Identification of Actinobacillus seminis as the cause of abortion in sheep by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and whole genome sequencing.

Abstract

Actinobacillus seminis is a gram-negative bacterium that affects reproductive organs, causing epididymitis, low fertility, and occasional abortions in sheep and goats. The virulence factors and the pathogenicity mechanisms of A. seminis have not been clearly elucidated yet. The aim of this study is to report a laboratory investigation performed on a sheep farm in the Basilicata region (southern Italy) following cases of abortion. Four samples of aborted fetuses taken from two sheep were analyzed to investigate the main pathogens causing abortions by bacterial isolation. In addition, serum samples belonging to the sheep have also been analyzed. Analysis by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) of the isolated colonies identified protein spectra referable to A. seminis. This result was also confirmed through the use of genome sequencing. Therefore, these data could explain cases of abortion that occurred on the farm and would confirm that MALDI-TOF MS technology is a rapid, accurate, and inexpensive method for identifying bacteria.