Innate lymphoid cells (ILCs) in teleosts against data on ILCs in humans

It is assumed that cells corresponding to innate lymphoid cells (ILCs) in humans, in addition to lymphoid tissue inducer cells (LTi), are also found in teleosts. In this systematic group of organisms, however, they are a poorly understood cell population. In contrast to the data on ILCs in humans, which also remain incomplete despite advanced research, in teleosts, these cells require much more attention. ILCs in teleosts have been presented as cells that may be evolutionary precursors of NK cells or ILCs identified in mammals, including humans. It is a highly heterogeneous group of cells in both humans and fish and their properties, as revealed by studies in humans, are most likely to remain strictly dependent on the location of these cells and the physiological state of the individual from which they originate. They form a bridge between innate and adaptive immunity. The premise of this paper is to review the current knowledge of ILCs in teleosts, taking into account data on similar cells in humans. A review of the knowledge concerning these particular cells, elements of innate immunity mechanisms as equivalent to, or perhaps dominant over, adaptive immunity mechanisms in teleosts, as presented, may inspire the need for further research.

Virophages-Known and Unknown Facts

The paper presents virophages, which, like their host, giant viruses, are "new" infectious agents whose role in nature, including mammalian health, is important. Virophages, along with their protozoan and algal hosts, are found in fresh inland waters and oceanic and marine waters, including thermal waters and deep-sea vents, as well as in soil, plants, and in humans and animals (ruminants). Representing "superparasitism", almost all of the 39 described virophages (except Zamilon) interact negatively with giant viruses by affecting their replication and morphogenesis and their "adaptive immunity". This causes them to become regulators and, at the same time, defenders of the host of giant viruses protozoa and algae, which are organisms that determine the homeostasis of the aquatic environment. They are classified in the family Lavidaviridae with two genus (Sputnikovirus, Mavirus). However, in 2023, a proposal was presented that they should form the class Maveriviricetes, with four orders and seven families. Their specific structure, including their microsatellite (SSR-Simple Sequence Repeats) and the CVV (cell-virus-virophage, or transpovirion) system described with them, as well as their function, makes them, together with the biological features of giant viruses, form the basis for discussing the existence of a fourth domain in addition to Bacteria, Archaea, and Eukaryota. The paper also presents the hypothetical possibility of using them as a vector for vaccine antigens.

Immunity of the intestinal mucosa in teleost fish

The paper presents the problem of intestinal mucosa immunity in teleost fish. The immunity of the intestinal mucosa in teleost fish depends on the elements and mechanisms with different organizational/structural and functional properties than in mammals. The organization of the elements of intestinal mucosal immunitya in these animals is associated with the presence of immune cells that fulfil the functions assigned to the induction and effector sites of mucosal immunity in mammals; they are located at various histological sites of the mucosa - in the lamina propria (LP) and in the surface epithelium. The presence of mucosa-associated lymphoid tissue (MALT) has not been demonstrated in teleost fish, and the terminology used in relation to the structure and function of the mucosa immunity components in teleost fish is inadequate. In this article, we review the knowledge of intestinal mucosal immunity in teleost fish, with great potential for knowledge and practical applications especially in the field of epidemiological safety. We discuss the organization and functional properties of the elements that determine this immunity, according to current data and taking into account the tissue definition and terminology adopted by the Society for Mucosal Immunology General Assembly (13th ICMI in Tokyo, 2007).

Macrophage efferocytosis in atherosclerosis

This paper presents the role of macrophage efferocytosis, the process of elimination of apoptotic bodies-elements formed during vascular atherosclerosis. The mechanisms of macrophage efferocytosis are presented, introducing the specific signals of this process, that is, 'find me', 'eat me' and 'don't eat me'. The role of the process of efferocytosis in the formation of vascular atherosclerosis is also presented, including the factors and mechanisms that determine it, as well as the factors that determine the maintenance of homeostasis in the vessels, including the formation of vascular atherosclerosis.

Haematopoiesis in Zebrafish (Danio Rerio)

Haematopoiesis in fish and mammals is a complex process, and many aspects regarding its model and the differentiation of haematopoietic stem cells (HSCs) still remain enigmatic despite advanced studies. The effects of microenvironmental factors or HSCs niche and signalling pathways on haematopoiesis are also unclear. This review presents Danio rerio as a model organism for studies on haematopoiesis in vertebrates and discusses the development of this process during the embryonic period and in adult fish. It describes the role of the microenvironment of the haematopoietic process in regulating the formation and function of HSCs/HSPCs (hematopoietic stem/progenitor cells) and highlights facts and research areas important for haematopoiesis in fish and mammals.

Mitochondria, pattern recognition receptors and autophagy under physiological and pathological conditions, including viral infections

Research on the health of mammals invariably shows how dynamic immunology is and how the role of many elements and immune processes of the macroorganism, developed in the process of evolution in protecting against threats, including infections, is changing. Among these elements conditioning the homeostasis of the macroorganism are mitochondria, PRR receptors (pattern recognition receptors) and the phenomenon of autophagy. In the context of physiological and pathological states in the body, mitochondria perform various functions. The primary function of these organelles is to produce energy in the cell, but on the other hand, they are heavily involved in various cellular processes, including ROS production and calcium homeostasis. They are largely involved in the activation of immune mechanisms during infectious and non-infectious conditions through mtDNA and the mitochondrial MAVS protein. Mitochondrial involvement has been also determined in PRR-related mechanisms as mtDNA has the ability to directly stimulate TLRs. On the other hand, mitochondria are also associated with apoptotic cell death and autophagy.

