Dried Blood Spots technology for veterinary applications and biological investigations: technical aspects, retrospective analysis, ongoing status and future perspectives

Dried Blood Spots (DBS) technology has become a valuable tool in medical studies, however, in veterinary and biological research DBS technology applications are still limited. Up-to-date no review has comprehensively integrated all the evidence existing across the fields, technologies and animal species. In this paper we summarize the current applications of DBS technology in the mentioned areas, and provide a scope of different types of dried sample carriers (cellulose and non-cellulose), sampling devices, applicable methods for analyte extraction and detection. Mammals, birds, insects and other species are represented as the study objects. Besides the blood, the review considers a variety of specimens, such as milk, saliva, tissue samples and others. The main applications of dried samples highlighted in the review include epidemiological surveys and monitoring for infections agents or specific antibodies for disease/vaccination control in households and wildlife. Besides the genetic investigations, the paper describes detection of environmental contaminants, pregnancy diagnosis and many other useful applications of animal dried samples. The paper also analyses dried sample stability and storage conditions for antibodies, viruses and other substances. Finally, recent developments and future research for DBS technology in veterinary medicine and biological sciences are discussed.

Antiviral adsorption activity of porous silicon nanoparticles against different pathogenic human viruses

New viral infections, due to their rapid spread, lack of effective antiviral drugs and vaccines, kill millions of people every year. The global pandemic SARS-CoV-2 in 2019-2021 has shown that new strains of viruses can widespread very quickly, causing disease and death, with significant socio-economic consequences. Therefore, the search for new methods of combating different pathogenic viruses is an urgent task, and strategies based on nanoparticles are of significant interest. This work demonstrates the antiviral adsorption (virucidal) efficacy of nanoparticles of porous silicon (PSi NPs) against various enveloped and non-enveloped pathogenic human viruses, such as Influenza A virus, Poliovirus, Human immunodeficiency virus, West Nile virus, and Hepatitis virus. PSi NPs sized 60 nm with the average pore diameter of 2 nm and specific surface area of 200 m2/g were obtained by ball-milling of electrochemically-etched microporous silicon films. After interaction with PSi NPs, a strong suppression of the infectious activity of the virus-contaminated fluid was observed, which was manifested in a decrease in the infectious titer of all studied types of viruses by approximately 104 times, and corresponded to an inactivation of 99.99% viruses in vitro. This sorption capacity of PSi NPs is possible due to their microporous structure and huge specific surface area, which ensures efficient capture of virions, as confirmed by ELISA analysis, dynamic light scattering measurements and transmission electron microscopy images. The results obtained indicate the great potential of using PSi NPs as universal viral sorbents and disinfectants for the detection and treatment of viral diseases.

Surface-Enhanced Raman Scattering-Active Gold-Decorated Silicon Nanowire Substrates for Label-Free Detection of Bilirubin

Bilirubin (BR) is a product of hemoglobin breakdown, and its increasing levels in the blood may indicate liver disorders and lead to jaundice. Kernicterus is most dangerous in newborns when the unconjugated BR concentration can quickly rise to toxic levels, causing neurological damage and even death. The development of an accurate, fast, and sensitive sensor for BR detection will help reduce diagnostic time and ensure successful treatment. In this study, we propose a new method for creating a surface-enhanced Raman scattering (SERS)-active substrate based on gold-decorated silicon nanowires (Au@SiNWs) for sensitive label-free BR detection. Gold-assisted chemical etching of crystalline silicon wafers was used to synthesize SiNWs, the tops of which were then additionally decorated with gold nanoparticles. The low detection limit of model analyte 4-mercaptopyridine down to the concentration of 10^-8 M demonstrated the excellent sensitivity of the obtained substrates for SERS application. The theoretical full-wave electromagnetic simulations of Raman scattering in the Au@SiNW substrates showed that the major contribution to the total SERS signal comes from the analyte molecules located on the SiNW surface near the gold nanoparticles. Therefore, for efficient BR adsorption and SERS detection, the surface of the SiNWs was modified with amino groups. Label-free detection of BR using amino modified Au@SiNWs with high point-to-point, scan-to-scan, and batch-to-batch reproducibility with a detection limit of 10^-6 M has been demonstrated. Artificial urine, mimicking human urine samples, was used as the matrix to get insights into the influence of different parameters such as matrix complexity on the overall BR SERS signal. The signal stability was demonstrated for 7 days after adsorption of BR with a concentration of 5 × 10^-5 M, which is the required sensitivity for clinical applications.

