Detection, Quantification and Molecular Characterization of Fowl Adenoviruses Circulating in Ecuadorian Chicken Flocks during 2019–2021

SIMPLE SUMMARY: Viral diseases cause high economic losses in poultry. One of them is IBH (inclusion body hepatitis) and HHS (hepatitis-hydropericardium syndrome) associated with fowl adenoviruses (FAdVs), a virus that spreads rapidly by feces. Thus, the aim of the present study was to detect, quantify, and identify the genotypes of FAdVs that are circulating in the chicken commercial flocks and could be responsible for outbreaks of hepatic diseases. The study showed the presence of genotypes FAdV-2/D2, FAdV-6/E1, FAdV-8a/E2, and FAdV-11/D3 of FAdV, all of them related to IBH and HHS. These results showed that in commercial birds with enteric problems, FAdV is circulating, pointing to the need for revising biosecurity programs and considering FAdV as being disseminated by feces and causing IBH and HHS. ABSTRACT: Fowl adenoviruses are a group of pathogens that cause large economic losses worldwide in the poultry industry, in addition to producing a wide range of diseases, such as IBH, HHS, and enteric and respiratory diseases. The objective of this study was to quantify, identify, and molecularly characterize the types of FAdV circulating in commercial poultry farms (broilers, breeders, and layers) in Ecuador from 2019 to 2021. Molecular characterization was performed by PCR, quantification by qPCR, and subsequent sequencing for each positive sample. The results indicated that the FAdV genotypes circulating in our country are FAdV-2/D2, FAdV-6/E1, FAdV-8a/E2, and FAdV-11/D3; the samples were grouped into different groups that contain sequences that were obtained from countries in Africa, Asia, and America, and that are found in birds at different ages, since early age where can cause different clinical signs, such as diarrhea, ruffled feathers and dwarfism. Therefore, these results indicate that several genotypes of the virus are circulating in commercial poultry flocks, suggesting that biosecurity measures on farms should be improved, in addition to carrying out new or improved vaccination plans.