Genetic diversity of Gallibacterium anatis isolates from different chicken flocks

Abstract

Amplified fragment length polymorphisms (AFLPs) were used to characterize the genotypic diversity of a total of 114 Gallibacterium anatis isolates originating from a reference collection representing 15 biovars from four countries and isolates obtained from tracheal and cloacal swab samples of chickens from an organic, egg-producing flock and a layer parent flock. A subset of strains was also characterized by pulsed-field gel electrophoresis and biotyping. The organic flock isolates were characterized by more than 94% genetic similarity, indicating that only a single clone was apparent in the flock. The layer parent flock isolates were grouped into two subclusters, each with similarity above 90%. One subcluster contained only tracheal isolates, while the other primarily included cloacal isolates. In conclusion, we show that AFLP analysis enables fingerprinting of G. anatis, which seems to have a clonal population structure within natural populations. There was further evidence of clonal lineages, which may have adapted to different sites within the same animal.

FIG. 1.

Dendrogram (unweighted pair group method using arithmetic averages) of AFLP similarities of 114 Gallibacterium strains. S_D(%), band-based Dice similarity coefficient expressed as a percentage. The dashed vertical line indicates the 90% similarity level between isolates. ND, not determined; P.sp., [Pasteurella] sp.