| the haemagglutination spectrum of psittacine beak and feather disease virus. | a simple method for concentrating psittacine beak and feather disease virus (pbfdv) from crude feather suspensions is described. the addition of 10% polyethylene glycol (mw 6000 to 9000) to feather suspensions facilitated the precipitation and pelleting of pbfdv by low speed centrifugation. pellets were resuspended in one-twentieth of the original volume with caesium chloride (cscl) buffer and subjected to isopycnic ultracentrifugation. peak haemagglutination activity (ha) occurred at 1.35 g/ml ... | 1994 | 18671129 |