Abstract
An anti-Zaire Ebola virus (EBOV) glycoprotein (GP) immunoglobulin G (IgG) enzyme linked immunosorbent assay (ELISA) was developed to quantify the serum levels of anti-EBOV IgG in human and non-human primate (NHP) serum following vaccination and/or exposure to EBOV. This method was validated for testing human serum samples as previously reported. However, for direct immunobridging comparability between humans and NHPs, additional testing was warranted. First, method feasibility experiments were performed to assess cross-species reactivity and parallelism between human and NHP serum samples. During these preliminary assessments, the goat anti-human IgG secondary antibody conjugate used in the previous human validation was found to be favorably cross-reactive with NHP samples when tested at the same concentrations previously used in the validated assay for human sample testing. Further, NHP serum samples diluted in parallel with human serum when tested side-by-side in the ELISA. A subsequent NHP matrix qualification and partial validation in the anti-GP IgG ELISA were performed based on ICH and FDA guidance, to characterize assay performance for NHP test samples and supplement the previous validation for human sample testing. Based on our assessments, the anti-EBOV GP IgG ELISA method is considered suitable for the intended use of testing with both human and NHP serum samples in the same assay for immunobridging purposes.
Highlights
The filoviruses from the genera Ebolavirus and Marburgvirus are etiologic agents of sporadic viral hemorrhagic fever outbreaks in humans with high mortality rates
In this report we show that the anti-Ebola virus (EBOV) GP immunoglobulin G (IgG) enzyme linked immunosorbent assay (ELISA) using human reference standard (RS) and secondary antibody conjugate can be used to test non-human primate (NHP) serum samples, which makes it useful for direct immunobridging applications
This study provides test data to support the use of the EBOV anti-GP IgG ELISA for evaluation of NHP test samples
Summary
The filoviruses (family Filoviridae) from the genera Ebolavirus and Marburgvirus are etiologic agents of sporadic viral hemorrhagic fever outbreaks in humans with high mortality rates. The model used to establish the efficacy and confirm the dose of ERVEBO1 was the cynomolgus macaque challenge model The application of this model to the analysis of vaccines against other filoviruses will require correlates of immunity that are predictive of clinical benefit using biomarkers to bridge from the effective dose in the nonhuman primate model to the immune response elicited by the vaccine in placebo-controlled human trials. Feasibility results indicated that goat anti-human secondary antibody conjugate was cross reactive with NHP serum samples at similar concentrations used in the previous method validation for human serum sample testing. Once crossspecies reactivity and parallelism were established, matrix qualification and partial validation were performed to characterize assay accuracy, precision, limits of quantification, and limit of detection for NHP samples when tested in the anti-EBOV GP IgG ELISA using a human RS and secondary antibody conjugate
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