Identification of four serotypes of fowl adenovirus in clinically affected commercial poultry co‐infected with chicken infectious anaemia virus in Trinidad and Tobago

Abstract

Summary Fowl adenovirus (FAdV), which causes the high‐impact diseases such as inclusion body hepatitis and hepatitis‐hydropericardium syndrome, is of major concern to the poultry industry internationally. This study was carried out in direct response to mortality rates of up to 75% in commercial broiler flocks in Trinidad, West Indies. Symptoms in 3‐ to 8‐week‐old broilers and 13‐ to 18‐week‐old pullets pointed to infection with an immunosuppressive viral pathogen. The objectives of the study were to determine whether the infectious agent FAdV, along with other viral pathogens, was responsible for the clinical disease, and to obtain information on the serotypes of FAdV that were infecting the birds. Tissue samples from clinically affected birds from eight different farms were tested for chicken infectious anaemia virus (CIAV) and infectious bursal disease virus (IBDV) by real‐time reverse transcription polymerase chain reaction (PCR) and for FAdV by conventional PCR. The birds tested positive for FAdV and CIAV, but negative for IBDV. The gene corresponding to the L1 loop of the hexon protein for FAdV was amplified and sequenced. Phylogenetic analysis of seven FAdV strains inferred that four serotypes were likely to be circulating in the chickens. Well supported genetic relatedness was observed for serotype 8a (97.8%), 8b (97.8%), 9 (95.8%) and 11 (98.8%–99.5%). This is the first published report from Trinidad and Tobago on the presence and circulation of pathogenic FAdV strains, in combination with CIAV, in poultry. The data demonstrate a possible need for the introduction of serotype‐specific vaccines against FAdV, as well as vaccines against CIAV, in broilers in the region and emphasize the importance of maintaining high levels of biosecurity on farms to prevent the spread of these potentially devastating viruses between farms.

Characterization of Co-infection With Fowl Adenovirus Serotype 4 and 8a

“… Yu et al (2019) reported that the infection rate of FAdV-4 has reached 65.2% in 36 farms in Shandong province, China, and co-infection with FAdV-4 and avian influenza virus (AIV), infectious bursal disease virus (IBDV), and chicken infectious anemia virus (CIAV) were found to be common in these samples. Co-infections with FAdVs and CIAV in broilers have been reported in India as well ( Brown Jordan et al, 2019 ). More recently, Yan et al (2020) reported the co-infection with FAdV-4 and avian orthoreovirus (ARV) in broilers, and that the co-infection rate in ARV-positive samples reached 63%.…”

Fowl adenovirus strains 1/A and 11/D isolated from birds with reovirus infection

“…In studies conducted in Trinidad and Tobago, three viruses have been identified (FAdV with three type/species designed as 8a/E, 8b/E, and 11/D) CIAV and IBDV have been participated in the coinfection. These adenoviruses which represent two species, D and E, are the most prevalent in Trinidad and Tobago today [ 55 ]. Adenoviruses and reoviruses were also isolated from pigeons and mallard ducks [ 25 ].…”

A comprehensive review of viruses in terrestrial animals from the Caribbean islands of Greater and Lesser Antilles

“…In another study during 2015, the same researchers reported anti‐CIAV antibodies in 10.3% of backyard chickens in Grenada (Sharma et al., 2015). Real‐time PCR (qPCR) assays identified CIAV DNA in tissue samples obtained from seven of eight broiler farms during 2015–2016 in Trinidad (Brown Jordan et al., 2019a).…”

“…During 2014–2015, a serosurveillance study on the islands of Trinidad and Tobago detected anti‐FAdV‐I antibodies in 100% of sampled layers from both the islands, whilst seroprevalence of 67% and 100% were observed against EDSV in Trinidad and Tobago, respectively (Brown Jordan et al., 2018d). In a subsequent study, conventional polymerase chain reactions (PCRs) identified fowl adenovirus DNA in tissue samples from clinically affected birds on eight different farms, and phylogenetically, four adenovirus serotypes were recognized (Brown Jordan et al., 2019a). A single fowl adenovirus strain was isolated and molecularly characterized (genotype E3) from the Dominican Republic (Schachner et al., 2016).…”