Enterovirus E infects bovine peripheral blood mononuclear cells. Implications for pathogenesis?

Introduction

Enterovirus E (EV-E) is a common viral pathogen endemic in cattle worldwide. Little is known, however, about its potential interactions with bovine immune cells.

Material and Methods

The EV-E-permissiveness of bovine peripheral blood mononuclear cells (PBMCs) was evaluated. The infectious titres of extracellular virus were measured and the intracellular viral RNA levels were determined by reverse transcription quantitative PCR after cell inoculation. The effects of EV-E on cell viability and proliferative response were investigated with a methyl thiazolyl tetrazolium bromide reduction assay, the percentages of main lymphocyte subsets and oxidative burst activity of blood phagocytes were determined with flow cytometry, and pro-inflammatory cytokine secretion was measured with an ELISA.

Results

Enterovirus E productively infected bovine PBMCs. The highest infectious dose of EV-E decreased cell viability and T-cell proliferation. All of the tested doses of virus inhibited the proliferation of high responding to lipopolysaccharide B cells and stimulated the secretion of interleukin 1β, interleukin 6 and tumour necrosis factor α pro-inflammatory cytokines.

Conclusion

Interactions of EV-E with bovine immune cells may indicate potential evasion mechanisms of the virus. There is also a risk that an infection with this virus can predispose the organism to secondary infections, especially bacterial ones.

Effects of long-term administration of various dietary prebiotic supplements on the growth, immune cell activity and digestive tract histology of juvenile vimba (Vimba vimba)

Introduction

The experiment was set to determine the effects of long-term (55-day) use of three commercial prebiotics including Saccharomyces cerevisiae-derived β-glucans and one including inulin on juvenile vimba (Vimba vimba) reared intensively under controlled conditions.

Material and Methods

Six-month-old fish were fed commercial feed (Control group, n = 90), or the same feed supplemented with 0.02% Leiber Beta-S (BS group, n = 90), 0.20% Biolex MB40 (MB group, n = 90), 0.30% CeFi (CE group, n = 90) or 1.00% inulin Orafti GR (IN group, n = 90) for 55 days.

Results

In the BS group, the final growth parameters were significantly lower than in the Control group, while the feed conversion ratio was significantly higher. No significant differences were found between any other group and the Control group in the respective parameters. The respiratory burst activity of the head-kidney phagocytes was significantly lower in all fish groups fed the prebiotic-supplemented diets compared to the Control group. The proliferative response of the head-kidney lymphocytes stimulated by concanavalin A was lower in the BS group than in the Control group, while in other groups this response was not affected. No significant differences were found in histopathological analyses of the digestive tract, liver or pancreas.

Conclusion

The long-term supplementation of fish diets with prebiotics can negatively influence the growth, feed conversion, nonspecific cellular resistance and proliferative activity of the T lymphocytes of vimba juveniles.

No indication for SARS-CoV-2 transmission to pet ferrets, in five cities in Poland, 2021 - antibody testing among ferrets living with owners infected with SARS-CoV-2 or free of infection

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first identified in China by the end of 2019 and was responsible for a pandemic in the human population that resulted in millions of deaths worldwide. Since the beginning of the pandemic, the role of animals as spill-over or reservoir hosts was discussed. In addition to cats and dogs, ferrets are becoming increasingly popular as companion animals. Under experimental conditions, ferrets are susceptible to SARS-CoV-2 and it appears that they can also be infected through contact with a SARS-CoV-2 positive owner. However, there is still little information available regarding these natural infections. Here, we serologically tested samples collected from pet ferrets (n = 45) from Poland between June and September 2021. Of the ferrets that were included in the study, 29% (13/45) had contact with owners with confirmed SARS-CoV-2 infections. Nevertheless, SARS-CoV-2-specific antibodies could not be detected in any of the animals, independent of the infection status of the owner. The obtained results suggest that ferrets cannot be readily infected with SARS-CoV-2 under natural conditions, even after prolonged contact with infected humans. However, due to the rapid mutation rate of this virus, it is important to include ferrets in future monitoring studies.

Does Aleutian Disease Occur among Domestic Ferrets in Poland? Results of Preliminary Studies Conducted in Two Regions of Poland

Although ferrets are becoming increasingly popular as companion animals, their population in households is still far lower compared to cats or dogs. This results in a much smaller number of ferret specialists, and thus poorer diagnosis of various diseases, including the Aleutian disease. Aleutian disease is a slowly progressing viral disease which can cause different symptoms in these animals. The virus can also cause symptoms in different species of animals, but in the case of ferrets, there is relatively less information on about both the prevalence and symptoms of this disease. Therefore, the aim of this study was to determine the presence of antibodies and the virus itself in ferrets from two regions of Poland. Blood samples and rectal swabs were obtained from 61 domestic ferrets from Mazowieckie and Dolnośląskie voivodships. The presence of antibodies was determined using serological methods and real-time PCR analysis was performed to determine presence of viral DNA. Serological analyses demonstrated that 49% (n = 30) of the ferrets had antibodies against Aleutian disease virus (ADV). No relationship was observed between the prevalence of antibodies and age, sex, habitual residence or origin of ferrets. The real-time PCR did not confirm DNA of the ADV in any of the blood and rectal swab samples. Obtained results suggest that ADV circulates in the analyzed population of ferrets, therefore further studies in this direction should be carried out.

