Effect of Activated Immunocompetent Cells on the Content of Multipotent Stromal Cells in Splenic Transplants of CBA and CBA/N Mice Administered with Polyvinylpyrrolidone.

One day after intraperitoneal injection of polyvinylpyrrolidone (PVP) to recipient CBA and CBA/N mice, the count of multipotent stromal cells (MSC) in the 4-month-old splenic transplants was minimum in CBA/N→CBA/N group in comparison with the transplants of intact recipients (0.6 from the control level), but increased by 2.3, 3.2, and 3.7 times in CBA/N→CBA, CBA→CBA, and CBA→CBA/N groups, respectively. In the blood serum of recipient CBA/N mice with 4-month splenic transplants of CBA donors, the levels of some cytokines (IL-5, TNFα, and IL-2) was significantly increased 1 and 24 h after PVP injection in contrast to mice with bone marrow transplants, which attests to activation of the innate immunity mechanisms in this (splenic) transplantation variant. Probably, this phenomenon can be explained by the fact that the splenic transplants contain a sufficient number of CD+B-1a lymphocytes that can restore the response of recipient CBA/N mice to PVP. Thus, similar to bone marrow transplants [5], MSC count in splenic transplants increased only in groups, where the recipients were capable of responding to PVP. In other words, after injection of PVP to recipient mice, MSC counts in the spleen and bone marrow at this moment are determined by availability of activated immunocompetent cells. Overall, the novel data attest to close relationships between the stromal tissue of hematopoietic and lymphoid organs, on the one hand, and immune system, on the other.

Combined Administration of TLR4 (LPS) and TLR3 (Poly I:C) Ligands to CBA Mice Elevates the Content of Osteogenic MSC by 1.6 Times and Increases Content of Bone Marrow MSC to Intermediate Level between Values Attained by Their Individual Administration.

In 1 and 24 h after combined administration of TLR4 (LPS) and TLR3 (Poly I:C) ligands to CBA mice, the content of MSC in bone marrow increased to intermediate value between the levels attained by their individual injections. The content of osteogenic MSC assessed in 24 h postinjection corresponded to the control level in Poly I:C group, decreased in LPS group by 2.5 times relatively to the control, and increased by 1.6 times (relatively to control) after combined administration of the ligands. In 3 h after combined addition of LPS and Poly I:C in vitro to 12-day-old primary culture of mouse bone marrow stromal cells, the concentration of TNFα in culture medium was intermediate between the levels attained by their individual application. The data revealed dependence of activation of stromal tissue on intensity of innate immunity reactions; they also attested to marked elevation of osteogenicity of MSC pool after costimulation with Poly I:C and LPS, which can underlie augmented calcification of the tissues during combined viral and bacterial infections.

Ligands of NOD2 (Muramyl Dipeptide) and TLR4 (LPS) in 24 h after Combined In Vivo Administration Produce a Synergistic Increase in the Content of Multipotent Stromal Cells in the Bone Marrow and Peritoneal Exudate of CBA Mice.

In 24 h after combined administration of ligands of NOD2 (muramyl dipeptide) and TLR4 (LPS) receptors to CBA mice, a synergistic increase (by 10 times compared to the intact control) in cloning efficiency and content of multipotent stromal cells was observed in the bone marrow in comparison with the total effects of their individual administration (by 2.1 and 4.1 times, respectively). A similar effect was also observed in the peritoneal exudate. When ligands were administered simultaneously, the concentration of osteogenic multipotent stromal cells in the bone marrow decreased to a greater extent than in case of individual injections of the ligands, but did not drop below 7% of the control, which is apparently indicative of a decline threshold. In 3 h after simultaneous addition of the ligands in vitro to 12-day primary cultures of mouse bone marrow stromal cells, a synergistic increase in TNFα concentration was observed (32-fold increase from the level of intact control), while IL-10 concentration did not differ from the control, which is indicative of the proinflammatory nature of the process and the absence of immunosuppressive effect. These results suggest that activation of the stromal tissue depends on the intensity of innate immunity reactions.

Effect of Activated Immunocompetent Cells on the Number of Multipotent Stromal Cells in Bone Marrow Transplants of CBA and CBA/N Mice in a Short Time after Polyvinylpyrrolidone Administration to Animals.

