Introduction
The study of histopathological changes caused by influenza A (H5N8) viral infection in bird species is essential for the understanding of their role in the spread of this highly infectious virus. However, there are few such studies under natural conditions in minor gallinaceous species. This article describes the pathomorphological findings in Colchis pheasants infected naturally with H5N8 during an epizootic outbreak in Bulgaria.
Material and Methods
Samples of internal organs of 10 carcasses were collected for histopathological and immunohistochemical evaluation, virus isolation and identification, and nucleic acid detection.
Results
Consistent macroscopic findings were lesions affecting the intestine, heart, lung, and pancreas. Congestion and mononuclear infiltrate were common findings in the small intestine, as were necrosis and lymphoid clusters in the lamina propria of the caeca. Congestion with small focal necrosis and gliosis with multifocal nonpurulent encephalitis were observed in the brain. Myocardial interstitial oedema and degenerative necrobiotic processes were also detected. Immunohistological analysis confirmed systemic infection and revealed influenza virus nucleoprotein in all analysed organs.
Conclusion
Variable necrosis was observed in the brain, liver, trachea, heart, small intestine, and caeca. Viral antigen was commonly found in the brain, heart, lung and trachea. Contact with migrating waterfowls was suspected as a reason for the outbreak.
In the pig farm with signs of a respiratory disease complex and laboratory confirmed enzootic pneumonia, the prophylactic efficacy of the combination vaccine (M. hyo+PCV2), a single injection administered intramuscularly 21 days after birth, at a dose of 2 ml was tested. The clinical condition, pathological changes in the lungs and some epidemiological and economic results were reported. It was found that vaccinated pigs are in a better clinical condition in comparison with the control group. Morbidity in the rearing period was reduced from 16.3% in the control group to 6.0% in vaccinated pigs, and in the fattening period, respectively, from 30.6% in the control group to 10.0% in the vaccinated group. Pathological features in the lung characteristic for the enzootic pneumonia in the vaccinated pigs were reduced from 25.5%±7.24 to 4.0%±2.44, and PCVIfrom 13.0%±4.66 to 0%. Vaccination of pigs has been received and a higher average daily gain in groups for rearing (0.624 kg) and for fattening (0.723 kg) was recorded.
The in vitro response of early haematopoietic progenitors or stem cells, common for myeloid (granulocyte, eosinophil, megacaryocyte) and marrow stromal (including dendritic CD34+) cells series, to neopterin, exogenously added to the liquid-and semi-liquid (agar-) mouse bone marrow cultures, at doses 12.5 -25 Jlg/ml culture medium, has been studied. The results obtained show a significant stimulation of common myeloid and stromal dendritic cell (CD34+) progenitors' proliferation and/or differentiation as early as 24h after the in vitro treatment of marrow cultures with neopterin. On day 4 of cultivation the granulocyte/macrophageal proliferation and differentiation has been attenuated giving place to the marrow stromal dendritic cell (probably CD34+) differentiation. The engagement of the nuclear proliferative factor NF-K B may playa role in the light of recent data that neopterin could activate this transcriptionally active nuclear factor. The significance of clonal selective stimulation of healthy (but not of leukaemic) dendritic CD34+ cells in some pathological cases as acute myeloid leukaemia has been also discussed because neopterin could be a more efficient marrow stem cell factor than cytokine cocktails with granulocyte/macrophage-colony stimulating factor. The ex vivo or clinical application of neopterin, alone and/or in specific combinations with other cytokines, in the induction of marrow myeloid and stromal cell proliferation and differentiation towards the dendritic (CD34+) cells merits further investigations ..
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