Disease associated with 7 week old isolation of an Avian Metapneumovirus vaccine derived virus

A virus was isolated in association with respiratory disease typical of turkey rhinotracheitis, from turkey which had been vaccinated with a B subtype licensed Avian Metapneumovirus vaccine. Sequencing of the virus showed that, as in a previous similar report, the virus had originated from a licensed live A subtype vaccine. In this istance the disease was much later, at 50 days of age, and there had been no recent history of use of the vaccine. This may indicate that AMPV vaccines are able to circulate in the environment for longer than was previously envisaged.