Pathogenicity of Fowl Adenovirus Isolated from Gizzard Erosions to Immuno-Suppressed Chickens

Abstract

ABSTRACT. Pathogenicity of a fowl adenovirus (FAV), JM1/1 strain of serotype 1 derived from gizzard erosions of a broiler chicken, was examined to specific pathogen-free (SPF) chickens pre-treated with infectious bursal disease viruses (IBDVs) or cyclophosphamide (CY). Virulent IBDVs, classical type, were inoculated orally at 3 days of age of SPF chickens. CY was treated subcutaniously for 3 days after hatch. FAV was given orally at 30 days of age. At 40 days of age, all chickens were bled and autopsied for serology and gross observation. Gizzard lesions were ranked by the scores depending on their severities. IBDV-or CY-treated chickens showed significantly higher gizzard lesion scores than non treated birds. There were no gross lesions in any other organs except for bursal atrophy. Serologically, antibody production against FAV was highly suppressed by IBDV infection or CY treatment. KEY WORDS: fowl adenovirus, gizzard erosion, immuno-suppression.J. Vet. Med. Sci. 68(3): 289-291, 2006 Recently, epizootic outbreaks of gizzard erosion in broiler flocks caused by fowl adenovirus infection have been reported in Japan [1,9,15]. Most of the FAV isolates from the gizzard lesions were serotype 1, but a few were serotype 8 [8,15]. The gizzard lesions were reproduced in broiler and specific pathogen-free (SPF) chickens by oral infection with the isolated FAVs [6][7][8]15]. However, some of the experimentally infected birds failed to show the gizzard lesions [5,15]. On the other hand, FAV has been well known as an agent of inclusion body hepatitis, which was rather facilitated in immuno-deficient birds caused by infectious bursal disease virus (IBDV) infection [2,5]. In this study, the pathogenicity of FAV strain isolated from gizzard erosion to immuno-deficient chickens was investigated using IBDV-infected or cyclophosphamide (CY)-treated chickens. IBDV infects and destroys B-cells inducing suppression of antibody production. CY, which has been used as one of immunosuppressive reagents or anticancer drugs, destroys both B-and T-cells, and also suppresses macrophage-function.FAV, strain JM1/1 isolated from a slaughtered broiler chicken affected with gizzard erosion and identified as serotype 1 [15], was prepared by chicken kidney cell culture (CKC) at the 6th passage level. IBDVs, strains G691 and Ku-52, both were classical type of virulent virus [12], were of homogenate of bursa of Fabricius (BF) of SPF chickens infected with each virus. SPF chickens derived from the Chemo-Sero-Therapeutic Research Institute (Kumamoto) were used and reared in isolated rooms. Three experiments were conducted as shown in TCID 50 /bird. In each experiment, non-treated group was contained. On the last day of each experiment, 40 days of age, all chickens were bled, weighed and sacrificed by anesthesia with chloroform for dissection and main organs were observed grossly. Bursa of Fabricius (BF) was removed and weighed to calculate the ratio to body weight [(weight of BF / body weight) × 100]. Gross gizzard lesions were ranked by the scores...

Reproduction of Adenoviral Gizzard Erosion by the Horizontal Transmission of Fowl Adenovirus Serotype 1

“…Outbreaks in broiler flocks obtained from seronegative hatcheries and differences in the prevalence of AGE lesions in outbreaks at broiler houses and farms suggest that horizontal transmission plays an important role in AGE outbreaks at broiler farms. AGE lesions have been reproduced in broilers and specific pathogen-free (SPF) White Leghorn chickens by oral infection with high doses (above 10 5 median tissue culture infectious dose (TCID 50 )/chicken or 10 7 plaque-forming units/ chicken) of FAV serotype 1, isolated from gizzard erosions, at a high probability [9,10,12,13]. However, titers of fecal virus excretion in the experimentally infected chickens were below 10 4 TCID 50 /0.05 ml [12,13].…”

Classification of Fowl Adenovirus Serotypes by Use of High-Resolution Melting-Curve Analysis of the Hexon Gene Region

“…In previous studies the use of techniques such as microtiter virus neutralization tests (11,16,33,(38)(39)(40), PCR alone (49,50,59) or in combination with either sequencing (2,14,15,30,32,48) or restriction fragment polymorphism (RFLP) (29,44,54), and a combination of these techniques (7,9,10,20,37,41,42,57) have been used to identify FAdV serotypes. Although each of these techniques is readily available to most laboratories, they have limitations, including the lengthy processes involved, need for extensive interpretation, and potential for indeterminate results, for example, the cross-neutralization of serum samples (7,10,16,27).…”

“…There are several strains in each serotype. FAdVs are endemic worldwide and known to cause inclusion body hepatitis, quail bronchitis, hydropericardium syndrome (18, 28), gizzard erosion, and pancreatic necrosis (33,34,43,44,56).Diagnosis of FAdV infections can be made from the observation of gross and histopathological changes in the liver and the use of electron microscopy (3, 11) and various serological tests, such as enzyme-linked immunosorbent assay (3,18,45), agar gel immunodiffusion, counterimmunoelectrophoresis, indirect hemagglutination, immunofluorescence (3), and Southern hybridization (10, 12). Identification of the serotype(s) involved is very useful for epidemiological tracing and is of critical importance where vaccination is to be used for the control of the disease (3, 20).…”

“…There are several strains in each serotype. FAdVs are endemic worldwide and known to cause inclusion body hepatitis, quail bronchitis, hydropericardium syndrome (18,28), gizzard erosion, and pancreatic necrosis (33,34,43,44,56).…”

Putative Host Cell Receptor for Fowl Adenovirus Detected in Gizzard

“…FAV serotypes 1 and 8 were isolated from the affected gizzards [2,15,17]. Gizzard erosion was experimentally reproduced in chickens inoculated with isolated FAV serotype 1 [10][11][12][13][14]18]. These results have shown a clear relationship between serotype 1 and virulence in some FAVs.…”