Infections In Laboratory Animals Research Articles

Mucosal Vaccines against Bacterial and Viral Pathogens

The mucosal membranes of the human body play a crucial role in the development, maintenance, and regulation of barrier functions and immune homeostasis, representing an integral component of the overall immune system. Mucosal vaccines elicit immune processes in the lymphoid tissue associated with the mucosal membranes. A critical objective of mucosal immunization is the identification of an antigen delivery vector capable of ensuring optimal vaccine efficacy. The authors of this article have conducted extensive research on the probiotic properties of enterococci over an extended period. They employ a safe and beneficial probiotic strain, Enterococcus faecium L3, as a delivery vector for vaccine antigens. Initially, the gene encoding the pathogenicity factor Bac, derived from group B streptococci (Streptococcus agalactiae), was successfully integrated into the genome of the probiotic strain E. faecium L3. Intravaginal, oral, and intranasal mucosal immunization methods utilizing the L3-Bac+ probiotic, which expresses antigenic determinants of pathogenic streptococci, were found to confer protection against bacterial infection in laboratory animals. Subsequently, recombinant technologies were refined, leading to the development of a universal method for incorporating a region of interest from the gene into the structure of the major pili protein gene of E. faecium L3. Using this technology, candidate vaccines against various infections, including Streptococcus pneumoniae, influenza A virus, and SARS-CoV-2 following the onset of the Covid-19 pandemic, have been obtained and tested. In this study, alongside the presentation of our own data, the challenges associated with utilizing recombinant probiotic bacteria as vectors for vaccine antigen delivery are discussed.

Pathogenicity of the SARS-CoV-2 Virus Variants of Concern for the Syrian Golden Hamster

The aim of the work was to study the pathogenicity of newly emerging variants of SARS-CoV-2 on the model of the Syrian golden hamster.Materials and methods. We used the strains of SARS-CoV-2 virus related to the VOC circulating in the territory of the Russian Federation. The experiments were carried out on outbreed Syrian hamsters obtained from the nursery of the SSC VB “Vector”. The infectious titer of coronavirus in tissue samples collected from infected laboratory animals was determined on a Vero E6 cell culture. The Ct in RT-PCR was considered an additional parameter for monitoring the viral load in the samples. The severity of lung tissue damage in Syrian hamsters with COVID-19 was assessed by histological preparations.Results and discussion. 50 % infecting doses in case of the intranasal infection have been determined, histological analysis of lung tissues performed. The pathogenicity of various variants of the SARS-CoV-2 virus for the Syrian hamster has been evaluated, differences in infecting doses and pathological changes in the lungs have been revealed. SARS-CoV-2 viruses belonging to Beta genetic variant have the highest virulence, while Alpha variant has the lowest one when comparing the studied strains by the ID50 value. The Delta and Omicron variants have a matched ability to cause specific damage to the tissues of the respiratory tract, while being inferior only to the Beta variant. It has been demonstrated that Syrian hamsters are an adequate model for assessing the pathogenicity of the SARS-CoV-2 virus variants of concern. Variants of SARS-CoV-2 virus during intranasal infection has shown different degree of pathogenicity in the Syrian hamster model.

An optimized visual loop mediated isothermal amplification assay for efficient detection of minute virus of mice with hydroxynaphthol blue dye

Minute virus of mice (MVM) is one of the most prevalent infectious agents in laboratory mouse colonies. In this study, we optimized a loop-mediated isothermal amplification (LAMP) assay using hydroxynaphthol blue (HNB) for rapid and visual detection of MVM. The reaction, which entailed addition of HNB dye prior to amplification, was performed in one step in a single tube at 62 °C for 45 min. The limit of detection of the assay was 104 copies, which was 100-fold lower than that of conventional PCR. The assay specifically amplified MVM DNA and did not cross-react with other viruses. To validate the established LAMP system, we applied it 287 samples and detected 19 positives. In conclusion, LAMP with HNB is a sensitive, and simple assay for rapid detection of MVM infections in laboratory animals, thus offers a platform for quality monitoring.

Why serology just is not enough: Strategic parvovirus risk assessment using a novel qPCR assay.

