|Gimeno, I. - USDA-ARS-MWA-ADOL|
|Neumann, U. - KLINIK FUR GEFLUGEL|
Submitted to: International Marek's Disease Symposium Abstracts and Proceedings
Publication Type: Proceedings
Publication Acceptance Date: November 22, 2000
Publication Date: N/A
Technical Abstract: Brain alterations induced by strain 648A (vv+MDV) in MD susceptible 15x7 chickens were chronologically studied. Viral DNA and MDV antigen expression (pp38) in the brain, demonstrated by quantitative PCR and histochemistry, respectively, were associated with the onset of histologic brain lesions. Two pathological phenomena were identified in the brain. Inflammatory lesions occurred between 6 and 12 days post inoculation (dpi) and were characterized by perivascular infiltration of macrophages, T cells CD8+ and T cells CD4. Proliferative lesions appeared later, (19-26 dpi) and were characterized by a severe infiltration of T cells CD+4 CD8- that exhibited blast type morphology and frequently expressed the viral antigen meq. Expression of Mhc antigens (class I and II) in endothelial and infiltrating cells within the brain was markedly influenced by MDV infection. Up- regulation of Mhc-II started as early as 6 dpi and persisted through the study. In contrast, Mhc-I expression was down regulated; and this effect was especially prominent later in our study (19-26 dpi). Our results showed that the inflammatory and lymphoprolifeative alterations in the brain may be similar to types of lesions induced by MDV in other tissues. Moreover, down regulation of Mhc-I expression as observed in the brain may be an important mechanism in MD pathogenesis by which the virus may evade immune responses.