HMPV A2b2's global expansion represents genuine directional evolution with potential selective advantages, highlighting the need for enhanced genomic surveillance.
Human metapneumovirus (HMPV), which belongs to the a family, has shown the emergence of the A2b2 clade as the dominant global genotype.Whether this represents true evolutionary selection or surveillance artifacts remains unclear.We analyzed 315 complete HMPV genome sequences from the Nextstrain database using sampling-corrected statistical approaches, including temporal homogeneity testing, rarefaction analysis, and entropy-based evolutionary dynamics to examine non-random patterns in A2b2 emergence.Temporal homogeneity testing revealed strong directional evolution toward A2b2 dominance (Z = -46.62,p < 0.001), confirming non-random evolutionary patterns rather than surveillance artifacts.The clade showed strong persistence (206 self-transitions) with limited backward transitions.After controlling for sampling bias, A2b2 represented 68.3% (CI: 58.2-78.4%) of isolates in 2023-2024.A2b2 demonstrated significantly higher temporal entropy (2.1) compared to other clades (A1: 1.2, A2a: 1.5, A2b1: 2.0), indicating more complex evolutionary dynamics.Geographic rarefaction analysis revealed significant regional structuring, with Africa showing the highest viral diversity (3.00, CI: 1.00-3.05)despite lower sampling intensity.HMPV A2b2's global expansion represents genuine directional evolution with potential selective advantages, similar to patterns observed in respiratory syncytial virus.These findings underscore the need for enhanced genomic surveillance and integration of HMPV monitoring into respiratory virus surveillance frameworks to track emerging variants and assess public health implications.
Bucala et al. (Wed,) studied this question.