Dietary supplementation with Lactobacillus plantarum and β-glucan affects immune parameters in the tench (Tinca tinca) fry

The aim of the experiment was to examine the effect of a diet enriched with Lactobacillus plantarum and/or β-glucan on the immune parameters in the juvenile tench (Tinca tinca). Fish were fed for 14 days different diets (phase 1 of the experiment), a dry commercial starter feed in the control group or the same feed supplemented with: 1% β-1,3/1,6-glucan in group G, 108 cfu L. plantarum g-1 in group L, 1% β-1,3/1,6-glucan + 108 cfu L. plantarum g-1 in group G+L. During consecutive 14 days all fish were fed the commercial feed alone (phase 2). The stimulating effects of the tested preparations was evaluated twice, at the end of each experimental phase. Dietary supplementation of β-1,3/1,6-glucan considerably improved the humoral innate immune response (activity of lysozyme and total Ig) and the pinocytotic activity of phagocytes. Supplement of L. plantarum improved the ability of the head kidney phagocytes (RBA) to carry out oxygen burst in L and G+L groups. A similar effect was observed for the killing activity of phagocytes (PKA) from the head kidney after the stimulation of A. hydrophila, and the effect persisted for two weeks after the commercial feed regime was resumed. A significant increase in the proliferative activity of B lymphocytes originating from the head kidney was observed in groups L and G+L. The study has revealed that the addition of the tested G+L synbiotic to dry diet stimulates the innate immune response mechanisms in the juvenile tench.

High cytotoxicity of betulin towards fish and murine fibroblasts: Is betulin safe for nonneoplastic cells?

Background

Betulin, a natural pentacyclic triterpene with the lupane structure that is present in significant amounts in the outer bark of birch, is known for its broad array of biological and pharmacological properties. Betulin has attracted attention as a potential, natural-origin antimicrobial substance. The literature describes it as selectively toxic to neoplastic cells but safe for normal cells.

The research aim was to evaluate the basal cytotoxicity of betulin towards fish (BF-2) and murine (NIH/3T3) fibroblasts. We used four colorimetric tests that provide a preliminary evaluation of possible mechanisms of the cytotoxicity of a compound to assess the degree of the toxicity of betulin after 24, 48 and 72 h of incubation with cells: the MTT assay (mitochondrial activity assessment), the NRU assay (lysosomal membrane integrity assessment), the LDH assay (cellular membrane integrity assessment) and the SRB assay (total cellular protein content determination).

Results

The results revealed an exceptionally high sensitivity of mitochondria to the effect of betulin, with the other endpoints being less sensitive. Although murine fibroblasts were more vulnerable to the toxic effect of betulin than fish fibroblasts, the betulin CC₅₀ values for both cell lines were comparable with analogous IC₅₀ values determined by other researchers in studies involving cancerous cells.

Conclusions

The results indicate the need to verify the claim about the selective toxicity of betulin towards malignant cells and to conduct safety/toxicity tests before any potential therapeutic use of betulin in veterinary medicine.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-02905-x.

Nisin-A lantibiotic with immunomodulatory properties: A review

Nisin, a member of class I bacteriocins known as lantibiotics, is produced by the lactic acid bacterium Lactococcus lactis and is characterized by a wide spectrum of antibacterial activity against gram-positive bacteria. This characteristic in conjunction with its low toxicity and safety of use in food has contributed to the worldwide success of nisin as a natural food preservative. This lantibiotic has attracted interest as a potential natural therapeutic agent for the control of bacterial infections. However, similar to other antimicrobial peptides of natural origin, the spectrum of biological activity of nisin surpasses its antibacterial properties, encompassing interesting and incompletely understood immunotropic characteristics. This paper is a systematic review of the current information about the potential immunomodulatory properties of nisin based on in vitro and in vivo studies in various experimental models. We also discuss the effect of potentially probiotic, nisin-producing L. lactis strains on the immune system of animals.

Streptococci as the new dominant aetiological factors of mastitis in dairy cows in north-eastern Poland: analysis of the results obtained in 2013-2019

The objective of our study was to evaluate prevalence of selected bacterial and fungal pathogens of mastitis in dairy cattle in north-eastern Poland. Our study was conducted from 2013 to 2019 in 1,665 clinically and sub-clinically infected quarter milk samples (2013, n = 368; 2014, n = 350; 2015, n = 290; 2016, n = 170; 2017, n = 173; 2018, n = 224; and 2019, n = 90). The isolation and identification of the pathogens were performed in keeping with generally accepted microbiological procedures. In 2013, mastitis was most commonly caused by Staphylococcus aureus (24%), Streptococcus spp. (22%), Streptococcus agalactiae (12%) and coagulase-negative staphylococci (11%). In 2014, the most common pathogens were Streptococcus spp. (25%), Staphylococcus aureus (18%) and coagulase-negative staphylococci (10%); in 2015, 2016, 2017, 2018 and 2019, Streptococcus spp. (from 39–49%) were the most frequent strains isolated from the quarter milk samples. Other pathogens were isolated occasionally (below 15% in all years). In conclusion, the role of environmental bacteria has been gradually increasing in the Warmia Province. The importance of infectious pathogens has been decreasing, indicating the efficacy of the applied preventive programmes and a need for the development of new programmes targeting environmental pathogens.

Can domestic pigeon be a potential carrier of zoonotic Salmonella?

