Plague Vaccine Research Articles

Quality Assessment of the Live Plague Vaccine Prepared Using nutrient Medium on the Basis of Hydrolysate of Concentrated Corn steep

Objectiveof the study was to test the nutrient medium based on the enzymatic hydrolysate of corn extract condensed for a scaled production of live plague vaccine and to check the quality of the obtained batches against the specified parameters.Materials and methods.A dense nutrient medium based on corn extract was used to grow biomass in the process of live plague vaccine production. The quality parameters of the vaccine preparation obtained were studied by the regulated methods set forth in the regulatory documentation.Results and conclusions. The vaccine was monitored at all stages of its manufacture, including control of the finished dosage form, in strict accordance with the approved regulatory documentation. All the experimental production series complied with the specified indices. Approbation of the production cycle environment for live plague vaccine manufacturing showed efficiency of the conditions and the possibility of environment’s application in the industrial production of the preparation.

One year immunogenicity and safety of subunit plague vaccine in Chinese healthy adults: An extended open-label study

ABSTRACTBackground: To evaluate the one-year immunogenicity and safety of a subunit plague vaccine. Methods: In the initial study, 240 healthy adults aged 18–55 years were administrated with 2 doses of 15 or 30 µg plague vaccines at day 0 and 28, respectively. In this extended follow-up study, we evaluated the immunogenicity and safety of the plague vaccine up to one year. Results: For antibody to envelope antigen faction 1 (F1) antigen, titers were up to new peaks at month 6, then declined slowly to month 12, but remained at higher levels than those at day 56. Geometric mean titers (GMTs) of F1 were significantly higher in 30 µg group than those in 15 µg group at month 6 and 12 (P < 0.0001 and P < 0.001). However, approximate 100% seroconversion rates of F1 antibodies were found in both 15 and 30 µg groups at the both time points. For antibody to recombinant virulence (rV) antigen, titers and seroconversion rates were decreased sharply at month 6 and continue to decrease at month 12. GMTs and seroconversion rates were not significantly different between the 15 and 30 µg groups, respectively. No serious adverse events (SAEs) related to vaccine occurred. Conclusion: The new plague vaccine (F1+rV) induced a robust immune response up to 12 months and showed a good safety profile in adults aged 18–55 years.

Comprehensive Immunological Study of Persons Vaccinated with Live Plague Vaccine Living on the Territory of the Pre-Caspian Sand Foci of the Plague in the Republic of Kalmykia

Relevance. In 2005 International Health Regulations, the plague, is on the list of dangerous infectious diseases that can cause emergency situations of interstate importance. Even single cases of human plague are considered as the basis for carrying out preventive measures. The paper presents the results of immunological monitoring conducted on the territory of the Republic of Kalmykia in order to assess the immunological efficacy and safety of the plague live vaccine The paper presents the results of immunological monitoring in the territory of the Kalmyk Republic over the individuals vaccinated against plague due to epidemiological reasons. Materials and methods. Studies of immunological efficacy of live plague vaccine were conducted alongside stepwise assessment of cellular and humoral components of innate and adaptive immunity in persons revaccinated against plague, using a complex of advanced informative tests. Results and conclusions. It is established that before the second revaccination all the surveyed persons retained expressed immune response by the mixed or cellular type, characterized by high level of spontaneous and induced production of Th1-associated cytokines. Activation of Th1 immune reaction was registered one month after the scheduled revaccination; immune response change-over from Th1 to Th2 type – after 6 months of observation, and retention of adaptive immunity by mixed type at the moderate level – in a year. Specific humoral immunity developed in 85% of the surveyed persons, but throughout the whole investigation the dynamics of antibody titers to plague microbe F1 individualized and did not coincide with cellular immunity indicators. Performed complex study has confirmed the relative safety of the live plague vaccine.