One hour after polyvinylpyrrolidone administration, the content of multipotent stromal cells in the spleen of CBA and CBA/N mice increased almost equally (by 2.5 and 2.9 times, respectively), but in 24 h, the effectiveness of multipotent stromal cell cloning in the spleen of CBA/N mice decreased almost to the control level, whereas in CBA mice, the number of multipotent stromal cells continued to increase. Serum concentration of IL-5, TNFα, and IL-2 in both lines was elevated in 1 h after polyvinylpyrrolidone administration, which is likely to reflect activation of the innate immunity. One day after polyvinylpyrrolidone administration, the number of multipotent stromal cells in bone marrow transplants in the CBA/N→CBA/N and CBA→CBA/N groups remained practically unchanged, while in groups CBA→CBA and CBA/N→CBA it was equally increased (by 3.6 and 3.4 times, respectively). Thus, the number of multipotent stromal cells in bone marrow transplants after 1 day was increased only in groups where recipients (CBA mice) were capable of responding to polyvinylpyrrolidone administration, i.e. the number of stromal cells by this term, was apparently determined by the presence of activated immunocompetent cells. These findings also indicate that activation of the stromal tissue dur ing immune response can have a two-phasic pattern: the first phase (1 h after antigen adminis tration) can be determined by activation of innate immunity receptors (in multipotent stromal cells or other cells) observed in CBA and CBA/N mice, and the second phase occurs during further development of the immune response (that was observed in CBA mice, but not in CBA/N mice due to absence of CD+B-1a lymphocytes). The findings attest to close interactions between the stromal tissue and the immune system.

NLR2 and TLR3, TLR4, TLR5 Ligands, Injected In Vivo, Improve after 1 h the Efficiency of Cloning and Proliferative Activity of Bone Marrow Multipotent Stromal Cells and Reduce the Content of Osteogenic Multipotent Stromal Cells in CBA Mice.

Ligands NLR2 (muramyldipeptide) and TLR (bacterial LPS, flagellin, CpG-dinucleotide, and Poly I:C) and S. typhimurium antigenic complex by 1.5-3-fold increase the efficiency of cloning and content of multipotent stromal cells (MSC) in the bone marrow of CBA mice as soon as 1 h postinjection. The counts of large colonies (150-500 cells) increased by 2.5-3.3 times in comparison with intact bone marrow cultures at the expense of a decrease in the number of smaller colonies, which attests to enhanced proliferation of stromal cells in the colonies. The efficiency of cloning and hence, MSC content in the femoral bone decreased by 1.2-1.9 times after 3 h and increased again after 24 h to the level 1.3-1.5 times higher than the level 1 h postinjection (LPS, Poly I:C, and S. typhimurium antigenic complex). The dynamics of bone marrow MSC cloning efficiency after 1-3 h corresponded to the dynamics of serum cytokine concentrations during the same period. However, the levels of serum cytokines after 24 h in general were similar to those in intact mice or were lower. The concentrations of osteogenic multipotent stromal cells in the bone marrow decreased 2-3-fold after 3 h and thus persisted by 24 h postinjection. Twofold (at 24-h interval) and a single injection of S. typhimurium antigenic complex to mice led to a significant increase of cloning efficiency, observed as early as just 1 h postinjection (1.9 and 1.5 times, respectively). The same picture was observed for serum cytokines. On the whole, injections of TLR and NLR ligands and of S. typhimurium antigenic complex led to stromal tissue activation within 1 h postinjection, this activation consisting in a significant increase of the efficiency of cloning and of MSC count in the bone marrow, and also in an increase in their proliferative activity and a decrease (after 3 h) of osteogenic MSC concentration.

Experimental Use of Common Marmosets (Callithrix jacchus) in Preclinical Trials of Antiviral Vaccines.

Common marmoset (Callithrix jacchus, CM) is a New World primate species that is of interest for preclinical trials of immunobiological products. In this study, we describe the approaches to long-term laboratory breeding and maintenance of CMs. We also establish the reference values of the main complete blood count and serum chemistry parameters evaluated during preclinical trials of immunobiological products and describe the histological characteristics of CM lymphoid organs during the development of post-vaccination immune response. We show that CMs bred in laboratory conditions excluding background infectious pathology are a relevant model that allows for a high degree of reliability in characterizing the safety and immunogenicity profile of antiviral vaccines during preclinical trials.