Salmonellosis is one of the most important bacterial diseases in pigeons. This study aimed to estimate the prevalence of Salmonella spp. in domestic pigeons (Columba livia f. domestica) in Poland, its antimicrobial susceptibility (both phenotypic and genotypic), and its capability for biofilm formation. The presence of selected virulence genes, nucleotide homology of selected genes, and susceptibility to bacteriophages were investigated as well. From the 585 pigeons tested, 5.47% turned out positive. All isolated strains were recognized as Salmonella enterica ser. Typhimurium. The asymptomatic pigeons were carriers of 37.5% of the isolates. The dominant variants were as follows: 1,4,[5],12,:i:1,2 (53.13%) and 1,4,[5],12,:‐:‐ (31.25%). Most of the strains analysed showed the ability to produce biofilm after 24 and 48 hr of incubation (59.38% and 53.13%, respectively). Over 90% of the strains were confirmed for lpfA, agafA, invA, sivH, and avrA virulence genes. Also, of the thirteen antimicrobial susceptibility genes, the following were confirmed: sul1, tet(A), bla_TEM‐1, floR, strA, and strB. The most common were the strB (18%) and tet(A) (12%) genes that are responsible for coding resistance to aminoglycosides and tetracyclines, respectively. Most of the strains were phenotypically resistant to oxytetracycline (46.88%), neomycin (53.13%) and tylosin (100%). The susceptibility of the investigated Salmonella strains to the bacteriophages was between 33% and 100%. MLST, PCR MP and ERIC PCR analyses indicated a very high genetic similarity of the investigated strains (over 99%). Results of our study indicate that Salmonella enterica ser. Typhimurium is still an important agent in domestic pigeons and that its antimicrobial resistance increases. Alarming is also the confirmation of a single‐phase variant 1,4,[5],12:i,‐, which could have increased virulence and multi‐drug resistance encoded on the plasmid. Most importantly, however, such strains have been isolated from humans with clinical symptoms of Salmonella infection.

Dietary administration of β-1,3/1,6-glucan and Lactobacillus plantarum improves innate immune response and increases the number of intestine immune cells in roach (Rutilus rutilus)

BACKGROUND

The aim of the study has been to compare the effect of dietary supplementation of β-1,3/1,6-glucan, Lactobacillus plantarum bacteria or their mixture on the growth performance, selected parameters of the immune system as well as the liver and intestinal histology of roach. Fish were fed for 14 days with four different diets, each treatment being carried out in triplicate. In control group, fish were fed dry commercial starter feed Aller Performa 2 (Aller Aqua, Denmark). The other experimental fish groups received the same commercial starter feed supplemented with: 1% β-1,3/1,6-glucan (Leiber® Beta-S) in group G; 108 cfu L. plantarum g- 1 in group L; 1% β-1,3/1,6-glucan + 108 cfu L. plantarum g- 1 in group G + L. The stimulating effect of the tested preparations was evaluated once the feeding with commercial feed exclusively was resumed and 2 weeks afterwards.

RESULTS

No effect on the survivability and growth performance of the fish was observed in any of the groups. Supplementation of feed with β-1,3/1,6-glucan improved (P < 0.05) selected parameters of innate humoral immunity and the pinocytotic activity of phagocytes. Increased respiratory burst activity of head kidney phagocytes (RBA) was observed in groups L and G + L (P < 0.05), and the effect persisted for 2 weeks after the commercial feed regime was resumed. An analogous tendency was determined for the killing activity of phagocytes (PKA) of the head kidney with respect to Aeromonas hydrophila, although this effect appeared only during the feed supplementation period. Supplying roach with β-1,3/1,6-glucan, singly or with L. plantarum, had no effect (P > 0.05) on the proliferation of mitogen-activated lymphocytes. However, an increase in the number of CD3-positive cells and goblet cells was noticed in the digestive system of the L group fish (P < 0.05).

CONCLUSIONS

The results show that feeding fish with added L. plantarum and β-1,3/1,6-glucan stimulates the non-specific resistance mechanisms and raises the counts of intestinal immune cells. Synbiotic may help to control serious bacterial diseases and offer an alternative to antibiotics commonly used in fish farming, and its prolonged immunostimulatory effect could increase fish surviving after release to the natural environment.

The applicability of the Migratest® kit for evaluating the chemotactic activity of peripheral blood neutrophils in goats on the example of animals supplemented with β-hydroxy-β-methylbutyrate (HMB)

The objective of this study was to determine the applicability of the Migratest® kit for evaluating the chemotactic activity of peripheral blood neutrophils in goats. The experiment was performed on 14 goat kids aged 30±2 days, divided into two groups of 7 animals each: C - control group, and E - experimental group, supplemented with β-hydroxy-β-methylbutyrate (HMB), a typical immunostimulant which influences the phagocytic activity of peripheral neutrophils. The feed administered to experimental goat kids was supplemented with HMB at 40 mg/kg BW, whereas control goat kids were administered standard farm-made feed without supplementation. Blood was sampled from the jugular vein immediately before the experiment (day 0) and on experimental days 15, 30 and 60 to determine the chemotactic activity of peripheral blood neutrophils in goats. The results of the study indicate that the Migratest® kit can be used to evaluate the influence of immunomodulators on the chemotactic activity of peripheral blood neutrophils in goats. The results of the assay are most effectively presented by calculating the chemotactic index which accounts for the chemotaxis or migration of neutrophils in the presence or absence of a chemotactic factor, respectively, and the percentage of granulocytes that migrate towards fMLP. The results of both presentation methods appear to be identical.

The Effects of β-Hydroxy-β-Methylbutyrate (HMB) on Chemotaxis, Phagocytosis, and Oxidative Burst of Peripheral Blood Granulocytes and Monocytes in Goats

Simple Summary

The main focus of industrial livestock production is to maximise production output without compromising the well-being of animals, which is why animal diets are supplemented with various feed additives. Feed additives boost immunity and protect animals against pathogens. The list of potential feed additives includes β-hydroxy-β-methylbutyrate (HMB) which occurs naturally in small quantities in citrus fruit, avocado, asparagus, cauliflower, selected fish species, red wine, milk, and alfalfa. However, its mechanism of action and effects on immune system cells have not been thoroughly investigated in animals, including goats. In the present study, the experimental goats whose diets were supplemented with HMB over a period of 60 days were characterised by higher levels of chemotactic and phagocytic activity and a higher rate of oxidative metabolism of peripheral blood granulocytes and monocytes than control group animals whose diets were not supplemented. Granulocytes and monocytes constitute the first line of defence against pathogens and protect animals against disease. They play a particularly important role in young animals which are more susceptible to viral and bacterial infections. Feed additives can deliver numerous benefits by boosting immunity and preventing the spread of infectious diseases in goats.