What Function Do Platelets Play in Inflammation and Bacterial and Viral Infections?

The article presents the function of platelets in inflammation as well as in bacterial and viral infections, which are the result of their reaction with the endovascular environment, including cells of damaged vascular endothelium and cells of the immune system. This role of platelets is conditioned by biologically active substances present in their granules and in their specific structures - EV (extracellular vesicles).

Immunological memory in teleost fish

Immunological memory can be regarded as the key aspect of adaptive immunity, i.e. a specific response to first contact with an antigen, which in mammals is determined by the properties of T, B and NK cells. Re-exposure to the same antigen results in a more rapid response of the activated specific cells, which have a unique property that is the immunological memory acquired upon first contact with the antigen. Such a state of immune activity is also to be understood as related to "altered behavior of the immune system" due to genetic alterations, presumably maintained independently of the antigen. It also indicates a possible alternative mechanism of maintaining the immune state at a low level of the immune response, "directed" by an antigen or dependent on an antigen, associated with repeated exposure to the same antigen from time to time, as well as the concept of innate immune memory, associated with epigenetic reprogramming of myeloid cells, i.e. macrophages and NK cells. Studies on Teleostei have provided evidence for the presence of immunological memory determined by T and B cells and a secondary response stronger than the primary response. Research has also demonstrated that in these animals macrophages and NK-like cells (similar to mammalian NK cells) are able to respond when re-exposed to the same antigen. Regardless of previous reports on immunological memory in teleost fish, many reactions and mechanisms related to this ability require further investigation. The very nature of immunological memory and the activity of cells involved in this process, in particular macrophages and NK-like cells, need to be explained. This paper presents problems associated with adaptive and innate immune memory in teleost fish and characteristics of cells associated with this ability.

Type I interferons in ray-finned fish (Actinopterygii)

Interferons (IFNs) are proteins of vital importance in the body's immune response. They are formed in different types of cells and have been found in fish, amphibians, reptiles and mammals. Two types of IFN have been found in ray-finned fish (Superclass: Osteichthyes, Class: Actinopterygii) so far, i.e. IFN type I (IFN I) and IFN type II (IFN II), while the presence of IFN type III (IFN III), which is found in phylogenetically older cartilaginous fishes, was not confirmed in this taxonomic group of vertebrates. Currently, type I IFN in Actinopterygii is divided into three groups, I, II and III, within which there are subgroups. These cytokines in these animals show primarily antiviral activity through the use of a signalling pathway JAK-STAT (Janus kinases - Signal transducer and activator of transcription) and the ability to induce ISG (IFN-stimulated genes) expression, which contain ISRE complexes (IFN-stimulated response elements). On the other hand, in Perciformes and Cyprinidae, it was found that type I/I interferons also participate in the antimicrobial response, inter alia, by inducing the expression of the inducible nitric oxide synthase (iNOS) and influencing the production of reactive oxygen species (ROS) in cells carrying out the phagocytosis process.

B and T lymphocytes in rabbits change according to the sex and throughout the year

The European rabbit (Oryctolagus cuniculus) is a good model in biomedicine used in research on several human diseases. The reference values of B and T cells and their subpopu- lations are very important to understand how the adaptive immune system is responding to infectious agents. The aim of this study was to determine values of B and T cells and their subpopulations in Polish mixed-breed rabbits, considering seasons of the year and sex. The study was performed on 200 Polish mixed-breed rabbits and the percentage of B and T lymphocytes was measured cytometrically using mouse anti-rabbit antibodies. The study revealed that the season of the year and sex of the animals affected the percentage of B- and T-cells and their subpopulations in peripheral blood. Statistically significant values of CD19+ B-cells in spring and autumn, of T CD5+ cells in spring and winter, of T CD4+ in spring, summer, autumn and winter, of T CD8+ in winter and of T CD25+ in spring were noted. Generally the highest values were found mainly in warm part of the year, while the lowest in colder months. A statistical significance was also observed between males and females - changes were found in T CD4+ and T CD25+ lymphocytes in spring, T CD8+ cells in winter and higher percentage was generally obtained in females than in males. The only exception was the T CD5+ subpopulation in which no differences were observed between the sexes and throughout the year. This is the first paper on adaptive immune system cell values in the European rabbit of domestic breeds.

The role of innate lymphoid cells in selected disease states - cancer formation, metabolic disorder and inflammation

Innate lymphoid cells (ILCs) are a recently described group of immune cells that can regulate homeostasis and protect mammalian organisms, including humans, from infections and diseases. Considering this, ILC research is still ongoing to better understand the biology of these cells and their roles in the human body. ILCs are a multifunctional group of immune cells, making it important for the medical community to be familiar with the latest research about the ILC families and their functions in selected disease states, such as cancer formation, metabolic disorders and inflammation. By discovering the roles of ILC populations and their participation in many disorders, we can improve disease diagnostics and patient healthcare.