Broadly Reactive Nanobody Targeting the H3 Hemagglutinin of the Influenza A Virus.

Monoclonal antibodies and recombinant antibody fragments are a very promising therapeutic tool to combat infectious diseases. Due to their unique paratope structure, nanobodies (VHHs) hold several advantages over conventional monoclonal antibodies, especially in relation to viral infections. Influenza A viruses (IAVs) remain a major threat to public health. The hemagglutinin (HA) protein is the main protective and immunodominant antigen of IAVs. In this study, three broadly reactive nanobodies (D9.2, E12.2, and D4.2) to H3N2 influenza strains were isolated and Fc-fusion proteins (VHH-Fcs) were obtained and characterized in vitro. This modification improved the nanobodies' binding activity and allowed for their interaction with a wider range of strains. The D9.2-Fc antibody showed a 100% protection rate against mortality in vivo in a mouse lethal model. Furthermore, we demonstrated that the observed protection has to do with Fc-FcγR interactions. These results indicate that D9.2-Fc can serve as an effective antiviral agent against the H3N2 influenza infection.

Interactions between sulfated polysaccharides from sea brown algae and Toll-like receptors on HEK293 eukaryotic cells in vitro.

We studied the interactions between sulfated polysaccharides, fucoidans from sea brown algae Laminaria japonica, Laminaria cichorioides, and Fucus evanescens, with human Toll-like receptors (TLR) expressed on membranes of cultured human embryonic kidney cells (HEK293-null, HEK293-TLR2/CD14, HEK293-hTLR4/CD14-MD2, and HEK293-hTLR5). Fucoidans interacted with TLR-2 and TLR-4, but not with TLR-5, and were nontoxic for the cell cultures. L. japonica fucoidan (1 mg/ml), L. cichorioides fucoidan (100 µg/ml and 1 mg/ml), and F. evanescens fucoidan (10 µg/ml-1 mg/ml) activated transcription nuclear factor NF-Ï°B by binding specifically to TLR-2. L. japonica fucoidan (100 µg/ml and 1 mg/ml), L. cichorioides fucoidan (10 µg/ml-1 mg/ml), and F. evanescens fucoidan (1 µg/ml-1 mg/ml) activated NF-Ï°B via binding to TLR-4. These results indicated that fucoidans could induce in vivo defense from pathogenic microorganisms of various classes.

[Contribution of L,D-carboxypeptidases in virulence of facultative intracellular pathogenic bacteria Listeria monocytogenes].

AIM: Evaluate influence of mutation of Listeria monocytogenes genes coding murein-tetrapeptide L,D-carboxypeptidase Lmo0028 and Lmo1638 on dynamics of infectious process and interaction of purified muropeptides with NOD1 receptor. MATERIALS AND METHODS: Wild type EGDe strain and recombinant strains GIMins1638 H GIMins0028 obtained on its basis by site-specific mutagenesis were used. Infectious process dynamics was studied on the model of intravenous infection of BALB/c mice. Ligand-receptor interaction activity of muropeptides isolated from recombinant and parent strains were assayed on HEK293-hNOD1 cell line expressing NOD1 receptor and containing in their genome beta-galactosidase reporter gene under the control of NF-kappaB dependent promoter expression. RESULTS: Lack of Lmo0028 decelerates reproduction of listerias in animal liver starting from 24 hours and at later terms after the infection whereas lack of Lmo1638 leads to increase of microbial load 6 and 24 hours after the infection with no influence on further infection. Differences in activation of NOD1 receptor by muropeptides isolated from recombinant and parent strains were not detected. CONCLUSION: Despite high homology murein-tetrapeptide L,D-carboxypeptidase Lmo0028 and Lmo1638 make a different contribution to the development of infectious process caused by L. monocytogenes in BALB/c line mice. Lack of differences in NOD1 receptor activation may be associated with compensation of enzymatic functions in strains with mutation in each of the genes owing to the presence of homologous protein.

[New approaches to therapy of persistent infections: elimination of intracellular Chlamydai trachomatis by exposure to low temperature argon plasma].

