Fig. 2

A Venn diagram showing the PCR detection results of Marek’s disease virus (MDV) and three subgroups of avian leukosis virus (ALV) in the diseased chickens. The red box shows chickens infected with MDV; the blue box shows chickens infected with ALV-A; the yellow box shows chickens infected with ALV-J; the green box shows chickens infected with ALV-K; the overlaps of different boxes show the co-infection status of the diseased chickens