Experimental Peroxidase Conjugate for Detection of Specific Antibodies to Anthrax Agent in Enzyme Immunoassay

Anthrax poses a pressing issue for veterinary medicine and public health in many countries, including the Russian Federation, which necessitates the improvement and development of new, sensitive and specific diagnostic tools.The aim of the work was to create an experimental peroxidase conjugate for the detection of specific antibodies to the anthrax pathogen and to optimize the conditions for performing enzyme immunoassay (ELISA).Materials and methods. The peroxidase conjugate was constructed using horseradish peroxidase and Staphylococcus aureus protein A (Sigma-Aldrich, USA). Bacterial antigens isolated from strains of Bacillus anthracis 55ΔTPA-1Spo, B. anthracis Sterne 34 F2 were used as sensitizing agents. The developed experimental batches of the conjugate were tested in ELISA for the ability to bind antibodies in the blood sera of anthrax patients and vaccinated individuals. The sensitivity, specificity, and accuracy of the method were calculated using the built-in functions of the ROCR software package.Results and discussion. The peroxidase conjugate to detect specific antibodies to the anthrax pathogen in the study of clinical material has been developed; conditions for the ELISA performance have been optimized. To interpret the results of the study, a threshold value of the positivity coefficient was used, below which the result was considered negative, and at an equal or higher value, positive. The test demonstrated significant differences in the “positivity coefficient” indicator for the “Healthy”/“Sick” and “Healthy”/“Vaccinated” groups, while the differences between the “Sick”/“Vaccinated” groups were statistically insignificant. The maximum accuracy of the method was observed at blood serum dilutions of 1:250 and 1:500. 100 % intra-run, run-to-run and series-to-series reproducibility has been established for all positive samples. The sensitivity and specificity of the experimental peroxidase conjugates were 100 and 95.8 %, respectively, and the accuracy was 97.6 %

Development of a protective lyophilisation medium and conditions to stabilise the erythrocyte diagnostic preparation of tularaemia immunoglobulin

Liquid erythrocyte diagnostic preparations have a practical disadvantage; i.e., long-distance transportation involving possible non-compliance with cold-chain requirements may result in a complete loss of biological activity. A lyophilisation technology is necessary to ensure that the preparations retain their original properties for a long time. The aim of the work was to develop a protective medium and conditions for lyophilisation to stabilise the erythrocyte diagnostic preparation of tularaemia immunoglobulin. Materials and methods: Gelatin, thiourea, trehalose, sucrose, dextran, and Tween 80 were used as excipients for protective media. The authors used nine strains of homologous and heterologous microorganisms of different genera and species to control the lyophilised diagnostic preparation sensitivity and specificity. Evaluation of the main stability-related quality attributes (appearance of the dried preparation, loss on drying, solubility, appearance after reconstitution, appearance after settling, sensitivity, specificity) considered the temperatures specific to the climatic zones where the in vitro diagnostics is intended to be marketed and used. Results: The authors developed protective stabilising media with different compositions, used them in freeze-drying of the preparation and carried out control testing. The most promising was the lyophilisation medium containing a smaller amount of ingredients —6% of dextran, 0.06% of Tween 80 and up to 0.01% of sodium azide—as it was the simplest one to prepare and ensured complete preservation of the quality attributes. The authors carried out practical evaluation of lyophilisation procedures, and the 12–14-hour procedure proved to be the most cost-effective. Conclusions: The results of long-term, or real time, and accelerated stability testing of the lyophilised diagnostic preparation demonstrated the possibility of two-year storage at a labelled temperature of 2–8 °C, as well as at elevated and low temperatures of 30±2 °С and –18 °С, respectively. The tests showed no negative effects of the temperatures on the controlled quality attributes

Validation of Technological Process of Production of Liquid Brucellosis Diagnosticum for Agglutination Reaction, Suspension for Diagnostic Purposes

Presented are the results of validation of technological process of production of brucellosis diagnosticu

Разработка защитной среды высушивания и режима лиофилизации для стабилизации диагностикума эритроцитарного туляремийного иммуноглобулинового