Abstract

The objective of this study was to determine the effect of β-hydroxy-β-methylbutyrate (HMB) on the chemotactic activity, phagocytic activity, and oxidative metabolism of peripheral blood granulocytes and monocytes in goats. Goat kids aged 30 ± 3 days were divided into two groups of 12 animals each: I—control, and II—experimental. Experimental group animals were fed a diet supplemented with HMB in the amount of 50 mg/Kg BW; whereas the diets of control goats were not supplemented. At the beginning of the experiment (day 0) and on experimental days 15, 30, and 60, blood was sampled from the jugular vein to determine and compare chemotactic activity (MIGRATEST^® kit), phagocytic activity (PHAGOTEST^® kit), and oxidative metabolism (BURSTTEST^® kit) of peripheral blood granulocytes and monocytes by flow cytometry. The analyses of the chemotactic and phagocytic activity of granulocytes and monocytes revealed statistically higher levels of phagocytic activity in the experimental group than in the control group, as expressed by the percentage of phagocytic cells and mean fluorescence intensity. HMB also enhanced the oxidative metabolism of both granulocytes and monocytes, expressed by the rate of oxidative metabolism and mean fluorescence intensity after stimulation with Escherichia coli bacteria and PMA (4-phorbol-12-β-myristate-13-acetate).

Antiviral effects of nisin, lysozyme, lactoferrin and their mixtures against bovine viral diarrhoea virus

Background

Bovine viral diarrhoea virus (BVDV), an enveloped, single-stranded, positive-sense RNA virus from the Flaviviridae family, is a globally distributed bovine pathogen. BVDV infection in cattle, despite having a wide range of clinical manifestations, is invariably responsible for significant economic losses. To counteract these losses, various schemes to control and eradicate BVDV have been implemented, although safe drugs effectively inhibiting the replication of the virus are still lacking. The purpose of this study was to characterize the antiviral effect of naturally occurring proteins and peptide, such as bovine lactoferrin, chicken egg lysozyme, and nisin from Lactococcus lactis, used both individually and in combination, against the cytopathic NADL strain of BVDV in vitro. After determining the cytotoxicity level of each protein or peptide to MDBK cells, its antiviral effects were evaluated using virucidal, cytopathic effect inhibition and viral yield reduction assays. In addition, the influence of the tested compounds on the intracellular viral RNA level was determined.

Results

The highest efficacy among the single treatments was achieved by bovine lactoferrin, which was effective both at the early stages of viral infection and during its entire course, although the effect weakened over time. Nisin and lysozyme were effective at later stages of infection, and the intensity of their effect did not diminish with time. Nisin+lactoferrin and lysozyme+lactoferrin combinations demonstrated stronger antiviral effects than did the single substances. The nisin+lactoferrin mixture present during the whole period of infection produced the strongest anti-BVDV effect in our entire research on both the extracellular viral titre (titre reduction up to 2.875 log ≈ 99.9%) and the intracellular viral RNA level (reduction up to 89%), and this effect intensified over the incubation time.

Conclusions

The tested substances could be applied in bovine viral diarrhoea prevention and therapy, especially when used in combination.

Electronic supplementary material

The online version of this article (10.1186/s12917-019-2067-6) contains supplementary material, which is available to authorized users.

In vitro immunomodulatory effect of nisin on porcine leucocytes

Nisin, a lantibiotic bacteriocin, has been used for years as a natural food preservative. In addition to its antimicrobial activity, nisin also shows immunomodulatory properties, and the nisin-producing Lactococcus lactis strain has been successfully tested as a probiotic in weaned piglets. However, the impact of nisin on porcine immune cells has not yet been explored. The objective of the present study was to examine the in vitro immunomodulatory effect of nisin on porcine peripheral blood leucocytes. The whole heparinized blood samples or freshly isolated peripheral blood mononuclear cells (PBMCs) were incubated with different nisin concentrations (0, 1.56, 3.125, 6.25, 12.5, 25 or 50 µg/ml) for 1, 24, 48 or 72 hr. Escherichia coli bacteria were used to stimulate blood phagocytes, while concanavalin A and lipopolysaccharide from E. coli were used as mitogens. Control cells remained unstimulated. MTT colorimetric assay was used to evaluate PBMCs viability and mitogenic response. Phagocyte activity and T-cell proliferation were measured by flow cytometry. Flow cytometer was also used for immunophenotyping of T cells. Cytokine levels in the culture media were determined using commercial immunoassay (ELISA) kits. The highest concentration of nisin exhibited proliferative activity (p ˂ 0.05), stimulated interleukin-1 beta (IL-1β) and interleukin-6 (IL-6) production (both at p ˂ 0.001), and increased the percentage of CD4⁺ CD8⁺ T cells (p ˂ 0.001) among unstimulated leucocytes. After cell stimulation, however, the highest nisin concentration showed antiproliferative activity (p ˂ 0.05), decreased phagocytic functions (p ˂ 0.05) and inhibited the synthesis of IL-6 (time- and concentration-dependent effect). As a typical bacterial product, nisin had a stronger impact on innate immune cells, and its effect on T cells was likely a consequence of the modulation of the activity of antigen-presenting cells. Nisin may be a good candidate as an immunomodulator in pig breeding.

