Tiled PCR amplification-based Whole Genome Sequencing and Phylogenetic Classification Accelerate the Implementation of Respiratory Syncytial Virus Genomic surveillance in Canada as a Pilot Study

Whole genome sequencing (WGS) has emerged as a powerful tool to facilitate the study of existing and emerging infectious diseases. WGS-based genomic surveillance provides information on the genetic diversity and tracks the evolution of important viral pathogens including Respiratory Syncytial Virus (RSV). Development and implementation of robust tiled multiplex PCR amplification-based WGS assays will facilitate high-throughput RSV surveillance initiatives. In this study, we developed multiplex PCR assays for targeted enrichment of viral genomes using PrimalScheme ( http://primal.zibraproject.org ) to amplify over 97% of the genome in the majority of contemporaneous specimens tested. A pilot dataset comprising 52 RSVA and 37 RSVB genomes derived from Canadian clinical specimens during the 2022-2023 respiratory virus season were used to perform phylogenetic analyses using both near complete genome and Glycoprotein (G) sequences. Overall, the RSV phylogenetic tree built with whole genomes showed identical lineage clusters as that compared to the G gene, but showed more confidence and discriminatory features within individual lineage. Moreover, availability of whole genomes enabled the identification of a broader range of mutations, for instance the identified S377N, K272M, S276N, S211N, S206I and S209Q in Canadian fusion proteins that could be potentially associated with effectiveness of vaccines or antiviral-based therapeutics. In conclusion, the tiled-PCR amplification assays described offer a more streamlined approach to facilitate high-throughput, high sensitivity of RSV WGS, which is capable of supporting enhanced genomic surveillance initiatives, as well as the more comprehensive genomic analyses required to inform public health strategies for the development and usage of vaccines and antiviral drugs.