Initial multi-target approach shows importance of improved caprine arthritis-encephalitis virus control program in Russia for hobbyist goat farms

Background and Aim:

Several reports described the detection of specific caprine arthritis-encephalitis virus (CAEV) antibodies in Russian goat populations, which indicates the circulation of CAEV in Russian goat farms. The aim of this study was to use a multi-target approach to testing with both serological tests and an in-house real-time (RT) molecular test to investigate the prevalence of CAEV in goats from three hobbyist farms in the Republic of Tatarstan, Russia.

Materials and Methods:

We applied a multi-target approach to testing with both enzyme-linked immunosorbent assay (ELISA) and an in-house RT polymerase chain reaction test to investigate the prevalence of CAEV in goats. Animals from the three hobbyist farms were used in this study. The animals from two farms (n=13 for F1 and n=8 for F2) had clinical signs of arthritis and mastitis. In the third farm (n=15 for F3), all goats were home-bred and had no contact with imported animals.

Results:

CAEV antibodies (ELISA targets TM env and gag genes) were detected in serum samples from two farms (F1 and F2), indicating seroprevalence of 87.50-92.31%. Specific CAEV antibodies were also detected in milk samples. CAEV proviral DNA was detected in 53.85-62.50%. The results from all tests performed in the third farm (F3) were negative, indicating that all tests were 100% specific.

Conclusion:

The results showed that CAEV is circulating and present in small hobbyist goat farms in Russia. Serological and molecular tests could be important for programs to control and eradicate CAEV in Russia for hobbyist goat farms.

Biosensor Immunoassay of Ivermectin in Bovine Milk

A rapid and sensitive biosensor immunoassay was developed for determination of ivermectin residues in bovine milk. A detection limit of 16.2 ng/mL was achieved. A Biacore optical biosensor based on surface plasmon resonance was used, and a range of extraction techniques was investigated. In the final assay procedure, ivermectin was extracted with acetonitrile followed by C8 solid-phase extraction cleanup. It was proven experimentally that 2 methods of milk storage, freezing or addition of mercury-containing compounds as preservatives, could be used without considerable change in detected concentrations (samples were fortified with ivermectin after storage). The average values for milk samples spiked at 100 and 50 ng/mL concentrations were 102.6 and 51.5 ng/mL, respectively. Extraction and analysis of 20 milk samples were performed within a single working day.

Strip-dried blood sampling: applicability for bovine leukemia virus detection with ELISA and real-time PCR

We recently proposed a new so-called strip-dried format aimed for convenient use of dried biomaterial in diagnostic purposes. In this work, 334 blood samples obtained in strip-dried form were used for bovine leucosis analysis with ELISA and real-time PCR methods. High percentage of seropositive animals (18.3%) let us estimate both indirect (serological) and direct methods applicability for the analysis of strip-dried blood samples and also to compare them (PCR results concurred with ELISA in 93.4% cases). Parallel analysis of native and corresponding strip-dried samples approved the proposed format as a reliable analytical way of sampling being in 100% concordance with conventional serum/whole blood ELISA and PCR analysis. Even distribution of antibodies against bovine leukemia virus along the membrane carrier was demonstrated by square-to-square analyzing of the sample strip (CV not exceeded 7%). Also, strip-dried blood samples showed enhanced stability at elevated temperatures comparing to liquid serum. The proposed strip-blood format is a promising way of sampling, storage and transportation and can find application in veterinary practice for infectious disease monitoring.

Strip-dried whole milk sampling technique for progesterone detection in cows by ELISA

New sampling format of whole cows' milk in strip-dried form was proposed. Few methodological issues of whole milk progesterone ELISA using samples dried on a membrane carrier in a form of strip were investigated and optimized: width of a strip, shape of punched/cut-off part of membrane, sample application method. It was shown that distribution of the hormone along narrow strip was even except the initial part of a strip (the first 0.5 × 0.5cm piece) where recovered concentration of progesterone was higher. Storage stability of progesterone in strip-dried whole cows' milk samples at 4°C, ambient temperature, 37°C and 60°C was investigated. Rising of the detected progesterone concentration over storage period at elevated temperatures was observed predominantly in milk samples with low hormone concentration (from non-pregnant cows). Strip-dried whole milk samples can be used for collection, transportation, storage and ELISA analysis of progesterone level which is correlated with reproductive status of cows.

