Detection and differentiation of avian adenoviruses: A review

Abstract

Avian adenoviruses are a very diverse group of pathogens causing a variety of problems for poultry production. For a long time, the diagnosis of an adenovirus infection was restricted to the isolation of the respective virus followed by various serological typing methods, such as immunofluorescence assay, neutralization test or haemagglutination-inhibition test. In addition, restriction enzyme analysis has been reported for differentiation of avian adenoviruses. Besides summarizing the classical diagnostic methods, this review is mainly focused on the challenges that occurred recently in the field of avian adenovirus diagnosis at the molecular level. Several polymerase chain reactions (PCRs) have been published to diagnose all three groups of avian adenoviruses. Most PCRs were established to detect fowl adenovirus (FAV) DNA. Some of them were combined with restriction enzyme analysis to investigate whether FAV reference strains and field isolates could be typed according to the restriction profiles of the PCR products. The great advantage of direct detection of the viral DNA in tissue samples was demonstrated for the haemorrhagic enteritis virus and egg drop syndrome virus. Other PCRs were developed with the aim of detecting viral DNA from all three groups of avian adenoviruses partially in target cells. Whereas the value of these PCRs for avian adenovirus diagnostics is not disputable, the problems and open questions that are still present are also discussed.

Production and characterization of monoclonal antibodies to fowl adenoviruses

“…The cost of the technique and skilled, time-consuming labour has limited the method to research applications. However, with the introduction of PCR as a routine diagnostic technique in many laboratories, molecular diagnosis may play an increasingly important role (Hess, 2000). This study appears to be the first report on a panel of mAbs produced to group I avian adenoviruses.…”

“…Group 1 includes the fowl adenoviruses (FAdV) 1 to 12 (Hess, 2000) that have been placed in five species based on genotype (A to E) (Benkö et al, 2000). Infections with FAdVs have been associated with disease syndromes such as inclusion body hepatitis (IBH), infectious hydropericardium, respiratory diseases, tenosynovitis, reduced egg production, aplastic anaemia and atrophy of the bursa and thymus (Helmboldt & Frazier, 1963;Winterfield et al, 1973;Aghakhan, 1974;Rosenberger et al, 1974;McFerran & Adair, 1977;Dhillon et al, 1982;Hess et al, 1999;Mazaheri et al, 1998;Hess, 2000). These diseases have been linked to the predisposin g role of immunosuppressive agents in FAdV infections (McFerran, 1980;Winterfield, 1984;McCracken & Adair, 1993).…”

Group I avian adenovirus and avian adeno-associated virus in turkey poults with inclusion body hepatitis

“…Atrophy of the bursa in addition to hepatitis due to group I adenovirus was seen in chickens and poults in an earlier study (Cho, 1976). In chickens, inclusion body hepatitis due to group I adenovirus has been associated with immunosuppression caused by infectious bursal disease virus (IBDV) and chicken anaemia virus (McFerran, 1997;Hess, 2000). The birds in this report were not examined for IBDV, but IBDV is considered to be non-pathogenic in turkeys (Lukert & Saif, 1997).…”

“…Avian adenoviruses (AAV) are classified into three serologically distinct groups (McFerran, 1997;Hess, 2000). Group III AAV can be isolated from clinically normal ducks, and cause egg drop syndrome in chickens.…”

“…Group II AAV cause haemorrhagic enteritis in turkeys (THE), marble spleen disease in pheasants, and splenomegaly in chickens. Group I AAV are common to many avian species, and have been associated with respiratory disease in chickens, turkeys and quail, and inclusion body hepatitis (IBH) in chickens and bronchitis in quail (Blalock et al, 1975;Jack et al, 1987;McFerran, 1997;Hess, 2000).…”