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Quantity of virulent fowl adenovirus serotype 1 correlates with clinical signs, macroscopical and pathohistological lesions in gizzards following experimental induction of gizzard erosion in broilers.

Grafl B, Liebhart D, Günes A, Wernsdorf P, Aigner F, Bachmeier J, Hess M - Vet. Res. (2013)

Bottom Line: Clinically, both infected groups showed significant decrease of weight compared to respective negative control groups.Tissue samples were investigated by a recently developed real-time PCR and the viral DNA load was calculated from gizzard, liver, spleen and cloacal swabs with the highest amounts of FAdV-1 DNA found in the gizzard.For the first time, successful reproduction of clinical signs in broilers as well as pathological lesions in the gizzard were achieved with a European FAdV-1 isolate displaying some genetic differences to so far reported virulent FAdV-1 from Japan.

View Article: PubMed Central - HTML - PubMed

ABSTRACT
In the present study day-old specific-pathogen-free (SPF) and commercial broilers with maternally derived fowl adenovirus serotype 1 (FAdV-1) antibodies were orally infected with a European "pathogenic" FAdV-1, isolated from broilers showing signs of gizzard erosion. During the experiment, broilers were observed and weighed daily up to 17 days post infection (dpi). Clinically, both infected groups showed significant decrease of weight compared to respective negative control groups. Birds were examined by necropsy at 3, 7, 10, 14 and 17 dpi. Pathological changes in the gizzards were noticed in both experimentally infected groups from 7 dpi onwards. Macroscopically, erosion of the koilin layer and inflammation or ulceration of the gizzard mucosa were observed. Histologically, presence of FAdV-1 in intranuclear inclusion bodies of degenerated glandular epithelial cells was demonstrated by in-situ hybridization and inflammatory cell infiltration of the lamina propria, submucosa and muscle layer was detected. Tissue samples were investigated by a recently developed real-time PCR and the viral DNA load was calculated from gizzard, liver, spleen and cloacal swabs with the highest amounts of FAdV-1 DNA found in the gizzard. For the first time, successful reproduction of clinical signs in broilers as well as pathological lesions in the gizzard were achieved with a European FAdV-1 isolate displaying some genetic differences to so far reported virulent FAdV-1 from Japan. Furthermore, highest viral load in gizzards could be linked with macroscopical and histological lesions. Therefore, the conducted analyses provide important insights into the pathogenesis of adenoviral gizzard erosion.

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Histopathological lesions in the gizzard. Gizzard from a commercial broiler experimentally infected on the first day-of-life with virulent FAdV-1. a) Expansion of the lamina propria mucosa by mixed population of inflammatory cells (arrowheads). Basophilic intranuclear inclusion bodies in degenerated epithelial cells (arrows). Haematoxilin & eosin staining. Bar = 20 μm. b) In-situ hybridization of the same gizzard sample with positive signal for FAdV-1 DNA in epithelial cells (arrows). Bar = 20 μm.
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Figure 2: Histopathological lesions in the gizzard. Gizzard from a commercial broiler experimentally infected on the first day-of-life with virulent FAdV-1. a) Expansion of the lamina propria mucosa by mixed population of inflammatory cells (arrowheads). Basophilic intranuclear inclusion bodies in degenerated epithelial cells (arrows). Haematoxilin & eosin staining. Bar = 20 μm. b) In-situ hybridization of the same gizzard sample with positive signal for FAdV-1 DNA in epithelial cells (arrows). Bar = 20 μm.

Mentions: From 7 dpi onwards, gizzards of orally infected broilers from groups SPFB and CB showed histological changes, such as necrosis, degeneration and disappearance of epithelial cells accompanied with mild to severe inflammation of the lamina propria mucosa, the submucosa and the muscle layer. Within and near such areas, multiple basophilic intranuclear inclusion bodies were observed in glandular epithelial cells at 7 and 10 dpi (Figure 2a). In group SPFB they were found more frequently at 7 dpi and in group CB at 10 dpi (Table 1). FAdV-1 DNA was demonstrated in affected gizzards, particularly in intranuclear inclusion bodies, by in-situ hybridization (Figure 2b). No lesions or intranuclear inclusion bodies were found in the other investigated organs or in organ samples taken from the negative control groups.


