Suppression of humoral immunity in chickens prevents transient paralysis caused by a herpesvirus

Marek's disease virus (MDV)3 is a highly oncogenic herpesvirus that usually causes visceral lymphomas and lymphoid infiltration of the peripheral nerves in chickens. A relatively rare encephalitic condition, first found in farm flocks and referred to as transient paralysis (TP), is also caused by MDV(1). TP symptoms occur 9 to 11 days after MDV inoculation and range from mild ataxia to profound coma. Most birds recover by 24 to 72 hr after onset of symptoms, although severely affected birds may die within the same time period. Previous studies in this laboratory (2) showed that susceptibility to TP is a recessive trait controlled by major histocompatibility complex (MHC) genes (i.e., B complex genes of chickens). Inbred line G-B1 chickens (B13/B13) are resistant to TP, whereas chickens from related inbred lines G-B2 (B6/B6) and G-B3 (B15/B15) are highly susceptible. In this study chickens were immunosuppressed by neonatal cyclophosphamide (CY) treatment or surgical bursectomy (BX) to determine the possible role of antibodies in the pathogenesis of TP.