Immune Functions of Erythrocytes in Osteichthyes

Red blood cells (RBCs)—erythrocytes—of Osteichthyes are primarily known for their involvement in the process of gas exchange and respiration. Currently, physiological properties of RCBs in fish should also include their ability to participate in defense processes as part of the innate and adaptive immune mechanisms. In response to viruses, bacteria, and fungi or recombinant nanoparticles, they can modulate expression of genes responsible for immune reactions, influence activity of leukocytes, and produce cytokines, antimicrobial peptides, and paracrine intercellular signaling molecules. Via the complement system (CR1 receptor) and owing to their phagocytic properties (erythrophagocytosis), RBCs of Osteichthyes can eliminate pathogens. In addition, they are probably involved in the immune response as antigen-presenting cells via major histocompatibility complex class II antigens.

"In sickness and in health" - how neutrophil extracellular trap (NET) works in infections, selected diseases and pregnancy

The discovery of the NET network (neutrophil extracellular trap) has revolutionized the perception of defense mechanisms used by neutrophils in infections and non-infectious states, as this mechanism proves the complexity of the ways in which neutrophils can act in the organism. The paper describes the NET network and its participation in bacterial, viral, fungal and parasitic infections, both in a positive and a negative aspect. In addition, attention was paid to the participation of NETs in the course of autoimmune diseases, cancer, as well as its impact on pregnancy and fertility in mammals.

The first detection of the sequence of bacteria from the Simkaniaceae family in surface waters in Poland

One of the most common reasons for horse lameness is subchondral bone cysts (SBCs), which are especially evident in young horse athletes. It is believed that SBC development is strongly associated with an individual's bone growth and/or bone microstructure impairment. Current methods of SBC treatment include pharmacological treatment or surgical procedures which may allow the bone within the cyst to rebuild and be restored to properly developed bone tissue. Thus, we propose filling the SBCs with a 3D complex of alginate hydrogel and autologous adipose derived mesenchymal stem cells (ASCs). We have observed at the in vitro level, that this hydrogel complex induces osteogenic and chondrogenic differentiation potential through the upregulation of bone morphogenetic protein, osteopontin, collagen type I and aggrecan mRNA levels. Moreover, we detected the creation of a 3D extracellular matrix (EM). To investigate the complex in vivo, we chose 8 horses of varying age suffering from SBC, which resulted in lameness, to undergo experimental surgery. We documented the horses' clinical appearance, lameness and radiographic appearance, to determine that there was clinical improvement in 87.75% of the patients (n=7, out of 8 horses) 6 months postoperatively and 100% (n=8, out of 8 horses) a year after surgery. These results are promising for the potential of this procedure to become the standard in SBC treatment.

Defensins in humans and animals

Defensins are immune peptides - HDP (Host Defense Peptides) that present high activity against viruses, bacteria and fungi in mammals, including humans. They are an important element of natural resistance in macroorganisms, when microorganisms couldn’t developed this resistance during the evolution. Defensins in vertebrate macroorganisms, have direct and indirect impact on germs, including stimulating the synthesis of immune substances such as cytokines, chemokines and growth factors.

Characteristics of virophages and giant viruses

Five years after being discovered in 2003, some giant viruses were demonstrated to play a role of the hosts for virophages, their parasites, setting out a novel and yet unknown regulatory mechanism of the giant viruses presence in an aqueous. So far, 20 virophages have been registered and 13 of them have been described as a metagenomic material, which indirectly impacts the number of single- and multi-cell organisms, the environment where giant viruses replicate.

Immunological memory cells

This article reviews immunological memory cells, currently represented by T and B lymphocytes and natural killer (NK) cells, which determine a rapid and effective response against a second encounter with the same antigen. Among T lymphocytes, functions of memory cells are provided by their subsets: central memory, effector memory, tissue-resident memory, regulatory memory and stem memory T cells. Memory T and B lymphocytes have an essential role in the immunity against microbial pathogens but are also involved in autoimmunity and maternal-fetal tolerance. Furthermore, the evidence of immunological memory has been established for NK cells. NK cells can respond to haptens or viruses, which results in generation of antigen-specific memory cells. T, B and NK cells, which have a role in immunological memory, have been characterized phenotypically and functionally. During the secondary immune response, these cells are involved in the reaction against foreign antigens, including pathogens, and take part in autoimmune diseases, but also are crucial to immunological tolerance and vaccine therapy.

Immunology of the eye

The eye is an organ of sight characterized by unusual immunological properties, resulting from its anatomical structure and physiology, as well as the presence of specific elements that, through the mechanisms of innate and adaptive immunity, provide homeostasis of the eyeball. This article reviews the defensive elements of individual eye structures: conjunctiva, cornea, lacrimal gland, anterior chamber of the eye, uvea, retina and eye-associated lymphoid tissue (EALT), where we distinguish associated lymphoid tissue (CALT) and lacrimal drainage associated lymphoid tissue (LDALT). In addition, the immunity of eyes is conditioned by the difference between the front chamber, anterior chamber – associated immune deviation (ACAID) and also conditioned by the specific barriers of the vascular and retina. These characterized elements, determining the immunity of the eye, are the anatomical, physiological and immunological barrier of the eye, crucial to its immune privilege.