CD4- and CD8-expressing cells found in the bovine and porcine anterior chamber of the eye

The aim of the present study was to investigate whether the anterior chamber constitutes part of the normal migratory pathway of CD4+ and CD8+ lymphocytes in cattle and swine. The cells obtained from aqueous humor of cows and pigs were stained for CD4 and CD8 receptors, and subsequently analyzed with flow cytometry. The mean percentage of CD4+CD8-, CD4-CD8+ and CD4+CD8+ cells within the total lymphocyte population of the bovine anterior chamber was, respectively, 17.88, 12.64 and 27.26%. In turn, the mean values of these parameters in pigs were 1.77, 38.48 and 17.45, respectively. Among bovine and porcine CD4+CD8+ cells prevalent were those displaying CD4lowCD8low and CD4lowCD8high phenotypes, respectively. The results suggest that the anterior chamber in cattle and swine is an element in the normal migratory pathway of CD4+, CD8+ and CD4+CD8+ cells. Furthermore, the contribution of these subsets in the anterior chamber lymphocyte population can differ considerably between animal species.

Biofilm production and other virulence factors in Streptococcus spp. isolated from clinical cases of bovine mastitis in Poland

Background

Mastitis is a common disease in dairy cattle throughout the world and causes considerable economic losses each year. An important aetiological agent of this disease is bacteria of the genus Streptococcus; hence, exploring the mechanisms of virulence in these bacteria is an extremely important step for the development of effective prevention programmes. The purpose of our study was to determine the ability to produce biofilm and the occurrence of selected invasiveness factors among bacteria of the genus Streptococcus isolated from cattle with the clinical form of mastitis in northeastern Poland.

Results

Most of the isolates analysed demonstrated an ability to produce biofilm (over 70%). Virulence genes were searched for in the three most common streptococci in our experiment: S. agalactiae, S. uberis and S. dysgalactiae. For S. agalactiae, only four genes were confirmed: rib (33%), cylE (78%), bca (37%), and cfb (100%). The genes pavA, scpB, bac and lmb were not present in any of the tested strains. The dominant serotypes of the species were Ia (n = 8) and II (n = 8), in addition to some strains that were not classified in any of the groups (n = 6). Out of the eight selected genes for S. uberis (sua, pauA/skc, gapC, cfu, lbp, hasA, hasB, hasC), only one was not found (lbp). Finally, two genes were chosen for S. dysgalactiae (eno and napr), and their presence was confirmed in 76% and 86% of the strains, respectively.

Conclusions

The experiment showed that strains of Streptococcus spp. isolated from dairy cattle with clinical cases of mastitis in the northeastern part of Poland possess several invasiveness factors that can substantially affect the course of the disease, and this should be considered when developing targeted prevention programmes.

Effect of feed supplementation with kynurenic acid on the morphology of the liver, kidney and gills in rainbow trout (Oncorhynchus mykiss Walbaum, 1792), healthy and experimentally infected with Yersinia ruckeri

Kynurenic acid (KYNA) is an endogenous substance produced on the kynurenine pathway which is primarily known for its neuroactive properties. Recently, it has been proven that KYNA is a selective ligand for G protein-coupled receptor (GPR 35), presented on immunocompetent cells such as T lymphocytes. This opens up new possibilities of its application as an immunostimulating substance in aquaculture. Thus far, no histopathological investigations in fish have been completed to evaluate influence of KYNA supplementation in feed. This study has been undertaken to determine the effect of feed supplementation with KYNA (2.5, 25, 250 mg kg^-1 of feed) for 28 days on the liver, gills and kidney in healthy fish and experimentally infected with Yersinia ruckeri. In a control group were observed a fatty liver, which is natural for this fish species in the autumn and winter season. As the dose of the supplement was increased, the fat liver changed, it decreased or completely disappeared. Additionally, inflammatory changes occurred in all the analysed organs, and their intensification was dose dependent. In the fish experimentally infected, KYNA caused aggravation of the signs in the liver, kidneys and gills, and the effect was dose dependent. The results implicate that KYNA may be a stressor for fish.

Phenotypic and genotypic antimicrobial susceptibility pattern of Streptococcus spp. isolated from cases of clinical mastitis in dairy cattle in Poland

Mastitis of dairy cattle is one of the most frequently diagnosed diseases worldwide. The main etiological agents of mastitis are bacteria of the genus Streptococcus spp., in which several antibiotic resistance mechanisms have been identified. However, detailed studies addressing this problem have not been conducted in northeastern Poland. Therefore, the aim of our study was to analyze, on phenotypic and genotypic levels, the antibiotic resistance pattern of Streptococcus spp. isolated from clinical cases of mastitis from dairy cattle in this region of Poland. The research was conducted using 135 strains of Streptococcus (Streptococcus uberis, n = 53; Streptococcus dysgalactiae, n = 41; Streptococcus agalactiae, n = 27; other streptococci, n = 14). The investigation of the antimicrobial susceptibility to 8 active substances applied in therapy in the analyzed region, as well as a selected bacteriocin (nisin), was performed using the minimum inhibitory concentration method. The presence of selected resistance genes (n = 14) was determined via PCR. We also investigated the correlation between the presence of resistance genes and the antimicrobial susceptibility of the examined strains in vitro. The highest observed resistance of Streptococcus spp. was toward gentamicin, kanamycin, and tetracycline, whereas the highest susceptibility occurred toward penicillin, enrofloxacin, and marbofloxacin. Additionally, the tested bacteriocin showed high efficacy. The presence of 13 analyzed resistance genes was observed in the examined strains [gene mef(A) was not detected]. In most strains, at least one resistance gene, mainly responsible for resistance to tetracyclines [tet(M), tet(K), tet(L)], was observed. However, a relationship between the presence of a given resistance gene and antimicrobial susceptibility on the phenotypic level was not always observed.

