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.

Staphylococcus aureus from Subclinical Cases of Mastitis in Dairy Cattle in Poland, What Are They Hiding? Antibiotic Resistance and Virulence Profile.

Bovine mastitis is a common disease worldwide, and staphylococci are one of the most important etiological factors of this disease. Staphylococcus aureus show adaptability to new conditions, by which monitoring their virulence and antibiotic resistance mechanisms is extremely important, as it can lead to the development of new therapies and prevention programs. In this study, we analyzed Staphylococcus aureus (n = 28) obtained from dairy cattle with subclinical mastitis in Poland. The sensitivity of the isolated strains to antibiotics were confirmed by the disc diffusion method. Additionally, minimum inhibitory concentration values were determined for vancomycin, cefoxitin and oxacillin. Genotyping was performed by two methods: PCR melting profile and MLVF-PCR (multiple-locus variable-number tandem-repeat fingerprinting). Furthermore, the presence of antibiotic resistance and virulence genes were checked using PCR reactions. The analyzed strains showed the greatest resistance to penicillin (57%), oxytetracycline (25%) and tetracycline (18%). Among the analyzed staphylococci, the presence of 9 of 15 selected virulence-related genes was confirmed, of which the icaD, clfB and sea genes were confirmed in all staphylococci. Biofilm was observed in the great majority of the analyzed bacteria (at least 70%). In the case of genotyping among the analyzed staphylococci (combined analysis of results from two methods), 14 patterns were distinguished, of which type 2 was the dominant one (n = 10). This study provides new data that highlights the importance of the dominance of biofilm over antibiotic resistance among the analyzed strains.

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 Dolnoslaskie 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.

High Seroprevalence against SARS-CoV-2 among Dogs and Cats, Poland, 2021/2022.

The coronavirus SARS-CoV-2 is responsible for a pandemic in the human population that has unfolded since the beginning of 2020 and has led to millions of deaths globally. Apart from humans, SARS-CoV-2 has been confirmed in various animal species, including felines, canines, mustelids, and primates. Of these species, dogs and cats are the most popular companion animals worldwide. Several seroprevalence studies have already been performed in these animal species; however, the results vary depending on the location and especially the time of sampling. Here, serum samples were collected from a total of 388 dogs and 243 cats from three veterinary clinics in two cities (Gdansk and Olsztyn) in Poland between October 2021 and February 2022, when the country was in the midst of the fourth wave of viral spread. All sera were tested for antibodies against SARS-CoV-2 by a multispecies ELISA based on the receptor-binding domain and by an indirect immunofluorescence assay (iIFA). Overall, 18.9% of the feline sera and 16.0% of the canine sera tested positive using ELISA and iIFA. This relatively high seroprevalence among randomly selected animals is most likely related to the high case numbers in the human population and indicates a continuous occurrence of transspecies virus transmissions from infected owners to their pets. Hence, dogs and cats should be included in monitoring studies and/or outbreak investigations for a better understanding of the epidemiology of this virus.

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.

Effect of Different Routes of Vaccination against Aeromonas salmonicida on Rearing Indicators and Survival after an Experimental Challenge of Pikeperch (Sander lucioperca) in Controlled Rearing.

Bacterial diseases are a significant problem in the controlled rearing of fish. Furunculosis (Aeromonas sp.), flavobacteriosis (Flavobacterium sp.), and pseudomonadosis (Pseudomonas sp.) are currently the most frequently identified diseases in recirculating aquaculture systems of various fish species. Such a situation is also observed in pikeperch rearing. Due to the emerging difficulties of effective prophylaxis using commercial vaccines, interest in the use of autovaccinations is increasing, not only in ichthyopathology but also in other veterinary fields. Our research aimed to assess the effect of the vaccination method on the overall condition of the fish and survival after the experimental infection with Aeromonas salmonicida. Pikeperch were vaccinated by (1) bath, (2) a single i.p. injection, or (3) feed. The fish were measured and weighed on day 0 and after 28 and 56 days of the experiment. Specific growth rate, daily growth rate, condition factor, and feed conversion ratio were calculated. On days 7, 14, 21, and 28 of the experiment, ceruloplasmin and lysozyme levels were rated. In addition, a challenge test was performed. The obtained results showed that the method of vaccination is important and affects the growth of fish, the overall condition of fish, and survival after experimental infection.

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.

Complete genome sequences of Aeromonas and Pseudomonas phages as a supportive tool for development of antibacterial treatment in aquaculture.