Pretreatment-free lateral flow enzyme immunoassay for progesterone detection in whole cows' milk

New rapid method of lateral flow enzyme immunoassay (LFEIA) for progesterone detection in whole cows' milk was developed. The test system utilized horseradish peroxidase as a label along with the substrate solution containing 3,3',5,5'-tetramethylbenzidine and dextran sulfate to obtain an insoluble blue colored product of the enzyme reaction on a surface of analytical membrane (test and control lines). Several aspects of LFEIA were optimized: time of the signal detection, membrane materials and assay conditions. Resulting competitive LFEIA can be performed within 15 minutes with the limit of progesterone detection of 0.8 ng/ml. Progesterone concentration in whole milk samples was determined by LFEIA and enzyme-linked immunosorbent assay (ELISA). The results obtained were in good correlation (R=0.97, n=46). Thus new sensitive LFEIA can be successfully used for on-site monitoring of oestrus status of cows' reproductive system and for early none-pregnancy detection. The method is fast, easy to perform and needs no preliminary sample preparation.

The identification of potential alternative biomarkers of nitrofurazone abuse in animal derived food products

Semicarbazide (SEM) was considered to be a characteristic protein-bound side-chain metabolite of the banned veterinary drug nitrofurazone and used as a marker of nitrofurazone abuse. It was recently discovered that SEM can arise in food from sources other than nitrofurazone. This uncertainty over the source of SEM may be overcome if alternative markers specific to tissue-bound nitrofurazone residues can be determined. The structure of nitrofurazone metabolites in vivo and particular proteins to which they are bound are not known. These proteins with altered structure due to the presence of the drug metabolites can be considered as potential alternative biomarkers of nitrofurazone abuse. The proteins implicated in the in vivo binding of nitrofurazone were separated and identified. A crude mixture of proteins extracted from the liver of a rat treated with the drug was separated using a series of different techniques such as preparative isoelectric focusing and size exclusion HPLC. Multiple fractions were assayed by LC-MS/MS to detect the presence of SEM. The proteins containing SEM residues were identified by peptide mass mapping using trypsin digestion and MALDI-TOF. The first protein identified as containing high concentration of SEM was albumin. It was also shown that low molecular weight species within a protein mixture whose main constituent was glutathione S-transferase contained a high concentration of SEM. The chemical composition of these components is under investigation. Preliminary data suggest the SEM forms part of a nitrofurazone metabolite conjugated to glutathione.

Enzyme immunoassay for semicarbazide—The nitrofuran metabolite and food contaminant

Semicarbazide (SEM), the marker residue for the banned nitrofuran veterinary antibiotic nitrofurazone (NFZ), has been detected regularly in foods (47% of recent nitrofuran EU Rapid Alerts involve SEM). However, the validity of SEM as a definitive marker for NFZ has been undermined by SEM arising from other sources including azodicarbonamide, a plastics blowing agent and flour treatment additive. An inexpensive screening test for SEM in food matrices is needed--all SEM testing currently uses expensive LC-MS/MS instrumentation. We now report the first production of antibodies against derivatised SEM. A novel carboxyphenyl SEM derivative was used to raise a polyclonal antibody that has been incorporated into a semi-quantitative microtitre plate ELISA, validated according to the criteria set out in Commission Decision 2002/657/EC, for use with chicken muscle. The antibody is highly specific for derivatised SEM, cross-reactivity being 1.7% with NFZ and negligible with a wide range of other nitrofurans and poultry drugs. Samples are derivatised with o-nitrobenzaldehyde and simultaneously protease digested before extraction by cation exchange SPE. The ELISA has a SEM detection capability (CCbeta) of 0.25 microg kg(-1) when a threshold of 0.21 microg kg(-1) is applied to the selection of samples for confirmation (lowest observed 0.25 microg kg(-1) fortified sample, n=20), thus satisfying the EU nitrofurans' minimum required performance limit of 1 microg kg(-1). NFZ-incurred muscles (12) containing SEM at 0.5-5.0 microg kg(-1) by LC-MS/MS, all screened positive by this ELISA protocol which is also applicable to egg and chicken liver.

