Artificial inoculation and susceptibility of Pinus armandii to Dothistroma septosporum

Dothistroma needle blight (DNB) is a serious needle disease of conifers that primarily affects pine species (Pinus spp.). Dothistroma septosporum is one of the DNB pathogens that has a diverse range of host species excluding Pinus armandii. In 15 inoculated P. armandii seedlings, D. septosporum acervuli were observed in 43 infected needles of ten seedlings with a mean disease severity of 1.11% at 25 weeks after inoculations, demonstrating the potential of D. septosporum to cause symptoms on the needles of P. armandii via artificial inoculation. The disease severity of P. armandii was similar to the positive control, Pinus nigra (median 0.75 for P. armandii to 0.70 for P. nigra), thus, P. armandii acts under artificial conditions as a susceptible host species.     

Early development of immune system in pigs

Prenatal and early postnatal immune system development has been studied in minipigs. First leukocytes were observed in the yolk sac and fetal liver (FL) on the 17th day of gestation, the majority of them being SWC3(+). The colonization of the thymus (TH) with leukocytes was observed 21 days later. Two waves of fetal TH colonization with pro-T cells were deduced from the frequency of thymocyte subsets. Thymic B cells and immunoglobulin-secreting cells (Ig-SC) were studied by flow cytometry and ELISPOT, respectively. When the total numbers of fetal Ig-SC were compared, the TH was identified as the main source of natural antibodies and the only site of IgA and IgG synthesis. In germ-free animals, the TH also represented the major site of IgG and IgA production and the number of Ig-SC was not influenced by colonization with microflora. FL and bone marrow were identified as primary B lymphopoietic sites. The phenotype of B precursors was characterized and pre-B II cells were shown to be the dominant mononuclear fraction between DG50 and DG105. In the periphery, relative proportions of lymphocyte subsets were determined. Studies in gnotobiotic piglets have revealed that the appearance of CD4(+)CD8(+) T cells and CD2(-) B cells is absolutely dependent on the contact of immune system with live viruses and bacteria, respectively.     

Monoclonal antibodies putatively identifying porcine B cells

Comparison was made of the binding of 38 test and three standard monoclonal antibodies (mAbs) to B cells from various pig lymphoid tissues by flow cytometry (FCM) and immunohistochemistry. Some mAbs were also tested on B cells from foetal pig tissues. Twenty of the new mAbs bound, though to variable degrees, to porcine B cells but only three were given cluster assignations: C35 (#147) and BB6-11C9 (#167) were assigned to wCD21 and 2F6/8 (#057) was assigned to SWC7.     

Specific contrast ultrasound using sterically stabilized microbubbles for early diagnosis of thromboembolic disease in a rabbit model

Specific contrast ultrasound is widely applied in diagnostic procedures on humans but remains underused in veterinary medicine. The objective of this study was to evaluate the use of microbubble-based contrast for rapid ultrasonographic diagnosis of thrombosis in small animals, using male New Zealand white rabbits (average weight about 3.5 kg) as a model. It was hypothesized that the use of microbubble-based contrast agents will result in a faster and more precise diagnosis in our model of thrombosis. A pro-coagulant environment had been previously established by combining endothelial denudation and external vessel wall damage. Visualization of thrombi was achieved by application of contrast microbubbles [sterically stabilized, phospholipid-based microbubbles filled with sulfur hexafluoride (SF₆) gas] and ultrasonography. As a result, rapid and clear diagnosis of thrombi in aorta abdominalis was achieved within 10 to 30 s (mean: 17.3 s) by applying microbubbles as an ultrasound contrast medium. In the control group, diagnosis was not possible or took 90 to 180 s. Therefore, sterically stabilized microbubbles were found to be a suitable contrast agent for the rapid diagnosis of thrombi in an experimental model in rabbits. This contrast agent could be of practical importance in small animal practice for rapid diagnosis of thrombosis.     

Deoxynivalenol and zearalenone residues in eggs of laying hens fed with a naturally contaminated diet: effects on egg production and estimation of transmission rates from feed to eggs

The potential for the Fusarium mycotoxins 4-deoxynivalenol (DON) and zearalenone (ZON) to enter the human food chain through contaminated eggs was assessed using a controlled feed study. Four groups of laying hens (eight in each group) were fed a diet that included differing amounts of naturally contaminated wheat containing DON ( approximately 20 mg kg(-1)) and ZON (0.5 mg kg(-1)). Eggs were collected and pooled from each group on a daily basis. Pooled samples were analyzed by liquid chromatography with mass spectrometry detection (LC-MS/MS). The method allowed DON, other type B trichothecenes, ZON, and its metabolites to be determined in a single multi-residue analysis. The selectivity of the MS/MS procedure allowed cleanup to be minimized (for DON, cleanup by immunoaffinity column was used) or eliminated (for ZON). The limits of detection of 0.01 microg kg(-1) for DON and 0.1 microg kg(-1) for ZON in eggs were lower than previously published methods. None of the samples analyzed had detectable levels of ZON or its metabolites. Although maximum levels of DON contamination (10 mg kg(-1) feed) were relatively high, no adverse effects were observed on egg production. On the basis of the determined DON levels in the hen's diet and the determined levels of DON in the corresponding eggs, transmission rates of 15 000:1, 18 000:1, and 29 000:1 for treatment levels 5, 7.5, and 10 mg DON kg(-1) feed, respectively, were found. These results show that, although eggs could be a human exposure route for DON, the levels are insignificant compared to the other sources, although the presence of metabolites of DON was not studied.     