BACKGROUND: Aquaculture is the fastest growing sector of food production worldwide. However, one of the major reasons limiting its effectiveness are infectious diseases among aquatic organisms resulting in vast economic losses. Fighting such infections with chemotherapy is normally used as a rapid and effective treatment. The rise of antibiotic resistance, however, is limiting the efficacy of antibiotics and creates environmental and human safety concerns due to their massive application in the aquatic environment. Bacteriophages are an alternative solution that could be considered in order to protect fish against pathogens while minimizing the side-effects for the environment and humans. Bacteriophages kill bacteria via different mechanisms than antibiotics, and so fit nicely into the 'novel mode of action' concept desired for all new antibacterial agents. METHODS: The bacteriophages were isolated from sewage water and characterized by RFLP, spectrum of specificity, transmission electron microscopy (TEM) and sequencing (WGS). Bioinformatics analysis of genomic data enables an in-depth characterization of phages and the choice of phages. This allows an optimised choice of phage for therapy, excluding those with toxin genes, virulence factor genes, and genes responsible for lysogeny. RESULTS: In this study, we isolated eleven new bacteriophages: seven infecting Aeromonas and four infecting Pseudomonas, which significantly increases the genomic information of Aeromonas and Pseudomonas phages. Bioinformatics analysis of genomic data, assessing the likelihood of these phages to enter the lysogenic cycle with experimental data on their specificity towards large number of bacterial field isolates representing different locations. CONCLUSIONS: From 11 newly isolated bacteriophages only 6 (25AhydR2PP, 50AhydR13PP, 60AhydR15PP, 22PfluR64PP, 67PfluR64PP, 71PfluR64PP) have a potential to be used in phage therapy due to confirmed lytic lifestyle and absence of virulence or resistance genes.

Pro- and antioxidant activity of chromium(III), iron(III), molybdenum(III) or nickel(II) and their mixtures.

The aim of this study was to examine the effect of chromium(III), iron(III), molybdenum(III) and nickel(II) and their combinations on pro- and antioxidant activity in mouse embryo fibroblasts and liver cancer cells. The present study shows that chromium(III), iron(III), nickel(II) and molybdenum(III) induce oxidative stress. In the case of chromium(III), nickel(II) and molybdenum(III) the intracellular ROS were dominant. However, in the case of iron(III) MDA was dominant - the end product of lipid peroxidation. Antioxidant activity of superoxide dismutase and catalase increased in low concentration of chromium(III); however, they decreased in higher concentrations. The same enzymes decreased after iron(III), nickel(II) and molybdenum(III) treatment in dose dependent manner. The activity of glutathione peroxidise decreased in dose dependent manner in all used microelements. Additions of Cr(III) at 200 µM plus Fe(III) at 1000 µM showed synergistic effect in ROS production and in lowering antioxidant activity. The same type of interaction in pairs Cr(III) at 1000 µM plus Fe(III) or Ni(II) or Mo(III) at concentration of 200 µM was observed. The protective effects of Cr(III) in antioxidant activity and in lowering intracellular ROS production in pairs of Cr(III) at 200 µM and Ni(II) or Mo(III) at concentration of 1000 µM were observed.

Influence of bacteriophages cocktail on European eel (Anguilla anguilla) immunity and survival after experimental challenge.

Inland fishery belongs to those branches of animal production that use very large amounts of chemotherapeutics, in particular antibiotics. The accumulation of chemotherapeutic agents in bottom sediments is a direct threat to the aquatic environment and directly affects the condition and health of the fish. Finding a preparation that could be used both prophylactically to increase the resistance of fish and therapeutically in case of infection with pathogenic bacteria, without side effects for fish and aquatic environment could be a great solution to this problem. Our aim was to determine influence of BAFADOR® the new bacteriophage-based preparation on European eel immunity and survival after experimental challenge. Application of BAFADOR® increased total protein level, immunoglobulin level, lysozyme activity and ceruloplasmin level in European eel serum. Potential killing activity and metabolic activity of spleen phagocytes as well as pronephros lymphocyte proliferation of was higher compared to control. The preparation also reduced mortality after experimental infections with the pathogenic bacteria Aeromonas hydrophila and Pseudomonas fluorescens. Our results showed that preparation BAFADOR® is well tolerated by the fish organism causing stimulation of cellular and humoral immunity parameters and reduces the mortality of the European eel after experimental challenge.

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.

Influence of Inosine Pranobex on Cell Viability in Normal Fibroblasts and Liver Cancer Cells.