CD25+CD127+Foxp3- Cells Represent a Major Subpopulation of CD8+ T Cells in the Eye Chambers of Normal Mice

The aim of this study has been to determine whether eye chambers constitute part of the normal migratory pathway of naive CD4⁺ and CD8⁺ T cells in mouse and if natural CD4⁺CD25⁺Foxp3⁺ and CD8⁺CD25⁺Foxp3⁺ regulatory T cells are present within these eye compartments. To this aim, the cells obtained from aqueous humor (AH) of normal mice were phenotyped in terms of the expression CD4, CD8, CD25, CD127 and transcription factor Foxp3. The mean percentage of CD8⁺ T cells in the total AH lymphocyte population was as high as 28.69%; the mean percentage of CD8^high and CD8^low cells in this population was 34.09% and 65.91%, respectively. The presence of cells with the regulatory phenotype, i.e. CD25⁺Foxp3⁺ cells, constituted only 0.32% of CD8⁺ T cell subset. Regarding the expression of CD25, AH CD8⁺ T cells were an exceptional population in that nearly 85% of these cells expressed this molecule without concomitant Foxp3 expression. Despite having this phenotype, they should not be viewed as activated cells because most of them co-expressed CD127, which indicates that they are naive lymphocytes. With regard to the markers applied in the present research, CD8⁺CD25⁺CD127⁺Foxp3^- T cells represent the most numerous subset of AH CD8⁺ cells. The results suggest that eye chambers in mice are an element in the normal migratory pathway of naive CD8⁺ T cells. The study presented herein demonstrated only trace presence of CD4⁺ cells in the eye chambers, as the mean percentage of these cells was just 0.56. Such selective and specific homing of CD8⁺ and CD4⁺ cells to the eye chambers is most clearly engaged in the induction and maintenance of ocular immune privilege.

Effect of oral administration of commercial gold nanocolloid on peripheral blood leukocytes in mice

During the last few decades, owing to their unique properties, gold nanoparticles (AuNPs) have found numerous biomedical applications. Studies on rodents prove that AuNPs entering an organism easily reach the bloodstream and undergo wide tissue distribution. The presence of nanoparticles inside blood and bone marrow cells of exposed animals may implicate its influence on hematopoesis and the functions of peripheral blood leukocytes. The aim of this study was to determine the effect of oral administration of commercial gold nanocolloid, recommended by the producer as a dietary supplement, on the percentage of lymphocyte populations and proliferative response, as well as the activity of phagocytes in the peripheral blood of mice. The colloid was given to the animals in three different doses (0.25, 2.5, 25 ppm), for three different time periods (7, 14, 28 days). Mice given nanoparticles showed increased activity of phagocytes and some changes in the lymphocyte phenotypes. The elevated activity of granulocytes and monocytes, in terms of both phagocytic and respiratory burst activity, was transient and noticed only after a short time of administration, which may indicate some adaptability of blood phagocytes to prolonged presence of gold nanoparticles in the body. However, phenotypic modifications among lymphocytes in the group of animals given the middle dose of colloid (i.e. increased percentage of B and CD4+CD8+ DP T cells) did not occur until after the 28-day administration, which in turn seems indicative of some immune dysregulation due to the prolonged contact with nanogold.

Commercial Metal-Based Nanocolloids - Evaluation of Cytotoxicity

The purpose of the study was to determine the cytotoxicity of commercial silver, gold, and copper nanocolloids towards two established cell lines (NIH/3T3 and GMK) and primary chick embryo cell culture (CECC), using routine colorimetric assays: MTT, NRU, and LDH, which enable a preliminary evaluation of the mechanism of cytotoxic effect of the tested substances. The MTT assay evaluates the activity of mitochondria, NRU assay reveals the damage to lysosomes, while LDH assay shows injuries to the cytoplasmic membrane. The NRU assay proved to be non-applicable to the tested nanocolloids, most probably due to the interaction of nanoparticles with neutral red dye, which affected the colorimetric reaction. The MTT assay was more sensitive than LDH because the intercellular effect of a substance occurs before permanent damage to the cytoplasmic membrane. Silver nanocolloid was distinguished by the highest cytotoxicity, irrespective of the applied cell model, although the other two metals showed some cytotoxic effects as well, with gold nanocolloid being more toxic than copper one. Although the primary chick embryo cell culture, as a model reflecting more faithfully the conditions in a living organism than continuous cell lines, was undistinguished by elevated tolerance to the most toxic silver nanocolloid, it showed the tendency to recovery from the growth suppression with longer exposure after the application of less toxic gold and copper nanocolloids.

The splenocyte proliferative response and cytokine secretion in mice after oral administration of commercial gold nanocolloid

Owing to their unique physicochemical properties, gold nanoparticles find numerous biomedical applications. Experiments on rodents prove that the main target organs of gold nanoparticles entering an organism are the liver and spleen, whose reticuloendothelial system removes foreign particles from the bloodstream. Through interactions with resident tissue macrophages, nanoparticles can evoke a systemic immunological response.

