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Diagnosis of equine Lyme borreliosis (LB), an infection caused by members of the Borrelia burgdorferi sensu lato complex ( Bb sl), is challenging due to the nonspecific clinical signs of the disease and due to the variety of non-standardized serological tests. Specific vaccine-induced antibodies against LB, providing an effective protection against the infection, complicate the issue further. The standard for the detection of specific antibodies against Bb sl is a two-tier test system based on an enzyme-linked immunosorbent assay (ELISA) or indirect fluorescent antibody test (IFA) for antibody screening combined with a qualitative, highly specific immunoassay (e. g. line immunoassay (LIA)) for confirmation. In this study, three LIAs available for detection of antibodies in equine serum samples were evaluated and compared. A total of 393 serum samples of 131 horses with known serostatus were used. It included groups of non-vaccinated horses, immunized horses (vaccinations against LB on days 0 and 14), and horses that had received an initial immunization plus an additional booster on day 180. Sera were collected on days 0, 135 and 210 of the study. Results were compared considering the tests’ sensitivity, specificity, diagnostic outcome, and the operability of each test. Agreements of the diagnostic results among the LIAs were calculated for overall test results and single antigen-antibody-complex signal results. They are presented as inter-rater agreement and statistic reliability, represented by the Fleiss’ kappa coefficient. Agreement scores ranged from poor to moderate depending on group and time-point of blood sample collection. Depending on LIA used, deficiencies were observed in the form of non-sufficient sensitivity of antigen signals on the LIA strips (especially for outer surface protein A (OspA) or variable major protein like sequence expressed (VlsE)) or as an inappropriate test interpretation of the OspA signal. Operability of the three LIAs was equally user-friendly with minor variations. In two LIAs, test-evaluation was simplified by a supplied scanner and evaluation software. To improve functionality of available LIAs for equine serum samples it is advisable to adjust sensitivity and specificity of single test antigen signals and establish appropriate evaluation protocols.

Background Immune thrombocytopenia (ITP) is a common cause of severe thrombocytopenia in dogs. The pathogenesis of nonassociative, primary ITP (pITP) appears complex, with ill‐defined thrombopoietic response. Objectives Develop an immunoassay to measure plasma canine thrombopoietin (TPO) concentration and characterize TPO concentrations in dogs with pITP. Animals Forty‐one healthy dogs, 8 dogs in an induced ITP model (3 control, 5 ITP), and 58 pITP dogs. Methods Recombinant canine TPO (rcTPO) was purchased and its identity confirmed by mass spectrometry. Monoclonal antibodies were raised to rcTPO and used to configure a sandwich ELISA using streptavidin‐biotin detection. Assay performance, coefficients of variability, and healthy dog plasma TPO reference interval (RI) were determined, followed by assay of ITP samples. Results Assay dynamic range was 15 pg/mL (lower limit of detection) to 1000 pg/mL TPO, with limit of quantitation of 62 pg/mL. Plasma TPO RI was 0 to 158 pg/mL, with plasma TPO <62 pg/mL for 35/41 healthy dogs. All dogs with induced ITP developed marked increases in plasma TPO concentration. Peak values ranged from 515 to >6000 pg/mL. In contrast, only 2/58 pITP dogs had TPO values above RI. Conclusions and Clinical Importance Plasma TPO concentration is paradoxically low at diagnosis for most dogs with pITP. This finding suggests that ineffective thrombopoiesis contributes to thrombocytopenia in pITP dogs and supports evaluating TPO receptor agonist treatment as used for pITP in humans. The TPO assay provides a new tool to study thrombopoiesis in pITP and other thrombocytopenic syndromes in dogs.

Equine infectious anemia (EIA) is an important viral disease characterized by persistent infection in equids worldwide. Most EIA cases are life-long virus carriers with low antibody reactions and without the appearance of clinical symptoms. A serological test with high sensitivity and specificity is required to detect inapparent infection. In this study, a B-cell common epitope-based blocking ELISA (bELISA) was developed using a monoclonal antibody together with the EIAV p26 protein labelled with HRP. The test has been evaluated against the standard and with field serum samples globally. This bELISA test can be completed within 75 min, and the sensitivity is higher than those of either the AGID or one commercial cELISA kit. This bELISA assay was 8–16 times more analytically sensitive than AGID, and 2 to 4 times more analytically sensitive than one cELISA kit by testing three sera from the USA, Argentina, and China, respectively. The 353 serum samples from Argentina were tested, in comparison with AGID, the diagnostic sensitivity and specificity of our bELISA assay were 100% (154/154) and 97.0% (193/199), respectively, and the accuracy of the bELISA test was 98.3%. The bELISA test developed in this study is a rapid, sensitive, specific method for the detection of EIAV infection, and could be a promising candidate for use in the monitoring of the EIA epidemic worldwide.Key points• A universal epitope-based blocking enzyme-linked immunosorbent assay (bELISA) was developed for detection of antibodies to EIAV.• The bELISA assay can be used to test EIAV serum samples from different regions of the world including North America, South America, Europe, and Asia.• The bELISA assay was evaluated in three different international labs and showed a better performance than other commercial kits.

