Increased specificity of Fasciola hepatica excretory-secretory antigens combining negative selection on hydroxyapatite and salt precipitation.

A single and rapid method to obtain an antigenic fraction of excretory-secretory antigens (ESAs) from Fasciola hepatica suitable for serodiagnosis of fascioliasis is reported. The procedure consists in the negative selection of F. hepatica ESAs by hydroxyapatite (HA) chromatography (HAC; fraction HAC-NR) followed by antigen precipitation with 50% ammonium sulphate (AS) and subsequent recovery by means of a Millex-GV or equivalent filter (Fi-SOLE fraction). Tested in indirect ELISA, the Fi-SOLE antigens detected natural infections by F. hepatica with 100% sensitivity and 98.9% specificity in sheep, and 97.7% sensitivity and 97.7% specificity in cattle, as determined by ROC analysis. The SDS-PAGE and proteomic nano-UHPLC-Tims-QTOF MS/MS analysis of fractions showed that the relative abundance of L-cathepsins and fragments thereof was 57% in fraction HAC-NR and 93.8% in fraction Fi-SOLE. The second most abundant proteins in fraction HAC-NR were fatty-acid binding proteins (11.9%). In contrast, free heme, and heme:MF6p/FhHDM-1 complexes remained strongly bond to the HA particles during HAC. Interestingly, phosphorylcholine (PC)-bearing antigens, which are a frequent source of cross-reactivity, were detected with an anti-PC mAb (BH8) in ESAs and fraction HAC-NR but were almost absent in fraction Fi-SOLE.

Bayesian hierarchical modelling of the geospatial distribution of fasciolosis in dairy cattle and the impact on production: Application to the main milk-producing region (Galicia) in Spain.

Fasciolosis caused by Fasciola hepatica is a common parasitic infection among cattle in many countries. Although infected adult cows rarely show overt clinical signs, milk production may be impaired. Thus, significant production losses may occur in dairy herds with a high prevalence of fasciolosis. In this study, Bayesian hierarchical modelling was used to estimate the geospatial distribution of dairy cattle fasciolosis and its impact on milk production. The study was conducted in Galicia, the main milk producing region in Spain and a geographically heterogeneous area. The aims were: 1) to model the geospatial distribution of fasciolosis in dairy herds in the study area, 2) to identify clusters of herds with a high prevalence of fasciolosis, and 3) to assess the effect of fasciolosis on milk yield and quality. A large number of dairy cattle farms (n = 4907), of which 1660 provided production records, were surveyed. Fasciola infection status was determined by applying the MM3-SERO ELISA test to bulk tank milk samples. A high probability of infection was predicted in several zones, particularly in the centre, northeast and southeast of Galicia. Conversely, the predicted probability was very low in some parts of the northwest of the region. Infections with high within-herd prevalence (> 25% lactating cows infected) predominated. High within-herd prevalence was associated with loss of milk production (-1.387 kg/cow/ day, on average). No association between Fasciola infection and either milk fat or protein content was observed. This study has generated the first maps of the spatial distribution of the probability of Fasciola infection in dairy cattle herds in Galicia. The maps presented here can be used for reference purposes, enabling the design of better targeted fasciolosis control programmes in the region. Use of Bayesian hierarchical statistical analysis enabled us to ascertain the uncertainty of the predictions and to account for the spatial autocorrelation in the data. It also enabled us to generate maps showing the residual spatial variation in milk production, a topic that may deserve more detailed study.

Field evaluation of the enhanced MM3-COPRO ELISA test for the diagnosis of Fasciola hepatica infection in sheep.

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.

Targeted proteomics and specific immunoassays reveal the presence of shared allergens between the zoonotic nematodes Anisakis simplex and Pseudoterranova decipiens.

The family Anisakidae, mainly represented by Anisakis simplex s.l. and Pseudoterranova decipiens, encompasses zoonotic nematodes infecting many marine fish. Both are responsible for gastrointestinal disease in humans after ingestion of a live larva by consumption of undercooked fish, and, in the case of A. simplex, an allergic reaction may occur after consuming or even handling infected fish. Due to its phylogenetic relatedness with A. simplex, few studies investigated the allergenic potential of P. decipiens, yet none of them focused on its excretory/secretory (E/S) proteins that easily get missed when working solely on extracts from crushed nematodes. Moreover, these E/S allergens remain behind even when the larva has been removed during fish quality processing. Therefore, the aim was to investigate if Anisakis-like allergens could also be detected in both crushed and E/S P. decipiens protein extract using targeted mass spectrometry analysis and immunological methods. The results confirmed that at least five A. simplex allergens have homologous proteins in P. decipiens; a result that emphasizes the importance of also including E/S protein extracts in proteomic studies. Not only A. simplex, but also P. decipiens should therefore be considered a potential source of allergens that could lead to hypersensitivity reactions in humans.