Expression of IL-1Ra, IL-6, IL-8, IL-18, TNF-α and IFN-γ genes in peripheral blood leukocytes of rabbits infected with RHDV (Rabbit Haemorrhagic Disease Virus)

Rabbit haemorrhagic disease virus (RHDV) induces a highly contagious and extremely lethal disease that fulfils many requirements of an animal model of fulminant hepatic failure (FHF); however, the pathogenesis of RHD has still not been fully elucidated. Cytokines play an important role in regulation of the immune response and pathogenesis of many diseases, including those caused by viral infections. Furthermore, recent studies indicate a role of the immune response, especially peripheral blood leukocytes (PBL), in the pathogenesis of RHD. Thus, in the present study we investigated the expression of IL-1Ra, IL-6, IL-8, IL-18, TNF-α and IFN-γ genes in PBL of RHDV-infected rabbits. We also compared the expression of genes encoding these cytokines in rabbits with different course of RHDV infection (in animals that died 36 h post infection or survived even over 60 h after infection). The study revealed increased expression of genes encoding pro-inflammatory cytokines: IL-6, IL-8, TNF-α, IFN-γ in PBL of RHDV-infected rabbits. Moreover, the level of cytokine gene expression depended on the course of RHD. Hence, the results obtained indicate the potential role of these cytokines in RHDV infection and their influence on the survival time of infected rabbits.

Mechanisms of type I interferon action and its role in infections and diseases transmission in mammals

Interferons (IFNs) are pivotal regulators of immunological processes. This paper describes mainly type I interferons -α and -β and their recently recounted signaling pathways, especially connected with ISGs - interferon stimulated genes, having a crucial role in regulating IFN recruitment. Moreover, the paper shows the data on the role of interferons -α and -β in infections - not only commonly known viral infections, but also bacterial, fungal and parasitic.

Values of apoptosis of lymphocytes and granulocytes in peripheral blood of Polish mixed-breed rabbits in the annual cycle

The objective of the study was to determine values of apoptosis for peripheral blood lymphocytes and granulocytes, including dependency on the season of the year, in Polish mixed-breed rabbits and in mixed-breed rabbits with the addition of blood of meat-breed rabbits. The study was carried out in four seasons of the year (spring, summer, autumn, winter) involving 120 Polish mixed-breed rabbits - group I, and 120 Polish mixed-breed rabbits with addition of meat-breed rabbit blood - group II. Assessment of apoptosis of lymphocytes and granulocytes was performed using as FACScan cytometer by Becton Dickinson with FACSDiva software (USA), using as ApoFluor® Green Caspase reagent kit (MP Biomedicals, USA) to detect the activity of the total caspase pool 1, 3, 4, 5, 6, 7, 8, 9 in granulocytes and lymphocytes of rabbit peripheral blood. The results for apoptosis of lymphocytes and granulocytes in peripheral blood in the animals investigated (group I and II) were subjected to statistical analysis with the t'Student test at p=0.05. It was noted that, in rabbits from group I, the values for apoptosis of lymphocytes were the highest in winter and autumn (36.02% and 31.24%, respectively), and the lowest in spring and summer (26.73% and 22.72%, respectively), whereas in the case of granulocytes the highest values were in summer and spring (14.69% and 12.95%, respectively), and the lowest in winter and autumn (8.16% and 8.57%, respectively). In mixed-breed rabbits with the addition of meat-breed blood (group II), the values for apoptosis of lympocytes were the highest in spring (29.13%), and the lowest in summer (25.43%); whereas in the case of granulocytes the highest values were in summer and spring (14.0% and 11.15%, respectively), and the lowest in autumn and winter (7.46% and 7.64%, respectively).

White and red blood cell picture in rabbits experimentally infected with strains of the rabbit haemorrhagic disease (RHD) virus without or with variable haemagglutination capacity

The aim of the study was to establish if haemagglutination of rabbit haemorrhagic disease virus (RHDV) affects haematological picture of peripheral blood in rabbits and the pathogenicity of the virus. The study analyzed white and red blood cell picture in rabbits experimentally infected with two non-haemagglutinating (HA-) RHDV strains (Frankfurt and Asturias) and one strain with variable haemagglutination capacity (HA+/-) (Hagenow). Studies with HA- and HA +/- are rare and relate only to 4 HA- strains (2 RHDV: BLA and Rainham; 2 RHDVa: Pv97 and 9905) and 1 HA+/- RHDV strain: ŻD, where less changes in haematological indices and less pathogenicity were observed. We found that changes caused by HA- Frankfurt strain were related to the number of neutrophils and thrombocytes, while in HA- strain Asturias, in thrombocytes and leukocytes. Changes evoked by HA+/- Hagenow strain pertained to the number of eosinophils, thrombocytes, leukocytes, monocytes, and concentration of hemoglobin. Mortality caused by the Frankfurt strain was 100% between 36 and 48 h post infection (p.i.), while that caused by Asturias strain was 100% between 24 and 36 h p.i., and that observed in case of Hagenow strain was 90% between 36 and 48 h p.i. The changes in haematological picture caused by the HA- and HA+/- RHDV strains were less intensive than those found in case of the HA+ RHDV strains, which cannot be confirmed for pathogenicity, and is not in line with the existing hypothesis suggesting higher pathogenicity in HA+ viruses.

