Genomic features of first bovine astrovirus detected in Egypt

Bovine astrovirus (BAstV) is a small single-stranded RNA virus, which belongs taxonomically to genus Mamastrovirus under the family Astroviridae. The BAstV is strongly linked to neonatal diarrhea of calves. A few studies are available on BAstV, mainly from Asia, and to a lesser extent from Europe, South America, and Africa. There is only one report from Egypt, in which BAstV was found in diarrheic calves, either in single- or co-infections, based on reverse transcription polymerase chain reaction (RT-PCR) and BAstV-polymerase enzyme targeting primers. One of the samples was further subjected to genomic characterization using Illumina platform for next generation sequencing (NGS). After being processed, the returned BAstV complete genome was subjected to sequence and phylogenetic analysis in comparison to reference strains. The BAstV open reading frames (ORF1a, ORF1b, and ORF2) followed a nearly similar genetic topology, as they belonged to the same unclassified lineage, which was earlier proposed as BAstV-lineage 1, and is known to be disseminated worldwide. This close phylogenetic relationship between the study strain and other members of this lineage was further confirmed by high nucleotide and amino acid (aa) identities. Additionally, a total of 24 unique aa residues were found through the entire BAstV genome. As being the first report in Egypt, indeed Africa, we believe that this record shall be useful in either taxonomic classification or epidemiological tracking of BAstV. The status of BAstV in Egypt should be carefully investigated with possible to-be-implemented precautions for the protection of animal-raising industries.