Health monitoring of laboratory rodents not only improves animal health but also enhances the validity of animal experiments. In particular, infections of laboratory animals with murine parvoviruses influence biomedical research data. Despite strict barrier housing, prevalence remains high in animal facilities, leading to increased risk of parvovirus introduction after the import of contaminated mice. Unfortunately, hygienic rederivation can be challenging, since gametes often contain residual virus material. Consequently, the process has to be closely monitored with highly sensitive diagnostic methods to verify parvovirus decontamination of the rederived progeny. However, diagnostic sensitivity of traditional methods is often low and requires testing of large animal cohorts. Therefore, we aimed to develop a powerful quantitative real-time polymerase chain reaction (qPCR) assay for the fast and reliable detection of murine parvoviruses in different sample materials. We validated the assay within an infection experiment and systematically analysed various animal-derived and environmental sample materials. We further developed a strategic risk assessment procedure for parvovirus monitoring after embryo transfer. Our novel qPCR assay reliably detected parvovirus DNA in a broad variety of sample materials, with environmental samples dominating in the acute phase of infection, whereas animal-derived samples were more suitable to detect low virus loads in the chronic phase. Here, the assay served as a highly sensitive screening method for parvovirus contamination in mouse colonies, requiring significantly lower sample sizes than traditional methods like conventional PCR and serology. Thus, the use of our novel qPCR assay substantially improves parvovirus diagnostics, enhancing research validity according to the 6Rs.

Pathogenicity of Bordetella bronchiseptica isolated from apparently healthy rabbits in guinea pig, rat, and mouse.

Bordetella bronchiseptica (B. bronchiseptica) is associated with respiratory tract infections in laboratory animals. In our laboratory animal facility, B. bronchiseptica was isolated from 21 of 27 apparently healthy rabbits obtained from a breeding farm contaminated with B. bronchiseptica. Restriction fragment length polymorphism (RFLP) analysis showed that the flagellin genotype of isolates from the laboratory animal facility and breeding farm was type A, which is seen relatively frequently in rabbits in Europe. To examine its pathogenicity, guinea pigs, rats, and mice were inoculated intranasally with a representative strain isolated in the laboratory animal facility. Following inoculation of 107 colony forming unit (cfu), severe inflammation was observed in the lungs of guinea pig and mice, although the inflammation was less severe in rats. The strain was recovered from the trachea and lungs of these species after inoculation with lower dose such as 103 or 104 cfu. These results suggest that the isolated strain causes respiratory tract infection in guinea pigs, rats, and mice, and that its pathogenicity higher in mice than in rats. This study extends our knowledge of interpreting the microbiologic status of laboratory animals, which will contribute to the development of reliable and reproducible animal experiments.

Experimental Hookworm Infection in Laboratory animals: Parasite behavior, Immune response and Chemotherapeutic Studies

Hookworm disease is known to be caused allergic manifestation and severe anemic pathogenicity in man and canine hosts. Attempts have been made to establish laboratory models of Necator americaus, Ancylostoma duodenale, and Ancylostoma ceylanicum, together with canine parasite, Ancylostoma caninum. The studies include pathophysiological aspects of the host-parasite relationship, and develop to establish patent infection. Immunological approach to selecting antigen for diagnosis and protective immunity purpose using larval and adult worm antigens and their secretions became the focus with the subsequent discovery of cloning in vaccine development as main research interest. Chemotherapy of newer drug screening in laboratory models ultimately selected to use for preventive chemotherapy in hookworm endemic areas using recommended drugs.

Effects of drug treatments on Worm burden and enzyme levels in Schistosoma haematobium infected laboratory Animals

This study was carried out to evaluate the effect of drug treatments and enzymes level on the worm burden in an experimental Schistosoma haematobium infected guinea pig. Eggs of S. haematobium were collected from the urine of infected persons and hatched into miracidia. Fresh water Snail species Bulinus truncatus were exposed to miracidia and allowed for five weeks to establish infection and develop to cercaria. Guinea pigs were exposed to S. haematobium cercaraie by subcutaneous injection. The infected guinea pigs were divided into four groups, designated as 7, 28, 90 days post infection and controls. The guinea pigs were treated singly and in combination with different doses of Praziquantel (PZQ), Artemether (ART) and Artequine (ARQ). The efficacy of the different drugs on worm burden were assessed. Blood samples were collected from the guinea pigs before and after treatment for determination of Alkaline Phosphatase (ALP), Alanine Aminotransferase (ALT) and Aspartate Aminotransferase (AST). Result showed that treatment with higher doses of PZQ/ART (100/200mg/kg) and PZQ/ARQ (100/200mg/kg) resulted in total worm reduction rate of 58 and a percentage efficacy of 98.3%. ARQ (300 mg/kg) had the highest percentage efficacy of 89.8% amongst the single drugs used with respect to higher doses. There were observed alteration in the levels of the enzymes after S. haematobium infection. The serum level of ALP, AST and ALT after infection generally decreased. There were various activities in the level of ALPAST and ALT after treatment with different drug regimen at different stages of S. haematobium infection. ARQ alone and in combination with PZQ had anti schistosomal effect and could be promising in controlling schistosomiasis.
 Keywords: S. haematobium, Guinea Pigs, Liver functioning enzymes, Worm burden