In 2013, several Austrian piglet-producing farms recorded outbreaks of action-related repetitive myoclonia in newborn piglets (“shaking piglets”). Malnutrition was seen in numerous piglets as a complication of this tremor syndrome. Overall piglet mortality was increased and the number of weaned piglets per sow decreased by more than 10% due to this outbreak. Histological examination of the CNS of affected piglets revealed moderate hypomyelination of the white substance in cerebellum and spinal cord. We detected a recently discovered pestivirus, termed atypical porcine pestivirus (APPV) in all these cases by RT-PCR. A genomic sequence and seven partial sequences were determined and revealed a 90% identity to the US APPV sequences and 92% identity to German sequences. In confirmation with previous reports, APPV genomes were identified in different body fluids and tissues including the CNS of diseased piglets. APPV could be isolated from a “shaking piglet”, which was incapable of consuming colostrum, and passaged on different porcine cells at very low titers. To assess the antibody response a blocking ELISA was developed targeting NS3. APPV specific antibodies were identified in sows and in PCR positive piglets affected by congenital tremor (CT). APPV genomes were detected continuously in piglets that gradually recovered from CT, while the antibody titers decreased over a 12-week interval, pointing towards maternally transmitted antibodies. High viral loads were detectable by qRT-PCR in saliva and semen of infected young adults indicating a persistent infection.

Research on chemokines in cattle is hampered by the relative lack of validated reagents. Bovine IP-10 is an important inflammatory chemokine and a promising diagnostic biomarker for an economically important disease (bovine tuberculosis) caused by infection of cattle with Mycobacterium bovis . Currently no monoclonal antibodies are available for bovine IP-10. The goal of this study was to generate novel mAbs for detection of bovine IP-10 using hybridoma technology. Five mAbs were developed and cross clone inhibition analyses showed a high degree of self-inhibition among the mAbs. One mAb (7C2) was used in conjugation with a commercial polyclonal antibody to develop a sandwich ELISA. Upon testing with recombinant bovine IP-10, this ELISA showed an enhanced linear range compared to the currently available polyclonal antibody-based ELISA. The ELISA using 7C2 was shown to detect native antigen-specific bovine IP-10 in samples from M. bovis infected animals. The 7C2 mAb could also detect intracytoplasmic IP-10. These novel mAbs will be useful in elucidating roles for IP-10 in bovine immune studies in health, disease and vaccination contexts.

Fasciolosis is a severe zoonosis responsible for major economic losses in livestock. The enhanced MM3-COPRO test (eMM3-COPRO) and the commercial version BIO K 201 (Bio-X Diagnostics, Rochefort, Belgium) are widely used as immunodiagnostic tools for the specific detection of coproantigens released by Fasciola during the late prepatent and patent stages of infection. However, performance of the eMM3-COPRO has never been evaluated under field conditions. To address this gap, a large number of ovine faecal samples, collected in a region where fasciolosis is endemic (Galicia, NW Spain), were analyzed. Two groups of sheep flocks were selected according to the Fasciola infection status: ‘ Fasciola -free’ and ‘ Fasciola -infected’ flocks. ‘ Fasciola -free’ flocks were seronegative flocks with no history of fasciolosis detected by either coproscopy or necropsy in the last 5 years. Faecal samples from these sheep were used to calculate a cut-off value for infection (OD = 0.021). The cut-off was calculated using a bootstrap resampling method that enables estimation of the sampling distribution of the statistical parameters without making assumptions about the underlying data distribution. ‘ Fasciola -infected’ flocks were characterized by high seroprevalence, a history of fasciolosis and periodical treatment with flukicides. Samples from these flocks were used to estimate the diagnostic accuracy of the eMM3-COPRO relative to coproscopy, which although limited by poor sensitivity is the only reference test available for diagnosing fasciolosis in vivo . To overcome this limitation, all animals classified positive by eMM3-COPRO were treated with triclabendazole and then retested. The eMM3-COPRO displayed higher sensitivity than coproscopy, as it detected coproantigens in all samples with positive coproscopy and in 12% of samples with negative coproscopy. The test also proved highly specific as coproantigens disappeared after the treatment. The eMM3-COPRO was less time consuming than coproscopy, particularly when the procedure involved numerous samples, and showed promise as a tool for monitoring flukicide efficacy.

