Growth of vaccine strains of avian pneumovirus in different cell lines

The isolation of avian pneumovirus (APV) (avian metapneumovirus) is usually performed in embryonated chicken eggs or chicken embryo fibroblast cell cultures followed by adaptation in continuous cell lines such as Vero cells. This study was conducted to find a suitable cell line that could be used to propagate vaccine strains of APV to high titre. For this purpose, we compared the growth of two Vero cell-adapted vaccine strains of APV (P63 and ca-APV) in seven different cell types with their growth in Vero cells. The cell types used were BGM-70, MA-104, QT-35, BHK-21, McCoy and DF-1 cells and primary turkey embryo fibroblast cells. When compared with growth in Vero cells, both viruses yielded higher titres in BGM-70 cells, while P63 also produced higher titres in MA-104 cells. In another experiment, the two viruses were grown and titrated in Vero cells under various cell culture conditions, such as age of cells, seeding concentration, and time of harvest. None of these cell culture variables were found to affect virus titres.