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Diseases of Aquatic Organisms

    DAO prepress abstract   -  DOI:

    Phylogeography of betanodavirus genotypes circulating in Tunisian aquaculture sites, 2012–2019

    Nadia Chérif*, Rym El Jeni, Fatma Amdouni, Sabrin Zreilli, Hanem Djabou, Sana Khemiri, Ines Tliba, Balkiss Bouhaouala-Zahar, Kaouther Maatoug, Sami Zaafran, David Groman

    *Corresponding author:

    ABSTRACT: The purpose of this study was to determine the phylogenetic relationships among the primary betanodavirus strains circulating in Tunisian coastal waters. A survey was conducted to investigate nodavirus infections at fifteen sea bass and sea bream farming sites located along the Tunisian North and Eastern coasts. The primary objective of the study was to create epidemiological awareness of these infections by determining phylogenetic relationships between the main betanodavirus strains circulating during the period from 2012-2019, using RNA1 and/or RNA2 genome segments . A total of 40% (118 of 294) tissue pools tested were found to be positive for betanodavirus.. Positive pools were found to be distributed across all of the sampling sites. While fish mortalities were always correlated with the presence of virus in sea bass, a severe outbreak was also identified in sea bream larvae in 2019. Phylogenetic analysis revealed that almost all Tunisian strains from both sea bass and sea bream irrespective of outbreaks clustered within the RGNNV genotype. It is noteworthy that samples collected during 2019 outbreak from sea bream, however, contained RNA1 and RNA2 fragments belonging both the RGNNV and SJNNV genotype respectively, an indication of viral genome reassortant. To the best of our knowledge, the current study is the first report ofreassortant betanodavirus in Tunisia.