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Apoptosis and immuno-suppression in sheep infected with bluetongue virus serotype-23

Umeshappa, Channakeshava Sokke, Singh, Karam Pal, Nanjundappa, Roopa Hebbandi, Pandey, Awadh Bihari
Veterinary microbiology 2010 v.144 no.3-4 pp. 310-318
sheep, Bluetongue virus, bluetongue, sheep diseases, immunosuppression (physiological), signs and symptoms (animals and humans), apoptosis, pathogenesis, disease course, spleen, monocytes, DNA damage, caspase-3, interferons, Pasteurella, animal pathogenic bacteria, pneumonia, bacterial pneumonia
The role of apoptosis in pathogenesis of bluetongue (BT) has been suggested from various in vitro studies. However, to date, no clear data are available regarding BTV-induced apoptosis and its consequences in natural host, sheep. In the present study, bluetongue virus (BTV)-induced apoptosis was studied in sheep blood and splenic mononuclear cells by analyzing annexin⁺-propidium iodide⁻ early apoptotic cells, DNA ladder pattern, and caspase-3 gene expression. The onset of apoptosis and lymphocyte depletion in viraemic phase and IFN-α response indicated the involvement of BTV and IFN-α in the pathogenesis of BT. The development of Pasteurella pneumonia in 4 of 7 infected sheep during the experiment pointed to possible BTV-induced immuno-suppression and predisposition to secondary microbial infections. These results have significant implications not only in understanding immuno-pathological consequences but also in studying interactions of BTV with host cells.