Construction of a green fluorescent protein (GFP) avian metapneumovirus (AMPV) recombinant lacking the small hydrophobic (SH) protein gene shows that giant syncytial formations are not a result of the reduction in genome size.

Avian Metapneumovirus (AMPV) is a member of the Paramyxoviridae family and is responsible for Turkey Rhinotracheitis in turkeys which is an upper respiratory tract infection. This can cause severe disease and losses where secondary pathogens exacerbate the situation. An AMPV reverse-genetics system have been developed which enables specific mutations to be introduced into the virus genome and the subsequent phenotypic consequences determined (Naylor et al., 2004). This system was used to show that infection with a recombinant virus, unable to express the SH gene, resulted in the production of unusually large syncytia in Vero cells. It is possible that this was due to a change in the pattern of genome transcription resulting from the loss of a transcription unit. In this work we replace the SH gene with GFP which is a gene of similar size, and in which expression can be confirmed by fluorescence of its gene product, in suitable UV irradiation.