title: Microevolution of Puumala hantavirus during a complete population cycle of its host, the bank vole (Myodes glareolus).
abstract: Microevolution of Puumala hantavirus (PUUV) was studied throughout a population cycle of its host, the bank vole (Myodes glareolus). We monitored PUUV variants circulating in the host population in Central Finland over a five-year period that included two peak-phases and two population declines. Of 1369 bank voles examined, 360 (26.3%) were found infected with PUUV. Partial sequences of each of the three genome segments were recovered (approx. 12% of PUUV genome) from 356 bank voles. Analyses of these sequences disclosed the following features of PUUV evolution: 1) nucleotide substitutions are mostly silent and deduced amino acid changes are mainly conservative, suggesting stabilizing selection at the protein level; 2) the three genome segments accumulate mutations at a different rate; 3) some of the circulating PUUV variants are frequently observed while others are transient; 4) frequently occurring PUUV variants are composed of the most abundant segment genotypes (copious) and new transient variants are continually generated; 5) reassortment of PUUV genome segments occurs regularly and follows a specific pattern of segments association; 6) prevalence of reassortant variants oscillates with season and is higher in the autumn than in the spring; and 7) reassortants are transient, i.e., they are not competitively superior to their parental variants. Collectively, these observations support a quasi-neutral mode of PUUV microevolution with a steady generation of transient variants, including reassortants, and preservation of a few preferred genotypes.
authors.affiliation: Department of Virology, Haartman Institute, University of Helsinki, Helsinki, Finland. maria.razzauti@helsinki.fi
authors.forename: Maria
authors.initials: M
authors.lastname: Razzauti
authors.forename: Angelina
authors.initials: A
authors.lastname: Plyusnina
authors.forename: Heikki
authors.initials: H
authors.lastname: Henttonen
authors.forename: Alexander
authors.initials: A
authors.lastname: Plyusnin
mesh_terms: D000818:Animals; D003411:Arvicolinae / Q000235:genetics / Q000821:virology*; D004199:Disease Vectors; D019143:Evolution, Molecular; D005814:Genes, Viral; D014644:Genetic Variation; D029262:Puumala virus / Q000235:genetics* / Q000302:isolation & purification; D020133:Reverse Transcriptase Polymerase Chain Reaction