Infectious Bursal Disease Virus in Algeria: Persistent Circulation of Very Virulent Strains in Spite of Control Efforts
Chafik Redha Messaï,
Nadia Safia Chenouf,
Oussama Khalouta,
Abdelhafid Chorfa,
Omar Salhi,
Claudia Maria Tucciarone,
Francesca Poletto,
Giovanni Franzo,
Chahrazed Aberkane,
Mattia Cecchinato,
Matteo Legnardi
Affiliations
Chafik Redha Messaï
Laboratory of Research Health and Animal Production, High National Veterinary School, Issad Abbes Street, Oued Smar, Algiers 16000, Algeria
Nadia Safia Chenouf
Faculty of Natural and Life Sciences, Earth and Universe Science, University Mohamed El Bachir El Ibrahimi of Bordj Bou Arreridj, El Anasser, Bordj Bou Arreridj 34000, Algeria
Oussama Khalouta
Laboratory of Life Sciences and Techniques, Institute of Agricultural and Veterinary Sciences, University Mohamed Cherif Messaadia, Souk Ahras 41000, Algeria
Abdelhafid Chorfa
Veterinary Office, Specialized in Avian Diseases and Analyses, El Eulma, Setif 19000, Algeria
Omar Salhi
Biotechnology Laboratory of Animal Reproduction, Institute of Veterinary Sciences, Blida 09000, Algeria
Claudia Maria Tucciarone
Department of Animal Medicine, Production and Health, University of Padova, 35020 Legnaro, Italy
Francesca Poletto
Department of Animal Medicine, Production and Health, University of Padova, 35020 Legnaro, Italy
Giovanni Franzo
Department of Animal Medicine, Production and Health, University of Padova, 35020 Legnaro, Italy
Chahrazed Aberkane
DEDSPAZA Laboratory, Department of Agricultural Sciences, Mohamed-Khider University, Biskra 07000, Algeria
Mattia Cecchinato
Department of Animal Medicine, Production and Health, University of Padova, 35020 Legnaro, Italy
Matteo Legnardi
Department of Animal Medicine, Production and Health, University of Padova, 35020 Legnaro, Italy
Infectious bursal disease (IBD) is among the most impactful immunosuppressive diseases of poultry. Its agent, infectious bursal disease virus (IBDV), is prone to both mutation and reassortment, resulting in a remarkable variability. Traditionally, IBDV characterization relies on antigenicity and pathogenicity assessment, but multiple phylogenetic classifications have been recently proposed, whose implementation in molecular surveys helps generating informative and standardized epidemiological data. In the present study, the Algerian IBDV scenario was assessed based on the novel classification guidelines by sequencing portions of both genome segments. Seventy pools of bursal samples were collected in 2022–2023 in 11 districts of Northern Algeria, mostly from broiler flocks. Out of 55 (78.6%) positive flocks, 40 (57.1%) were infected by field strains, which were characterized as very virulent strains (genotype A3B2) and phylogenetically related to previously reported Algerian strains. Significant differences in the percentage of field infections were observed between vaccinated (25/52, 46.2%) and unvaccinated (14/17, 82.3%) groups, and also between birds immunized with live intermediate (13/20, 65.0%) and intermediate plus (10/28, 35.7%) vaccines. Nonetheless, the number of field strain detections suggests a high infectious pressure and the inadequacy of current vaccination efforts, demanding a reevaluation of control measures coupled with attentive monitoring activities.