Evidence of population structuring following population genetic analyses of Fasciola hepatica from Argentina.

Fasciola hepatica, the liver fluke, is a trematode parasite that causes disease of economic importance in livestock. As a zoonosis this parasite also poses a risk to human health in areas where it is endemic. Population genetic studies can reveal the mechanisms responsible for genetic structuring (non-panmixia) within parasite populations and provide valuable insights into population dynamics, which in turn enables theoretical predictions of evolutionary dynamics such as the evolution of drug resistance. Here we genotyped 320 F. hepatica collected from 14 definitive hosts from four provinces in Argentina. STRUCTURE analysis indicated three population clusters, and principal coordinate analysis confirmed this, showing population clustering across provinces. Similarly, pairwise FST values amongst all four provinces were significant, with standardised pairwise FST (F'ST) ranging from 0.0754 to 0.6327. Therefore, population genetic structure was evident across these four provinces in Argentina. However, there was no evidence of deviation from Hardy-Weinberg equilibrium, so it appears that within these sub-populations there is largely random mating. We identified 263 unique genotypes, which gave a clonal diversity of 82%. Parasites with identical genotypes, clones, accounted for 26.6% of the parasites studied and were found in 12 of the 14 hosts studied, suggesting some clonemate transmission.

Current Challenges for Fasciolicide Treatment in Ruminant Livestock.

Pharmacological treatment remains essential to control fasciolosis in areas where infection is endemic. However, there are major constraints to treating food-producing animals. Of particular concern is the lack of flukicides for treating early Fasciola infections in ruminant livestock in some countries. In addition, the information provided in package leaflets, particularly regarding withdrawal periods, is often incomplete, confusing, and/or contradictory. International regulatory bodies should harmonize the use of flukicides in livestock in favor of fairer, safer international trade. In addition, monitoring the efficacy of fasciolicides on farms is also essential to minimize the spread of drug-resistant populations of Fasciola. The current situation regarding flukicide formulations in the European Union and other, non-European countries is analyzed in this review paper.

Author Correction: Analysis of Ani s 7 and Ani s 1 allergens as biomarkers of sensitization and allergy severity in human anisakiasis.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Analysis of Ani s 7 and Ani s 1 allergens as biomarkers of sensitization and allergy severity in human anisakiasis.

The high frequency of infection by Anisakis simplex (A. simplex) has led to an increase in IgE sensitization, turning allergy to this parasite a relevant contemporary health problem. Improving the lack of conventional diagnosis test specificity is crucial to better understand these clinical scenarios. Specific IgE (sIgE) to A. simplex extract by ImmunoCAP (Anisakis-sIgE) was determined in sera from 403 blood donors (BD) from Cantabria (North of Spain) of which 51 subjects resulted sensitized. Among these latter, 47 were asymptomatic (sABD). The values of total IgE, prick-test, Anisakis-sIgE, and sIgE to Ani s 1 (anti-rAni s 1) and Ani s 7 (anti-rAni s 7) were compared between 46 sABD and 49 A. simplex allergic patients. The IgE seroprevalence by ImmunoCAP among BD was 12.65%. Allergic patients and sABD showed significant differences in all serum biomarkers evaluated. The area under the curve was assessed for Anisakis-sIgE (0.892), sIgE-rAni s 1 (0.672) and sIgE-rAni s 7 (0.668). After a severe reaction, significantly higher levels of Anisakis-sIgE and sIgE anti-rAni s 1 were detected. Determinations of sIgE by ImmunoCAP, Ani s 1 and Ani s 7 presented different sensitization patterns between allergic and asymptomatic individuals. The Ani s 1 allergen arises as a possible biomarker to detect patients at risk of suffering severe allergic reactions.

Genetic diversity of Fasciola hepatica in Spain and Peru.

