Reducing Supply Chain Dependencies for Viral Genomic Surveillance: Get by with a Little HELP from Commercial Enzymes already in your Lab Freezer

Abstract

The COVID-19 pandemic exposed vulnerabilities in global laboratory supply chains, disrupting genomic surveillance efforts essential to epidemic response. To address this challenge, we developed ARTIC HELP (Homebrew Enzymes for Library Preparation), a practical, open-source adaptation of the widely adopted ARTIC nanopore sequencing protocol for viral genomic surveillance. We describe generic, cost-effective alternatives to all enzyme mixes used in tiling multiplex RT-PCR amplification of the virus genome, and the nanopore native barcoding workflow, including end-prep (EP), barcode ligation (BL), and adapter ligation (AL), making it broadly applicable to any laboratory. Through systematic evaluation, we identified a wild-type M-MLV reverse transcriptase and two types of proofreading DNA polymerases as effective alternatives when standard reagents are unavailable due to high cost or limited supply: B-family Pfu-based polymerases with a fused Sso7d DNA-binding domain, and blends combining A-family (Taq-based) and B-family (Pfu-based) polymerases. Validation on clinical samples of SARS-CoV-2 and Norovirus GII confirmed that the HELP workflow achieves genome coverage comparable to the ARTIC LoCost protocol. For SARS-CoV-2 samples (Ct [≤]28), the wild-type M-MLV RT combined with selected Pfu or A+B polymerases, along with optimised HELP mixes (EP, BL, AL), achieved genome coverage of 84.0-99.6%. For Norovirus GII (Ct [≤]32), the HELP workflow using one of the Pfu polymerases achieved genome coverage of >85% for six out of eight genotypes tested. Notably, several of the other polymerases tested showed reduced performance at higher Ct values. However, they still achieved strong coverage at Ct <24, supporting their use as emergency alternatives in rapid outbreak-response sequencing when viral input is high and RNA quality is sufficient. Our approach, ARTIC HELP, provides a framework which can be implemented to address supply chain disruptions, while maintaining robust genomic sequencing capabilities. A cost analysis highlights the well-known significant global disparities in reagent pricing, driven not by protocol differences but by import fees and supply barriers. Thus, our findings highlight the need for fairer global pricing models and support for local sourcing strategies like HELP, to promote equity in genomic research and ensure preparedness for future public health challenges.