Abstract:
Respiratory syncytial virus (RSV) circulates worldwide, occurring seasonally in
communities, and is a leading cause of acute respiratory illness in young children. There
is paucity of genomic data from purposively sampled populations by which to investigate
evolutionary dynamics and transmission patterns of RSV. Here we present an analysis of
295 RSV group B (RSVB) genomes from Kilifi, coastal Kenya, sampled from individuals
seeking outpatient care in nine health facilities across a defined geographical area (∼890
km2), over two RSV epidemics between 2015 and 2017. RSVB diversity was
characterized by multiple virus introductions into the area and co-circulation of distinct
genetic clusters, which transmitted and diversified locally with varying frequency.
Increase in relative genetic diversity paralleled seasonal virus incidence. Importantly, we
identified a cluster of viruses that emerged in the 2016/17 epidemic, carrying distinct
amino-acid signatures including a novel nonsynonymous change (K68Q) in antigenic site
∅ in the Fusion protein. RSVB diversity was additionally marked by signature
nonsynonymous substitutions that were unique to particular genomic clusters, some under
diversifying selection. Our findings provide insights into recent evolutionary and
epidemiological behaviors of RSVB, and highlight possible emergence of a novel
antigenic variant, which has implications on current prophylactic strategies in
development.