In the present study, molecular characterization of Fasciola flukes from Spain was performed to reveal the relation with the previously reported Peruvian F. hepatica population. The nuclear DNA markers, phosphoenolpyruvate carboxykinase (pepck) and DNA polymerase delta (pold), were used for species identification of Fasciola flukes. A total of 196 Fasciola flukes were identified as F. hepatica by pepck and pold, and 26 haplotypes were detected in mitochondrial NADH dehydrogenase subunit 1 (nad1). Only one of them was previously found in Spanish samples; which indicates the existence of high genetic diversity and population structure in F. hepatica from Spain. Three haplotypes were identical to those from Peruvian F. hepatica. The pairwise fixation index value confirmed a relatively close relationship between the Spanish and Peruvian F. hepatica samples. The Spanish samples showed clearly higher genetic variability than the Peruvian population. These results are discussed in relation with the hypothesis of the introduction of the parasite in America from Europe and recent evidence of pre-Hispanic F. hepatica from Argentina revealed by ancient DNA.

Anisakis Sensitization in the Croatian fish processing workers: Behavioral instead of occupational risk factors?

We undertook the first study systematically evaluating the risk of Anisakis-sensitization in Croatian fish-processing workers and potential genetic susceptibility to anisakiasis. Anti-Anisakis IgE seroprevalence and risk factors for 600 employees of Croatian fish processing facilities and 466 blood donor controls, were assessed by indirect ELISA targeted with: recombinant Ani s 1 and Ani s 7 allergens, an Anisakis crude extract, the commercial ImmunoCAP kit, and questionnaires. Genetic susceptibility to anisakiasis was evaluated by genotypisation of human leukocytes alleles (HLA). Anti-Anisakis seropositive and a fraction of negative subjects were also assessed by ELISA and Western Blot (WB) for IgG seroprevalence to Trichinella spp. Overall, the observed anti-Anisakis seroprevalence inferred by indirect ELISA was significantly higher in fish processing workers (1.8%, 95% CI 0.9-3.3%) compared to the controls (0%, 0-0.8%). Seven out of 11 Ani s 1 and Ani s 7-positives and none of selected 65 negative sera, tested positive on whole-Anisakis extract (ImmunoCAP), whereas Anisakis crude extract ELISA detected 3.9% (2.4-6.0%) seropositives in fish processing workers, three (14%) of which showed IgE reactivity to milk proteins. The highest risk associated with Anisakis-sensitization among workers was fishing in the free time, rather than any of attributes related to the occupational exposure. Although no association was observed between anti-Anisakis seropositivity and wearing gloves or protective goggles, the majority of workers (92%) wore protective gloves, minimizing the risk for Anisakis sensitization via skin contact. Six HLA alleles within DRB1 gene were significantly associated with seropositivity under dominant, allelic or recessive models. All sera confirmed negative for anti-Trichinella spp. IgG. The study exhaustively covered almost all marine fish processing workers in Croatia, reflecting real-time Anisakis sensitization status within the industry, already under the influence of wide array of allergens.

In-plate recapturing of a dual-tagged recombinant Fasciola antigen (FhLAP) by a monoclonal antibody (US9) prevents non-specific binding in ELISA.

Recombinant proteins expressed in E. coli are frequently purified by immobilized metal affinity chromatography (IMAC). By means of this technique, tagged proteins containing a polyhistidine sequence can be obtained up to 95% pure in a single step, but some host proteins also bind with great affinity to metal ions and contaminate the sample. A way to overcome this problem is to include a second tag that is recognized by a preexistent monoclonal antibody (mAb) in the gene encoding the target protein, allowing further purification. With this strategy, the recombinant protein can be directly used as target in capture ELISA using plates sensitized with the corresponding mAb. As a proof of concept, in this study we engineered a Trichinella-derived tag (MTFSVPIS, recognized by mAb US9) into a His-tagged recombinant Fasciola antigen (rFhLAP) to make a new chimeric recombinant protein (rUS9-FhLAP), and tested its specificity in capture and indirect ELISAs with sera from sheep and cattle. FhLAP was selected since it was previously reported to be immunogenic in ruminants and is expressed in soluble form in E. coli, which anticipates a higher contamination by host proteins than proteins expressed in inclusion bodies. Our results showed that a large number of sera from non-infected ruminants (mainly cattle) reacted in indirect ELISA with rUS9-FhLAP after single-step purification by IMAC, but that this reactivity disappeared testing the same antigen in capture ELISA with mAb US9. These results demonstrate that the 6XHis and US9 tags can be combined when double purification of recombinant proteins is required.