AIM: Study microbicidal activity of low temperature argon plasma (LTP) that is a stream of partially ionized argon having macroscopic temperature of the environment against Chlamydia trachomatis obligate intracellular parasites. Study viability of host cells in parallel. MATERIALS AND METHODS: McCoy line cells infected with C. trachomatis (Bu-434/L2 strain) were exposed to LTP obtained by using atmospheric pressure plasma SHF generator. Intracellular localization of chlamydiae was visualized by luminescent microscopy. RESULTS: Exposure of infected McCoy line cells resulted in the destruction of chlamydia inclusions and practically complete elimination of intracellular bacteria. At the same time LTP exposure did not result in immediate death of host cells, an insignificant reduction of the number of cells was observed 24 hours after the exposure to LTP. CONCLUSION: The effect of LTP for elimination of intracellular chlamydia without significant changes in viability of eukaryotic host cells was demonstrated.

[The role of pattern-recognizing receptors in anti-infectious immunity].

Pattern-recognizing receptors (PRR) play a key role in the functioning of human immune system. They are the primary sensors of infection capable of distinguishing between various highly conservative molecular patterns (pathogen-associated molecular patterns (PAMPs)) contained in pathogenic organisms. Binding of these molecular patterns to PRR induces a variety of reactions of innate (secretion of proinflammatory cytokines and antimicrobial peptides, activation of phagocytosis, etc.) and adaptive (antibody processing and presentation, polarization of T-cell response, etc.) immunity. Great interest in the molecular mechanisms of pathogen recognition resulted in the discovery of numerous PRR. The aim of this review is to systematize the currently available data on PRR, their specificity, and role in the formation of anti-inflammatory immunity.

[Opportunities for effective skin regeneration by topical stimulation of immunity].

A murine model of incisional wound was used to evaluate effect of topical application of purified bacterial lipopolysaccharide on the wound healing process. Thirty five ICR mice were used in the study. It was shown that bacterial lipopolysaccharide is a strong promotor of wound healing. It increases tensile strength, accelerates completion of the inflammatory process, stimulates collagen deposition and early remodeling.

Nanobodies Are Potential Therapeutic Agents for the Ebola Virus Infection.

Ebola fever is an acute, highly contagious viral disease with a mortality rate that can reach 90%. There are currently no licensed therapeutic agents specific to Ebola in the world. Monoclonal antibodies (MAbs) with viral-neutralizing activity and high specificity to the Ebola virus glycoprotein (EBOV GP) are considered as highly effective potential antiviral drugs. Over the past decade, nanobodies (single-domain antibodies, non-canonical camelid antibodies) have found wide use in the diagnosis and treatment of various infectious and non-infectious diseases. In this study, a panel of nanobodies specifically binding to EBOV GP was obtained using recombinant human adenovirus 5, expressing GP (Ad5-GP) for alpaca (Vicugna pacos) immunization, for the first time. Based on specific activity assay results, affinity constants, and the virus-neutralizing activity against the recombinant vesicular stomatitis virus pseudotyped with EBOV GP (rVSV-GP), the most promising clone (aEv6) was selected. The aEv6 clone was then modified with the human IgG1 Fc fragment to improve its pharmacokinetic and immunologic properties. To assess the protective activity of the chimeric molecule aEv6-Fc, a lethal model of murine rVSV-GP infection was developed by using immunosuppression. The results obtained in lethal model mice have demonstrated the protective effect of aEv6-Fc. Thus, the nanobody and its modified derivative obtained in this study have shown potential protective value against Ebola virus.

Toll-like receptors and their adapter molecules.

Toll-like receptors (TLR) are among key receptors of the innate mammalian immune system. Receptors of this family are able to recognize specific highly conserved molecular regions (patterns) in pathogen structures, thus initiating reactions of both innate and acquired immune response finally resulting in the elimination of the pathogen. In this case every individual TLR type is able to bind a broad spectrum of molecules of microbial origin characterized by different chemical properties and structures. Recent data demonstrate the existence of a multistep mechanism of the TLR recognition of the pathogen in which, in addition to receptors proper, the involvement of different adapter molecules is necessary. However, functions of separate adapter molecules as well as the principles of formation of a multicomponent system of ligand-specific recognition are still not quite understandable. We describe all identified as well as possible (candidate) adapter TLR molecules by giving their brief characteristics, and we also propose generalized possible variants of the TLR ligand-specific recognition with involvement of adapter molecules.

Preclinical Studies of Immunogenity, Protectivity, and Safety of the Combined Vector Vaccine for Prevention of the Middle East Respiratory Syndrome.

