Molecular Diagnosis of Avihepatovirus a in Naturally Infected Duck Flocks in Egypt
Molecular Diagnosis of Avihepatovirus a in Naturally Infected Duck Flocks in Egypt
A. El-Shemy1*, Hoda M. Mekky2, M. A. Bosila2, A. M. Allam1, Kh. M. Elbayoumi2, M. M. Amer3
ABSTRACT
Duck virus hepatitis (DVH) is one of the most significant viral diseases in young ducklings; it results inhigh potential mortality and great economic losses. We collected liver samples from three duck farms representing Muscovy and Pekin breeds at ages ranging from 2 to 4 weeks and located in two Egyptian governorates between August and October 2018. The affected ducks were suffering from a short course of nervous signs, and mortality was high, reaching 75% within 3–4 days. Implementation of one-step reverse transcription polymerase chain reaction (RT-PCR) for processed livers using specific primers aiming the 3D gene of duck hepatitis A virus-1 (DHAV-1) showed the output of the amplified band in all examined specimens at the certain supposed size of the 3D encoding gene (467 bp). The successfully amplified 3D gene of DHAV-1 isolates, namely DHV/Duck/Egypt/Monofia-Shemy-1/2018, DHV/Duck/Egypt/Al-Gharbia-Shemy-3/2018, and DHV/Duck/Egypt/Monofia-Shemy-2/2018, was subjected to sequencing and then submitted to NCBI GenBank, and the obtained accession numbers are MT157210, MT157211,and MT157212, respectively. Nucleotide sequences alignment analysis of the 3D gene exhibited 92.5%–98.6% homology between our sequenced isolates. The three examined isolates had 77.4%–80.2% nucleotide similarities with the most frequently used DHAV-1 vaccine in Egypt. However, the phylogenetic relationship using the partial 3D protein revealed that the isolated Egyptian strains in this study were distant from the vaccine strain used in Egypt. In conclusion, three isolates of DHAV-1 were characterized from the examined duck flocks. Phylogenetic analysis of these isolates revealed the occurrence of differentiation between our field DHAV-1 isolates and the vaccine strain. Therefore, applying an appropriate vaccination program for breeder duck flocks is significant in controlling DHAV-1 infection. Thus, we recommend the application of further studies to detect the efficacy of the used vaccine against the current field strains of DHAV-1
Keywords | Nervous signs, DHAV-1, RT-PCR, Nucleotide sequences, Phylogenetic analysis
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