'Haemophilus gallinarum'--a re-examination

The growth factor requirements and other properties of two strains of avian haemophili, labelled as 'Haemophilus gallinarum' (an X- and V-factor-dependent organism) and stored since the 1940s and 1950s, were examined. Both strains were X-factor independent and V-factor dependent and possessed the typical biochemical, serological and pathological properties of H. paragallinarum. In experiments repeating the tests used in the 1930s that reported the existence of X- and V-factor-dependent avian haemophili, we found that the methodology used resulted in reference strains of H. paragallinarum (X-factor independent and V-factor dependent) appearing to be X- and V-factor dependent. It is likely that the early descriptions of the aetiological agent of infectious coryza as an X- and V-factor-dependent organism were incorrect.