Phylodynamics of Merkel-cell polyomavirus and human polyomavirus 6: A long-term history with humans

TORRES, CAROLINA; BARRIOS, MELINA ELIZABETH; CAMMARATA, ROBERTINA VIVIANA; VICTORIA, MATÍAS; FERNANDEZ-CASSI, XAVIER; BOFILL-MAS, SILVIA; COLINA, RODNEY; BLANCO FERNÁNDEZ, MARÍA DOLORES; MBAYED, VIVIANA ANDREA

MOLECULAR PHYLOGENETICS AND EVOLUTION

ACADEMIC PRESS INC ELSEVIER SCIENCE

Año: 2018 vol. 126 p. 210 - 220

1055-7903

New human polyomaviruses have been described in the last years, including the Merkel-cell polyomavirus(MCPyV; Human polyomavirus 5) and the Human polyomavirus 6 (HPyV6). Although their infection is usuallyasymptomatic, in immunocompromised host can cause life-threatening pathologies, such as the Merkel cellcarcinoma, an aggressive skin neoplasia associated to the MCPyV. Despite being prevalent viruses in population,epidemiological data from South America are scarce, as well as the characterization of the viral types circulatingand their origin. The aims of this work were to describe MCPyV and HPyV6 from environmental samples withdifferent geographical origin and to analyze their phylogenetic and evolutionary histories, particularly forMCPyV.Partial and complete genome sequences were obtained from sewage samples from Argentina, Uruguay andSpain. A total number of 87 sequences were obtained for MCPyV and 33 for HPyV6. Phylogenetic analysisshowed that MCPyV sequences distributed according to their geographic origin in Europe/North America,Africa, Asia, South America and Oceania groups, suggesting that viral diversification might have followedhuman migrations across the globe. In particular, viruses from Argentina associated with Europe/North Americaand South America genotypes, whereas those from Uruguay and Spain also grouped with Africa genotype, reflectingthe origin of the current population in each country, which could arrive not only during ancient humanmigration but also during recent migratory events. In addition, the South American group presented a high levelof clusterization, showing internal clusters that could be related to specific locations, such as French Guiana andBrazil or the Southern region into South America, such as Argentina and Uruguay, suggesting a long termevolutionary process in the region.Additionally, in this work, we carried out the first analysis about the evolutionary history of MCPyV troughthe integration of phylogenetic, epidemiological and historical data. Since a strong association is observed betweenthe phylogenetic relationships and the origin of the sampled population, this analysis was based on thehypothesis of co-divergence between the virus and human populations. This analysis resulted in a substitutionrate of 5.1×10−8 s/s/y (∼5.1% of divergence per million years) for the complete genome of MCPyV, which isin the range of those estimated for other double-stranded DNA viruses.Regarding HPyV6, a South American group with clusterization was observed (sequences from Uruguay).Meanwhile, sequences from Argentina grouped with European ones (France and Spain) and remained separatedfrom those isolated in China, USA or Australia.The analysis of viruses from the environment allowed us to deep characterize prevalent infections in differentgeographic regions, reveling that viruses circulating in each population reflected its origin and that there arespecific lineages associated with South America