Experience in using P. hamadryas for assessing the effectiveness of a peroral vaccination method against plague]

For the first time P. hamadryas were used for studying the effectiveness of oral immunization with dried live plague vaccine. Oral immunization was shown to produce morphological changes in the organs and tissues of the monkeys, which indicated the immune transformation of the organism. The challenge of the immunized animals with the infective agent introduced in aerosol showed the effectiveness of the inhalation and oral methods of immunization. P. hamadryas proved to be a suitable model for the evaluation of the effectiveness of oral vaccination. A more precise quantitative evaluation of the effectiveness of oral vaccination against plague requires further research.     

Assessment of the effectiveness of different methoods of immunization with live plague vaccine EB in aerosol infections]

The work deals with the results of the comparative evaluation of the effectiveness of vaccines developed at the Sanitary Research Institute (Zagorsk) and the Mechnikov Research Institute for Vaccines and Sera (Moscow), as well as two methods of immunization against plague, by inhalation and subcutaneous injection, under the conditions of aerosol infection. The immunogenic effectiveness of both vaccines, when evaluated in terms of LD50, was shown to be approximately the same, but the animals immunized by the inhalation method with the vaccine developed at the Sanitary Research Institute proved to be less susceptible to infection than those immunized with the vaccine developed at the Mechnikov Research Institute for Vaccines and Sera in Moscow. After immunization by the inhalation method the vaccine developed at the Sanitary Research Institute rendered more effective protection (3- to 4-fold) against aerosol infection than after immunization by subcutaneous injection. The animals immunized by the inhalation method proved to be capable of surviving plague in the primary pneumonic form.     

Results of basic and applied investigations on oral immunization against smallpox

The results of fundamental and applied investigations on the development and trial of the oral administration of smallpox vaccine and live recombinant smallpox-hepatitis vaccine (Revax VT) in tablets are summarized. In comparative experiments on animals (rabbits, monkeys and guinea pigs) and human immunization the oral smallpox vaccine in tablets was shown to ensure equal effectiveness and greater safety in comparison with traditional smallpox vaccine for skin application. The study confirmed the natural and physiological character of oral immunization as a result of direct contact of immunogen with the mucous membrane of the digestive tract--an essential immunocompetent organ of the lymphoid system. The conclusion was made that oral immunization was the safe and most promising method of immunization against smallpox under modern conditions.     

Biological activity of the components of F1-antigen of Yersinia pestis

Components of the capsule antigen (Baker), described early as F17, F18, F43, Flp, which positively reacts with commercial poly- and monoclonal antifractions plague diagnosticums were studied. Differences and their impacts on vaccine bacteria survival within peritoneal macrophages, guinea pigs and protection of white mice after immunization and fast protection against plague were shown. Hemolytic, cytolytic and hemo- and cytoagglutinations activities of lipoprotein (Flp) and capacity of glycoproteins F17 and F43 for induction of hemo- and cytoagglutinations were detected. Similarity of properties of enumerated components and lectins and their role in infection development and immunogenesis are discussed.     

猪传染性胃肠炎病毒基因工程疫苗研究进展

猪传染性胃肠炎是由猪传染性胃肠炎病毒(TGEV)引起猪的一种高度接触性肠道疾病,可导致仔猪发生严重的呕吐、腹泻与脱水,死亡率可达100%。口服疫苗是TGEV基因工程疫苗研究的主要方向,目前已在腺病毒、细菌、转基因植物及DNA疫苗中对TGEV的S基因进行了表达,并对其口服免疫后的免疫原性进行研究。现针对TGEV基因工程疫苗近年来研究的概况进行综述,分析其优点与不足,并对其未来的发展进行展望。     

Investigations on the efficacy of monovalent Pseudomonas aeruginosa vaccine for oral administration in Pseudomonas aeruginosa experimental infection