Liquid erythrocyte diagnostic preparations have a practical disadvantage; i.e., long-distance transportation involving possible non-compliance with cold-chain requirements may result in a complete loss of biological activity. A lyophilisation technology is necessary to ensure that the preparations retain their original properties for a long time. The aim of the work was to develop a protective medium and conditions for lyophilisation to stabilise the erythrocyte diagnostic preparation of tularaemia immunoglobulin. Materials and methods: Gelatin, thiourea, trehalose, sucrose, dextran, and Tween 80 were used as excipients for protective media. The authors used nine strains of homologous and heterologous microorganisms of different genera and species to control the lyophilised diagnostic preparation sensitivity and specificity. Evaluation of the main stability-related quality attributes (appearance of the dried preparation, loss on drying, solubility, appearance after reconstitution, appearance after settling, sensitivity, specificity) considered the temperatures specific to the climatic zones where the in vitro diagnostics is intended to be marketed and used. Results: The authors developed protective stabilising media with different compositions, used them in freeze-drying of the preparation and carried out control testing. The most promising was the lyophilisation medium containing a smaller amount of ingredients —6% of dextran, 0.06% of Tween 80 and up to 0.01% of sodium azide—as it was the simplest one to prepare and ensured complete preservation of the quality attributes. The authors carried out practical evaluation of lyophilisation procedures, and the 12–14-hour procedure proved to be the most cost-effective. Conclusions: The results of long-term, or real time, and accelerated stability testing of the lyophilised diagnostic preparation demonstrated the possibility of two-year storage at a labelled temperature of 2–8 °C, as well as at elevated and low temperatures of 30±2 °С and –18 °С, respectively. The tests showed no negative effects of the temperatures on the controlled quality attributes.Практическое применение эритроцитарных диагностических препаратов выявило недостатки, связанные с их транспортировкой на значительные расстояния с возможным несоблюдением режимов холодовой цепи, что может привести к полной потере их биологической активности. Для стабилизации основных свойств жидких форм эритроцитарных диагностических препаратов в настоящее время необходима разработка технологии получения лиофилизированных форм диагностикумов, которая позволит сохранить первоначальные свойства препарата в течение длительного времени. Цель работы: разработка защитной среды высушивания и режима лиофилизации для стабилизации диагностикума эритроцитарного туляремийного иммуноглобулинового. Материалы и методы: были использованы вспомогательные вещества для подготовки защитных сред (желатин, тиомочевина, трегалоза, сахароза, декстран, твин 80). Для контроля чувствительности и специфичности лиофилизированных диагностикумов использовали 9 штаммов гомологичных и гетерологичных микроорганизмов разных родов и видов. При изучении стабильности основных показателей качества препаратов для диагностики in vitro (внешний вид высушенного препарата; потеря в массе при высушивании; растворимость, внешний вид восстановленного препарата; внешний вид препарата после отстаивания; чувствительность; специфичность) учитывали температуры различных климатических зон, в которых предполагается их реализация и использование. Результаты: разработаны и использованы стабилизирующие защитные среды с различным составом, с последующей сублимационной сушкой препарата и постановкой контрольных исследований. Наиболее перспективной признана среда высушивания для эритроцитарных диагностикумов, содержащая в своем составе меньшее количество ингредиентов — 6% декстрана, 0,06% твин 80 и азид натрия до 0,01%, как наиболее простая в исполнении и обеспечивающая полное сохранение качественных показателей препарата. Отработан рентабельный 12–14-часовой режим лиофилизации. Выводы: по совокупности полученных результатов изучения стабильности в реальном времени (долговременная стабильность) и ускоренном исследовании стабильности лиофилизированных форм диагностикума показана возможность хранения в течение двух лет при регламентированной температуре от 2 до 8 °С, а также в условиях повышенных и пониженных температур при 30±2 °С и минус 18 °С соответственно. Отрицательного влияния указанных температур на результаты контролируемых показателей не выявлено

Научно-методические разработки биотехнологий производства иммунобиологических препаратов для экспресс-диагностики инфекционных заболеваний и детекции их возбудителе

The present article describes the scientific and methodological development of biotechnological manufacture of test-system components (diagnostic preparations) for instant diagnosis of plague, brucellosis, tularemia, anthrax, cholera. In this regard, in the first place the effective methods for obtaining complete antigenic complexes used for immunizing animals for the purpose of developing highly potent immune sera have been established. These antisera were used in determining optimum parameters of manufacture on the basis of their diagnosticums. Methodical basis of developing magnetic immunosorbents for selective concentration of infectious agents and their instant diagnosis methods has been mentioned. Moreover, the article describes the development of piezoelectric quartz crystal biosensors to detect plague, brucellosis and tularemia pathogens by gravimetric flow injection analysis, allowing to quickly implement the process of reliable identification of a test pathogen in antigen-antibody complex.Представлены научно-методические разработки биотехнологий производства компонентов тест-систем (диагностических препаратов) для экспресс-диагностики чумы, бруцеллеза, туляремии, сибирской язвы, холеры. Для этого, прежде всего, были отработаны эффективные методики получения полноценных антигенных комплексов, применяемых для иммунизации животных в целях получения высокоактивных иммунных сывороток. Полученные иммунные сыворотки были использованы при определении оптимальных параметров производства на их основе диагностикумов. Приведены методические основы конструирования магноиммуносорбентов для селективного концентрирования возбудителей инфекционных заболеваний и их индикации экспресс-методами. Кроме того, приведена разработка пьезокварцевых биосенсорных устройств для выявления возбудителей чумы, бруцеллеза, туляремии в гравиметрическом проточно-инжекционном анализе, позволяющих быстро реализовать процесс достоверного распознавания исследуемого патогена в образовавшемся комплексе антиген-антител