Vaccination of sheep with Quil-A® adjuvant expands the antibody repertoire to the Fasciola MF6p/FhHDM-1 antigen and administered together impair the growth and antigen release of flukes.

Fasciolosis continues to be a major cause of economic losses in the livestock industry and a growing threat to humans. The limited spectrum of effective anthelmintics and the appearance of resistances urge the need for developing an effective vaccine. Most studies have been focused on the use of TH1-polarizing adjuvants and the use of recombinant Fasciola critical molecules and, despite the efforts, no reproducible protections have been achieved. The F. hepatica MF6p/FhHDM-1 protein is a heme-binding protein also reported to have immunomodulatory properties, constituting a promising target for vaccination and/or as target for the development of new flukicides. Thus, in this study, we investigated the effects of the TH1-polarizing adjuvant Quil A® on sheep immune response to MF6p/FhHDM-1, and the vaccine potential of both native and synthetic forms of this protein against ovine fasciolosis. Subcutaneous injection of Quil A® alone, i.e., without co-injecting any antigen, expands the antibody repertoire to MF6p/FhHDM-1 triggered by a subsequent primoinfection with metacercariae. This effect was not observed with aluminum hydroxide, the most frequently adjuvant used in commercial vaccines. On the other hand, vaccination with synthetic MF6p/FhHDM-1 in Quil A® prompted a 2-4-week delay in the antibody response induced in sheep by a challenge experimental infection. Moreover, fluke populations stablished showed stunted growth and low antigen release probably due to reduced metabolic activity. These observations suggest that primary circulating antibodies induced by the immunization had harmful effects on fluke development. Such effects could not be demonstrated to be associated to TH1 immune response linked events (production of IgG2 isotype antibodies and IFN-γ).

Comparison of recombinant cathepsins L1, L2, and L5 as ELISA targets for serodiagnosis of bovine and ovine fascioliasis.

Infections caused by Fasciola hepatica are of great importance in the veterinary field, as they cause important economic losses to livestock producers. Serodiagnostic methods, typically ELISA (with either native or recombinant antigens), are often used for early diagnosis. The use of native antigens, as in the MM3-SERO ELISA (commercialized as BIO K 211, BIO-X Diagnostics), continues to be beneficial in terms of sensitivity and specificity; however, there is interest in developing ELISA tests based on recombinant antigens to avoid the need to culture parasites. Of the antigens secreted by adult flukes, recombinant procathepsin L1 (rFhpCL1) is the most commonly tested in ELISA to date. However, although adult flukes produce three different clades of CLs (FhCL1, FhCL2, and FhCL5), to our knowledge, the diagnostic value of recombinant FhCL2 and FhCL5 has not yet been investigated. In the present study, we developed and tested three indirect ELISAs using rFhpCL1, rFhpCL2, and rFhpCL5 and evaluated their recognition by sera from sheep and cattle naturally infected with F. hepatica. Although the overall antibody response to these three rFhpCLs was similar, some animals displayed preferential recognition for particular rFhpCLs. Moreover, for cattle sera, the highest sensitivity was obtained using rFhpCL2 (97%), being equal for both rFhpCL1 and rFhpCL5 (87.9%), after adjusting cut-offs for maximum specificity. By contrast, for sheep sera, the sensitivity was 100% for the three rFhpCLs. Finally, the presence of truncated and/or partially unfolded molecules in antigen preparations is postulated as a possible source of cross-reactivity.

Complex Network Study of the Immune Epitope Database for Parasitic Organisms.

BACKGROUND: Complex network approach allows the representation and analysis of complex systems of interacting agents in an ordered and effective manner, thus increasing the probability of discovering significant properties of them. In the present study, we defined and built for the first time a complex network based on data obtained from Immune Epitope Database for parasitic organisms. We then considered the general topology, the node degree distribution, and the local structure (triadic census) of this network. In addition, we calculated 9 node centrality measures for observed network and reported a comparative study of the real network with three theoretical models to detect similarities or deviations from these ideal networks. RESULT: The results obtained corroborate the utility of the complex network approach for handling information and data mining within the database under study. CONCLUSION: They confirm that this type of approach can be considered a valuable tool for preliminary screening of the best experimental conditions to determine whether the amino acid sequences being studied are true epitopes or not.

