CD4 and infection: The MDV life cycle in chickens encompasses four distinct infectious phases: the early cytolytic infection phase (which affects chickens' B-lymphocytes 3–6 days after inhalation of virus particles), the latency phase (emerging in activated CD4+ T-lymphocytes 7–10 days postinfection), the reactivation phase (stimulating late cytolytic infection), and the transformation phase (resulting in tumors across various organs in latently infected CD4+ T-lymphocytes) [11].