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Influence of time on the genetic heterogeneity of Spanish porcine reproductive and respiratory syndrome virus isolates |
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| Authors: | Prieto Cinta Vázquez Ana Núñez José I Alvarez Esther Simarro Isabel Castro José M |
| Institution: | aDepartamento de Sanidad Animal, Facultad de Veterinaria, Universidad Complutense de Madrid, Avda, Puerta de Hierro s/n, 28040 Madrid, Spain;bCentre de Recerca en Sanitat Animal, Campus de Bellaterra, Edifici V, 08193 Bellaterra, Barcelona, Spain |
| Abstract: | The aim of the present study was to establish the degree of diversity of porcine reproductive and respiratory virus (PRRSV) isolates that circulate in the same geographical area in different years. Nucleotide sequences of open reading frame (ORF) 5 were determined for 28 Spanish field PRRSV isolates from different years and three European-type modified live virus vaccines. Sequences were aligned using Clustal W software and a phylogenetic tree constructed using the neighbour joining method. The results of pairwise homology comparisons of nucleotide and deduced amino acid sequences of these PRRSV isolates indicate a tendency for heterogeneity to increase with time. The study of the phylogenetic tree revealed that Spanish PRRSV isolates constitute two well-defined clades and a group of unrelated sequences. The observed heterogeneity does not appear to be due to temporal evolution exclusively. Early and recent isolates group themselves into different clusters independently of the time of isolation, indicating the co-circulation of different variants and the maintenance of variants of the original isolates in the field. |
| Keywords: | Porcine reproductive and respiratory syndrome virus Genomic variability Temporal evolution Europe Spain |
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