title: Aquabirnavirus polyploidy: a new strategy to modulate virulence?
abstract: One of the main research issues regarding infectious pancreatic necrosis virus (IPNV) is its virulence mechanisms. The basis for understanding the molecular virulence determinants of this virus was established over the last decade when it was demonstrated that certain amino acid domains in the VP2 and VP2-NS inter-region determined the level of virulence of IPNV. However, certain variability was still inexplicable and therefore other factors may also be involved. To this end, it was demonstrated recently that infectious bursal disease virus (IBDV), a virus in a different genus of the same family as IPNV, can package more than two dsRNA segments, and that polyploidy may be associated with virulence. In the present report, we analysed the viral fractions obtained after gradient centrifugation to demonstrate that IPNV virions can also package more than two segments, thus indicating that polyploidy is a common birnavirus trait. The differential replicationex vivoand virulencein vivoadditionally suggested that such a characteristic is involved in the modulation of virus infectivity. However, although theex vivoresults clearly demonstrated that the replication capacity was enhanced as the viral ploidy increased, thein vivoresults could not strongly support a direct relationship between ploidy and virulence to the host, thus suggesting that other virulence determinants are also involved.
authors.affiliation: Departamento de Microbiología y Parasitología, Instituto de Acuicultura,Universidad de Santiago de Compostela, Santiago de Compostela 15706,Spain.
authors.forename: M
authors.initials: M
authors.lastname: Lago
authors.affiliation: Department of Molecular and Cellular Biology, Centro Nacional de Biotecnología/CSIC,Cantoblanco, 28049 Madrid,Spain.
authors.forename: José F
authors.initials: JF
authors.lastname: Rodríguez
authors.affiliation: Departamento de Microbiología y Parasitología, Instituto de Acuicultura,Universidad de Santiago de Compostela, Santiago de Compostela 15706,Spain.
authors.forename: I
authors.initials: I
authors.lastname: Bandín
authors.affiliation: Departamento de Microbiología y Parasitología, Instituto de Acuicultura,Universidad de Santiago de Compostela, Santiago de Compostela 15706,Spain.
authors.forename: C P
authors.initials: CP
authors.lastname: Dopazo