We also evaluated replication, tropism, and pathogenesis following intranasal infection in 1-day-old chicks and 2-week-old chickens. In 1-day-old chickens, only the APMV-1 strain BC and APMV-3 were able to spread to the brain and replicate, demonstrating neuroinvasiveness and neurotropism. These two viruses, plus APMV-1 strain LaSota, also were detected in the spleen of 1-day-old chicks. Conversely, replication of the other APMVs was mostly detected the in trachea of chicks, and the virus titers were moderate.