Biacore biosensor immunoassay for 4-nonylphenols: assay optimization and applicability for shellfish analysis

A rapid Biacore biosensor immunoassay of 4-nonylphenols was developed. Two types of antibodies were used in the study: polyclonal antibodies with high cross-reactivity towards technical 4-nonylphenol and a monoclonal antibody very specific to 4-n-nonylphenol. 9-(p-Hydroxyphenyl)nonanoic acid was immobilized onto surface of a sensor chip. The best assay sensitivity was achieved using a flow rate of 50 microl min(-1) and injection time of 2 min. For the assay incorporating monoclonal antibodies a limit of detection 2 ng ml(-1) for 4-n-nonylphenol was achieved. With polyclonal antibodies one order lower sensitivity was observed for 4-nonylphenols. High background level of calibration curve for technical 4-nonylphenol was decreased by using IgG fraction of polyclonal antibodies in combination with lower amount of immobilised 9-(p-hydroxyphenyl)nonanoic acid. Sensitivity of the assay was improved by using a chip with a new derivative on a surface-N-aminobutyl [2-(4-hydroxyphenyl)ethylamine] (limit of detection--5 ng ml(-1)). Applicability of the developed assays to ecological monitoring was checked in experiments using shellfish samples. 4-n-Nonylphenol from spiked samples was extracted into hexane followed by clean-up on NH2 SPE columns. Calibration curves generated for cockles, mussels and oyster samples were identical (limit of detection about 10 ng g(-1)) whereas for scallop samples a slight decrease (about 5-10%) of absolute response was observed. In the assay using the monoclonal antibody specific to 4-n-nonylphenol 31 shellfish samples were found to be negative. Results obtained with polyclonal antibodies indicated that two scallop samples contained a quantity of 4-nonylphenols. The developed biosensor assay could be applied for shellfish analysis as a preliminary screening method.

Determination of 4-n-nonylphenol in water by enzyme immunoassay

A range of monoclonal antibody-based competitive immunoassays in the format of microtitre plate ELISA and dipstick tests for quantitative and semi-quantitative detection of 4- n -nonylphenol in water was developed. A simple visual dipstick test was based on changing of spot colour from green to brown in the presence of 4- n -nonylphenol at concentrations within the range 10-100 ng mL(-1). Two different detection systems were used for quantitative immunoassay. Application of enhanced chemiluminescence (ECL) resulted in an increase of the sensitivity of ELISA when compared to conventional colorimetric detection. Thus a detection limit of 0.06 ng mL(-1 )of 4- n -nonylphenol was achieved with IC(50) 2.0 ng mL(-1). The tests developed were applied to natural and spiked water samples.

Biosensor immunoassay of ivermectin in bovine milk

A rapid and sensitive biosensor immunoassay was developed for determination of ivermectin residues in bovine milk. A detection limit of 16.2 ng/mL was achieved. A Biacore optical biosensor based on surface plasmon resonance was used, and a range of extraction techniques was investigated. In the final assay procedure, ivermectin was extracted with acetonitrile followed by C8 solid-phase extraction cleanup. It was proven experimentally that 2 methods of milk storage, freezing or addition of mercury-containing compounds as preservatives, could be used without considerable change in detected concentrations (samples were fortified with ivermectin after storage). The average values for milk samples spiked at 100 and 50 ng/mL concentrations were 102.6 and 51.5 ng/mL, respectively. Extraction and analysis of 20 milk samples were performed within a single working day.

Determination of ivermectin in bovine liver by optical immunobiosensor

A rapid and sensitive biosensor immunoassay was developed for residues of the antiparasitic agent ivermectin in bovine liver. A detection limit of 19.1 ng g(-1) was achieved. The sensor employed was a Biacore optical instrument based on surface plasmon resonance. 5-O-succinoylivermectin-apo-transferrin conjugate was used to produce monoclonal antibody while a second derivative, ivermectin-oxime, was immobilised onto the surface of a sensor chip. A range of assay parameters (flow rate, injection time, temperature) and extraction techniques were investigated. In the final assay procedure, ivermectin was extracted with acetonitrile followed by C(8) SPE clean-up. Matrix effect was minimised by increasing the flow rate to 25 microl min(-1) and reducing the sample injection time to 2 min. The average value for liver samples spiked at 100 ng g(-1) (the MRL for the drug) and 50 ng g(-1) concentrations were 93.7 and 43.2 ng g(-1), respectively.

Chemiluminescent multiassay of pesticides with horseradish peroxidase as a label

Competitive chemiluminescent immunoassay based on a combination of five antibodies was used in a combination with neural network to identify and estimate amounts of three cross-reacting s-triazines (atrazine, terbythylazine and ametryn). Antibodies with different cross-reactivity towards s-triazines were immobilized in separate wells an eight-well microtiter strip. Training of neural networks was carried out with four different learning procedures. The best topology for the data measured was a net with two hidden layers with ten neurons in the first and 15 in the second layer trained with the Schmidhuber method. s-Triazine classification of environmental samples containing various analyte mixtures was correct in 70-100% of all cases depending on the type of analyte. The test developed can be proposed as an alternative field test for multianalyte environmental monitoring.