Distribution and main biological properties of Pseudomonas Aeruginosa isolates in pig farms of Krasnodar region

Bacteria of the genus Pseudomonas aeruginosa are widespread microorganisms in pig breeding enterprises of the region, and due to virulent factors and pathogenic properties, in the etiological aspect, it poses a significant threat to the body of various sex and age groups of pigs. In the form of a monoculture, Pseudomonas aeruginosa was isolated in 14.7% of cases, in association with other microorganisms - in 85.2%, and the highest proportion of Pseudomonas aeruginosa was manifested in association with Escherichia coli (47.8%), microorganisms that cause the clinic of gastrointestinal diseases in piglets during suckling and weaning periods. A feature of the epizootic manifestation of pseudomonosis in pigs in the conditions of industrial pig breeding is enzootic outbreaks. In 79.9% of cases, growth is accompanied by the formation of a water-soluble pigment of the phenotazine series pyocyanin on selective nutrient media in isolate colonies, in 80-83 % of cases, on MPA with 5 % defibrinated blood, Pseudomonas aeruginosa colonies cause hemolysis zones. Biochemical activity of P. aeruginosa cultures showed low-expressed biochemical properties, they assimilated glucose and arabinose, galactose to the formation of acid, decomposed urea, had proteolytic properties, liquefied gelatin and peptonized milk for 72 hours, showed phosphatous activity, did not form indole and H2S, cultures producing exotoxin A, with intraperitoneal infection of laboratory animals show maximum toxigenic properties. Pseudomonas aeruginosa isolates exhibit plasma-coagulating and agesive activity. The obtained results of studying the main biological properties of P. aeruginosa isolates can be used for diagnostic studies and anti-epizootic measures in the region.

Professor V.A. Waldman and his family: a contribution to Russian medicine

Outstanding representatives of the St. Petersburg medical dynasty from the Waldman family: V.A. Waldman, his son A.V. Waldman and sister A.A. Waldman made a huge contribution to the health care of our country. The founder and first head of the department of faculty therapy at the Leningrad State Pediatric Medical Institute, Viktor A. Waldman, is an outstanding therapist, cardiologist, rheumatologist, classic of domestic medicine, a successor to the best traditions of the Botkin school. Cardiovascular pathology was studied clinically and experimentally by him and his staff, the pathogenesis of various forms of rheumatism was studied, methods for its diagnosis and treatment were developed. He did a great job of creating the rheumatological service of the city, for the first time founded in Leningrad cardiac rheumatology rooms at large enterprises, and later on a cardiac rheumatology clinic. Arthur V. Waldman son of V.A. Waldman, a prominent pharmacologist, head of the department of pharmacology of the 1st Leningrad Medical Institute named after academician I.P. Pavlov, academician of the Academy of Medical Sciences of the USSR made a significant contribution to the study of the mechanism of action of various pharmacological substances on synaptic transmission of excitation in the central nervous system. A large series of works by A.V. Waldman is devoted to the pharmacology of emotional stress, the problem of the experimental study of emotions and means of controlling them. Alisa A. Valdman sister of V.A. Waldman, a pathologist, an employee of the All-Union Institute of Experimental Medicine, studied the role of nervous and hormonal regulation in the development of the infectious process, which she studied on a paratyphoid model for enteric infection in laboratory animals.

