title: Genetic and immunobiological diversities of porcine reproductive and respiratory syndrome genotype I strains.
abstract: Genetic diversity of porcine reproductive and respiratory syndrome virus (PRRSV) has been based on ORF5/GP5 and ORF7/N protein variations. Complete viral genome studies are limited and focused on a single or a few set of strains. Moreover, there is a general tendency to extrapolate results obtained from a single isolate to the overall PRRSV population. In the present study, six genotype-I isolates of PRRSV were sequenced from ORF1a to ORF7. Phylogenetic comparisons and the variability degree of known linear B-epitopes were done considering other available full-length genotype-I sequences. Cytokine induction of all strains was also evaluated in different cellular systems. Non structural protein 2 (nsp2) was the most variable part of the virus with 2 out of 6 strains harboring a 74 aa deletion. Deletions were also found in ORF3 and ORF4. Phylogenetic analyses showed that isolates could be grouped differently depending on the ORF examined and the highest similarity with the full genome cluster was found for the nsp9. Interestingly, most of predicted linear B-epitopes in the literature, particularly in nsp2 and GP4 regions, were found deleted or varied in some of our isolates. Moreover, 4 strains, those with deletions in nsp2, induced TNF-α and 3 induced IL-10. These results underline the high genetic diversity of PRRSV mainly in nsp1, nsp2 and ORFs 3 and 4. This variability also affects most of the known linear B-epitopes of the virus. Accordingly, different PRRSV strains might have substantially different immunobiological properties. These data can contribute to the understanding of PRRSV complexity.
authors.affiliation: Departament de Sanitat i Anatomia Animals, Universitat Autònoma de Barcelona, 08193 Bellaterra, Spain. laila.darwich@uab.cat
authors.forename: Laila
authors.initials: L
authors.lastname: Darwich
authors.forename: Mariona
authors.initials: M
authors.lastname: Gimeno
authors.forename: Marina
authors.initials: M
authors.lastname: Sibila
authors.forename: Ivan
authors.initials: I
authors.lastname: Diaz
authors.forename: Eugenia
authors.initials: E
authors.lastname: de la Torre
authors.forename: Silvia
authors.initials: S
authors.lastname: Dotti
authors.forename: Liudmila
authors.initials: L
authors.lastname: Kuzemtseva
authors.forename: Margarita
authors.initials: M
authors.lastname: Martin
authors.forename: Joan
authors.initials: J
authors.lastname: Pujols
authors.forename: Enric
authors.initials: E
authors.lastname: Mateu
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D016000:Cluster Analysis; D016207:Cytokines / Q000276:immunology; D018985:Epitopes, B-Lymphocyte / Q000235:genetics; D014644:Genetic Variation; D016679:Genome, Viral; D005838:Genotype; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D010802:Phylogeny; D019316:Porcine respiratory and reproductive syndrome virus / Q000235:genetics* / Q000276:immunology*; D017384:Sequence Deletion; D013552:Swine; D017361:Viral Nonstructural Proteins / Q000235:genetics
chemical_list: D016207:Cytokines; D018985:Epitopes, B-Lymphocyte; D017361:Viral Nonstructural Proteins