Experimental Adaptation of a strain of the plague microbe to lyophilization process

The use of lyophilization as a means of preserving commercial properties of the dried live plague vaccine is closely linked to a number ofresistant microbial cells surviving in the preparation after microbial population exposure to such stress action. Lyophilized live vaccine efficiency, even without violation of storage rules at low temperatures (4 ± 2 – 6 ± 2 оС), decreases gradually due to death of live cells of microorganisms forming the base of a vaccine. Aim: The aim of this study was to enhance resistance of the reference vaccine strain Yersinia pestis EV of NIIEG lineage to freeze-drying in vacuum (lyophilization) by different techniques: the use of lyophilization process per se as a selection factor, resistant clone selection from populations of strains which underwent single, double and triple lyophiliation, strain culturing at low temperatures (4 ± 2 – 6 ± 2 °С). Summary and conclusion: It was demonstrated that after double and triple lyophilization the Y. pestis EV strain resistance to the process increased by 3–3.5 times. Clonal selection of twice and three times lyophilized variant facilitated detection of resistant clones and stabilization of this property.The clones selected were characterized by increased immunogenicity, high heat stability, as well as by increased duration of vaccine efficiency (by 2.3 times). A psychrophilic variant of Y. pestis EV strain was obtained in vitro acquiring higher resistance to lyophilization (in 2 times or more) in comparison with the reference strain. The number of psychrophilic variant cells surviving post-liophilization was higher in comparison with the commercial strain. Thus the methods used in this study for selection of strains and clones with the highest resistance to lyophilization from Y. pestis EV reference strain population showed a significant potential for quality improvement of dried live plague vaccine. So, the possibility of receiving of a vaccine of more high quality by means of the ways of selection explained in our work is experimentally confirmed. Effectiveness of these ways creates prerequisites for their use in production of a live plague vaccine.

Humoral and cellular immune responses to Yersinia pestis Pla antigen in humans immunized with live plague vaccine.

BackgroundTo establish correlates of human immunity to the live plague vaccine (LPV), we analyzed parameters of cellular and antibody response to the plasminogen activator Pla of Y. pestis. This outer membrane protease is an essential virulence factor that is steadily expressed by Y. pestis.Methodology/Principal findingsPBMCs and sera were obtained from a cohort of naïve (n = 17) and LPV-vaccinated (n = 34) donors. Anti-Pla antibodies of different classes and IgG subclasses were determined by ELISA and immunoblotting. The analysis of antibody response was complicated with a strong reactivity of Pla with normal human sera. The linear Pla B-cell epitopes were mapped using a library of 15-mer overlapping peptides. Twelve peptides that reacted specifically with sera of vaccinated donors were found together with a major cross-reacting peptide IPNISPDSFTVAAST located at the N-terminus. PBMCs were stimulated with recombinant Pla followed by proliferative analysis and cytokine profiling. The T-cell recall response was pronounced in vaccinees less than a year post-immunization, and became Th17-polarized over time after many rounds of vaccination.Conclusions/SignificanceThe Pla protein can serve as a biomarker of successful vaccination with LPV. The diagnostic use of Pla will require elimination of cross-reactive parts of the antigen.

Impact of Sylvatic Plague Vaccine on Non-target Small Rodents in Grassland Ecosystems.

Oral vaccination is an emerging management strategy to reduce the prevalence of high impact infectious diseases within wild animal populations. Plague is a flea-borne zoonosis of rodents that often decimates prairie dog (Cynomys spp.) colonies in the western USA. Recently, an oral sylvatic plague vaccine (SPV) was developed to protect prairie dogs from plague and aid recovery of the endangered black-footed ferret (Mustela nigripes). Although oral vaccination programs are targeted toward specific species, field distribution of vaccine-laden baits can result in vaccine uptake by non-target animals and unintended indirect effects. We assessed the impact of SPV on non-target rodents at paired vaccine and placebo-treated prairie dog colonies in four US states from 2013 to 2015. Bait consumption by non-target rodents was high (70.8%, n = 3113), but anti-plague antibody development on vaccine plots was low (23.7%, n = 266). In addition, no significant differences were noted in combined deer mice (Peromyscus maniculatus) and western harvest mouse (Reithrodontomys megalotis) abundance or community evenness and richness of non-target rodents between vaccine-treated and placebo plots. In our 3-year field study, we could not detect a significant positive or negative effect of SPV application on non-target rodents.