Behavioural effects of the common brain-infecting parasite Pseudoloma neurophilia in laboratory zebrafish (Danio rerio)

Research conducted on model organisms may be biased due to undetected pathogen infections. Recently, screening studies discovered high prevalence of the microsporidium Pseudoloma neurophilia in zebrafish (Danio rerio) facilities. This spore-forming unicellular parasite aggregates in brain regions associated with motor function and anxiety, and despite its high occurrence little is known about how sub-clinical infection affects behaviour. Here, we assessed how P. neurophilia infection alters the zebrafish´s response to four commonly used neurobehavioral tests, namely: mirror biting, open field, light/dark preference and social preference, used to quantify aggression, exploration, anxiety, and sociability. Although sociability and aggression remained unaltered, infected hosts exhibited reduced activity, elevated rates of freezing behaviour, and sex-specific effects on exploration. These results indicate that caution is warranted in the interpretation of zebrafish behaviour, particularly since in most cases infection status is unknown. This highlights the importance of comprehensive monitoring procedures to detect sub-clinical infections in laboratory animals.

Molecular identification and subtyping of Blastocystis sp. in laboratory rats in China.

Blastocystis sp. is a ubiquitous protist that has been frequently reported in humans and animals worldwide. A total of 355 fecal samples of experimental rats were collected from four laboratory rearing facilities in China, and Blastocystis sp. was detected by PCR amplification of the partial small subunit ribosomal (SSU) rRNA gene. Twenty-nine (8.2%, 29/355) samples were positive for Blastocystis sp., with the highest infection rate (20.7%, 24/116) in rats of the Zhengzhou1, followed by that in the Zhengzhou2 (5.0%, 2/40), Shenyang (3.0%, 3/100) and Wuhan (0) rearing facilities. Among the three rat strains, Sprague–Dawley (SD) rats had higher infection rates (11.3%, 17/151) compared to Wistar rats (8.7%, 9/104) and spontaneously hypertensive (SH) rats (3.0%, 3/100). Two Blastocystis sp. subtypes (ST4 and ST7) were identified. ST4 was the predominant subtype detected in 26 samples (89.7%). A phylogenetic analysis demonstrated that the sequences of ST4 and ST7 obtained in this study were clustered with their reference subtypes. To our knowledge, this is the first report of Blastocystis sp. in experimental rats in China. Pathogen infections in laboratory animals need to be monitored due to fecal-oral transmission.

Cryptosporidium Oocyst Purification Using Discontinuous Gradient Centrifugation.

Many laboratory studies in cryptosporidial research require a source of purified oocysts. Sources can include experimentally infected laboratory animals or from samples collected from naturally infected animals and from clinical cases of human cryptosporidiosis. Purification of oocysts can be accomplished with readily available laboratory equipment including tabletop centrifuges and microcentrifuges. Following purification, oocysts can be stored in antibiotic-supplemented buffers or in 2.5% aqueous potassium dichromate for over 6months. Ultimately, oocyst viability and infectivity decline to less than 10% after 1year, so if isolates are expected to be maintained, serial passage in a suitable host at ≤6-month intervals is recommended. Oocysts purified as described in this chapter are suitable for animal infection studies, cell culture studies, and a wide range of molecular biological studies, environmental studies, drug testing, and disinfection studies.

Evaluation of Acha (Digitaria exilis) Grain Fermented with Lactobacillus Species as a Probiotic Food

Aims: This study assess the effect of the fermented Acha samples in-vivo using apparently healthy and infected laboratory animals.
 Study Design: Acha was fermented in two forms (Local fermentation and controlled fermentation).
 Place and Duration of Study: Sample: Department of Medicine (Medical Unit IV) and Department of Radiology, Services Institute of Medical Sciences (SIMS), Services Hospital Lahore, between June 2009 and July 2010.
 Methodology: Acha was weighed into a fermenting container of 100 g and water of 1 litre was added to submerge it for 72 hours in the ratio 1:3. Microbial, proximate and mineral analysis was carried on all the samples. For 21 days, all fermented samples were used to feed rats infected with Escherichia coli and Shigella dysenteriae except for the control for in vivo study and evaluated for their probiotic potential. Also, hematological study and histopathology analysis were carried out on the small and large intestine of the Albino rats that was fed with the fermented samples. The various fermented samples were freeze dried to retain the organisms used for the fermentation.
 Results: Haematological study (PCV, WBC, RBC, Platelets, haemoglobin and differential leucocytes) and histopathology analysis (small intestine and large intestine) of rats from all experimental groups showed that Acha fermented with Lactobacillus acidophilus was able to rebuild shrinked and ruptured cells on the mucosal lining of the walls of the intestines.
 Conclusion: Acha fermented with Lactobacillus acidophilus was observed to have the best results on the weight of rats, white blood cell count, red blood cell count and probiotic effect on the intestine of the rats fed with it.