Serological methods for detection of the causative agent of tularemia and their evaluation

Aim. A comparative study of serological methods for the detection of the causative agent of tularemia and their evaluation. Materials and methods. We used experimental diagnostic kits and test systems for the production of serological methods: indirect hemagglutination reaction (RGA); the reaction immunofluorescence (RIF); enzyme immunoassay (ELISA) using traditional microplate; IFA after selective concentration of the pathogen of tularemia in magnoimmunosorbents (MIS); microgravimetric analysis (MGA) based on piezoresistors (SP) and surface plasmon resonance (SPR). The experiments were carried out with homologous strains of tularemia microbe (test strains) and with strains of heterologous microorganisms in model experiments on tap water contaminated with different concentrations of the pathogen. Results. The parameters of each diagnostic method are determined and evaluated according to the following indicators: sensitivity (when working with pure cultures (test strains), contaminated samples of large volumes), specificity, time of setting and taking into account the results, informativeness, determining the modes of setting and accounting. Conclusion. The above diagnostic methods have their advantages and disadvantages. Therefore, when choosing a method, the researcher should be guided by the goals pursued. So, for screening studies it is advisable to carry out the formulation of ELISA, RIF, RGA, in identifying the pathogen in large volumes and contaminated samples, the effective use of selective concentration on MIS followed by the formulation of ELISA, to identify small amounts of samples and take into account the reaction in real time, it is possible to use MGA and SPR

Scientific and methodical development of biotechnological production of immunobiological preparations for instant diagnosis of infectious diseases and detection of pathogens

The present article describes the scientific and methodological development of biotechnological manufacture of test-system components (diagnostic preparations) for instant diagnosis of plague, brucellosis, tularemia, anthrax, cholera. In this regard, in the first place the effective methods for obtaining complete antigenic complexes used for immunizing animals for the purpose of developing highly potent immune sera have been established. These antisera were used in determining optimum parameters of manufacture on the basis of their diagnosticums. Methodical basis of developing magnetic immunosorbents for selective concentration of infectious agents and their instant diagnosis methods has been mentioned. Moreover, the article describes the development of piezoelectric quartz crystal biosensors to detect plague, brucellosis and tularemia pathogens by gravimetric flow injection analysis, allowing to quickly implement the process of reliable identification of a test pathogen in antigen-antibody complex

Qualitative Indicators of Experimental Brucellosis Antigen Preparations Designed for Cellular Tests in vitro

In order to develop the most diagnostically informative methods for carrying out antigen-stimulated cellular tests in vitro a careful selection of stimulating agent (antigen) is required, possessing an adequate activating potential and providing specificity of the reaction.Objective of the study was to identify the qualitative indicators of experimental batches of brucellosis antigen preparations designed for cellular tests in vitro.Materials and methods. Initially we produced antigen complexes of brucellosis microbe on the basis of the vaccine strains of three epidemically significant Brucella species (B. abortus, B. melitensis, B. suis). Quantitative determination of WsAg and PPBC proteins of experimental preparation series was performed applying capillary electrophoresis. Qualitative composition was assessed through ion exchange liquid chromatography with refractometric detection.Results and discussion. We have specified physical-chemical features, investigated chromatographic profiles and composition of protein fractions, as well as tried the produced experimental batches of brucellosis antigen preparations. After analyzing the defined protein and polysaccharide composition of the obtained WsAg samples, one can conclude that WsAg preparation cannot be used for cellular tests as the probability of non-specific lymphocyte reaction manifestation in vitro was experimentally proven. By contrast, complex brucellosis antigen preparation PPBC has an expressed specific activity and specificity under in vitro conditions and the prospects to be used when developing methodological approaches for laboratory diagnosis of brucellosis and assessment of de facto immunity rate in risk contingents after vaccination. The obtained parameters will allow for proper quality provision when manufacturing the developed experimental PPBC preparation designed for cellular tests in vitro, taking into account modern validation and standardization regulations