RSV neutralizing antibodies in dried blood

Abstract

AbstractThe key correlate of protection of respiratory syncytial virus (RSV) vaccines and monoclonal antibodies (mAb) is virus neutralization, measured using sera obtained through venipuncture. Dried blood obtained with a finger prick can simplify acquisition, processing, storage, and transport in trials, and thereby reduce costs. In this study we aim to validate a low-tech assay to measure RSV neutralization in dried capillary blood. Recovery of mAb from dried blood (volumetric absorptive microsampling) was used to validate the elution method using indirect ELISA. Functional antibodies measured by a neutralization assay were compared between matched serum and dried blood samples from a phase I trial with RSM01, a novel investigational anti-RSV Prefusion F mAb. Hep-2 cells were infected with a serial dilution of sample-virus mixture using RSV-A2-mKate to determine half-maximal inhibitory concentration. Stability of dried blood was evaluated over time and during temperature stress. Functional antibodies in dried blood were highly correlated with serum (R2= 0.98, p < 0.0001). The intra-assay, inter-assay, and inter-operator precision of the assay for dried blood was similar to serum. The function of mAb remained stable for 9 months at room temperature and frozen dried blood samples but lower concentrations showed instability after 6 months. Dried blood samples resisted 48 hours of temperature stress. We demonstrated the feasibility of measuring RSV neutralization using dried blood as an alternative to serum. Measuring antibody function using dried blood is a patient-centered solution that may replace serology testing in trials against RSV or other viruses, such as influenza and SARS-CoV-2.Summary pointsNeutralizing antibodies against RSV in serum and dried blood from clinical samples are highly correlated.Neutralizing antibodies are stable in dried blood for 6 months and can withstand temperature variation.Dried blood samples are a patient-centered and logistical solution for vaccine trials in remote areas and low- and lower-middle income countries.