Expression of IL-1β, IL-2, IL-10, TNF-β and GM-CSF in peripheral blood leukocytes of rabbits experimentally infected with rabbit haemorrhagic disease virus

Rabbit haemorrhagic disease (RHD) is a highly morbid and mortal viral infection of European rabbits. This disease is one of the main causes of death in wild rabbits, and results in large economic losses in farms of rabbits worldwide. Although the first outbreak of this disease was noted in 1984, the pathogenesis of RHD and mechanisms of RHDV (rabbit haemorrhagic disease virus) pathogenecity have still not been fully elucidated. Recent studies indicate a role of the immune response, especially peripheral blood leukocytes (PBL), in the pathogenesis of this disease. Thus, in the present study we investigated the expression of IL-1β, IL-2, IL-10, TNF-β and GM-CSF genes in PBL of RHDV-infected rabbits. We also compared the expression of genes encoding these cytokines in rabbits with different course of RHDV infection (in animals that died 36h postinfection or survived until 60th h after infection). The study revealed that three (IL-10, TNF-β and GM-CSF) out of five investigated genes encoding cytokines showed increased expression in PBL of RHDV-infected rabbits, and the level of expression depended on the course of RHD. The results indicate the potential role of these cytokines in RHDV infection and their influence on the survival time of infected rabbits.

Stress granules (SG) and processing bodies (PB) in viral infections

During reaction to stress caused by viral infection, RNA granules are formed in order to protect mRNA. Stress granules (SG) and processing bodies (PB) provide cell homeostasis and mRNA stability. They are formed, for example, during polio virus and MRV (mammalian orthoreovirus) infections. Some viruses, such as influenza virus and HTLV-1 (Human T-lymphotropic virus 1), block the formation of granules. In addition, there are viruses like West Nile Virus, Hepatitis C Virus (HCV) or human Herpes viruses, which influence the functioning of the granules.

Hematological parameters in Polish mixed breed rabbits with addition of meat breed blood in the annual cycle

In the paper we studied haematologic values, such as haemoglobin concentration, haematocrit value, thrombocytes, leucocytes: lymphocytes, neutrophils, basophils, eosinophils and monocytes in the pheral blood in Polish mixed-breeds with addition of meat breed blood in order to obtain the reference values which are until now not available for this animals. In studying this indices we took into consideration the impact of the season (spring, summer, autumn, winter), and sex of the animals. The studies have shown a high impact of the season of the year on those rabbits, but only in spring and summer. Moreover we observed that the sex has mean impact on the studied values of haematological parameters in those rabbits. According to our knowledge, this is the first paper on haematologic values in this widely used group of rabbits, so they may serve as reference values.

Natural immunity factors in Polish mixed breed rabbits

Mixed-breed rabbits in Poland are widely used for diagnostic and scientific research and as utility animals, therefore there is a need to know their immunological status, as well as their haematological status. In this study natural immunity factors were analyzed in Polish mixed-breed rabbits and Polish mixed-breed rabbits with addition of blood of meet-breed, considering the impact of sex and season of the year (spring, summer, autumn, winter) using measurement of non-specific cellular and humoral immunity parameters in peripheral blood. The study has revealed that there is a variety between the two commonly used mixed-breed types of rabbits, especially when sex and season is concerned, which is crucial for using these animals in experiments.

The importance of liver lesions and changes to biochemical and coagulation factors in the pathogenesis of RHD

RHDV (rabbit haemorrhagic disease virus) is an etiologic factor of RHD (rabbit haemorrhagic disease), which is highly morbid and mortal viral infection of an adult European rabbit. Although three decades have passed since the first outbreak of rabbit haemorrhagic disease, the pathogenesis of RHD has still not been fully elucidated. It is known that RHDV replicates in the liver within the first hours following infection, causing necrotic and apoptotic cell death of hepatocytes. Anatomopathological changes are also observed in other organs of infected rabbits, i.e. lungs, spleen, kidneys, heart, as well as central nerve system. These changes leading to animals death are predominantly caused by systemic hemorrhagic diathesis with disseminated intravascular coagulation (DIC), appearing most likely as a consequence of liver cell loss through RHDV-induced apoptosis. In this paper, we presented previously described changes in biochemical and coagulation factors in RHDV infection.

Antifungal immunity in selected fungal infections

Fungi are omnipresent in the environment; hence they are frequent factors causing infections in humans and animals even if their immune system works correctly. These facts stimulated interest in and the will to understand the antifungal immunity mechanisms. It has been, however, evidenced that the immunological response to mycotic pathogens is related to the species and morphological form of the fungus. Nevertheless, it is assumed that always in the antifungal response, there are mechanisms of innate and adaptive immunity that cooperate with one another to eliminate such pathogens. It has been evidenced that the main elements of antifungal immunity are physical barriers of the organism, phagocytosis, cytotoxicity, and possibly trogocytosis of PMN and MN cells, as well as T-cells, and to a smaller extent B-cells, the proportion of which is principally related to their products activating the processes of PMN and MN cells. An important role in this immunity also belongs to PRR, which activate the main processes of phagocytosis and cytotoxicity of PMN, MN, NK and DC cells.

