Full genome sequence analysis of parechoviruses from Brazil reveals geographical patterns in the evolution of non-structural genes and intratypic recombination in the capsid region.

Due to high genome plasticity, the evolutionary fate and geographical history of picornaviruses is hard to follow. Here, we determined the complete coding sequences of eight human parechoviruses (HPeV) of types 1, 5 and 6 directly from clinical samples from Brazil. The capsid genes of these strains were not remarkably different from European, North American and Japanese HPeV. Full genome analysis revealed frequent intertypic recombination in the non-structural genome region. In addition, evidence of recombination between viruses of the same type in the capsid-encoding genome region among HPeV1 and HPeV4 was obtained. Bayesian phylogenetic analysis indicated that strains without evidence of recombination with each other in any genome region were separated by no more than 35 years of circulation. Interestingly, in the 3C gene, all Brazilian parechoviruses grouped together regardless of serotype. The most recent common ancestor of these strains dated back 108 years, suggesting long-term endemicity of this particular P3 genome lineage in South America. Our results support the idea that picornavirus replicative genes acquire capsid proteins introduced by new strains. Under certain epidemiological conditions, replicative genes may be maintained in circumscript geographical regions.