Therapeutic efficacy of Pseudomonas aeruginosa vaccine for oral use (10(10) killed germs/ml), prepared from strain 4922, belonging to serotype XV, by Meitert-Meitert scheme, on 4 experimental models in mice (pneumonia, infected burn, septicaemia and urinary tract infection) was studied in comparison with monovalent Ps. aeruginosa vaccine serotype XV (10(9) killed germs/ml) for subcutaneous use and also with associated administration of the two vaccine variants. Mice immunization by using vaccine for oral use was performed by 0.5 ml vaccine per day, for 10 days and vaccine for subcutaneous use was administrated in a volume of 0.5 ml x 2, at 3 days interval. Mice immunization by using the two vaccine types, in association was concomitantly performed and in the same quantity as for separate immunization. In experimental pneumonia, Ps. aeruginosa vaccine for oral use protected mice in 35% of cases, those with infected burns were protected in 33.3% of cases, those with septicemia--in 96.6% of cases and those with urinary tract infection in 50% of cases. As compared to Ps. aeruginosa vaccine for subcutaneous use, the results obtained by vaccine for oral use are less favourable but associated administration of both vaccine variants led to superior results. Thus, in experimental pneumonia, it was obtained a surviving rate of 65% for animals immunized with both vaccine types, in comparison with 50% for animals immunized with vaccine for subcutaneous use only, and in Ps. aeruginosa infected burn, it was obtained a recovering rate of 79.1% for the animals immunized by using both vaccines, in comparison with 70.8% surviving for animals immunized with vaccine for subcutaneous use. In experimental septicaemia and urinary tract infection, combined use of both vaccine variants determined animals surviving and recovering in percents similar to those obtained by separate administration of vaccine for subcutaneous use (in septicemia--100% protection; in urinary tract infection--75% protection).     

鼠疫F1抗原和V抗原双组分候选疫苗的免疫学评价

目的通过由提取的鼠疫F1抗原和重组鼠疫V(rV)抗原组成的鼠疫候选疫苗免疫豚鼠,对其免疫效果进行评价。方法将豚鼠随机分成5个试验组,在免疫后不同时间点采血进行抗体检测、MTT法淋巴细胞增殖试验以及皮肤迟发型超敏反应(DTH)检测。结果抗体检测结果显示,双组分鼠疫候选疫苗能诱导较强的体液免疫应答;MTT细胞增殖结果显示,脾脏淋巴细胞特异性增殖不明显;中剂量组、高剂量组针对F1和rV抗原DTH阳转率均为100%。结论双组分鼠疫候选疫苗能诱导豚鼠体液免疫和细胞免疫应答,该疫苗有希望成为我国新一代鼠疫疫苗。     

Isotypic characteristics of serum and secretory O antibodies and local immunological memory in the parenteral immunization of guinea pigs with a ribosomal Shigella vaccine

Guinea pigs were immunized subcutaneously with ribosomal vaccine prepared from S. sonnei and their systemic and local humoral response was studied by means of ELISA techniques with the use of monospecific antisera to guinea pig IgA and IgG. Injection of the ribosomal vaccine leads to a significant rise in the levels of IgA O-antibodies in tears, IgG and IgA O-antibodies in the serum. The presence of IgA O-antibodies in tears was seemingly the result of their local synthesis rather than the seepage of serum IgA. The stimulation of the local and systemic anti-O response was more pronounced after parenteral immunization with the ribosomal vaccine than after immunization with the corresponding dose of lipopolysaccharide (LPS). Parenteral immunization with the ribosomal vaccine induced the development of both systemic and local memory. The priming effect produced by relatively small doses of this vaccine (40 micrograms), administered parenterally, was similar to the effect of prolonged and intensive stimulation ensured by 10-day feeding with LPS (the total dose being 5,000 micrograms).     

Use of the RSP-1M device in practice for the aerosol immunization of humans with dry plague vaccine]

Creating high concentrations of dry vaccine aerosols, RSP-1M pulverizer provides aspiration doses adequate for effective immunization against plague. Aerosol of dry plague vaccine obtained with the aid of RSP-1M was polydispersive; this provides distribution of the preparation along the whole respiratory tract (in man) and its low reactogenic properties.     

