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Updated: Sep 12, 2025

Following the Dynamics of Structural Variants in Experimentally Evolved Populations
Published on: February 3, 2023
Phylodynamics of human metapneumovirus and evidence for a duplication-deletion model in G gene variant evolution
Stephanie Goya1, Ethan B Nunley1, Preston C Longley1
1Department of Laboratory Medicine and Pathology, University of Washington, 850 Republican St, 98109 Seattle, WA, USA.
Background:
In December 2024, human metapneumovirus (hMPV) gained global attention amid rising cases in Chinese hospitals, prompting a World Health, Organization (WHO) statement indicating case numbers remained within expected ranges. To assess whether a variant of public health concern was emerging and to examine global hMPV phylodynamics, we conducted a genomic surveillance study in western Washington State.
Study Design:
We sequenced hMPV genomes from inpatient and outpatient samples collected between 2021 and 2025 in western Washington State and constructed phylogenomic and phylodynamic trees.
Results:
We obtained 60 hMPV-A and 39 hMPV-B genomes, including 13 from November 2024 to January 2025. Following COVID-19 pandemic disruptions, hMPV seasonality returned to typical patterns after 2023. Genomic analysis showed hMPV-A predominance since 2022-23, with co-circulation of A2b1, A2b2, B1, and B2 sublineages. The A2b2 sublineage was most prevalent and all genomes carried a 111-nt G gene duplication. Phylogenetic evidence suggests the 111-nt variant evolved from a prior 180-nt duplication via a 69-nt deletion rather than through independent duplication events. Most sublineages showed multiple co-circulating clades, except A2b1. Phylodynamics showed recovery of global diversity after pandemic-related declines and a higher evolutionary rate in hMPV-A compared to hMPV-B. No distinct evolutionary features of heightened concern were detected.
Conclusions:
Despite recent concerns, our findings indicate that hMPV circulation in, the USA follows expected seasonal patterns, with ongoing introductions of diverse viral variants from preexisting sublineages rather than emergence of a novel variant. Continued genomic surveillance is essential, particularly as vaccine development progresses.
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