Natural Bagaza virus infection in game birds in southern Spain

Abstract

In late summer 2010 a mosquito born flavivirus not previously reported in Europe called Bagaza virus (BAGV) caused high mortality in red-legged partridges (Alectoris rufa) and ring-necked pheasants (Phasianus colchicus). We studied clinical findings, lesions and viral antigen distribution in naturally BAGV infected game birds in order to understand the apparently higher impact on red-legged partridges. The disease induced neurologic signs in the two galliform species and, to a lesser extent, in common wood pigeons (Columba palumbus). In red-legged partridges infection by BAGV caused severe haemosiderosis in the liver and spleen that was absent in pheasants and less evident in common wood pigeons. Also, BAGV antigen was present in vascular endothelium in multiple organs in red-legged partridges, and in the spleen in common wood pigeons, while in ring-necked pheasants it was only detected in neurons and glial cells in the brain. These findings indicate tropism of BAGV for endothelial cells and a severe haemolytic process in red-legged partridges in addition to the central nervous lesions that were found in all three species.

Oculopathologic Findings in Flavivirus-Infected Gallinaceous Birds

“…The mild inflammatory reaction and the scarce BAGV antigen presence in the retina of pheasants could be related to the apparently lower virulence of this virus in this species. 1,3 On the contrary, the higher abundance and wider distribution of BAGV antigen in the retina of infected partridges accompanied by a more severe inflammatory reaction may be the cause of the more prominent effect of BAGV on visual capacity in this species. This matches clinical observations of apparent blindness in BAGV-infected partridges absent in the experimental WNV infection.…”

“…10-15) and 3 common pheasants (Nos. 16-18, corresponding to references 1, 2, and 3 from Gamino et al 3 ) that died or were euthanized in a moribund state during the recent BAGV outbreak in Spain. 3 In these samples, the objective was to compare microscopic lesions and BAGV antigen distribution between the 2 species.…”

“…16-18, corresponding to references 1, 2, and 3 from Gamino et al 3 ) that died or were euthanized in a moribund state during the recent BAGV outbreak in Spain. 3 In these samples, the objective was to compare microscopic lesions and BAGV antigen distribution between the 2 species. The aim was to expand our recent description of species-specific tissue tropism of BAGV and to investigate the lesions causing blindness observed in the affected partridges.…”

Usutu Virus in Migratory Song Thrushes, Spain

“…A full necropsy was conducted on the 2 thrushes (which died shortly after capture), and samples were collected for virus detection and histopathologic examination. Total RNA was extracted from oral and cloacal swab specimens, from serum from a cardiac blood clot, and from heart, kidney, spleen, and brain tissues by using High Pure RNA Tissue Kit (Roche Diagnostics, Barcelona, Spain) and analyzed by generic flavivirus SYBR Green (QIAGEN, Madrid, Spain) real-time reverse transcription PCR (RT-PCR) and by a generic conventional nested flavivirus RT-PCR ( 9 ). The product of the first PCR (1,048 bp) was resin purified, cloned into pGEM-T (Promega, WI, USA), and sequenced.…”

“…This sequence was compared with sequences of European and African USUV strains that were available in GenBank. In addition to the histopathologic examination, we used a polyclonal primary rabbit antibody directed against West Nile virus with proven cross-reactivity to other flaviviruses for viral antigen detection by immunohistochemical testing ( 9 ). …”