The Middle East Respiratory Syndrome (MERS) is an acute inflammatory disease of the respiratory system caused by the MERS-CoV coronavirus. The mortality rate for MERS is about 34.5%. Due to its high mortality rate, the lack of therapeutic and prophylactic agents, and the continuing threat of the spread of MERS beyond its current confines, developing a vaccine is a pressing task, because vaccination would help limit the spread of MERS and reduce its death toll. We have developed a combined vector vaccine for the prevention of MERS based on recombinant human adenovirus serotypes 26 and 5. Studies of its immunogenicity have shown that vaccination of animals (mice and primates) induces a robust humoral immune response that lasts for at least six months. Studies of the cellular immune response in mice after vaccination showed the emergence of a specific CD4+ and CD8+ T cell response. A study of the vaccine protectivity conducted in a model of transgenic mice carrying the human DPP4 receptor gene showed that our vaccination protected 100% of the animals from the lethal infection caused by the MERS-CoV virus (MERS-CoV EMC/2012, 100LD50 per mouse). Studies of the safety and tolerability of the developed vaccine in rodents, rabbits, and primates showed a good safety profile and tolerance in animals; they revealed no contraindications for clinical testing.

Immunogenicity of Different Forms of Middle East Respiratory Syndrome S Glycoprotein.

The Middle East respiratory syndrome coronavirus (MERS-CoV) was identified in 2012 during the first Middle East respiratory syndrome (MERS) outbreaks. MERS-CoV causes an acute lower-respiratory infection in humans, with a fatality rate of ~35.5%. Currently, there are no registered vaccines or means of therapeutic protection against MERS in the world. The MERS-CoV S glycoprotein plays the most important role in the viral life cycle (virus internalization). The S protein is an immunodominant antigen and the main target for neutralizing antibodies. In the present study, the immunogenicities of five different forms of the MERS-CoV S glycoprotein were compared: the full-length S glycoprotein, the full-length S glycoprotein with the transmembrane domain of the G glycoprotein of VSV (S-G), the receptor-binding domain (RBD) of the S glycoprotein, the membrane-fused RBD (the RBD fused with the transmembrane domain of the VSV G glycoprotein (RBD-G)), and the RBD fused with Fc of human IgG1 (RBD-Fc). Recombinant vectors based on human adenoviruses type 5 (rAd5) were used as delivery vehicles. Vaccination with all of the developed rAd5 vectors elicited a balanced Th1/Th2 response in mice. The most robust humoral immune response was induced after the animal had been vaccinated with the membrane-fused RBD (rAd5-RBD-G). Only immunization with membrane forms of the glycoprotein (rAd5-S, rAd5-S-G, and rAd5-RBD-G) elicited neutralizing antibodies among all vaccinated animals. The most significant cellular immune response was induced after vaccination of the animals with the full-length S (rAd5-S). These investigations suggest that the full-length S and the membrane form of the RBD (RBD-G) are the most promising vaccine candidates among all the studied forms of S glycoprotein.

Assessment of the Parameters of Adaptive Cell-Mediated Immunity in Naïve Common Marmosets (Callithrix jacchus).

Common marmosets are small New World primates that have been increasingly used in biomedical research. This report presents efficient protocols for assessment of the parameters of adaptive cell-mediated immunity in common marmosets, including the major subpopulations of lymphocytes and main markers of T- and B-cell maturation and activation using flow cytometry with a multicolor panel of fluorescently labelled antibodies. Blood samples from eight common marmosets were stained with fluorescently labeled monoclonal antibodies against their population markers (CD45, CD3, CD20, CD4, CD8) and lymphocyte maturation and activation markers (CD69, CD62L, CD45RO, CD107a and CD27) and analyzed by flow cytometry. Within the CD45+ population, 22.7±5.5% cells were CD3- CD20+ and 67.6±6.3% were CD3+CD20-. The CD3+ subpopulation included 55.7±5.5% CD3+CD4+CD8- and 34.3±3.7% CD3+CD4-CD8+ cells. Activation and maturation markers were expressed in the following lymphocyte proportions: CD62L on 54.0±10.7% of CD3+CD4+ cells and 74.4±12.1% of CD3+CD8+ cells; CD69 on 2.7±1.2% of CD3+CD4+ cells and 1.2±0.5% of CD3+CD8+ cells; CD45RO on 1.6±0.6% of CD3+CD4+ cells and 1.8±0.7% of CD3+CD8+ cells; CD107a on 0.7±0.5% of CD3+CD4+ cells and 0.5±0.3% of CD3+CD8+ cells; CD27 on 94.6±2.1% of CD3+ cells and 8.9±3.9% CD20+ cells. Female and male subjects differed in the percentage of CD3+CD4+CD45RO+ cells (1.9±0.5 in females vs 1.1±0.2 in males; p < 0.05). The percentage of CD20+CD27+ cells was found to highly correlate with animals' age (r = 0.923, p < 0.005). The basal parameters of adaptive cell-mediated immunity in naïve healthy marmosets without markers of systemic immune activation were obtained. These parameters and the described procedures are crucial in documenting the changes induced in common marmosets by prophylactic and therapeutic immune interventions.