[Immune system and influenza virus]

Influenza viruses are a significant cause of respiratory infections, causing 3-5 million clinical infections and 250-500 thousand deaths per year. Infections caused by the influenza virus induce a host immune response at the non-specific and specific level (defined as natural and acquired), which leads to limitation of virus replication. Moreover the elements of immunological memory are induced so that they can protect against subsequent infection by the influenza virus. However, there is still no effective way for the total elimination of this virus, and the only effective method to combat this pathogen appears to be vaccination, which through immune system activation greatly limits its spread. The present paper presents the immune reaction at different levels in response to the influenza virus after entering the body and the mechanisms of the influenza virus for avoiding reactions of the immune system, which correspond to its high variability at the molecular level. Moreover, in this paper we describe various methods of stimulating the organism's immune systems with different generations of vaccines and their effectiveness in the fight against this pathogen.

Chlamydial plasmids and bacteriophages

Chlamydia are absolute pathogens of humans and animals; despite being rather well recognised, they are still open for discovery. One such discovery is the occurrence of extrachromosomal carriers of genetic information. In prokaryotes, such carriers include plasmids and bacteriophages, which are present only among some Chlamydia species. Plasmids were found exclusively in Chlamydia (C.) trachomatis, C. psittaci, C. pneumoniae, C. suis, C. felis, C. muridarum and C. caviae. In prokaryotic organisms, plasmids usually code for genes that facilitate survival of the bacteria in the environment (although they are not essential). In chlamydia, their role has not been definitely recognised, apart from the fact that they participate in the synthesis of glycogen and encode proteins responsible for their virulence. Furthermore, in C. suis it was evidenced that the plasmid is integrated in a genomic island and contains the tetracycline-resistance gene. Bacteriophages specific for chlamydia (chlamydiaphages) were detected only in six species: C. psittaci, C. abortus, C. felis, C. caviae C. pecorum and C. pneumoniae. These chlamydiaphages cause inhibition of the developmental cycle, and delay transformation of reticulate bodies (RBs) into elementary bodies (EBs), thus reducing the possibility of infecting other cells in time. Plasmids and bacteriophages can be used in the diagnostics of chlamydioses; although especially in the case of plasmids, they are already used for detection of chlamydial infections. In addition, bacteriophages could be used as therapeutic agents to replace antibiotics, potentially addressing the problem of increasing antibiotic-resistance among chlamydia.

Excitotoxicity and Wallerian degeneration as a processes related to cell death in nervous system

Cell death is one of the processes that are currently extensively studied. Beside the commonly used terminology regarding cell death, i.e. apoptosis, autophagy, necrosis, and cornification, in recent years there has been a growing number of additional definitions of this process, such as mitotic catastrophe, anoikis, entosis, paraptosis, pyroptosis, pyronecrosis, excitotoxicity, and Wallerian degeneration, which are described in 2009 by the Nomenclature Committee on Cell Death as atypical. The recent report of that Committee significantly alter the classification and nomenclature of the cell death processes, in which excitotoxicity and Wallerian degeneration have not been taken into account. Thus the present review describes excitotoxicity, and Wallerian degeneration, as two processes associated to cell death phenomena characteristic for nervous system. Excitotoxicity is a neuronal death caused by excessive, or prolonged activation of receptors for the excitatory amino acids. Depending on the intensity of the initiating stimulus, the excitotoxicity may overlap with other types of cell death such as apoptosis and necrosis. Wallerian degeneration is a process that results when a nerve fiber is cut or crushed, in which the part of the axon separated from the neuron's cell body degenerates distal to the injury. Wallerian degeneration is not a typical cell death mechanism, since neurons undergoing this process remain alive.

[Chlamydiosis of urogenitary tract in humans]

Chlamydiae are bacteria commonly found in the environment of human life and they cause many diseases. Chlamydial infections are common among men and women, although they are more often diagnosed in women and they are frequently asymptomatic, due to the biology of chlamydiae. Incorrectly diagnosed and untreated, they cause many complications which can lead to infertility in both, men and women. This work presents the diseases caused by chlamydiae of the urogenitary tract, including environmental chlamydiae, so far in Polish literature rarely presented, which extends the panel responsible for chlamydial genital tract disease, particularly in women. A major problem is that the knowledge of the immune mechanisms that occur in the case of infection with these bacteria, especially in view of prevention of these infection, mainly in the context of creation of the vaccine. Also important fact from the knowledge of immunity in chlamydiosis is base for diagnosis of these infection.

mRNA Regulatory elements and bacterial virulence

Pathogenic bacteria cause many diseases, some of which are fatal. For researchers, it is a challenge to understand bacterial mechanisms of pathogenicity, including their virulence pathways regulated by RNA. This work presents data on the mechanisms of regulation and expression of several virulence factors coded by RNA, namely 5' UTR fragments, riboswitches and small non-coding RNA (sRNA).

mRNA Regulatory elements and bacterial virulence

Pathogenic bacteria cause many diseases, some of which are fatal. For researchers, it is a challenge to understand bacterial mechanisms of pathogenicity, including their virulence pathways regulated by RNA. This work presents data on the mechanisms of regulation and expression of several virulence factors coded by RNA, namely 5' UTR fragments, riboswitches and small non-coding RNA (sRNA).

