Comparison of the Fibers of Fowl Adenovirus A Serotype 1 Isolates from Chickens with Gizzard Erosions in Europe and Apathogenic Reference Strains

Abstract

Abstract. A total of 18 samples from 4 outbreaks of gizzard erosions in broiler chickens in Europe were used in the current study. Fowl adenoviruses were found in samples from all 4 outbreaks, and isolates were identified as Fowl adenovirus A (FAdV-A) serotype 1. As described earlier, polymerase chain reactionrestriction fragment length polymorphism (PCR-RFLP) analysis of the long fiber gene was conducted. However, all 18 samples showed the same pattern as apathogenic FAdV-1 strains: Ote and chicken embryo lethal orphan (CELO) viruses. Nucleotide and amino acid sequences of the long and short fiber of several isolates from broiler chickens with gizzard erosions were analyzed, and 100% identity between the field isolates on the protein level was revealed. Only 1 nonsynonymous mutation (TRA) was present in the long fiber of studied isolates compared to the CELO strain. The same mutation was also present in the Ote strain. Four nonsynonymous mutations were present in the long fiber of studied isolates compared to Ote strain. In the short fiber, 6 nonsynonymous mutations were found in the studied isolates compared to the CELO strain. However, the short fiber of pathogenic isolates was 100% identical to apathogenic Ote strain. In conclusion, the usefulness of PCR-RFLP analysis of the long fiber gene of FAdV-1 isolates in distinguishing between those that induce gizzard erosions and those that do not remains questionable for the isolates obtained from European poultry flocks. The role of certain FAdV-1 strains with their long and short fiber in pathogenicity regarding gizzard erosions is still not clear.

Whole genome sequencing of Fowl aviadenovirus A - a causative agent of gizzard erosion and ulceration, in adult laying hens

“…Also, analysis of the partial short fiber gene of the PL/060/08 FAdV-1 isolate from a GEU outbreak in broilers, showed that the amino acid sequence is identical to our isolates. Previous analysis of the short fiber gene of GEU isolates from European countries, performed by Marek et al (2010), revealed exactly the same mutations to our W-15 and 61/11z isolates. Surprisingly, another apathogenic strain, FAdV-1 Ote, also has the same 6 mutations in short fiber.…”

“…Therefore, it is unlikely that changes in the fiber protein alone contribute to the pathogenicity of FAdV (Marek et al, 2010). In contrast, studies on virulence factors of FAdV-8 revealed that the fiber gene plays a role in the pathogenicity of this serotype (Pallister et al, 1996).…”

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

“…During the last 15 years some FAdV-1 strains have been shown to cause gizzard erosions in broiler chickens in Japan (Abe et al, 2001;Okuda et al, 2001;Nakamura et al, 2002;Ono et al, 2003), several European countries (Manarolla et al, 2009;Marek et al, 2010;Domanska-Blicharz et al, 2011;Grafl et al, 2012;Kaján et al, 2013;Schade et al, 2013) and in Korea (Lim et al, 2012). The FAdV-1 field isolate used in this study was isolated from the bursa of a healthy broiler chicken, as in other studies in which serotype 1 isolates were obtained from healthy birds Nakamura et al, 2002).…”

“…It is believed that the strain of FAdV-1 used in our study may not have been a true representative of this serotype. Inter-strain variation in pathogenicity of a FAdV serotype has been reported (Pallister et al, 1993;Okuda et al, 2006;Marek et al, 2010;Grafl et al, 2014). The FAdV-1 isolate used in our study was included since it was the only contemporary FAdV-1 isolate available in Australia and its pathogenicity and role in IBH outbreaks in Australia were unknown.…”

A comparative pathogenicity analysis of two adenovirus strains, 1/A and 8a/E, isolated from poultry in Poland

“…The full genome sequence of the FAdV-1-61/11z virus strain was reported by Matczuk et al in 2017 [22]. Interestingly, some strains of FAdV-8a may be implicated in the development of GEU [16,17,19] and IBH [14,21,23,24,37]. Adenoviruses have been suggested to play a role in immunodeficiency [24,28,35].…”