The aim of this study has been to determine the effect of oral administration of commercial gold nanocolloid, recommended by the producer inter alia as a dietary supplement, on the proliferative activity and cytokine secretion by murine splenocytes. The colloid was given to the animals in three different doses (0.25, 2.5, 25 ppm), for three different time periods (7, 14, 28 days). The influence of nanogold on splenocyte functions was time-dependent and the various doses were distinguished by distinct modes of action. The lowest dose had a pro-inflammatory or immunostimulating effect, enhancing the synthesis of pro-inflammatory cytokines (IL-1β, IL-6, TNF-α). The effect of the highest dose can be considered as a pro-inflammatory, or immunotoxic one, because the stimulated cytokine synthesis was accompanied by a drastic decline in the proliferative activity of lymphocytes. The medium dose, while inhibiting the synthesis of pro-inflammatory cytokines of macrophages, simultaneously stimulated the proliferation of lymphocytes. All the doses also modulated the synthesis of IL-2, which may implicate their effect on the immunoregulatory mechanisms of an organism. The effect of alimentary administration of gold nanocolloid on the immune system seems to be difficult to predict, hence a risk that this type of dietary supplements might have some adverse impact on the immunity cannot be excluded, especially after their chronic administration.

On the toxicity of kynurenic acid in vivo and in vitro

BACKGROUND

Kynurenic acid (KYNA), a tryptophan metabolite is an antagonist of ionotropic glutamate receptors and alpha-7 nicotinic receptor. Moreover, it is an agonist of G-protein receptor GPR35. Its neuroprotective, anticonvulsant, anti-inflammatory and antioxidant activity was documented. KYNA is present in food and herbal medicines. However, the data on effects induced by a long-lasting treatment with KYNA is lacking. The aim of the study was the assessment of toxicity of a prolonged administration of KYNA in rodents. The cytotoxicity of KYNA in vitro was also examined.

METHODS

Adult mice and rats were used. KYNA was administered in the drinking water in concentrations of 25 or 250mg/L for 3-21 days. The following cells were cultured in an in vitro study: mouse fibroblast (NIH/3T3), green monkey kidney cells and primary chick embryo cells (CECC). Cell viability was determined with methyl thiazol tetrazolium reduction assay, neutral red uptake assay and lactate dehydrogenase leakage assay.

RESULTS

KYNA affected neither body gain nor body composition. Blood counts were also unaffected. The viability of cells in the culture was lowered at high millimolar concentrations of KYNA. An elevated viability of GMK and CECC cells was detected in the presence of KYNA in micromolar concentrations.

CONCLUSIONS

The obtained results showed that a long-term application of KYNA in the drinking water is well-tolerated by rodents. No evidence of a toxic response was recorded. Achieved results indicate that diets containing a high amount of KYNA or enriched with KYNA should not cause any risk to the human health.

The in vitro effect of bovine lactoferrin on the activity of organ leukocytes in rainbow trout (Oncorhynchus mykiss), European eel (Anguilla anguilla) and wels catfish (Silurus glanis)

Lactoferrin (LF) is a glycoprotein found in milk, neutrophil granules, secretions and selected organs of mammals. Lactoferrin exhibits antibacterial, antiviral, fungicidal, immunoregulatory and other functions. Although fish are devoid of this protein and its cell receptors, LF effect on the immune mechanisms of fish has been demonstrated. The objective of this study was to investigate the effect of bovine lactoferrin, applied in vitro, on the activity of head kidney and spleen leukocytes in three freshwater fish species: rainbow trout (Oncorhynchus mykiss), European eel (Anguilla anguilla) and wels catfish (Silurus glanis). The obtained results validate LF beneficial effect on the respiratory burst of phagocytes in rainbow trout and wels catfish despite the fact that the potential killing activity against Aeromonas hydrophila was not stimulated in any of the studied species. Bovine lactoferrin enhanced the proliferation of T-lymphocytes in rainbow trout and European eel, as well as of B-lymphocytes in rainbow trout.

Immunomodulating effect of Inter Yeast S on the non-specific and specific cellular and humoral immunity in lambs

The objective of this study was to determine the stimulating effect of the Inter Yeast S dietary supplement on selected parameters of specific and non-specific humoral and cellular immunity in lambs. The study involved 32 lambs aged 30 +/- 3 days, divided into two equal groups: II--control, and II--experimental. Experimental group animals were fed a C-J concentrate mixed with a prebiotic, the Inter Yeast S, commercially available, containing dried brewer's yeast Saccharomyces cerevisiae in the amount of 3 g/kg of the concentrate. At the beginning of the experiment (day 0) and on the 15th, 30th and 60th day of the study, blood was sampled from the jugular vein to determine selected parameters of biochemical, specific and non-specific humoral and cellular immunity in lambs (total protein levels, gamma globulin levels, lysozyme activity, ceruloplasmin activity, proliferative response of blood lymphocytes (MTT) after stimulation with LPS or ConA, the metabolic activity (RBA) and potential killing activity (PKA) of phagocytes). As regards humoral immunity parameters, significantly higher gamma globulin levels and higher lysozyme and ceruloplasmin activity were found in blood serum of experimental lambs administered the Inter Yeast S, compared with those determined in control lambs not fed the supplement. No statistically significant differences in serum total protein were found between the control and experimental groups. An analysis of cellular immunity indicators revealed significantly higher levels of RBA and PKA, and higher proliferative response of blood lymphocytes (MTT) after stimulation with LPS and ConA in the experimental group, compared with those observed in the control group.

Biological properties of Roakin strain of NDV and TK900 strain of ADV after serial passages in CECC in the presence of methisoprinol and KLP-602

Twenty serial passages of the TK900 strain of Aujeszky's disease virus (ADV) and the Roakin strain of Newcastle disease virus (NDV) were made in a chicken embryo cell culture (CECC), in the presence of two antiviral agents: Methisoprinol and KLP-602. The physicochemical properties of passaged viruses were determined. The results obtained suggest that Methisoprinol causes changes in the structure of viral proteins, whereas KLP-602 affects the envelope-dependent properties of the virus. It was also found that the alternations observed in passaged viruses were temporary phenotypic changes only, and not a consequence of permanent transformations of their genotypes.

