In Vivo Bacteriophages' Application for the Prevention and Therapy of Aquaculture Animals-Chosen Aspects.

To meet the nutritional requirements of our growing population, animal production must double by 2050, and due to the exhaustion of environmental capacity, any growth will have to come from aquaculture. Aquaculture is currently undergoing a dynamic development, but the intensification of production increases the risk of bacterial diseases. In recent years, there has been a drastic development in the resistance of pathogenic bacteria to antibiotics and chemotherapeutic agents approved for use, which has also taken place in aquaculture. Consequently, animal mortality and economic losses in livestock have increased. The use of drugs in closed systems is an additional challenge as it can damage biological filters. For this reason, there has been a growing interest in natural methods of combating pathogens. One of the methods is the use of bacteriophages both for prophylactic purposes and therapy. This work summarizes the diverse results of the in vivo application of bacteriophages for the prevention and control of bacterial pathogens in aquatic animals to provide a reference for further research on bacteriophages in aquaculture and to compare major achievements in the field.

Influence of Infectious Pancreatic Necrosis Virus and Yersinia ruckeri Co-Infection on a Non-Specific Immune System in Rainbow Trout (Oncorhynchus mykiss).

BACKGROUND: The IPNV is one of the most common viral pathogens of rainbow trout (Oncorhynchus mykiss), while Y. ruckeri infections are widespread among bacterial agents. The current study aimed to determine the influence of IPNV and Y. ruckeri co-infection on a non-specific immune response. METHODS: Two experiments were conducted. The first experiment determined the changes in non-specific immunity parameters upon the simultaneous occurrence of IPNV and Y. ruckeri infection. In the second experiment, infection with the IPNV was performed two weeks before Y. ruckeri infection. The level of total protein, gamma globulins, the activity of lysozyme and ceruloplasmin, as well as the metabolic activity and potential killing activity of phagocytes were measured: 0, 24 h, 72 h, 7 days, 14 days, and 21 days after co-infection. RESULTS: A differentiated effect on the parameters of the non-specific immune response was shown between single infections with the IPNV and Y. ruckeri as well as co-infection with these pathogens. CONCLUSIONS: The immune response in the course of a co-infection depended on the time between infections. IPNV infection causes lysozyme activity suppression, which may lead to secondary bacterial infections.

The Prevalence of Yersinia enterocolitica and Yersinia pseudotuberculosis in Small Wild Rodents in Poland.

Rodents are a large group of mammals that can be carriers of zoonotic pathogens such as Yersinia strains that cause yersiniosis. The prevalence of Yersinia enterocolitica and Yersinia pseudotuberculosis was determined in 214 small wild rodents from south-eastern Poland. Samples were analyzed by precultivation and PCR. Nine (4.2%) Y. enterocolitica and one (0.5%) Y. pseudotuberculosis isolates were received. Most of them (n = 5) were obtained from the common vole (Microtus arvalis). All Y. enterocolitica strains were classified as biotype (BT) 1A. A PCR analysis of virulence markers revealed that all Y. enterocolitica isolates contained the ystB gene and five isolates harbored a rare genetic combination of ail/ystB. Three of the four ail/ystB-positive isolates belonged to serotype O:5.27. The Y. pseudotuberculosis inv-positive isolate was classified as BT 1. A genetic analysis of Y. enterocolitica harboring the ystB gene revealed 100% similarity between the analyzed sequences and the sequences from diarrhea patients in India and the United Kingdom as well as high similarity with the sequences from different species of wild animals from Poland. The Y. pseudotuberculosis inv sequence was 100% identical to the sequence isolated from fully virulent clinical strain from France and Australia. The results of our study suggest that small wild rodents, especially voles and yellow-necked mice, may act as carriers of Yersinia strains. The high similarity of the tested gene sequences between our isolates and the isolates from other free-living animals indicates that small wild rodents can play a role in the epidemiology of yersiniosis and can shed Yersinia spp. into the environment.

Applicability of Thyroxine Measurements and Ultrasound Imaging in Evaluations of Thyroid Function in Turtles.

INTRODUCTION: The thyroid and parathyroid glands play a major role in maintaining physiological homeostasis in all vertebrates. Reptiles have plasma concentrations of thyroid hormones far lower than mammals. Low levels of these hormones in reptiles impede thyroid hormone detection with assays designed for the higher levels of mammals. The aim of this study was to explore teaming this with ultrasound imaging of the thyroid to appraise glandular function. MATERIAL AND METHODS: Thyroid function of four pond sliders was evaluated based on the results of T4 analyses and ultrasound. RESULTS: The concentrations of T4 varied considerably between the examined animals from <9 nmol/L to >167.3 nmol/L. Ultrasound examination revealed uniform echogenicity and a smooth outline of the thyroid gland in all animals. CONCLUSION: Monitoring of thyroid function based on T4 and electrolyte concentrations is helpful in assessing the health and living conditions of reptiles, which is important in veterinary practice but problematic. Ultrasound examinations are useful in diagnosing changes in gland structure, such as tumours and goitres, and a combination of both methods supports comprehensive assessments of the anatomy and function of the thyroid gland.

