Selected clinical chemistry analytes correlate with the pathogenesis of inclusion body hepatitis experimentally induced by fowl aviadenoviruses

Abstract

In the present study, clinical chemistry was applied to assess the pathogenesis and progression of experimentally induced inclusion body hepatitis (IBH). For this, five fowl aviadenovirus (FAdV) strains from recent IBH field outbreaks were used to orally inoculate different groups of day-old specific pathogen-free chickens, which were weighed, sampled and examined during necropsy by sequential killing. Mortalities of 50% and 30% were recorded in two groups between 6 and 9 days post-infection (dpi), along with a decreased weight of 23% and 20%, respectively, compared to the control group. Macroscopical changes were seen in the liver and kidney between 6 and 10 dpi, with no lesions being observed in the other organs. Histological lesions were observed in the liver and pancreas during the same period. Plasma was collected from killed birds of each group at each time point and the following clinical chemistry analytes were investigated: aspartate aminotransferase (AST), glutamate dehydrogenase (GLDH), bile acids, total protein, albumin, uric acid and lipase. Plasma protein profile, AST and GLDH, together with bile acids values paralleled the macroscopical and histopathological lesions in the liver, while plasma lipase activity levels coincided with lesions observed in pancreas. In agreement with the histology and clinical chemistry, viral load in the target organs, liver and pancreas, was highest at 7 dpi. Thus, clinical chemistry was found to be a valuable tool in evaluating and monitoring the progression of IBH in experimentally infected birds, providing a deeper knowledge of the underlying pathophysiological mechanisms of a FAdV infection in chickens.

Epidemiological and pathological investigation of fowl aviadenovirus serotypes 8b and 11 isolated from chickens with inclusion body hepatitis in Spain (2011–2013)

“…Contact birds were probably infected by the oral route from the contaminated faeces of the inoculated chickens. In other trials, horizontal transmission of different FAdV serotypes (including 8b and 11) was also achieved (Mendelson et al, 1995;Ono et al, 2007;Matos et al, 2016b). In our study, shedding results correlated with the administered dose; that is, birds infected with the higher viral dose excreted the virus at a higher concentration, and birds in contact with them started to excrete the virus earlier than the ones infected with a low dose.…”

“…While some studies (Dar et al, 2012;Zhao et al, 2015, Matos et al, 2016a obtained moderate to severe clinical signs and mortalities when infecting chickens at different ages (from 1 day to 3 weeks of age) with FAdV serotypes 8b and 11, Grgic and colleagues (2011) could reproduce neither clinical signs nor mortality after infecting 10-day-old birds with an FAdV serotype 8 strain. Moreover, in a recently published trial (Matos et al, 2016b), birds infected with FAdV-8b and FAdV-11 showed more severe clinical signs and mortalities than those inoculated with FAdV serotypes 2, 7 and 8a.…”

Pathogenicity of field strain of fowl aviadenovirus serotype 11 isolated from chickens with inclusion body hepatitis in Morocco

“…In recent years, increasing clinical cases of FAdV infections have been concerned and many FAdV strains related to IBH have been identified in many countries [ 11 , 15 , 25 , 33 , 38 – 43 ]. Some of them were highly pathogenic to chickens and were associated to considerable economic losses [ 15 , 26 , 33 , 44 ].…”

Fowl Adenovirus (FAdV) Recombination with Intertypic Crossovers in Genomes of FAdV-D and FAdV-E, Displaying Hybrid Serological Phenotypes

“…Recombinant FAdV-E strains addressed in this study were isolated from IBH outbreaks, or induced disease in experimental settings [70], underlining their clinical relevance. Antigenic segments with parental origin of types -6 and -7, which are usually not linked to IBH, were also found among field isolates (12-10101, 09-8330, and 13-19395), although experimental data on the pathogenicity of the latter two strains are unavailable so far.…”