Suchergebnisse

After the introduction of West Nile virus (WNV) into North America, bird mortalities associated with West Nile disease have dramatically increased in this continent and, to a lesser extent, in Europe. The different West Nile disease incidence in birds in these 2 continents demands an explanation, and experimental studies can provide important information. The authors inoculated thirteen 9-week-old red-legged partridges (Alectoris rufa) with 10 plaque-forming units of a WNV strain isolated in New York in 1999. The objective was to study the pathogenesis of the infection in a native Euro-Mediterranean bird species with a WNV strain known to be highly pathogenic for numerous native American bird species. Additionally, the authors evaluated the dynamics of inflammatory cell activation and recruitment into the brain. WNV was detected in tissues 3 days postinoculation (dpi), and the birds developed macroscopic and microscopic lesions. Two partridges succumbed to the disease. The most affected tissues were the heart, brain, and spinal cord. The main microscopic findings were the presence of mononuclear infiltrates in the heart and brain, gliosis, and degeneration and necrosis of cardiomyocytes and neurons. These lesions were aggravated in the birds that died or were euthanized 7 dpi or later. In the brain, there was an upregulation of microglial cells and astrocytes and an increase in the number of T cells, especially after 7 dpi. These results show that this WNV strain is of moderate virulence for the red-legged partridge and that WNV-infected red-legged partridges develop an immune cell response in the brain similar to that of mammals. ; This study was supported by grant SAF2008-04232, funded by the Spanish Ministry for Science and Innovation, and grants FAU2008-00006, RTA2011-00036, and RTA2013-0013-C04, from the Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria. V. Gamino (323/09) was a research fellow supported by the Regional Government of Castilla–La Mancha. ; Peer Reviewed

The mosquito-borne flaviviruses USUV and WNV are known to co-circulate in large parts of Europe. Both are a public health concern, and USUV has been the cause of epizootics in both wild and domestic birds, and neurological cases in humans in Europe. Here, we explore the susceptibility of magpies to experimental USUV infection, and how previous exposure to USUV would affect infection with WNV. None of the magpies exposed to USUV showed clinical signs, viremia, or detectable neutralizing antibodies. After challenge with a neurovirulent WNV strain, neither viremia, viral titer of WNV in vascular feathers, nor neutralizing antibody titers of previously USUV-exposed magpies differed significantly with respect to magpies that had not previously been exposed to USUV. However, 75% (6/8) of the USUV-exposed birds survived, while only 22.2% (2/9) of those not previously exposed to USUV survived. WNV antigen labeling by immunohistochemistry in tissues was less evident and more restricted in magpies exposed to USUV prior to challenge with WNV. Our data indicate that previous exposure to USUV partially protects magpies against a lethal challenge with WNV, while it does not prevent viremia and direct transmission, although the mechanism is unclear. These results are relevant for flavivirus ecology and contention. ; This work was supported by grants RTA2015-009 and E-RTA2017-003-C02 from Instituto Nacional de Investigación y Tecnología Agraria y Alimentaria (INIA). Institutional Review Board Statement: Magpies were captured for this experiment under permit 346760/2018 of the regional government of the autonomic Community of Castilla-La Mancha (Spain), as part of a specific pest control program in the area. Guidelines of the European Community 86/609/CEE for handling of animals were strictly followed and the protocols were approved by the Committee on Ethics of animal experimentation of our Institution (INIA permit number 2018-04). Food and water were provided ad libitum throughout the experiment. Magpies were monitored daily for clinical signs, and those showing severe ones were anesthetized with isoflurane and euthanized by intravenous injection of an overdose of sodium pentobarbital (Dolethal, Vetoquinol, Madrid, Spain), as were all surviving animals at the end of the experiment (37 d.p.i.). Infectious virus manipulation was carried out in our dedicated biosafety level 3 facilities (BSL-3) in strict accordance with biosecurity rules. ; Peer reviewed