Molecular characterization and phylogenetic analysis of structural protein Vp1 to new isolate of duck hepatitis A virus

Abstract

Duck hepatitis A virus (DHA) is very fatal viral disease affecting young ducklings under one month old. The disease is generally spread among duckling flocks inducing sever dramatic and economic losses. The present research highlights investigation of duck hepatitis virus through collection of hundred spleen and liver field samples from various commercial 3-11 days old duckling sectors (Pekin and Mullard) at ten Egyptian governorates in 2022 and 2023 with historical view of high mortalities and nervous manifestations with background of previous immunization. The clinically infected specimens were directly screened using RT-PCR assay to detect duck hepatitis A virus through amplification of VP1 gene that reveals only one sample (obtained from Menofia governorate) was positive for DHAV-3. BLAST analysis of Partial obtained sequence of VP1 gene showed that it was closely related Egyptian strain (accession number OR543968) besides nucleotides and amino acid changes were observed in comparison with other strains. Phylogenetic analysis of the obtained strain revealed clustering with viruses of Chinese origin and distinctive from vaccinal strains utilized in Egypt. Successful isolation of duck hepatitis A virus was achieved through inoculation of tissue homogenates into allantoic cavity of 9-11 day old embryonated chicken eggs. The outcomes of this work supplied rationalized knowledge about the epidemiological criteria of DHA virus in Egypt; emphasize the significance of DHA survey and vaccine selection.