Bacterial determinants of importance in the virulence of Gallibacterium anatis in poultry

Abstract

Gallibacterium anatis, a member of the Pasteurellaceae family, constitute a part of the normal micro-flora of the upper respiratory tract and the lower genital tract in chickens. However, increasing evidence indicate that G. anatis is also associated with a wide range of pathological changes, particularly in the reproductive organs, which leads to decreased egg production, lowered animal welfare and increased mortality. As a recently defined opportunistic pathogen limited focus has been placed on the pathogenesis and putative virulence factors permitting G. anatis to cause disease. One of the most studied virulence determinants is a large RTX-like toxin (GtxA), which has been demonstrated to induce a strong leukotoxic effect on avian macrophages. A number of fimbria of different sizes and shapes has been described. Particularly fimbriae belonging to the F17-like family appears to be common in a diverse selection of G. anatis strains. Mutants lacking the FlfA fimbria were severely attenuated in experimentally infected chickens. Additional characteristics including the ability to express capsular material possibly involved in serum resistance; secretion of metalloproteases capable of degrading immunoglobulins, and hemagglutinins, which may promote biofilm formation are all factors likely linked to the virulence of G. anatis. A major advantage for the study of how G. anatis interact with its host is the ability to perform biologically relevant experimental infections where natural routes of exposure allows reproduction of lesions observed during spontaneous infections. This review summarizes the current understanding of the G. anatis pathogenesis and discusses the contribution of the established and putative virulence factors described for this bacterium to date.

Etiology, epidemiology, pathology, and advances in diagnosis, vaccine development, and treatment ofGallibacterium anatisinfection in poultry: a review

“…are involved in causing septicemia (Fisher et al 1998;Ewers et al 2004;Abdul-Aziz et al 2016). In recent past, several reports of clinical cases in avian and experimental studies in chickens revealed Gallibacterium anatis to be an important bacterial pathogen associated with septicemia (Bojesen et al 2004;Neubauer et al 2009;Jones et al 2013;Paudel et al 2013;Elbestawy 2014;Paudel, Liebhart, Aurich, et al 2014;Paudel et al 2015;Persson & Bojesen 2015).…”

Hydrostatic Filtration Enables Large-Scale Production of Outer Membrane Vesicles That Effectively Protect Chickens against Gallibacterium anatis

“…Gallibacterium anatis is a Gram-negative bacterium belonging to the Pasteurellaceae family. Although commonly present in healthy birds, most G. anatis isolates can cause opportunistic infections in both domesticated and non-domesticated birds [1,2]. G. anatis infections can result in a wide variety of pathological manifestations, including septicemia, pericarditis, hepatitis, respiratory tract lesions and enteritis, but are most commonly associated with the development of salpingitis, acute peritonitis and hemorrhagic/ruptured follicles [2][3][4][5].…”

Evaluation of the efficacy of an autogenous Escherichia coli vaccine in broiler breeders

“…The lack of correlation between IgY antibodies and level of protection is not an uncommon observation in studies of avian bacterial infection. In fact, some studies have documented convincing effects of a bacterial vaccine candidate, although no rise in IgY antibodies could be detected (Persson and Bojesen 2015). This may likely be explained by another, antibody independent mode of vaccine protection, e.g.…”