Single vector platform vaccine protects against lethal respiratory challenge with Tier 1 select agents of anthrax, plague, and tularemia

Bacillus anthracis, Yersinia pestis, and Francisella tularensis are the causative agents of Tier 1 Select Agents anthrax, plague, and tularemia, respectively. Currently, there are no licensed vaccines against plague and tularemia and the licensed anthrax vaccine is suboptimal. Here we report F. tularensis LVS ΔcapB (Live Vaccine Strain with a deletion in capB)- and attenuated multi-deletional Listeria monocytogenes (Lm)-vectored vaccines against all three aforementioned pathogens. We show that LVS ΔcapB- and Lm-vectored vaccines express recombinant B. anthracis, Y. pestis, and F. tularensis immunoprotective antigens in broth and in macrophage-like cells and are non-toxic in mice. Homologous priming-boosting with the LVS ΔcapB-vectored vaccines induces potent antigen-specific humoral and T-cell-mediated immune responses and potent protective immunity against lethal respiratory challenge with all three pathogens. Protection against anthrax was far superior to that obtained with the licensed AVA vaccine and protection against tularemia was comparable to or greater than that obtained with the toxic and unlicensed LVS vaccine. Heterologous priming-boosting with LVS ΔcapB- and Lm-vectored B. anthracis and Y. pestis vaccines also induced potent protective immunity against lethal respiratory challenge with B. anthracis and Y. pestis. The single vaccine platform, especially the LVS ΔcapB-vectored vaccine platform, can be extended readily to other pathogens.

Usage of Solid Medium on the Basis of Corn-Steep Extract Hydrolysate in Manufacturing of Live Plague Vaccine and for Plague Agent Strain Preservation

Objective of the study was to develop a solid medium on the basis of enzyme digest of corn-steep extract for manufacturing of live plague vaccine and storage of plague agent strains. Materials and methods. Vaccine strain and virulent strains of Yersinia pestis, nutrient media for accumulation and storage. Investigated parameters were assessed according to regulatory documentation. Results and conclusions. Developed has been nutrient medium based on enzyme digest of corn-steep extract with growth stimulation additives – Mohr’s salt and sodium sulphite. Studied have been its physical-chemical and biological properties. Approbation of the medium in manufacturing laboratory has revealed its high efficiency and possibility of usage in industrial production of live plague vaccine. Batches of preparation with optical concentration of 100 mlrd/ml and (68.2±0.9) % viability have been manufactured. Application of the stated medium allows for increase in biomass output and decrease in prime cost of final product. Confirmed has been the possibility to store the virulent plague agent strains on the medium at (4±2) °C for 18 months without reduction of the culture viability.

EVALUATION OF HUMORAL AND CELLULAR IMMUNITY LEVEL AMONG PERSONS LIVING IN THE CASPIAN NATURAL SANDY FOCUS TERRITORY AFTER ANTI-PLAGUE REVACCINATION

In view of increasing epidemic danger potential of some natural plague foci and performing measures to provide specific prevention of this infection, it becomes necessary to carefully monitor the state of immunity in vaccinated (revaccinated) individuals. The aim of the study was to assess humoral and cellular immunity levels in the persons after repeated anti-plague revaccination performed for appropriate epidemiological indications. Evaluation of immune responses to anti-plague revaccination was carried out according to studies of blood samples from 20 people aged 24 to 53 years living in the Caspian sandy natural plague focus located at the territory in Kalmykia Republic. Specific antibody titers to the F1 antigen of plague microbe were assessed in blood serum by immunoassay testing using an “ELISA-AT-F1 YERSINIA PESTIS” test system (Russian Research Anti-Plague Institute “Microbe”, Russia), along with spontaneous and concanavalin A-induced production of different cytokines, i.e., IFNγ, TNFα, IL-4, IL-10 (Vector-Best, Russia), IL-17A (Bender Medsystems, Austria). The studies were performed before vaccination, and 1, 6, 12 month after the booster vaccination. The results of the study indicate that immunological reconstitution after revaccination with live plague vaccine occurs occurred mostly according to mixed Th1/Th2 type. Detection of antibodies to the F1 specific plague microbe antigen before and 1 month after revaccination (65 and 85%, respectively) was indicative of development of humoral response. The most informative cytokine markers (IFNγ and TNFα) for evaluation of an anti-plague cellular immune response have been identified. The threefold increase in IFNγ induced production before revaccination indicates to initial immunological competence of all the examined individuals. A high correlation between TNFα and other cytokine levels was determined. The fact of high correlation for the studied cytokines (TNFα, IFNγ, IL-10) indicated to a synchronism in the immunocompetent T helper cell reaction. By measuring the levels of spontaneous and induced cytokine production levels, one may indirectly judge on degree of anti-plague cell immunity in humans.