Prevention of bubonic and pneumonic plague using plant-derived vaccines

Yersinia pestis, the causative agent of bubonic and pneumonic plague, is an extremely virulent bacterium but there are currently no approved vaccines for protection against this organism. Plants represent an economical and safer alternative to fermentation-based expression systems for the production of therapeutic proteins. The recombinant plague vaccine candidates produced in plants are based on the two most immunogenic antigens of Y. pestis: the fraction-1 capsular antigen (F1) and the low calcium response virulent antigen (V) either in combination or as a fusion protein (F1–V). These antigens have been expressed in plants using all three known possible strategies: nuclear transformation, chloroplast transformation and plant-virus-based expression vectors. These plant-derived plague vaccine candidates were successfully tested in animal models using parenteral, oral, or prime/boost immunization regimens. This review focuses on the recent research accomplishments towards the development of safe and effective pneumonic and bubonic plague vaccines using plants as bioreactors.     

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.     

Immunogenicity of B-antigen in experimental plague and pseudotuberculosis

The results of the evaluation of the immunogenic properties of B-antigen, earlier identified in the culture fluid of Yersinia pseudotuberculosis submerged culture, with respect to experimental plague and pseudotuberculosis are presented. B-antigen has been shown to produce protective effect in guinea pigs and, probably, hamadryas baboons, but not in white mice infected with the causative agent of plague. Immunizaton with B-antigen protects guinea pigs from primary pneumonic plague caused by both capsule-forming and noncapsular Y. pestis virulent strains. Passive immunization with antibodies to B-antigen induces limitedly pronounced protective effect in guinea pigs and is not effective for white mice with respect to experimental plague. No active or passive protection of white mice or guinea pigs, infected with Y. pseudotuberculosis cultures, has been achieved by the injection of B-antigen or antibodies to it.     

Experimental study on the possibility of using live tularemia vaccine to increase resistance to heterologous infection disease

In experiments on guinea pigs immunized with Francisella tularensis 15, or live tularemia vaccine (LTV), the level of heterologous protective effect to dangerous infectious diseases caused by Yersinia pestis, Burkholderia pseudomallei, B. mallei, Mycobacterium tuberculosis was studied. The study revealed that during the first 4 weeks after the subcutaneous immunization with LTV the level of resistance of the immunized animals to heterologous infective agent reliably increased as indicated by the survival rate of the animals, as well as by the survival time of those killed by infection, in comparison with the controls. Later (on day 150 after immunization) differences in death rate between the groups perceptibly decreased. Nevertheless, the 1 1/2-fold increase of the survival time of the challenged immunized animals in comparison with the controls proved the possibility of using immunization with LTV for the urgent prophylaxis and treatment not only of tularemia, but also of plague, glanders, melioidosis and tuberculosis.     

The effect of the immunization of animals with a live plague vaccine on the lysosome count in organ-specific macrophages

Vital fluorochromatic lysosomes of peritoneal, liver, splenic and lung macrophages of white mice, white rates, and guinea-pigs are studied. Reliable differences in a quantity of lysosomal granules of macrophages from various tissues as well as differences between macrophages from the same tissues of different experimental animals are found. At 21 days after animal immunization with live plague vaccine EV the most significant changes in the number of lysosomal granules are revealed in white mice. The number of lysosomes in guinea pigs increased in 1 and 7 days after vaccination, in 14 days their number became normal.     

基于rV270抗原的鼠疫多孔微球疫苗的制备及其免疫保护作用评价

目的：评价生物可降解高分子材料多孔微球作为鼠疫亚单位疫苗佐剂的可行性。方法：制备可生物降解的高分子材料多孔微球,将rV270抗原蛋白吸附到多孔微球中制备微球疫苗,肌肉注射免疫BALB/c小鼠,初次免疫后21d加强免疫1次,于初次免疫后第10周用600LD50鼠疫耶尔森氏菌攻毒,攻毒后观察14d。结果：攻毒后,微球疫苗免疫的小鼠全部存活,且健康状况良好,对照组小鼠几乎全部死亡。结论：生物可降解多孔微球可作为免疫佐剂用于鼠疫亚单位疫苗研制。     

A new rabies vaccine in public health practice in the USSR

A new antirabies vaccine prepared on the basis of virus grown in the ovine brain, purified from 85-90% of brain-tissue ballast substances and inactivated with beta-propilactone has been developed at the Moscow Research Institute of Viral preparations (USSR Acad. Med. Sci.). The preparation produces no neuro-allergenic effect in tests on guinea pigs. When injected to humans, the vaccine shows much lower reactogenicity than Fermi vaccine. High antigenic and immunogenic activity of the new vaccine has made it possible to work out a less intensive immunization schedule in comparison with that used for immunization with Fermi vaccine and nonconcentrated tissue-culture vaccine, viz. doses of 3 ml for 12 days or doses of 3 ml for 20 days with two booster immunizations. The preparation has been introduced into medical practice.     

