Analyzing the genetic diversity of teschoviruses in Spanish pig populations using complete VP1 sequences

Porcine teschoviruses (PTVs) have been previously shown to be the most abundant cytopathic viruses found in swine feces. In the present study, the diversity of PTVs was studied, using PTV isolates collected between 2004 and 2009 in a wide territory in Spain. In order to characterize genetically the isolates, phylogeny reconstructions were made using maximum likelihood and Bayesian inference methods, based on the 1D (VP1) gene, and including sequences available in public databases. The phylogenetic trees obtained indicated that PTVs present 12 main lineages, 11 corresponding to the PTV serotypes described to date, and one lineage distinct from the rest. The geographic distribution of the different lineages does not seem to be strongly associated to particular territories, and co-circulation of multiple lineages was found in the same geographic areas. Nevertheless, some spatial structuring of the viral populations studied is indicated by the differences found between Spanish samples with respect to other European countries. A coalescent-based approach indicated that mutation may have been the main factor in originating the genetic diversity observed in the VP1 gene region. This study revealed a high diversity of teschoviruses circulating in the pig populations studied, and showed that molecular analysis of the complete VP1 protein is a suitable method for the identification of members of the porcine teschovirus group. However, further analyses are needed to clarify the geographical structuring of the different PTV populations.