Rapid sequence modification in the highly polymorphic region (HPR) of the hemagglutinin gene of the infectious salmon anaemia virus (ISAV) suggests intra‐segmental template switching recombination

Abstract The ISAV has a genome composed of eight segments of (–)ssRNA, segment 6 codes for the hemagglutinin–esterase protein, and has the most variable region of the genome, the highly polymorphic region (HPR), which is unique among orthomyxoviruses. The HPR has been associated with virulence, infe...

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Bibliographic Details
Published in:Journal of Fish Diseases
Main Authors: Cárdenas, Matías, Galleguillos, Claudia, Acevedo, Karina, Ananias, Catarina, Alarcón, Javiera, Michelson, Sofía, Toledo, Jorge, Montoya, Margarita, Meneses, Claudio, Castro‐Nallar, Eduardo, Vásquez‐Martínez, Yesseny, Cortez‐San Martin, Marcelo
Other Authors: Fondo Nacional de Desarrollo Científico y Tecnológico, Departamento de Investigaciones Científicas y Tecnológicas, Universidad de Santiago de Chile
Format: Article in Journal/Newspaper
Language:English
Published: Wiley 2020
Subjects:
Atlantic salmon
Online Access:http://dx.doi.org/10.1111/jfd.13242
https://onlinelibrary.wiley.com/doi/pdf/10.1111/jfd.13242
https://onlinelibrary.wiley.com/doi/full-xml/10.1111/jfd.13242
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Summary:Abstract The ISAV has a genome composed of eight segments of (–)ssRNA, segment 6 codes for the hemagglutinin–esterase protein, and has the most variable region of the genome, the highly polymorphic region (HPR), which is unique among orthomyxoviruses. The HPR has been associated with virulence, infectivity and pathogenicity. The full length of the HPR is called HPR0 and the strain with this HPR is avirulent, in contrast to strains with deleted HPR that are virulent to varying degrees. The molecular mechanism that gives rise to the different HPRs remains unclear. Here, we studied in vitro the evolution of reassortant recombinant ISAV (rISAV) in Atlantic salmon head kidney (ASK) cells. To this end, we rescued and cultivated a set of rISAV with different segment 6‐HPR genotypes using a reverse genetics system and then sequencing HPR regions of the viruses. Our results show rapid multiple recombination events in ISAV, with sequence insertions and deletions in the HPR, indicating a dynamic process. Inserted sequences can be found in four segments of the ISAV genome (segments 1, 5, 6, and 8). The results suggest intra‐segmental heterologous recombination, probably by class I and class II template switching, similar to the proposed segment 5 recombination mechanism.

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