Pathogenicity and Cytokine Gene Expression Pattern of a Serotype 4 Fowl Adenovirus Isolate

Abstract

Hydropericardium-hepatitis syndrome (HHS), a recently emerged disease of chickens, is caused by some strains of fowl adenovirus serotype 4 (FAdV-4). In this study, a Canadian FAdV-4 isolate, designated as FAdV-4 ON1, was evaluated for pathogenicity after oral and intramuscular (im) infection of specific pathogen free (SPF) chickens. Pathogenicity was evaluated by observation of clinical signs and gross and histological lesions. The highest viral DNA copy numbers, irrespective of the inoculation route, were detected in the cecal tonsils. Virus titers in cloacal swabs collected over the entire study period were compared between the orally and im inoculated chickens, and the difference in titers between the two groups was significant (P<0.001), the oral group had a higher rank. The antibody response of infected chickens tested by an adenovirus-specific ELISA showed a statistically significant (P<0.001) difference between the orally and im inoculated chickens. The im inoculated chickens had higher values than birds inoculated orally (P<0.001). Serum samples from both groups collected at 14 days post-infection completely neutralized FAdV-4 ON1. In addition, the effects of FAdV-4 ON1 infection on transcription of a number of avian cytokines were studied in vivo. The expression of interferon (IFN)-γ and interleukin (IL)-10 in the liver was induced at early times after infection. This FAdV-4 ON1 potentially could be used as a live vaccine against HHS and developed as vaccine vector. The GenBank/EMBL/DDBJ accession number for the FAdV-4 ON1 sequence is GU188428.

Fowl Adenovirus Serotype 4 SD0828 Infections Causes High Mortality Rate and Cytokine Levels in Specific Pathogen-Free Chickens Compared to Ducks

“…In some studies, chickens were infected with FAdV-4 via IM, oral, or intranasal routes ( 17 , 36 – 38 ). When compared with the oral and intranasal routes, IM produces stronger pathogenicity ( 17 , 37 ). In duck AdV infection models, the IM infection route was often used ( 27 ).…”

Clinicopathological characterization and genomic sequence differences observed in a highly virulent fowlAviadenovirusserotype 4

“…So far, the whole genome sequences of FAdV-4 strains KR5 (Marek et al, 2012) and ON1 (Griffin & Nagy, 2011) have been reported, both of which are of low virulence (Cook, 1983;Grgic et al, 2013). However, it should be noted that during the preparation of this manuscript, the complete genome of a highly pathogenic FAdV-4 was reported (Zhao et al, 2015).…”

User-Friendly Reverse Genetics System for Modification of the Right End of Fowl Adenovirus 4 Genome

“…These genes are engaged in the interaction between FAdV and the host cell or host immune system [2,8]. Elucidation of the gene functions will facilitate the development of attenuated vaccines, which havethe advantages over inactivated or subunit vaccines of high efficacy, easy inoculation and low costs [24][25][26][27]. On the other hand, gene function study will help the construction of FAdV-based gene delivery tools.…”