EMERGENCY PROPHYLAXIS OF EXPERIMENTAL MELIOIDOSIS USING SYNTHETIC IMMUNOMODULATORS AND HETEROLOGOUS VACCINES

Melioidosis is a particularly dangerous infection caused by Burkholderia pseudomallei , against which a vaccine has not yet been created. In this regard, the development of effective treatment regimens and emergency prevention of melioidosis is very relevant. To improve the effectiveness of emergency prophylaxis of melioidosis, synthetic peptides (bestim, imunofan) and thiopoietin preparation glutoxim were used when combined with the antibiotic doxycycline. In addition, in experiments on white mice, the ability of heterologous vaccines (plague and tularemia), used in the emergency prevention mode, to increase the resistance of animals to melioidosis infection was assessed. It was shown that the most effective was imunofan, which, when combined with doxycycline, increased by 20% the survival rate of 5LD50 Burkholderia pseudomallei infection and significantly increased the average life span of mice infected with 5-12 LD50 (p &lt; 0.05). The efficiency of use for stimulation of non-specific resistance to melioidosis of a heterologous plague vaccine EV, once administered 1 day prior to infection, protected 90% of mice from 6 LD50 Burkholderia pseudomallei and 60% - with an increase in the infectious dose of the pathogen of melioidosis up to 15 LD50. The same level of protection from melioidosis was provided by a 3 day course of antibiotic therapy with doxycycline. It was concluded that the tularemia vaccine is not suitable for immunostimulation in melioidosis due to its high residual virulence and reactogenicity.

A safety and immunogenicity study of a novel subunit plague vaccine in cynomolgus macaques.

Plague has led to millions of deaths in history and outbreaks continue to the present day. The efficacy limitations and safety concerns of the existing killed whole cell and live-attenuated vaccines call for the development of new vaccines. In this study, we evaluated the immunogenicity and safety of a novel subunit plague vaccine, comprising native F1 antigen and recombinant V antigen. The cynomolgus macaques in low- and high-dose vaccine groups were vaccinated at weeks 0, 2, 4 and 6, at dose levels of 15 μg F1 + 15 μg rV and 30 μg F1 + 30 μg rV respectively. Specific antibodies and interferon-γ and interleukin-2 expression in lymphocytes were measured. For safety, except for the general toxicity and local irritation, we made a systematic immunotoxicity study on the vaccine including immunostimulation, autoimmunity and anaphylactic reaction. The vaccine induced high levels of serum anti-F1 and anti-rV antibodies, and caused small increases of interferon-γ and interleukin-2 in monkeys. The vaccination led to a reversible increase in the number of peripheral blood eosinophils, the increases in serum IgE level in a few animals and histopathological change of granulomas at injection sites. The vaccine had no impact on general conditions, most clinical pathology parameters, percentages of T-cell subsets, organ weights and gross pathology of treated monkeys and had passable local tolerance. The F1 + rV subunit plague vaccine can induce very strong humoral immunity and low level of cellular immunity in cynomolgus macaques and has a good safety profile.

Vaccines for Conservation: Plague, Prairie Dogs & Black-Footed Ferrets as a Case Study.

The endangered black-footed ferret (Mustela nigripes) is affected by plague, caused by Yersinia pestis, both directly, as a cause of mortality, and indirectly, because of the impacts of plague on its prairie dog (Cynomys spp.) prey base. Recent developments in vaccines and vaccine delivery have raised the possibility of plague control in prairie dog populations, thereby protecting ferret populations. A large-scale experimental investigation across the western US shows that sylvatic plague vaccine delivered in oral baits can increase prairie dog survival. In northern Colorado, an examination of the efficacy of insecticides to control fleas and plague vaccine shows that timing and method of plague control is important, with different implications for long-term and large-scale management of Y. pestis delivery. In both cases, the studies show that ambitious field-work and cross-sectoral collaboration can provide potential solutions to difficult issues of wildlife management, conservation and disease ecology.

Sylvatic Plague Vaccine Partially Protects Prairie Dogs (Cynomys spp.) in Field Trials