Oral immunisation of wild boar against classical swine fever: uptake studies of new baits and investigations on the stability of lyophilised C-strain vaccine

The aim of this study was to investigate the uptake of new spherical and cuboid baits by wild boar and domestic pigs and to evaluate the stability of lyophilised C-strain vaccine stored at different environmental temperatures. New baits were designed to improve the consumption of the vaccine against classical swine fever by young wild boar. Our uptake studies showed that neither wild boar nor domestic pigs at the age of 2 months picked up the baits at all. Although the animals began to pick up the baits incompletely at the age of 3 months, a complete uptake of both the new baits and the older ones was only observed from the age of 4 (domestic pigs) and 4.5 (wild boar) months on. Nevertheless, the larger spherical baits with a diameter of 3 cm were taken up more effectively than the recent vaccine baits. As expected, lyophilised vaccine showed a higher stability than liquid vaccine, especially at temperatures ≥24°C. Independently of the stabiliser (GS4 or TSM) used, there are no differences between the virus titres detected within a storage period of 7 days. As the lyophilised C-strain vaccine was more stable at higher temperatures than the liquid vaccine formulation, we recommend to use lyophilised vaccine for oral immunisation of wild boar in the future, as oral vaccination is also carried out in the summertime.     

Evaluation of the vaccinal process in skin-scarification and oral immunization of rabbits with live smallpox vaccines

On the basis of comparative experimental evaluation of specific features in the course of the vaccinal process after the immunization of laboratory animals with live smallpox vaccines, intended for oral use (in tablets) and for skin scarification was proposed. In experiments on rabbits, made with the use of virological and immunological methods, the counteraction of the elements constituting the vaccinal process was analyzed, the integral evaluation of its course was given, the greater safety of the oral preparation in comparison with the traditional vaccine for immunization by skin-scarification method were established. The conclusion was made that oral immunization was the safest immunization method under modern conditions and promising one for using live vaccines with population immunity being at a low level or absent.     

Stability of the immunogenic properties of plague vaccine strain EV, Research Institute of Epidemiology and Hygiene line, during long-term storage]

The experiments in guinea pigs showed that the immunogenic properties of plague vaccine strain EV, line NIIEG, freeze-dried in 1947 and stored under vacuum without animalization, remained unchanged for 30 years. The subcultures prepared from this train showed, after three passages in guinea pigs, good immunogenic properties which preserved for 6--10 years (the term of observation). After 30-years storage the stock culture of strain EV, line NIIEG, can be used for the preparation of NIIS live plague vaccine.     

Immunogenicity of Plague Vaccines in Mice and Guinea Pigs

The median effective doses (ED₅₀) of 28 lots of killed Pasteurella pestis strain 195/P vaccine were determined in mice and guinea pigs. Mice were injected with vaccine alone, whereas guinea pigs received vaccine suspended in incomplete Freund's adjuvant. Potency ratios of vaccines were obtained by comparing the ED₅₀ of the test with that of a reference vaccine. Mean potency ratios of 1.82 ± 0.50 in mice and 3.22 ± 0.56 in guinea pigs were obtained, and the difference between these means was significant, P = <0.01. The number of organisms in the challenge dose did not significantly affect the ED₅₀ of a vaccine in guinea pigs. However, irrespective of vaccinating route, nearly 1,000 times as much vaccine was required in the absence of adjuvant as in its presence to produce comparable protective indexes in the guinea pig. The response of guinea pigs did not offer any improvement over mice in evaluating the efficacy of plague vaccines.