Visceral leishmaniasis (VL) caused by Leishmania infantum is endemic in the Mediterranean basin with most of the infected human patients remaining asymptomatic. Recently, the saurian-associated Leishmania tarentolae was detected in human blood donors and in sheltered dogs. The circulation of L . infantum and L . tarentolae was investigated in humans, dogs and cats living in the Pelagie islands (Sicily, Italy) by multiple serological and molecular testing. Human serum samples (n = 346) were tested to assess the exposure to L . infantum by immunofluorescence antibody test (IFAT), enzyme-linked immunosorbent assay (ELISA) and Western blot (WB) and to L . tarentolae by IFAT. Meanwhile, sera from dogs (n = 149) and cats (n = 32) were tested for both Leishmania species by IFAT and all blood samples, including those of humans, by specific sets of real time-PCR for L . infantum and L . tarentolae . The agreement between serological tests performed for human samples, and between serological and molecular diagnostic techniques for both human and animal samples were also assessed. Overall, 41 human samples (11.8%, 95% CI: 8.9–15.7) were positive to L . infantum (5.2%, 95% CI: 3.3–8.1), L . tarentolae (5.2%, 95% CI: 3.3–8.1) and to both species (1.4%, 95% CI: 0.6–3.3) by serology and/or molecular tests. A good agreement among the serological tests was determined. Both Leishmania spp. were serologically and/or molecularly detected in 39.6% dogs and 43.7% cats. In addition to L . infantum , also L . tarentolae circulates in human and animal populations, raising relevant public health implications. Further studies should investigate the potential beneficial effects of L . tarentolae in the protection against L . infantum infection.

Thirty-five serum samples and six hygroma fluid samples were collected from sexually mature cattle in one herd with clinical signs of brucellosis (abortion and hygromas) in the Western Region of the Gambia in order to isolate and characterise Brucella species. Information on the sex, age, number of calvings, number of abortions, presence of hygromas, and presence of orchitis was also collected for each animal sampled. Twenty-six (74 per cent) of the serum samples were positive in the rose bengal test and 29 (83 per cent) were positive by indirect ELISA. Three isolates of Brucella, biotyped as Brucella abortus biovar 3, were cultured from six hygroma fluid samples. The multiple locus variable number tandem repeat analysis assay clustered the isolates as B abortus with the same profile for the three isolates, suggesting a common origin of contamination.

Mycoplasma bovis (Mbovis) was first detected in cattle in New Zealand (NZ) in July 2017. To prevent further spread, NZ launched a world-first National Eradication Programme in May 2018. Existing diagnostic tests for Mbovis have been applied in countries where Mbovis is endemic, for detecting infection following outbreaks of clinical disease. Diagnostic test evaluation (DTE) under NZ conditions was thus required to inform the Programme. We used Bayesian Latent Class Analysis on paired serum ELISA (ID Screen Mycoplasma bovis Indirect from IDvet) and tonsillar swabs (qPCR) for DTE in the absence of a gold standard. Tested samples were collected at slaughter between June 2018 and November 2019, from infected herds depopulated by the Programme. A first set of models evaluated the detection of active infection, i.e. the presence of Mbovis in the host. At a modified serology positivity threshold of SP %> = 90, estimates of animal-level ELISA sensitivity was 72.8% (95% credible interval 68.5%—77.4%), respectively 97.7% (95% credible interval 97.3%—98.1%) for specificity, while the qPCR sensitivity was 45.2% (95% credible interval 41.0%—49.8%), respectively 99.6% (95% credible interval 99.4%—99.8%) for specificity. In a second set of models, prior information about ELISA specificity was obtained from the National Beef Cattle Surveillance Programme, a population theoretically free—or very low prevalence—of Mbovis. These analyses aimed to evaluate the accuracy of the ELISA test targeting prior exposure to Mbovis, rather than active infection. The specificity of the ELISA for detecting exposure to Mbovis was 99.9% (95% credible interval 99.7%—100.0%), hence near perfect at the threshold SP%=90. This specificity estimate, considerably higher than in the first set of models, was equivalent to the manufacturer’s estimate. The corresponding ELISA sensitivity estimate was 66.0% (95% credible interval 62.7%-70.7%). These results confirm that the IDvet ELISA test is an appropriate tool for determining exposure and infection status of herds, both to delimit and confirm the absence of Mbovis.

Background Dirofilaria immitis and D. repens are mosquito-borne filaroids that primarily infect dogs but also cats. Diagnosing feline dirofilariosis is challenging because of the low parasitic burdens and transient or absent microfilaremia. To improve detection of antibodies against Dirofilaria spp. in cats, an indirect enzyme-linked immunosorbent assay (ELISA) using somatic antigens of D. immitis was standardized. Methods Serum samples from cats positive for D. immitis , D. repens , bronchopulmonary metastrongylids and gastrointestinal helminths as well as negative sera were tested to evaluate the sensitivity (Se) and specificity (Sp). Three different antigen concentrations (2, 3 and 4 μg/ml) and two concentrations of horseradish peroxidase (HRP) IgG anti-cat conjugate (1:10,000 and 1:20,000) were used to screen the optimal titration of the test. Once the best conditions were established, Se and Sp were assessed by testing 151 serum samples positive for D. immitis , D. repens and other parasites (i.e. feline lungworms, gastrointestinal helminths) or negative. Results The optimized ELISA showed 89% Se and 98% Sp in detecting D. immitis infections, presenting a cross-reactivity with D. repens . A cut-off point of 1.150 was established to classify positive and negative samples. Conclusions The developed ELISA may improve the detection of antibodies against Dirofilaria spp. in cats, also in epidemiological contexts characterized by multiple helminth infections. Future efforts will focus on reducing the cross-reactivity with D. repens , therefore increasing ELISA Sp. Graphical Abstract