Sylvatic plague, caused by Yersinia pestis, frequently afflicts prairie dogs (Cynomys spp.), causing population declines and local extirpations. We tested the effectiveness of bait-delivered sylvatic plague vaccine (SPV) in prairie dog colonies on 29 paired placebo and treatment plots (1–59 ha in size; average 16.9 ha) in 7 western states from 2013 to 2015. We compared relative abundance (using catch per unit effort (CPUE) as an index) and apparent survival of prairie dogs on 26 of the 29 paired plots, 12 with confirmed or suspected plague (Y. pestis positive carcasses or fleas). Even though plague mortality occurred in prairie dogs on vaccine plots, SPV treatment had an overall positive effect on CPUE in all three years, regardless of plague status. Odds of capturing a unique animal were 1.10 (95% confidence interval [C.I.] 1.02–1.19) times higher per trap day on vaccine-treated plots than placebo plots in 2013, 1.47 (95% C.I. 1.41–1.52) times higher in 2014 and 1.19 (95% C.I. 1.13–1.25) times higher in 2015. On pairs where plague occurred, odds of apparent survival were 1.76 (95% Bayesian credible interval [B.C.I.] 1.28–2.43) times higher on vaccine plots than placebo plots for adults and 2.41 (95% B.C.I. 1.72–3.38) times higher for juveniles. Our results provide evidence that consumption of vaccine-laden baits can protect prairie dogs against plague; however, further evaluation and refinement are needed to optimize SPV use as a management tool.

Burrow Dusting or Oral Vaccination Prevents Plague-Associated Prairie Dog Colony Collapse

Plague impacts prairie dogs (Cynomys spp.), the endangered black-footed ferret (Mustela nigripes) and other sensitive wildlife species. We compared efficacy of prophylactic treatments (burrow dusting with deltamethrin or oral vaccination with recombinant “sylvatic plague vaccine” [RCN-F1/V307]) to placebo treatment in black-tailed prairie dog (C. ludovicianus) colonies. Between 2013 and 2015, we measured prairie dog apparent survival, burrow activity and flea abundance on triplicate plots (“blocks”) receiving dust, vaccine or placebo treatment. Epizootic plague affected all three blocks but emerged asynchronously. Dust plots had fewer fleas per burrow (P < 0.0001), and prairie dogs captured on dust plots had fewer fleas (P < 0.0001) than those on vaccine or placebo plots. Burrow activity and prairie dog density declined sharply in placebo plots when epizootic plague emerged. Patterns in corresponding dust and vaccine plots were less consistent and appeared strongly influenced by timing of treatment applications relative to plague emergence. Deltamethrin or oral vaccination enhanced apparent survival within two blocks. Applying insecticide or vaccine prior to epizootic emergence blunted effects of plague on prairie dog survival and abundance, thereby preventing colony collapse. Successful plague mitigation will likely entail strategic combined uses of burrow dusting and oral vaccination within large colonies or colony complexes.

Host Iron Nutritional Immunity Induced by a Live Yersinia pestis Vaccine Strain Is Associated with Immediate Protection against Plague.

Prompt and effective elicitation of protective immunity is highly relevant for cases of rapidly deteriorating fatal diseases, such as plague, which is caused by Yersinia pestis. Here, we assessed the potential of a live vaccine to induce rapid protection against this infection. We demonstrated that the Y. pestis EV76 live vaccine protected mice against an immediate lethal challenge, limiting the multiplication of the virulent pathogen and its dissemination into circulation. Ex vivo analysis of Y. pestis growth in serum derived from EV76-immunized mice revealed that an antibacterial activity was produced rapidly. This activity was mediated by the host heme- and iron-binding proteins hemopexin and transferrin, and it occurred in strong correlation with the kinetics of hemopexin induction in vivo. We suggest a new concept in which a live vaccine is capable of rapidly inducing iron nutritional immunity, thus limiting the propagation of pathogens. This concept could be exploited to design novel therapeutic interventions.

THE ANTIGEN-SPECIFIC CELL IN VITRO TESTS FOR POST-VACCINATION ANTIPLAGUE IMMUNITY FORMATION

The possibility of post-vaccination anti-plague immunity evaluation was researched using antigen-stimulated cells tests in vitro and cytometry analysis. The object of study — the blood samples of 17 people immunised by the live plague vaccine (Yersinia pestis EV) epicutaneously. Blood taking was carried out before vaccination and after immunisation on 7 and on 21 days, in 3 and in 6 months. Intensity antigen reactivity of lymphocytes was detected by cell tests in vitro, analysing markers of early (CD45+CD3+CD25+) and late (CD45+CD3+HLA-DR+) lymphocyte activation using flow cytometry. The complex of water-soluble Y. pestis antigens and allergen — pestin PP was tested as antigen. The high stimulating potential was defined of the water-soluble antigens Y. pestis complex. It is shown that coefficient of stimulation of relative level T- lymphocytes which express receptors for IL-2 was positive for all observation times after immunisation. The coefficient of stimulation had maximum values at 21 days (56.37%) and at 3 (47.41%) months. In identifying HLADR-positive lymphocytes before vaccination, the negative coefficient of stimulation was indicated on 7 and 21 days and the positive coefficient of stimulation was indicated at 3 and at 6 months. Analysis of intensity expression of early and late lymphocyte activation markers dynamics showed the possibility and prospect of application of cellular in vitro tests for the laboratory evaluation of specific reactivity of cellular immunity in both the early (7 days) and late (6 months) periods after vaccination. The results can be the basis for developing a new algorithm for assessment of immunological effectiveness of vaccination people against plague. It is the algorithm based on the identification of lymphocyte activation markers by antigen stimulation in conditions in vitro.

