In vivostudies ofGallibacterium anatisinfection in chickens

Abstract

The aim of the present study was to investigate the pathology in normal or immunosuppressed chickens followed intravenous or intraperitoneal inoculation with a well-characterized strain of Gallibacterium anatis. Two groups of 30 15-week-old commercial brown laying chickens were used, having been screened and found negative for Gallibacterium organisms. One group was treated with 5-fluorouracil to promote heterophil depletion, while the other was saline treated. Ten days later 15 chickens from each group were inoculated either intravenously or intraperitoneally with 3.3 x 10(7) colony-forming units of G. anatis strain 12656-12. Subsets of chickens were sacrificed at 3, 12 or 24 h post-infection and examined for lesions. Livers and spleens were examined by culture and by fluorescent in situ hybridization. Intravenously infected birds showed severe septicaemic lesions in both the normal and immunosuppressed birds. Mortality was recorded only in the latter, with an overall rate of 73%. The intraperitoneally infected chickens of normal immune status showed various degrees of localized purulent peritonitis at the inoculation site, but in the immunosuppressed birds the entire peritoneum tended to be involved along with the abdominal organs. This was similar to previous descriptions of natural infections and may represent a useful infection model for detailed analysis of Gallibacterium virulence factors and pathogenesis.

Impact of heterophil granulocyte depletion caused by 5-fluorouracil on infectious bursal disease virus infection in specific pathogen free chickens

“…However, the number of heterophil granulocytes was drastically reduced in both treated groups 7 and 8 days after 5-FU treatment, 2 and 3 days after virus inoculation, when viraemia was expected. The results of the blood cell counts were too few to be statistically evaluated, but the effect of 5-FU on blood cells seemed already discussed in detail by Kogut et al (1993) and Bojesen et al (2004). The histological studies of bursa tissues confirmed the results of lymphocyte counts, revealing cellular depletion 5 days after 5-FU treatment.…”

“…A model for heterophil depletion of chickens by treatment with the cytostatic drug 5-flurouracil (5-FU) has been described (Kogut et al ., 1993) and used for investigation of the influence of heterophil granulocytes on bacterial (Bojesen et al ., 2004) andviral (Raj et al ., 1997) infections in chickens. In a previous, unpublished experiment, chickens treated with the recommended dose of 5-fluorouracil (5-FU) and subsequently infected with IBDV showed mild clinical symptoms, but survived the infection.…”

Tissue distribution of haemolyticGallibacterium anatisisolates in laying birds with reproductive disorders

“…In the present investigation, ascending infections may have contributed to the finding of G. anatis and E. coli in the reproductive tract, in addition to the heart, liver and spleen. Bojesen et al (2004) used fluorescence in situ hybridization to demonstrate bacteria in the spleen and liver following intraperitoneal infection of chickens with Gallibacterium, indicating that ascending infections might be of relevance. The gross pathological lesions of reproductive disorders due to Gallibacterium infection cannot be distinguished from infections with E. coli, and for this reason all samples were also investigated for E. coli.…”

“…Furthermore, a mortality of 73% was noted in experimentally immunosuppressed 15-week-old brown layers after intravenous infection, emphasizing the importance of Gallibacterium spp. as a pathogen (Bojesen et al, 2004). In a field study performed in Denmark, Bojesen et al (2003b) demonstrated that the biosecurity level influenced the prevalence of Gallibacterium spp., with a lower level of biosecurity resulting in a more frequent detection of these pathogens.…”

Complete Genome Sequence of Gallibacterium anatis Strain UMN179, Isolated from a Laying Hen with Peritonitis

“…This bacterium is known to be a member of the normal upper respiratory tract and lower reproductive tract of chickens but has also been implicated in peritonitis and salpingitis in commercial laying hens (3)(4)(5)16). To this end, G. anatis has been experimentally shown to induce natural infection in the chicken model (2). While studies aimed at the molecular pathogenesis of G. anatis are limited, some potential virulence factors/functions have been identified, including the production of secreted metalloproteases (9), hemagglutinating activity (9), and the production of a cytolytic RTX toxin known as GtxA (11).…”