Background: Human metapneumovirus (HMPV) is a recently discovered paramyxovirus that is a major cause of respiratory infections worldwide.
Objectives: We aim to describe the molecular evolution of the HMPV F (fusion) and G (attachment) surface glycoproteins because they are targets for vaccines, monoclonal antibodies and antivirals currently in development.
Study setting: Nasopharyngeal aspirates were collected in children <3 years old with acute respiratory infection in Quebec City during 2001-2010. HMPV-positive samples (n = 163) underwent HMPV-F and -G gene sequencing. Furthermore, HMPV-F (n = 124) and -G (n = 217) sequences were obtained from GenBank and other studies. Evolutionary analyses (phylogenetic reconstruction, sequence identity, detection of recombination and adaptive evolution) were computed.
Results: Sequences clustered into 5 genetic lineages (A1, A2a, A2b, B1 and B2). Multiple lineages circulated each year in Quebec City. With the exception of B1, each of the 5 subgroups was the predominant lineage during ≥1 season. The A1 lineage was not detected since 2002-2003 in our local cohort. There was no evidence of inter- or intragenic recombination. HMPV-F was highly conserved, whereas HMPV-G exhibited greater diversity. HMPV-F demonstrated strong evidence of purifying selection, both overall and in an abundance of negatively selected amino acid sites. In contrast, sites under diversifying selection were detected in all HMPV-G lineages (range, 4-15), all of which were located in the ectodomain.
Conclusions: Predominant circulating HMPV lineages vary by year. HMPV-F is highly constrained and undergoes significant purifying selection. Given its high genetic variability, we found a modest number of positively selected sites in HMPV-G.
Keywords: Attachment (G) protein; CHUQ; Centre Hospitalier Universitaire de Québec; Fusion (F) protein; Genetic selection; HMPV; Human metapneumovirus; Phylogeny; RT-PCR; RTI; human metapneumovirus; respiratory tract infection; reverse-transcriptase polymerase chain reaction.
Copyright © 2013 Elsevier B.V. All rights reserved.