Fasciola spp: Mapping of the MF6 epitope and antigenic analysis of the MF6p/HDM family of heme-binding proteins.

MF6p/FhHDM-1 is a small cationic heme-binding protein which is recognized by the monoclonal antibody (mAb) MF6, and abundantly present in parenchymal cells and secreted antigens of Fasciola hepatica. Orthologs of this protein (MF6p/HDMs) also exist in other causal agents of important foodborne trematodiasis, such as Clonorchis sinensis, Opisthorchis viverrini and Paragonimus westermani. Considering that MF6p/FhHDM-1 is relevant for heme homeostasis in Fasciola and was reported to have immunomodulatory properties, this protein is expected to be a useful target for vaccination. Thus, in this study we mapped the epitope recognized by mAb MF6 and evaluated its antigenicity in sheep. The sequence of the MF6p/FhHDM-1 ortholog from F. gigantica (MF6p/FgHDM-1) was also reported. By means of ELISA inhibitions with overlapping synthetic peptides, we determined that the epitope recognized by mAb MF6 is located within the C-terminal moiety of MF6p/FhHDM-1, which is the most conserved region of MF6p/HDMs. By immunoblotting analysis of parasite extracts and ELISA inhibitions with synthetic peptides we also determined that mAb MF6 reacted with the same intensity with F. hepatica and F. gigantica, and in decreasing order of intensity with C. sinensis, O.viverrini and P. westermani orthologs. On the contrary, mAb MF6 showed no reactivity against Dicrocoelium dendriticum and Schistosoma mansoni. The study of the recognition of peptides covering different regions of MF6p/FhHDM-1 by sera from immunized sheep revealed that the C-terminal moiety is the most antigenic, thus being of potential interest for vaccination. We also demonstrated that the production of antibodies to MF6p/FhHDM-1 in sheep infected by F. hepatica occurs relatively early and follows the same pattern as those produced against L-cathepsins.

A study of the Immune Epitope Database for some fungi species using network topological indices.

In the last years, the encryption of system structure information with different network topological indices has been a very active field of research. In the present study, we assembled for the first time a complex network using data obtained from the Immune Epitope Database for fungi species, and we then considered the general topology, the node degree distribution, and the local structure of this network. We also calculated eight node centrality measures for the observed network and compared it with three theoretical models. In view of the results obtained, we may expect that the present approach can become a valuable tool to explore the complexity of this database, as well as for the storage, manipulation, comparison, and retrieval of information contained therein.

Delineating distinct heme-scavenging and -binding functions of domains in MF6p/helminth defense molecule (HDM) proteins from parasitic flatworms.

MF6p/FhHDM-1 is a small protein secreted by the parasitic flatworm (trematode) Fasciola hepatica that belongs to a broad family of heme-binding proteins (MF6p/helminth defense molecules (HDMs)). MF6p/HDMs are of interest for understanding heme homeostasis in trematodes and as potential targets for the development of new flukicides. Moreover, interest in these molecules has also increased because of their immunomodulatory properties. Here we have extended our previous findings on the mechanism of MF6p/HDM-heme interactions and mapped the protein regions required for heme binding and for other biological functions. Our data revealed that MF6p/FhHDM-1 forms high-molecular-weight complexes when associated with heme and that these complexes are reorganized by a stacking procedure to form fibril-like and granular nanostructures. Furthermore, we showed that MF6p/FhHDM-1 is a transitory heme-binding protein as protein·heme complexes can be disrupted by contact with an apoprotein (e.g. apomyoglobin) with higher affinity for heme. We also demonstrated that (i) the heme-binding region is located in the MF6p/FhHDM-1 C-terminal moiety, which also inhibits the peroxidase-like activity of heme, and (ii) MF6p/HDMs from other trematodes, such as Opisthorchis viverrini and Paragonimus westermani, also bind heme. Finally, we observed that the N-terminal, but not the C-terminal, moiety of MF6p/HDMs has a predicted structural analogy with cell-penetrating peptides and that both the entire protein and the peptide corresponding to the N-terminal moiety of MF6p/FhHDM-1 interact in vitro with cell membranes in hemin-preconditioned erythrocytes. Our findings suggest that MF6p/HDMs can transport heme in trematodes and thereby shield the parasite from the harmful effects of heme.

