Identification and Virulence Characterization of Fowl Adenoviruses in Korea

Abstract

Since 2007, 55 adenovirus strains have been isolated from commercial chicken flocks in Korea and have been identified and the pathogenicity of these isolates was confirmed in specific-pathogen-free chickens of different age. Based on sequencing analysis of the hexon gene, 55 FAdV isolates were genetically related to the IBH-2A strain of FAdV3 (4 isolates, 99.2% to 100%), the KR5 strain of FAdV4 (22 isolates, 97.9% to 99.2%), the 764 strain of FAdV9 (11 isolates, 99.1% to 99.3%), and the 1047 strain of FAdV11 (18 isolates, > 99%). Experimental infections with four serotypes of FAdV resulted in high mortality of 18-day-old chicken embryos and 1-day-old chicks with marked liver necrosis similar to those observed in the natural outbreaks. Notably, specific hydropericardium was observed in chicks challenged with the K531 strain (serotype 4). However, 3-wk-old chickens challenged with FAdVs, regardless of serotype, did not show any clinical signs or mortality except histologic lesions of focal hepatocytic necrosis with mild lymphocytic infiltration. The results indicate that four FAdV serotypes (3, 4, 9, and 11) are the dominant serotypes of FAdVs in the Korea and are pathogenic enough to cause clinical disease in young chicks. The present investigation provides important information on the epidemiology and pathogenesis of FAdVs and highlights the importance of control strategies against FAdV infection in Korea.

Chronological analysis of gross and histological lesions induced by field strains of fowl adenovirus serotypes 1, 8b and 11 in one-day-old chickens

“…Very few experimental studies have been able to induce IBH disease using natural routes of infection in young SPF chickens (Hess, 2013), and where this has been achieved the dose of virus inoculated was greater than that used in this study (Cook, 1983;Saifuddin & Wilks, 1991;Lim et al, 2011). Ocular inoculation of the birds with serotypes 8b and 11 led to an incubation period of 3 days, followed by a degenerative period between days 4 and 7 PI, when the severity and prevalence of gross and histological lesions were greatest (Figure 1).…”

“…FAdV-8b and FAdV-11 have been identified in several countries in association with IBH (Ojkic et al, 2008;Lim et al, 2011;Zadravec et al, 2011;Hess, 2013), as well as with HPS (Nakamura et al, 2000) and gizzard erosion (Okuda et al, 2004). The primary purpose of this investigation was to determine if field strains of FAdV-1, FAdV8b and FAdV-11, all isolated in association with IBH field outbreaks without evidence of immunosuppression, are primary pathogens.…”

“…Given the global nature of the poultry industry and the detection of FAdV-8b and FAdV-11 in many countries (Gomis et al, 2006;Lim et al, 2011;Hess, 2013), this information has implications for the poultry industry worldwide, as control of immunosuppressive agents such as chicken anaemia virus and infectious bursal disease virus alone may not fully control IBH.…”

Molecular Identification of Fowl Adenovirus Associated with Inclusion Body Hepatitis in Iran

“…Inclusion body hepatitis (IBH) has been occurring as an economically important and reemerging disease of broiler breeder and broiler chickens in several countries (9,24,(29)(30)(31)(32). Although the IBH outbreaks are usually associated with serotype 6, 7, and 8, the viruses associated with outbreaks in Iran were adenovirus serotype 11, based on hexon gene sequencing of the PCR products (20).…”

Epidemiological investigation of outbreaks of fowl adenovirus infection in commercial chickens in Korea

“…In recent years, the number of IBH and HPS cases has increased in the Korean poultry industry, especially in broiler and native chickens (Kim et al, 2008;Lim et al, 2011). In particular, there have been questions about the involvement of immunosuppressive agents in outbreaks of FAdV infection.…”