Effect of methisoprinol and KLP-602 on virus replication in chicken embryos

The aim of the present study was to examine the effects of two immunomodulators (KLP-602 and Methisoprinol) on the proliferation of two strains of Newcastle disease virus in chick embryos. The effect of the maximum tolerable doses of both drugs (Methisoprinol--6 mg/embryo, KLP-602--5 mg/embryo) on lymphocyte reactivity were determined prior to the experiment. Both drugs inhibited the replication of the Roakin strain of NDV in various experimental designs, but neither of them affected the proliferation of the LaSota strain of NDV.

[Melanocytic nevi as one of the risk factors of melanoma malignum]

The paper presents the contemporary view on the melanocytic nevi and their role in the pathogenesis of skin malignant melanoma. There is a strong relationship between the presence of the melanocytic naevi and the incidence of melanoma malignum. Therefore dermatologists should pay close attention to patients from the risk group, with many common melanocytic naevi and atypical melanocytic naevi, family history of melanoma, bright fair skin, with history of sun burns. These patients should be thoroughly and regularly checked up. Examination should include photographic surveillance and dermatoscopy and every suspected mole should be excised with further histological examination. This kind of procedure intensifies the possibility of early recognition of melanoma malignum of the skin, which is crucial for successful treatment of this dangerous disease.

Effect of KLP-602 on virus replication in cell cultures

The effect of KLP-602 (active substance: lysozyme dimer) on the replication of two animal viruses: the TK900 strain of Aujeszky's disease virus and the Roakin strain of the Newcastle disease virus were investigated. The maximal tolerable dose of the drug was determined for two cell cultures (CECC and GMK) and the effect of the medicine on the titre range of infectious viruses and their adsorption was assayed. The direct impact of KLP-602 on the viral strains used was also determined. And finally the replication dynamics of viruses in the presence of KLP-602 preparation was estimated. KLP-602 showed no direct effect on either the viruses applied in the study or their adsorption. The drug, introduced into the culture 24 hours before its infection, did not affect the replication of the pseudorabies virus, but decreased the titre of the Newcastle disease virus. KLP-602 introduced simultaneously with the infection considerably lowered the final titres of both viruses. The medicine had the greatest inhibitory effect on the replication dynamics of both types of viruses in the CECC and of the pseudorabies virus in the GMK culture upon the maximal tolerable concentrations of drug and low infectious doses of viruses applied.

Effect of methisoprinol on virus replication in cell cultures

The effect of Methisoprinol (active substance: isoprinozine) on the replication of two animal viruses, the TK900 strain of Aujeszky's disease virus and the Roakin strain of the Newcastle disease virus was investigated. When the maximal tolerable doses of the drug were added to two cell cultures (CECC and GMK), its effect on the level of infectious titres of theviruses and their adsorption were assayed. Investigations were also performed to assess the direct effect of Methisoprinol on the viral strains used. The final stage of the experiment aimed at analysing of the replication dynamics of the viruses in the presence of Methisoprinol. Methisoprinol showed no direct effect on the viruses used in the study. Nor did it affect their adsorption. The preparation applied to the culture 24 hours before infection did not influence the replication of viruses, but administered simultaneously with the infection significantly lowered the final titres of viruses. The highest inhibitory effect of the drug was observed during the analysis of the replication dynamics of both viruses in CECC and of pseudorabies virus in GMK cell culture upon the application of the maximal tolerable doses of Methisoprinol and low infectious doses of the viruses.

Influence of methisoprinol on the replication of rhabdoviruses isolated from carp (Cyprinus carpio) and catfish (Ictalurus melas): in vitro study

Rhabdoviruses constitute one of the most pathogenic viruses isolated from rainbow trout and carp culture. Several viruses were also isolated from other species of fish. These viruses are mostly associated with epizootics and heavy losses. Spring viraemia of carp virus (SVCV) and pike fry rhabdovirus (PFRV) have been the most extensively studied, due to their significant economic impact. Significant progress has been made towards controlling the major bacterial fish diseases using vaccines, but this approach has not yet been successful in preventing viral diseases in fish culture. However, for an effective therapeutic approach, specific drugs should be developed to selectively inhibit virus replication and/or stimulate antiviral protection. In this investigation we examined the in vitro influence of methisoprinol on the SVCV and virus isolated from catfish (Ictalurus melas) replication by measuring their RNA synthesis. The viruses were propagated in EPC cells and cell cultures containing methisoprinol were followed by infection with SVCV or catfish rhabdovirus suspension containing 10(7) TCID50/ml. Methisoprinol (Polfa, Poland) at concentrations of 0, 100, 200, 300, 400 and 500 microg/ml of medium (Glasgow MEM) was used in this study. The results of this study show the strong inhibition of incorporation (cpm) of [3H]-uridine into SVCV and catfish rhabdovirus RNA in cell culture exposed to methisoprinol at various concentrations. The highest percent of inhibition of viral RNA at 72 h after infection with two rhabdoviruses were observed in doses of 400 and 500 microg/ml of methisoprinol in medium. The results of this in vitro study showed that methisoprinol inhibits the rhabdoviruses isolated from carp and catfish.

Effect of Methisoprinol and KLP-602 on the development of immunocompetent organs and selected biochemical indices of the allantoic fluid of chicken embryos

The immunostimulating effect of Methisoprinol and KLP-602 on the development of organs of the immunological system, the reactivity of lymphocytes and selected biochemical parameters of allantoic fluid (the activity of ceruloplasmin and lysozyme) during embryogenesis was tested. A positive effect of these drugs, especially KLP-602, was found. KLP-602 positively affected the reactivity of lymphocytes and the development of immunocompetent organs of chicken embryos as well as it increased the activity of ceruloplasmin in allantoic fluid 6 hours after injection.