# Quantitative Biomarkers for Loiasis

> **NIH NIH R21** · WASHINGTON UNIVERSITY · 2022 · $196,875

## Abstract

PROJECT SUMMARY / ABSTRACT
Significance. A quantitative antigen assay for loiasis is needed to diagnose active infection in non-endemic
areas, to follow response to treatment, and to prevent severe adverse events by identifying and excluding from
mass drug administrations individuals with heavy Loa loa infections (>20,000 microfilariae [Mf] per mL of blood).
The goal of the work proposed here is to determine which circulating L. loa proteins adequately differentiate
infected from uninfected individuals, and to define serum metabolic profiles that are associated with heavy L. loa
microfilarial loads.
Innovation. Prior attempts to develop quantitative antigen assays for loiasis have relied on targeted selection of
candidate protein biomarkers based on their predicted specificity for L. loa and other factors felt to increase the
chances of finding these candidates in infected plasma/serum. To date, these attempts have produced assays
with inadequate sensitivity and poor to moderate correlation between the candidate biomarker and Mf loads. We
propose an alternative approach that prioritizes detection of biomarkers with discriminatory capacity over
predicted specificity. Using immunoaffinity purification and tandem mass spectrometry, we have previously
detected over 200 L. loa proteins in plasma from one individual and one pooled plasma sample from patients
with loiasis and falsely-positive rapid diagnostic tests for lymphatic filariasis (LF). We hypothesize that a subset
these L. loa proteins found in cross-reactive sera are excreted/secreted by Mf and will therefore be present in
sera from all loiasis patients in proportion to microfilarial loads. We further hypothesize that alteration in serum
metabolite levels will correlate with the presence excreted/secreted filarial antigens, and will be more reliable
than circulating filarial antigen levels at predicting total Mf load. We will test these hypotheses by defining the
filarial antigen and metabolite profiles of banked plasma samples from 146 patients with L. loa Mf loads ranging
from 8,000 – 114,000 Mf/mL and a matching number of amicrofilaremic endemic controls. Key to the success of
this project is our access to 354 de-identified patient samples collected in collaboration with colleagues in
Cameroon over the past 4 years. This will be the first application of metabolomic profiling to loiasis, and will be
the most extensive proteomics analysis of loiasis samples to date.
Impact. These studies will identify protein and metabolite biomarkers that correlate with L. loa infection intensity,
and will identify metabolic processes that correlated with the presence of circulating Mf and filarial antigen in
individuals with loiasis. This will provide promising candidates for the development of quantitative diagnostic
tests for loiasis that can improve clinical case management and simplify test and not treat strategies for
preventing loiasis-related adverse events during mass drug distributions for LF and ...

## Key facts

- **NIH application ID:** 10415212
- **Project number:** 5R21AI156582-02
- **Recipient organization:** WASHINGTON UNIVERSITY
- **Principal Investigator:** Philip Budge
- **Activity code:** R21 (R01, R21, SBIR, etc.)
- **Funding institute:** NIH
- **Fiscal year:** 2022
- **Award amount:** $196,875
- **Award type:** 5
- **Project period:** 2021-06-01 → 2024-05-31

## Primary source

NIH RePORTER: https://reporter.nih.gov/project-details/10415212

## Citation

> US National Institutes of Health, RePORTER application 10415212, Quantitative Biomarkers for Loiasis (5R21AI156582-02). Retrieved via AI Analytics 2026-05-22 from https://api.ai-analytics.org/grant/nih/10415212. Licensed CC0.

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