo A leishmaniose canina (Lcan) é uma causada pela Leishmania infantum. Os métodos sorológicos são as técnicas diagnósticas mais utilizadas para o diagnóstico da leishmaniose canina. O objetivo do nosso estudo foi estimar a sensibilidade e a especificidade de um kit ELISA interno (ELISA UNIZAR) e de três testes sorológicos disponíveis comercialmente, feitos pelo mesmo fabricante (MEGACOR Diagnostik GmbH), incluindo um teste rápido imunocromatográfico (FASTest LEISH®), um teste de anticorpos imunofluorescentes (Megafluo LEISH®) e um ensaio de imunoabsorção enzimática (Megaelisa LEISH®), utilizando-se modelos de classe latentes numa análise bayesiana. Foram incluídas duzentas e quinze amostras de soro. A maior sensibilidade foi alcançada para Fastest LEISH® (99,38%), ELISA UNIZAR (99,37%), Megafluo LEISH® (99,36%) seguida por Megaelisa LEISH® (98,49%). A melhor especificidade foi obtida por FASTest LEISH® (98,43%), seguida por ELISA UNIZAR (97,50%), enquanto Megafluo LEISH® e Megaelisa LEISH® obtiveram a menor especificidade (91,94% e 91,93%, respectivamente). Os resultados do presente estudo indicam que o teste rápido imunocromatográfico, avaliado por FASTest LEISH® mostra níveis similares de sensibilidade e especificidade aos testes comerciais quantitativos incluídos. Entre os testes sorológicos quantitativos, a sensibilidade e a especificidade foram semelhantes, considerando-se as técnicas de ELISA ou IFI.

Expression and antigenic analysis of the recombinant TRP36 protein from Ehrlichia canis São Paulo strain for serologic tests / Expressão e análise antigênica da proteína RTP36 recombinante da amostra São Paulo de Ehrlichia canis para testes sorológicos

Abstract Ehrlichia canis is the main etiological agent of canine monocytic ehrlichiosis (CME), a globally canine infectious disease. In Brazil, CME is considered to be endemic, and its prevalence can reach 65% in some states. The diagnosis of ehrlichiosis is important for treatment and epidemiological purposes. The E. canis TRP36 (Tandem Repeat Protein) protein elicits the earliest acute-phase antibody response observed during the course of the disease. This study aimed to generate the recombinant TRP36 protein from E. canis São Paulo strain and to evaluate its potential as a tool for the serologic diagnosis of CME. The E. canis São Paulo isolate was cultivated in DH82 lineage cells, and its genomic DNA was obtained. The bacterial DNA fragment encoding the entire ORF of TRP36 was cloned into the pBAD/Thio-TOPO vector and transformed into Escherichia coli DH10B competent cells with the trp36-bearing plasmid for protein expression. To evaluate the protein antigenicity, 16 canine serum samples were previously tested (by PCR and the commercial SNAP®4Dx® serological test). The results were in accordance with the SNAP®4Dx® test. Experiments using this recombinant protein as an antigen, targeting the development of a serologic test based on ELISA methodology, are the next step to produce a reliable, affordable and useful diagnostic tool for CME in Brazil.

Resumo Ehrlichia canis é o principal agente etiológico da erliquiose monocítica canina (EMC), uma doença infecciosa canina globalmente dispersa. No Brasil, a EMC é considerada endêmica, e a infecção pode atingir 65% em cães em alguns estados. O diagnóstico de erliquiose é importante para fins de tratamento e epidemiológicos. A proteína TRP36 de E. canis leva a uma resposta humoral com produção de anticorpos em fase aguda, encontrada durante o curso da doença. O objetivo deste estudo foi obter a proteína TRP36 recombinante da amostra São Paulo de E. canis e avaliar seu potencial como ferramenta para o diagnóstico sorológico da CME. O isolado de E. canis São Paulo foi cultivado em células da linhagem DH82 e o DNA genômico foi obtido. O fragmento de DNA bacteriano que codifica toda a ORF de TRP36 foi clonado no vetor pBAD / Thio-TOPO e transformado em células competentes Escherichia coli DH10B, com o plasmídeo portador de trp36 para expressão de proteínas. Para avaliar a antigenicidade da proteína, 16 amostras de soro canino foram previamente analisadas (por PCR e teste sorológico comercial SNAP®4Dx®). Os resultados estavam de acordo com o teste SNAP®4Dx®. Os experimentos que utilizam essa proteína recombinante como antígeno, visando ao desenvolvimento de um teste sorológico baseado no ELISA, são o próximo passo para produzir um teste de diagnóstico confiável, acessível e útil para o diagnóstico da EMC no Brasil.