Responses of Juvenile Black-tailed Prairie Dogs ( Cynomys ludovicianus ) to a Commercially Produced Oral Plague Vaccine Delivered at Two Doses.

We confirmed safety and immunogenicity of mass-produced vaccine baits carrying an experimental, commercial-source plague vaccine (RCN-F1/V307) expressing Yersinia pestis V and F1 antigens. Forty-five juvenile black-tailed prairie dogs ( Cynomys ludovicianus ) were randomly divided into three treatment groups (n=15 animals/group). Animals in the first group received one standard-dose vaccine bait (5×107 plaque-forming units [pfu]; STD). The second group received a lower-dose bait (1×107 pfu; LOW). In the third group, five animals received two standard-dose baits and 10 were left untreated but in contact. Two vaccine-treated and one untreated prairie dogs died during the study, but laboratory analyses ruled out vaccine involvement. Overall, 17 of 33 (52%; 95% confidence interval for binomial proportion [bCI] 34-69%) prairie dogs receiving vaccine-laden bait showed a positive anti-V antibody response on at least one sampling occasion after bait consumption, and eight (24%; bCI 11-42%) showed sustained antibody responses. The STD and LOW groups did not differ (P≥0.78) in their proportions of overall or sustained antibody responses after vaccine bait consumption. Serum from one of the nine (11%; bCI 0.3-48%) surviving untreated, in-contact prairie dogs also had detectable antibody on one sampling occasion. We did not observe any adverse effects related to oral vaccination.

Immunological Efficiency of Plague Vaccination in the Active Natural Focus. Report 1. Cytokine and immunoglobulin status

Some data of the complex immune status study of humans vaccinated with live plague vaccine EV are represented. These people constantly reside and work at the territory of Gorno-Altai high-mountain natural plague focus that today demonstrates high epidemic activity. It was shown that 93% of the vaccinated humans developed positive seroconversion in 1 month after immunization, but after 6 months the protective antibody titers significantly decreased and did not exceed the diagnostic level. At the same time the revealed changes of the main immunoglobulin concentrations ranged within the physiological norm. Furthermore, increased production of TNF-and IFN- in blood cells in 1 month after vaccination may indicate the development of cellular immune response in humans immunized against plague and confirms the predominant role of cellular response in comparison with humoral reactions.

Using Off-the-Shelf Technologies to Mass Manufacture Oral Vaccine Baits for Wildlife.

Technology and infrastructure costs can limit access to oral vaccination tools for wildlife disease control. We describe vaccine bait mass manufacturing employing off-the-shelf technologies. Our approach has helped advance scaling-up of plague vaccination campaigns, but components of this production system could be translated into other wildlife vaccination applications.

PLAGUE INFECTION SIMULATING IN CASE OF INOCULATION WITH AVIRULENT YERSINIA PESTIS STRAINS

Biological method of investigation is specified for the laboratory diagnostics of plague. Mastering of this method by the trainees within the frames of further vocational education is associated with the use of avirulent Yersinia pestis strains and vaccine Y. pestis strain EV line, which while providing safety does not allow for typical pathomorphological pattern on biomodels, as well as for isolation of microorganisms from internal organs. Objective of the study is to select avirulent Yersinia pestis strains and to conduct comparative analysis of the simulation techniques for plague on biomodels. Materials and methods. Utilized were Y. pestis strains. Virulence was evaluated both, in vitro (polymerase chain reaction) and in vivo (LD50 for white mice). Results and conclusions. Set forward have been avirulent Y. pestis strains, prospective in terms of mastering biological method of laboratory diagnostics of plague, and means of their application for simulating plague in biomodels. The designed approach allows for exercising biological methods of plague investigation to the fullest extent, enhancing biological safety of practical studies and reducing the time line for isolation and accumulation of pure bacterial culture.