[Characteristics of T lymphocyte subpopulations]

The paper describes the characteristics, receptor profile and functions of T lymphocyte subpopulations (helper, cytotoxic, regulatory, memory and others). Among T helper cells one can enumerate Th0, Th1, Th2, Th9, Th17, Th22, T(FH) and nTh2, while T cytotoxic cells include Tc, NKT, Tγδ, and T CD8αα (IEL). Among regulatory cells there are nTreg, iTreg, T(R)1, and iT(R)35, as well as T lymphocytes with CD8, such as CD8+CD122+, CD8+CD28-, and CD11c+CD8+. And among memory T cells there are Tcm and Tem. Moreover, there are some so-called other T cells, such as Tn (T αβ CD4+ and T αβ CD8+), T exhausted and T anergic.

Apoptosis of peripheral blood leucocytes in rabbits infected with different strains of rabbit haemorrhagic disease virus

The pathogenicity of RHDV (rabbit haemorrhagic disease virus) is mainly associated with its affinity to blood vessels, with causing disseminated intravascular coagulations (DIC), and with the stimulation of the host immune system. Moreover, there are implications suggesting that apoptosis may be a pivotal process in understanding the basis of viral haemorrhagic disease in rabbits - a serious infectious disease causing mortality to wild and domestic rabbits. The aim of this study is to evaluate, by means of flow cytometry, the dynamics of apoptosis in peripheral blood granulocytes and lymphocytes in rabbits experimentally infected with seven different strains of RHDV and so-called antigenic variants of RHDV denominated as RHDVa, i.e.: Hungarian 24V/89, 1447V/96, 72V/2003; Austrian 01-04, 237/04, V-412 and French 05-01. The results showed that all of the RHDV and RHDVa strains cause an increase in the number of apoptotic cells throughout the infection, which might indicate the need for further analysis of the importance of this process.

Apoptosis of peripheral blood leucocytes in rabbits infected with different strains of rabbit haemorrhagic disease virus

The pathogenicity of RHDV (rabbit haemorrhagic disease virus) is mainly associated with its affinity to blood vessels, with causing disseminated intravascular coagulations (DIC), and with the stimulation of the host immune system. Moreover, there are implications suggesting that apoptosis may be a pivotal process in understanding the basis of viral haemorrhagic disease in rabbits - a serious infectious disease causing mortality to wild and domestic rabbits. The aim of this study is to evaluate, by means of flow cytometry, the dynamics of apoptosis in peripheral blood granulocytes and lymphocytes in rabbits experimentally infected with seven different strains of RHDV and so-called antigenic variants of RHDV denominated as RHDVa, i.e.: Hungarian 24V/89, 1447V/96, 72V/2003; Austrian 01-04, 237/04, V-412 and French 05-01. The results showed that all of the RHDV and RHDVa strains cause an increase in the number of apoptotic cells throughout the infection, which might indicate the need for further analysis of the importance of this process.

Analysis of genetic variability and phylogenetic analysis of selected Czech and French strains of rabbit haemorrhagic disease virus (RHDV)

The objective of this study was to analyse the genetic variability and phylogenetic analysis of six strains of rabbit haemorrhagic disease virus (RHDV), including four Czech strains (CAMPV-351, CAMPV-561, CAMPV-562, CAMPV-558) and two French strains (Fr-1, Fr-2), on the basis of a fragment of the VP60 capsid structural protein-coding gene N-terminal region. The results of our own studies were compared to 26 RHDV strains obtained from GenBank. The analysis of the genetic variability of six RHDV strains indicated that the CAMPV-561 strain is the most genetically variable. Less variable were the Fr-1 and Fr-2 strains, while the least variable was CAMPV-351. In turn, the genetic distance among the six analysed strains and 26 strains obtained from GenBank was the greatest for CAMPV-351 and Whn/China [11.3 % according to the observed divergence (OD) method and 12.2 % according to the maximum likelihood (ML) method], while it was the lowest for CAMPV-351 and FRG (0.8 % in both the OD and ML methods). In turn, the scale of the genetic distances among the six analysed strains and five RHDVa strains (99-05, NY-01, Whn/China, Triptis, Iowa2000) ranged from 9.3–10.3 % in the OD method to 10.3–13.7 % in the ML method. The image of phylogenetic dependencies generated for the strains analysed and those obtained from GenBank revealed their distribution to be in five genetic groups (G1–G5), whereas the analysed strains were included in genetic groups 2 and 3.

Genetic variation and phylogenetic analysis of rabbit haemorrhagic disease virus (RHDV) strains

Rabbit haemorrhagic disease virus (RHDV) belongs to the family Caliciviridae and is the etiological agent of the haemorrhagic disease, also known as rabbit plague. Its genome is a linear single-stranded (ss) RNA of 7437 nucleotides and the capsid is built from a single structural protein VP60. In connection with the discovery of new RHDV strains, there is a constant need to investigate the genetic variation of this virus and perform phylogenetic analyses which may show the evolutionary relationships among the RHDV strains. Studies on the divergence of RHDV have shown that it is genetically quite stable, although recent observations indicate that some new RHDV strains, significantly different from the original RHDV subtype and the new RHDVa subtype, are appearing. These latest findings suggest that a new group of RHDV strains has evolved. The present review summarizes the current knowledge on the genetic variation and the latest achievements in phylogenetic analyses of RHDV strains isolated in various countries.

