Figure 2.

MDV replication in lymphoid organs of infected-chicks at early time points. A MDV DNA loads in lymphoid organs of MDV-infected chicks. The MDV genome copy number per million cells was quantified at 6, 10 and 14 dpi using a Taqman real-time qPCR in thymus, bursa, PBMC and spleen. The viral loads were already high since 6 dpi in thymus, bursa, PBMC and spleen of all infected chicks and no significant or little further increase were detected at later time points. The median is represented as a black line. B Expression of lytic viral antigens in the thymus and the bursa. Cryosections of both thymus (a–c) and bursa (d–f) at 6, 10 and 14 dpi were stained with a cocktail of three mAb directed against MDV lytic antigens (VP22, ICP4, gB) (Green). Nuclei were stained with Hoescht 33342 dye (blue). MDV lytic antigens were detected in all birds in both primary lymphoid organs at 6 dpi; in 2/6 chicks for the thymus and 3/6 chicks for the bursa at 10 dpi and in 2/8 chicks for the bursa at 14 dpi (no detection in thymus at 14 dpi). In the bursa, MDV-infected cells in lytic cycle were predominantly located in the medulla at 6 dpi. Bar, 20 µm