Rapid Enhanced MM3-COPRO ELISA for Detection of Fasciola Coproantigens.

ELISA-based methods of detecting Fasciola cathepsins in feces are powerful techniques for diagnosing infections by F. hepatica and F. gigantica. In the last decade, the in-house MM3-COPRO ELISA and its commercial version BIO K 201 (BIO X Diagnostics, Belgium) have been recognized as useful tools for detecting early infections by such trematodes and for monitoring the efficacy of anthelmintic treatments in human and animal species, as they provide some advantages over classic fecal egg counts. However, the sensitivity of MM3-COPRO ELISA can sometimes be compromised by the high variability in the concentration of cathepsins in fecal samples throughout the biological cycle of Fasciola (mainly in cattle) and by differences in the between-batch performance of peroxidase-labeled anti-mouse IgG polyclonal antibodies. To prevent such problems, we investigated whether the incorporation of a commercial streptavidin-polymerized horseradish peroxidase conjugate, in order to reveal bound biotinylated monoclonal antibody MM3, can improve the sensitivity of the MM3-COPRO ELISA. We observed that inclusion of this reagent shifted the previous detection limit of the assay from 0.6 ng/mL to 150 pg/mL and that the modified test is able to identify infection in cows harboring only one fluke. Moreover, we demonstrated that maximal OD values can be achieved with short incubations (30 min each step) at RT with shaking, rather than standard incubations, which significantly accelerates the diagnostic procedure. Finally, we did not find a significant correlation between coproantigen concentration and parasite burden in cattle, which may be due to the low parasite burden (1-10 adult flukes) of the animals used in the present study. As the usefulness of the classic MM3-COPRO test for detecting animal and human infections has already been demonstrated, it is expected that the improvements reported in this study will add new insights into the diagnosis and control of fasciolosis.

Usefulness of ELISA Methods for Assessing LPS Interactions with Proteins and Peptides.

Lipopolysaccharide (LPS), the major constituent of the outer membrane of Gram-negative bacteria, can trigger severe inflammatory responses during bacterial infections, possibly leading to septic shock. One approach to combatting endotoxic shock is to neutralize the most conserved part and major mediator of LPS activity (lipid A) with LPS-binding proteins or peptides. Although several available assays evaluate the biological activity of these molecules on LPS (e.g. inhibition of LPS-induced TNF-α production in macrophages), the development of simple and cost-effective methods that would enable preliminary screening of large numbers of potential candidate molecules is of great interest. Moreover, it would be also desirable that such methods could provide information about the possible biological relevance of the interactions between proteins and LPS, which may enhance or neutralize LPS-induced inflammatory responses. In this study, we designed and evaluated different types of ELISA that could be used to study possible interactions between LPS and any protein or peptide. We also analysed the usefulness and limitations of the different ELISAs. Specifically, we tested the capacity of several proteins and peptides to bind FITC-labeled LPSs from Escherichia coli serotypes O111:B4 and O55:B5 in an indirect ELISA and in two competitive ELISAs including casein hydrolysate (hCAS) and biotinylated polymyxin B (captured by deglycosylated avidin; PMX) as LPS-binding agents in the solid phase. We also examined the influence of pH, detergents and different blocking agents on LPS binding. Our results showed that the competitive hCAS-ELISA performed under mildly acidic conditions can be used as a general method for studying LPS interactions, while the more restrictive PMX-ELISA may help to identify proteins/peptides that are likely to have neutralizing properties in vitro or in vivo.

Fasciola hepatica in goats from north-western Spain: Risk factor analysis using a capture ELISA.

In order to study the seroprevalence of Fasciola hepatica infection in goats from north-western Spain, a total of 603 serum samples from 47 herds were tested using a capture ELISA (MM3-SERO). The identification of risk factors was assessed by a mixed-effects logistic regression analysis. The results showed that F. hepatica is widespread in this area with 57.4% of the herds and 22.7% of the animals testing positive. Breed and age were identified as determining factors for caprine F. hepatica infection. Seroprevalence in cross-bred animals was significantly higher than in the autochthonous Cabra Galega breed. A significantly higher seroprevalence was observed in older animals. The use of locally adapted breeds and the implementation of suitable management practices could provide a substantial improvement over the current F. hepatica control measures carried out in goat herds and should be considered when designing new F. hepatica control programs.