To evaluate the ability of APMVs to replicate in chicken brains, ten 1-day-old SPF chicks were inoculated with 0.05 ml of a 1:10 dilution of fresh infective allantoic fluid for each virus via the intracerebral route. Two birds were sacrificed daily until 5 days post-infection (dpi). Brain tissue samples were collected from the sacrificed birds and processed for immunohistochemistry as described later. Brain tissue samples also were homogenized and virus titers were determined by limiting dilution and immunoperoxidase assay in DF1 cells or Vero cells using polyclonal antibodies against the respective N protein.