Inferring within-host bottleneck size: A Bayesian approach

Recent technical developments in microbiology have led to new discoveries on the within-host dynamics of bacterial infections in laboratory animals. In particular, they have highlighted the importance of stochastic bottlenecks at the onset of invasive disease.A number of approaches exist for bottleneck-size estimation with respect to within-host bacterial infections; however, some are more appropriate than others under certain circumstances. A Bayesian comparison of several approaches is made in terms of the availability of isogenic multitype bacteria (e.g., WITS), knowledge of post-bottleneck dynamics, and the suitability of dilution with monotype bacteria. A sampling approach to bottleneck-size estimation is also introduced.The results are summarised by a guiding flowchart, which we hope will promote the use of quantitative models in microbiology to refine the analysis of animal experiment data.

In vitro infectivity and differential gene expression of Leishmania infantum metacyclic promastigotes: negative selection with peanut agglutinin in culture versus isolation from the stomodeal valve of Phlebotomus perniciosus.

BackgroundLeishmania infantum is the protozoan parasite responsible for zoonotic visceral leishmaniasis in the Mediterranean basin. A recent outbreak in humans has been reported in this area. The life cycle of the parasite is digenetic. The promastigote stage develops within the gut of phlebotomine sand flies, whereas amastigotes survive and multiply within phagolysosomes of mammalian host phagocytes. The major vector of L. infantum in Spain is Phlebotomus perniciosus. The axenic culture model of promastigotes is generally used because it is able to mimic the conditions of the natural environment (i.e. the sand fly vector gut). However, infectivity decreases with culture passages and infection of laboratory animals is frequently required. Enrichment of the stationary phase population in highly infective metacyclic promastigotes is achieved by negative selection with peanut agglutinin (PNA), which is possible only in certain Leishmania species such as L. major and L. infantum. In this study, in vitro infectivity and differential gene expression of cultured PNA-negative promastigotes (Pro-PNA−) and metacyclic promastigotes isolated from the sand fly anterior thoracic midgut (Pro-Pper) have been compared.ResultsIn vitro infectivity is about 30 % higher in terms of rate of infected cells and number of amastigotes per infected cell in Pro-Pper than in Pro-PNA−. This finding is in agreement with up-regulation of a leishmanolysin gene (gp63) and genes involved in biosynthesis of glycosylinositolphospholipids (GIPL), lipophosphoglycan (LPG) and proteophosphoglycan (PPG) in Pro-Pper. In addition, differences between Pro-Pper and Pro-PNA− in genes involved in important cellular processes (e.g. signaling and regulation of gene expression) have been found.ConclusionsPro-Pper are significantly more infective than peanut lectin non-agglutinating ones. Therefore, negative selection with PNA is an appropriate method for isolating metacyclic promastigotes in stationary phase of axenic culture but it does not allow reaching the in vitro infectivity levels of Pro-Pper. Indeed, GIPL, LPG and PPG biosynthetic genes together with a gp63 gene are up-regulated in Pro-Pper and interestingly, the correlation coefficient between both transcriptomes in terms of transcript abundance is R2 = 0.68. This means that the correlation is sufficiently high to consider that both samples are physiologically comparable (i.e. the experiment was correctly designed and performed) and sufficiently low to conclude that important differences in transcript abundance have been found. Therefore, the implications of axenic culture should be evaluated case-by-case in each experimental design even when the stationary phase population in culture is enriched in metacyclic promastigotes by negative selection with PNA.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2672-8) contains supplementary material, which is available to authorized users.

Saposin-like Proteins, a Multigene Family of Schistosoma Species, are Biomarkers for the Immunodiagnosis of Schistosomiasis Japonica.