Bacteriophage-based cocktail modulates selected immunological parameters and post-challenge survival of rainbow trout (Oncorhynchus mykiss).

Recently, a rapid increase in the resistance of pathogenic bacteria to antibiotics and chemotherapeutics admitted for use in aquaculture has been observed. This happens especially often in intensive breeding. The use of drugs in closed circuits is problematic because it can damage biological filters. Therefore, in recent years, there has been a growing interest in natural methods of combating pathogens. These include bacteriophages. The aim of the study was to determine the safety of the new BAFADOR® bacteriophage-based preparation, its effect on selected immunological parameters and the effectiveness of prophylactic and therapeutic use after experimental infections with pathogenic bacteria Aeromonas hydrophila and Pseudomonas fluorescens. The use of BAFADOR® increased the activity of lysozyme, total protein level and immunoglobulin level. The level of ceruloplasmin in the rainbow trout serum remained unchanged regardless of the route of administration of the preparation. Potential killing activity and metabolic activity of spleen phagocytes and proliferation of pronephros lymphocytes were higher compared to the control group. Both therapeutic and prophylactic application of the preparation after mixed experimental infection of A. hydrophila and P. fluorescens limited the mortality of rainbow trout.

Influence of trans-resveratrol on macrophage and lymphocyte activity in rainbow trout (Oncorhynchus mykiss) - in vitro study.

The objective of this study was to investigate the effect of trans-resveratrol, a potent antioxidant with anti-inflammatory and chemopreventive properties, naturally occurring in many fruits and plants on lymphocytes proliferation and also on macrophages metabolic and phagocytic activity. The aim of this study was to demonstrate the immunomodulatory effects of the compound on fish immunocompetent cells and determine the type of this interaction (immunosuppression or immunostimulation). Proliferative activity of lymphocytes was studied by MTT assay, and the respiratory burst was evaluated using the respiratory burst activity (RBA) test. Phagocytic killing was tested using the PKA test. The experiment have shown that trans-resveratrol suppressed blood B cells, while there was no significant influence on blood T lymphocytes. However, insignificant stimulatory effect occurred at the lowest concentration. In addition, the compound inhibited proliferation of T and B lymphocytes isolated from the organs. Importantly, trans-resveratrol caused stimulation of blood and organs macrophages phagocytic killing, and also increased the respiratory burst of macrophages isolated from organ. These results suggest a potential use of trans-resveratrol as an immunomodulator of innate immunity in fish. This is particularly important, as this kind of resistance plays leading role in protecting the body against infection. In comparison, adaptive immunity is slower and also much less precise.

The prevalence of Yersinia enterocolitica in game animals in Poland.

Natural reservoirs of Yersinia (Y.) enterocolitica comprise different animal species, but little is known about the role of wild animals in the epidemiology of yersiniosis. The aim of the study was to evaluate the prevalence of Y. enterocolitica among game animals in Poland. The bio-serotypes and the pathogenicity markers of the analyzed isolates were determined. The experimental material comprised rectal swabs from 857 free-living animals hunter-harvested over a period of 2 years (2013-2014) in hunting districts across Poland. The isolates from bacteriological studies were confirmed by PCR and bio-serotyped based on the results of biochemical and agglutination tests. In the group of the 218 analyzed isolates of Y. enterocolitica, 133 were derived from wild boars, 70 from red deer, 11 from roe deer and 4 from fallow deer, and they accounted for 61.0%, 32.1%, 5.1% and 1.8% of all isolates, respectively. Bio-serotyping assays revealed that 91.7% of the examined isolates belonged to biotype 1A (200/218). The remaining 18 isolates belonged to bio-serotypes 1B/NI (3/218, 1.4%), 1B/O:8 (1/218, 0.5%), 2/NI (6/218, 2.8%), 2/O:27 (1/218, 0.5%), 2/O:3 (1/218, 0.5%), 2/O:9 (2/218, 0.9%), 3/NI (2/218, 0.9%), 4/O:3 (1/218, 0.5%) and 4/O:9 (1/218, 0.5%). The ail gene, a suggestive virulence gene for Y. enterocolitica, has been found in 30 isolates from 20 wild boars, in 6 isolates from red deer, and in 1 isolate from roe deer. Our study demonstrated that Y. enterocolitica is frequently isolated from game animals in Poland, which poses a risk of spreading these infectious agents to other animal species and humans.