Leukocytic responses and intestinal mucin dynamics of broilers protected with Enterococcus faecium EF55 and challenged with Salmonella Enteritidis

The protective effect of Enterococcus faecium EF55 in chickens challenged with Salmonella enterica serovar Enteritidis phage type 4 (SE PT4) was assessed. The antibacterial effect on the bacterial microflora in the small intestine in relation to white blood cell count, phenotyping of peripheral blood and intestinal lymphocytes, functional activity of lymphocytes and phagocytes and mucin quantitation were investigated. Day-old chicks (85) were randomly divided into four groups. The probiotic group (EF) and Salmonella + probiotic group (EFSE) received E. faecium EF55 (10⁹ CFU – 3 g/group/day) for 21 days. The Salmonella group (SE) and EFSE group were infected with Salmonella Enteritidis (10⁸ CFU in 0.2 ml PBS) in a single dose per os on day four of the experiment. The control group chicks (C) were fed a commercial diet without added bacteria. Supplementation of EF55 in the diet of the chickens in the EFSE group, challenged with S. Enteritidis, caused the density of the intestinal mucin layer to increase significantly in non-specific regions (duodenum and jejunum), but decrease significantly in target regions (caeca) for S. Enteritidis. Probiotic treatment also appeared to result in a significantly higher number of lymphocytes in peripheral blood and a tendency to increase CD3, CD4, CD8, and IgM positive cells 3 days post-infection with S. Enteritidis. The results demonstrated an antibacterial effect and suggested that EF55 had a moderating effect on intestinal mucin production and leukocytic response in the early phase of S. Enteritidis infection.     

Effects of caprylic acid and triacylglycerols of both caprylic and capric acid in rabbits experimentally infected with enteropathogenic Escherichia coli O103

Eighty-eight rabbits weaned at the age of 35 days were divided into four groups. Rabbits of the first two groups were fed a granulated feed, free of antimicrobials. Rabbits of the 3rd and the 4th groups were fed the same diet, supplemented with caprylic acid at 5 g/kg, and with triacylglycerols (TAG) of caprylic and capric acid at 10 g/kg, respectively. Rabbits of the 2nd, 3rd and 4th groups were challenged orally with 10(9) cells of Escherichia coli of the O103 serogroup. Numbers of coliform bacteria in faeces of non-infected rabbits averaged 4.66 log(10)cfu/g. Six days after inoculation, caprylic acid and TAG of caprylic and capric acid decreased faecal output of coliforms from 10.18+/-0.62 to 7.79+/-0.48 log(10)cfu/g and 8.04+/-0.50 log(10)cfu/g, respectively. In the 2nd, 3rd and 4th groups 15, 11 and 9 infected rabbits died, respectively. However, the differences in mortality rate were not statistically significant. Surviving rabbits were slaughtered at 53 days of age. In caecal contents of infected rabbits, numbers of coliform bacteria were significantly reduced from 8.71 log(10)cfu/g to 5.55-5.83 log(10)cfu/g in treated groups. It can be concluded that both antimicrobial lipids are active against coliform bacteria, and may improve the resistance of weaned rabbits to enterocolitis.     

Needle blight caused by Dothistroma pini in Slovakia: distribution,host range and mating types

Dothistroma needle blight (DNB) has been observed in Slovakia during the last two decades. Up until 2017, Dothistroma septosporum has only been detected and molecularly confirmed to cause DNB in Slovakia. Here, we report the detection of Dothistroma pini at six localities around Slovakia, representing different plantation types. Four pine species (Pinus sylvestris, P. nigra, P. mugo and P. jeffreyi) were confirmed as hosts of D. pini in Slovakia, of which only P. mugo has been previously reported as host in Slovakia. Three gene regions (ITS, EF1 –α, and ß-tubulin) of each of the 13 isolates were sequenced and assigned as D. pini. Based on ITS sequences, the studied isolates represent the haplotypes Dp_HAP.1, Dp_HAP.2. Both mating types were detected but at different localities. Our results suggest that in addition to D. septosporum, D. pini may contribute to DNB also in Slovakia.