Quantity of virulent fowl adenovirus serotype 1 correlates with clinical signs, macroscopical and pathohistological lesions in gizzards following experimental induction of gizzard erosion in broilers.

Grafl B, Liebhart D, Günes A, Wernsdorf P, Aigner F, Bachmeier J, Hess M - Vet. Res. (2013)

Histopathological lesions in the gizzard. Gizzard from a commercial broiler experimentally infected on the first day-of-life with virulent FAdV-1. a) Expansion of the lamina propria mucosa by mixed population of inflammatory cells (arrowheads). Basophilic intranuclear inclusion bodies in degenerated epithelial cells (arrows). Haematoxilin & eosin staining. Bar = 20 μm. b) In-situ hybridization of the same gizzard sample with positive signal for FAdV-1 DNA in epithelial cells (arrows). Bar = 20 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3672026&req=5

Figure 2: Histopathological lesions in the gizzard. Gizzard from a commercial broiler experimentally infected on the first day-of-life with virulent FAdV-1. a) Expansion of the lamina propria mucosa by mixed population of inflammatory cells (arrowheads). Basophilic intranuclear inclusion bodies in degenerated epithelial cells (arrows). Haematoxilin & eosin staining. Bar = 20 μm. b) In-situ hybridization of the same gizzard sample with positive signal for FAdV-1 DNA in epithelial cells (arrows). Bar = 20 μm.
Mentions: From 7 dpi onwards, gizzards of orally infected broilers from groups SPFB and CB showed histological changes, such as necrosis, degeneration and disappearance of epithelial cells accompanied with mild to severe inflammation of the lamina propria mucosa, the submucosa and the muscle layer. Within and near such areas, multiple basophilic intranuclear inclusion bodies were observed in glandular epithelial cells at 7 and 10 dpi (Figure 2a). In group SPFB they were found more frequently at 7 dpi and in group CB at 10 dpi (Table 1). FAdV-1 DNA was demonstrated in affected gizzards, particularly in intranuclear inclusion bodies, by in-situ hybridization (Figure 2b). No lesions or intranuclear inclusion bodies were found in the other investigated organs or in organ samples taken from the negative control groups.

Bottom Line: Clinically, both infected groups showed significant decrease of weight compared to respective negative control groups.Tissue samples were investigated by a recently developed real-time PCR and the viral DNA load was calculated from gizzard, liver, spleen and cloacal swabs with the highest amounts of FAdV-1 DNA found in the gizzard.For the first time, successful reproduction of clinical signs in broilers as well as pathological lesions in the gizzard were achieved with a European FAdV-1 isolate displaying some genetic differences to so far reported virulent FAdV-1 from Japan.

View Article: PubMed Central - HTML - PubMed

ABSTRACT
In the present study day-old specific-pathogen-free (SPF) and commercial broilers with maternally derived fowl adenovirus serotype 1 (FAdV-1) antibodies were orally infected with a European "pathogenic" FAdV-1, isolated from broilers showing signs of gizzard erosion. During the experiment, broilers were observed and weighed daily up to 17 days post infection (dpi). Clinically, both infected groups showed significant decrease of weight compared to respective negative control groups. Birds were examined by necropsy at 3, 7, 10, 14 and 17 dpi. Pathological changes in the gizzards were noticed in both experimentally infected groups from 7 dpi onwards. Macroscopically, erosion of the koilin layer and inflammation or ulceration of the gizzard mucosa were observed. Histologically, presence of FAdV-1 in intranuclear inclusion bodies of degenerated glandular epithelial cells was demonstrated by in-situ hybridization and inflammatory cell infiltration of the lamina propria, submucosa and muscle layer was detected. Tissue samples were investigated by a recently developed real-time PCR and the viral DNA load was calculated from gizzard, liver, spleen and cloacal swabs with the highest amounts of FAdV-1 DNA found in the gizzard. For the first time, successful reproduction of clinical signs in broilers as well as pathological lesions in the gizzard were achieved with a European FAdV-1 isolate displaying some genetic differences to so far reported virulent FAdV-1 from Japan. Furthermore, highest viral load in gizzards could be linked with macroscopical and histological lesions. Therefore, the conducted analyses provide important insights into the pathogenesis of adenoviral gizzard erosion.

Show MeSH
Related in: MedlinePlus