INTRODUCTION: Inosine pranobex (Isoprinosine) stimulates cell-mediated immune responses to viral infections in humans and might have also therapeutic use in animals. The aim of this study was to compare three in vitro cytotoxicity assays on mouse embryo fibroblasts and liver cancer cells and determine their ability to detect early cytotoxic effects for inosine pranobex. MATERIAL AND METHODS: BALB/3T3 clone A31and HepG2 cells were incubated with inosine pranobex at concentrations from 0.1 to 1,000 µg/mL. Cell viability was determined with the MTT reduction, the LHD release, and the NRU tests. RESULTS: A decrease in the cell viability was observed after incubating the BALB/3T3 clone A31and HepG2 cells with inosine pranobex. CONCLUSIONS: Based on the cytotoxicity endpoints measured in these investigations in BALB/3T3 clone A31cells, it can be concluded that the cell membrane may be the first part of the cell to be affected by inosine pranobex. The disintegration of lysosomes and mitochondria follows mitochondria damage. In HepG2 cells likewise, the cell membrane may be the first part of the cell to be affected by inosine pranobex. Also in liver cancer cells, the disintegration of mitochondria (assessed with the MTT reduction assay) and next of lysosomes (assessed with the NRU assay) follows mitochondria damage.

Genotoxicity and Mutagenicity of Inosine Pranobex.

INTRODUCTION: Inosine pranobex (Methisoprinol, ISO, Isoprinosine) is an immuno-modulatory antiviral drug that has been licensed since 1971 in several countries worldwide. In humans, the drug is approved for the treatment of viral infections, and it might also have therapeutic use in animals. The aims of the presented work were to investigate the genotoxicity of inosine pranobex on BALB/3T3 clone A1 and HepG2 cell lines and to elucidate its mutagenicity using the Ames test. MATERIAL AND METHODS: The BALB/3T3 clone A1 and HepG2 cells were incubated with inosine pranobex at concentrations from 0.1 to 1,000 µg/mL. The genotoxicity was determined by comet and micronucleus assays, and the mutagenicity was determined by Ames assay. RESULTS: Inosine pranobex did not induce a significant dose-related increase in the number of comets or micronuclei in BALB/3T3 clone A1 and HepG2 cells. Moreover, based on the results of the Ames test, it was concluded that inosine pranobex is not mutagenic in the Salmonella typhimurium reverse mutation assay. CONCLUSION: Based on the results of a comet assay, micronucleus assay, and Ames test, it was concluded that inosine pranobex is neither genotoxic nor mutagenic.

Interactions between chromium(III) and iron(III), molybdenum(III) or nickel(II): Cytotoxicity, genotoxicity and mutagenicity studies.

The aim of this study was to examine the effect of chromium(III) and iron(III) and molybdenum(III) and nickel(II) and their combinations on cyto-, genotoxicity and mutagenicity in BALB/3T3 and HepG2 cells. The results obtained from cytotoxicity assays indicate that there are differences between BALB/3T3 and HepG2 cell lines in their sensitivity to chromium chloride, iron chloride, molybdenum trioxide and nickel chloride. The statistically significant increase of DNA damage of all used microelements in both cell lines was observed. The micronucleus assay performed with the use of all concentrations shows statistically significant induction of chromosomal aberrations in all tested microelements in both cell lines. Moreover, treated cells display characteristic apoptosis in comparison to control cells. In all tested microelements, the increase of number of reverse mutations was observed with and without metabolic activation. Additions of Cr(III) at 200 µM plus Fe(III) at 1000 µM showed synergistic effect in decrease of cell viability and increase of comets, micronuclei and number of revertants in both cell lines. In case of Cr(III) at 200 µM plus Mo(III) at 1000 µM, a protective effect of chromium against molybdenum at 1000 µM toxicity in both cell lines (assessed by MTT, LDH and NRU, comet, micronucleus and Ames assays) was observed. The protective effect of Cr(III) in decrease of cell viability was observed in pair of Cr(III) at 200 µM and Ni(II) at 1000 µM in BALB/3T3 and HepG2 cell lines assessed by MTT, LDH and NRU, comet, micronucleus and Ames assays.

Early Cytokine Response After Vaccination with Coxiella Burnetii Phase I in an Infected Herd of Dairy Cattle.