1-(4-Phenoxybenzyl) 5-Aminouracil Derivatives and Their Analogues - Novel Inhibitors of Human Adenovirus Replication.

Adenovirus infections are characterized by widespread distribution. The lack of causal therapy, which is effective in treating this group of diseases, explains the need for new therapeutic drugs. Notably, anti-adenoviral activity of [4-(phenoxy)benzyl]-5-(phenylamino)-6-azauracil, 1-[4-(phenoxy)benzyl]-5-(morpholino) uracil, 1-[4-(4-chlorophenoxy)benzyl]-5-(morpholino) uracil, and 1-[4-(4-fluorophenoxy)-benzyl]-5-(morpholino) uracil was observed.

Virus-Vectored Ebola Vaccines.

The Ebola virus disease (EVD) is one of the most dangerous infections affecting humans and animals. The first EVD outbreaks occurred in 1976 in Sudan and Zaire. Since then, more than 20 outbreaks have occurred; the largest of which (2014-2016) evolved into an epidemic in West Africa and claimed the lives of more than 11,000 people. Although vaccination is the most effective way to prevent epidemics, there was no licensed vaccine for EVD at the beginning of the latest outbreak. The development of the first vaccines for EVD started in 1980 and has come a long technological way, from inactivated to genetically engineered vaccines based on recombinant viral vectors. This review focuses on virus-vectored Ebola vaccines that have demonstrated the greatest efficacy in preclinical trials and are currently under different phases of clinical trial. Particular attention is paid to the mechanisms of immune response development, which are important for protection from EVD, and the key vaccine parameters necessary for inducing long-term protective immunity against EVD.

Safety and immunogenicity of GamEvac-Combi, a heterologous VSV- and Ad5-vectored Ebola vaccine: An open phase I/II trial in healthy adults in Russia.

Ebola hemorrhagic fever, also known as Ebola virus disease or EVD, is one of the most dangerous viral diseases in humans and animals. In this open-label, dose-escalation clinical trial, we assessed the safety, side effects, and immunogenicity of a novel, heterologous prime-boost vaccine against Ebola, which was administered in 2 doses to 84 healthy adults of both sexes between 18 and 55 years. The vaccine consists of live-attenuated recombinant vesicular stomatitis virus (VSV) and adenovirus serotype-5 (Ad5) expressing Ebola envelope glycoprotein. The most common adverse event was pain at the injection site, although no serious adverse events were reported. The vaccine did not significantly impact blood, urine, and immune indices. Seroconversion rate was 100 %. Antigen-specific IgG geometric mean titer at day 42 was 3,277 (95 % confidence interval 2,401-4,473) in volunteers immunized at full dose. Neutralizing antibodies were detected in 93.1 % of volunteers immunized at full dose, with geometric mean titer 20. Antigen-specific response in peripheral blood mononuclear cells was also detected in 100 % of participants, as well as in CD4+ and CD8+ T cells in 82.8 % and 58.6 % of participants vaccinated at full dose, respectively. The data indicate that the vaccine is safe and induces strong humoral and cellular immune response in up to 100 % of healthy adult volunteers, and provide a rationale for testing efficacy in Phase III trials. Indeed, the strong immune response to the vaccine may elicit long-term protection. This trial was registered with grls.rosminzdrav.ru (No. 495*), and with zakupki.gov.ru (No. 0373100043215000055).