One major obstacle to schistosomiasis prevention and control is the lack of accurate and sensitive diagnostic approaches, which are essential for planning, targeting, and evaluating disease control efforts. Based on bioinformatics analysis, we identified a multigene family of saposin-like protein (SAPLP) in the schistosome genomes. Schistosoma japonicum SAPLPs (SjSAPLPs), including recently reported promising biomarker SjSP-13, were systematically and comparatively assessed as immunodiagnostic antigens for schistosomiasis japonica. Two novel antigens (SjSAPLP4 and SjSAPLP5) could specifically react to serum samples from both S. japonicum-infected laboratory animals and patients. The sensitivities of SjSAPLP4, SjSAPLP5, and SjSP-13 for immunodiagnosis were 98% (95% confidence interval, 88.0%-99.9%), 96% (85.1%-99.3%), and 88% (75.0%-95.0%), respectively, and 100% (91.1%-100%) specificity was observed for the 3 antigens with enzyme-linked immunosorbent assay; there was no cross-reaction with clonorchiosis (0 of 19 patients), echinococcosis (0 of 20 patients), or trichinellosis (0 of 18 patients) for the 3 antigens. Antibodies to the 3 antigens could be detected in the serum samples of rabbits infected with 1000 cercariae as early as 3-4 weeks after infection. These results suggest that SjSAPLP4 and SjSAPLP5 could serve as novel biomarkers for the immunodiagnosis of schistosomiasis japonica, which will further improve diagnostic sensitivity and specificity.

An LPS based method to stimulate the inflammatory response in growing rabbits

<p>Reliable indicators are needed to study the relationship between the inflammatory response of the growing rabbit and breeding factors such as feeding practices. A lipopolysaccharide (LPS) stimulation of the inflammatory response is a valid model of bacterial infection in laboratory animals, but no data on the growing rabbit has yet been obtained. The aim of our study was to determine an adequate dose of LPS to inject in growing rabbits in order to elicit a measurable inflammatory response in terms of plasmatic TNF-α and rise in rectal temperature. Three trials were carried out in this study: 2 development trials, the first (n=18) testing 3 doses of LPS (2, 10, 50 μg/kg) on the plasmatic TNF-α concentration at 90 and 180 min post injection, and the second trial (n=36) testing 4 doses of LPS (50, 75, 100 and 150 μg/kg) on the TNF-α concentration 90 min post injection and the rectal temperature. The third trial was designed as an application of the method in a large number of animals (n=32) to study the effect of feed restriction and dietary increase in digestible fibre to starch ratio on the LPS inflammatory challenge response of growing rabbits. In development trials 1 and 2, animals had measurable TNF-α responses for doses higher than 10 μg/kg at 90 min post injection, with an increase in the number of responsive animals along with the dose. High variability was observed in TNF-α concentrations in responsive animals (coefficient of variation from 44 to 94%). Animals demonstrated an increase in rectal temperature for all doses injected in the range of 50-150 μg/kg from 90 min post injection with a peak at 180 min (Δ<sub>Tr </sub>=1.9±0.7°C). Our observations led us to choose a dose of 100 μg/kg of LPS for our following studies, as the responses in terms of temperature and TNF-α were the most satisfactory. The application of our LPS injection protocol to our nutritional study enabled us to validate our protocol (Δ<sub>Tr </sub>=1.1±0.7°C at 180 min and 15/32 TNF-α responsive animals) even though we were not able to demonstrate any effect of the feeding level or diet on the inflammatory response to an LPS injection.</p><p> </p>

Simulation of Viral Hepatitis E in Marmosets.

We developed a model of hepatitis E virus infection in common marmosets (Callithrix jacchus) and determined optimal route of infection, duration, clinical and virological characteristics of infection in laboratory animals. Using this model, we demonstrated that replication of hepatitis E virus primarily occurs in the liver, while virus replication presumed to take place in the intestine was not confirmed in this experiment.

Genome Sequence of Porphyromonas gingivalis Strain AJW4.

Porphyromonas gingivalis is associated with oral and systemic diseases. Strain-specific P. gingivalis invasion phenotypes have been correlated with disease presentation in infected laboratory animals. Here, we present the genome sequence of AJW4, a minimally invasive strain, with a single contig of 2,372,492 bp and a G+C content of 48.27%.

Aging and respiratory infections in laboratory animals

Respiratory infections are known as one of significant causes of death in old human as well as aged laboratory animals. However, there is not strong evidence of increase of spontaneous pneumonias incidence in aged rats and mice. Moreover, numerous experimental investigations with different respiratory pathogens did not elucidate clear age-related changes of infection susceptibility even for one and same disease agent yet. It is paradoxical that decline of lung infection mortality of aged animals in compare to young animals was found in some observations. Respectively, investigations of innate and adoptive immunity role in pathogenesis of respiratory infections in old laboratory animals also produced undetermined results. It is probable that such situation is not only related to complex character of age-associated changes in respiratory system, but also to absence of conventional and adequate models for research of the problem.