INTRODUCTION: Coxiella (C.) burnetii, the aetiological agent of Q fever, is able to modulate the macrophage/T-lymphocyte axis in an infected organism and impair synthesis of monokines and lymphokines. MATERIAL AND METHODS: The purpose of this research was to determine the levels of the cytokines that play a key role in the response to C. burnetii antigens (IL-1ß, IL-2, IL-6, IL-10, IFN-γ and TNF-α) in the serum of animals originating from an infected herd prior to vaccination (day 0) and at 1, 7, and 21 days afterwards. RESULTS: The vaccination of animals did not affect the production of IL-6, IL-1ß, or IL-2. The serum levels of these cytokines were too low to measure in most of the samples. The initial levels of TNFα, IFNγ, and IL-10 were higher in seropositive than in seronegative animals, although significant differences between seropositive shedders and seropositive nonshedders appeared only in the levels of IFNγ and IL-10. Additionally, the course of the post-vaccination response concerning these two cytokines was different among seronegative nonshedders, seropositive nonshedders, and seropositive shedders. CONCLUSION: It seems that analysis of the IFNγ and IL-10 concentrations in animal blood serum may have some practical value in an assessment of the health status of seropositive animals and post-vaccination response.

Cytotoxicity of Iron (III), Molybdenum (III), and their Mixtures in BALB/3T3 and HepG2 Cells.

INTRODUCTION: Iron and molybdenum are essential trace elements for cell metabolism. They are involved in maintaining proper functions of enzymes, cell proliferation, and metabolism of DNA. MATERIAL AND METHODS: BALB/3T3 and HepG2 cells were incubated with iron chloride or molybdenum trioxide at concentrations from 100 to 1,400 µM. The cells were also incubated in mixtures of iron chloride at 200 µM plus molybdenum trioxide at 1,000 µM or iron chloride at 1,000 µM plus molybdenum trioxide at 200 µM. Cell viability was determined with MTT reduction, LHD release, and NRU tests. RESULTS: A decrease in cell viability was observed after incubating both cell lines with iron chloride or molybdenum trioxide. In cells incubated with mixtures of these trace elements, a decrease in cell viability was observed, assessed by all the used assays. CONCLUSION: Iron (III) and molybdenum (III) decrease cell viability in normal and cancer cells. A synergistic effect of the mixture of these elements was observed.

Cell Viability in Normal Fibroblasts and Liver Cancer Cells After Treatment with Iron (III), Nickel (II), and their Mixture.

INTRODUCTION: Nickel and iron are very commonly occurring metals. Nickel is used in industry, but nowadays it is also used in medical biomaterials. Iron is an element necessary for cell metabolism and is used in diet supplements and biomaterials, whence it may be released along with nickel. MATERIAL AND METHODS: BALB/3T3 and HepG2 cells were incubated with iron chloride or nickel chloride at concentrations ranging from 100 to 1,400 µM. The following mixtures were used: iron chloride 200 µM plus nickel chloride 1,000 µM, or iron chloride 1,000 µM plus nickel chloride 200 µM. The cell viability was determined with MTT, LHD, and NRU tests. RESULTS: A decrease in cell viability was observed after incubating the BALB/3T3 and HepG2 cells with iron chloride or nickel chloride. A synergistic effect was observed after iron chloride 1,000 µM plus nickel chloride 200 µM treatment in all assays. Moreover, the same effect was observed in the pair iron chloride 200 µM plus nickel chloride 1,000 µM in the LDH and NRU assays. CONCLUSIONS: Iron (III) and nickel (II) decrease cell viability. Iron chloride at a concentration of 200 µM protects mitochondria from nickel chloride toxicity.

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.

Chromium(III) and iron(III) inhibits replication of DNA and RNA viruses.

The aim of this study was to examine the effect of treating of chromium(III) and iron(III) and their combinations on Herpes Simplex Virus type 1 (HSV-1) and Bovine Viral Diarrhoea virus (BVDV) replication. The antiviral efficacies of chromium(III) and iron(III) on HSV-1 and BVDV were evaluated using Real Time PCR method. Moreover, the cytotoxicity of these microelements was examined using the MTT reduction assay. The IC50 (50% inhibiotory concentration) for the chromium chloride was 1100 µM for Hep-2 cells and 1400 µM for BT cells. The IC50 for the iron chloride was 1200 µM for Hep-2 cells and more than1400 µM for BT cells. The concentration-dependent antiviral activity of chromium chloride and iron chloride against HSV-1 and BVDV viruses was observed. In cultures simultaneously treated with (1) 200 µM of CrCl3 and 1000 µM of FeCl3, (2) 1000 µM of CrCl3 and 200 µM of FeCl3, (3) 400 µM of CrCl3 and 800 µM of FeCl3, (4) 800 µM of CrCl3 and 400 µM of FeCl3 a decrease in number of DNA or RNA copies was observed compared with control cells and cells incubated with chromium(III) and iron(III) used separately. The synergistic antiviral effects were observed for chromium(III) and iron(III) against HSV-1 and BVDV.