Genetic variation and phylogenetic analysis of rabbit haemorrhagic disease virus (RHDV) strains

Rabbit haemorrhagic disease virus (RHDV) belongs to the family Caliciviridae and is the etiological agent of the haemorrhagic disease, also known as rabbit plague. Its genome is a linear single-stranded (ss) RNA of 7437 nucleotides and the capsid is built from a single structural protein VP60. In connection with the discovery of new RHDV strains, there is a constant need to investigate the genetic variation of this virus and perform phylogenetic analyses which may show the evolutionary relationships among the RHDV strains. Studies on the divergence of RHDV have shown that it is genetically quite stable, although recent observations indicate that some new RHDV strains, significantly different from the original RHDV subtype and the new RHDVa subtype, are appearing. These latest findings suggest that a new group of RHDV strains has evolved. The present review summarizes the current knowledge on the genetic variation and the latest achievements in phylogenetic analyses of RHDV strains isolated in various countries.

[NET and NETosis--new phenomenon in immunology]

Neutrophils are one of the first cells of the immune system recruited to the site of infection, representing the host's most effective and numerous front-line defenders. Recently, a novel antimicrobial mechanism of neutrophils has been described: upon activation, they release DNA and a subset of their granule content, forming neutrophil extracellular traps (NETs). These extracellular, chromatin structures, which contain histones and neutrophil granule proteins, can trap and kill a broad spectrum of microbes, including Gram-positive and Gram-negative bacteria, fungi, protozoa and viruses. Some of the pathogens, which are trapped and exposed to high local concentrations of antimicrobial compounds, employ strategies against NET binding, including surface modification and/or degradation of NET by DNases. It has been suggested that NETs are formed during active cell death, recently named NETosis. New data indicate that this novel mechanism of cell death requires interaction between three processes--reactive oxygen species generation, histone citrullination and autophagy--and significantly differs from previously known types of cell death, including apoptosis and necrosis. Moreover, the release of nuclear chromatin was also described for other types of cells--mast cells and eosinophils. Mast cells, like neutrophils, under certain conditions release nuclear chromatin and may undergo a similar active cell death program, while eosinophils release only mitochondrial chromatin, and its release does not lead to the death of these cells.

Apoptosis of peripheral blood leukocytes from rabbits infected with non-haemagglutinating strains of rabbit haemorrhagic disease virus (RHDV)

The report demonstrates that the induction of apoptosis in peripheral blood granulocytes and lymphocytes of rabbits infected with three non-haemagglutinating RHDV strains (English Rainham, German Frankfurt, and Spanish Asturias) is a crucial determinant of the pathogenesis of rabbit haemorrhagic disease. Apoptosis was measured by flow cytometric detection of caspase activity. These studies demonstrated that the investigated RHDV (rabbit haemorrhagic disease virus) viral strains affected leukocyte apoptosis to varying degrees. Enhanced leukocyte apoptosis was detected between 4 and 36 h after infection and was more pronounced in lymphocytes than in granulocytes. The data presented here thus provide a preliminary understanding of the kinetics of apoptosis in leukocytes of rabbits infected with RHDV.

[Cells of the immune system in atherosclerosis--chosen data]

Development of artherosclerosis is associated with participation of various cell types of the immune system such as: granulocytes, B and T lymphocytes, mast cells, dendritic cells and progenitor cells. Cytokines and growth factors have a great impact on activation of the atheromatous plaque. This pathological process results in increase of artery's tunic intima thickness, leading to coronary heart disease, myocardial infarction or stroke. It is suggested that a closer look at participation of the immune system cells in artherosclerosis may contribute to a change in the profile of therapy of this disease.

Cytometric analysis of lymphocytes T and B in rabbits infected with non-haemagglutinogenic strains of RHD virus (rabbit haemorrhagic disease)--Rainham, Frankfurt and Asturias

The present paper refers to the cytometric analysis of lymphocytes T (with receptor CD5+), Th (with receptor CD4+), Tc/Ts (with receptor CD8+), lymphocytes CD25+ and lymphocytes B with receptor CD19+ in rabbits experimentally infected with strains of RHD virus--Rainham, Frankfurt and Asturias, not having haemagglutinogenic capacities, which makes them unique, as haemagglutinogenic capacity is a classic and typical property of most strains of this virus. The study was performed in the dynamic system, drawing blood samples from animals at hour 0, namely before the administration of the viral antigen, and then at 4, 8, 12, 24 and 36 h after the infection. The study indicated that Rainham and Asturias strains of RHD virus cause a similar amount of changes as the most immunogenic haemagglutinogenic strains CAMP V-561 and CAMP V-562 of the RHD virus do. In contrast, the Frankfurt strain of the RHD virus is characterised with 5-6-fold lower reactivity in this respect and is most similar to the least immunogenic haemagglutinogenic strain CAMP V-558 of the RHD virus.