Metabolomics analyses identify platelet activating factors and heme breakdown products as Lassa fever biomarkers

<div><p>Lassa fever afflicts tens of thousands of people in West Africa annually. The rapid progression of patients from febrile illness to fulminant syndrome and death provides incentive for development of clinical prognostic markers that can guide case management. The small molecule profile of serum from febrile patients triaged to the Viral Hemorrhagic Fever Ward at Kenema Government Hospital in Sierra Leone was assessed using untargeted Ultra High Performance Liquid Chromatography Mass Spectrometry. Physiological dysregulation resulting from Lassa virus (LASV) infection occurs at the small molecule level. Effects of LASV infection on pathways mediating blood coagulation, and lipid, amino acid, nucleic acid metabolism are manifest in changes in the levels of numerous metabolites in the circulation. Several compounds, including platelet activating factor (PAF), PAF-like molecules and products of heme breakdown emerged as candidates that may prove useful in diagnostic assays to inform better care of Lassa fever patients.</p></div

Diagnostic sensitivity and specificity of top biomarkers comparing fatal Lassa fever versus nonfatal Lassa fever patients.

<p>Diagnostic sensitivity and specificity of top biomarkers comparing fatal Lassa fever versus nonfatal Lassa fever patients.</p

Diagnostic sensitivity and specificity of top biomarkers comparing fatal Lassa fever versus nonfatal Lassa fever patients.

<p>Diagnostic sensitivity and specificity of top biomarkers comparing fatal Lassa fever versus nonfatal Lassa fever patients.</p

Principal component analysis of serum metabolites in subjects with different Lassa virus serostatus.

<p>Spectral values extracted from post-XCMS data for each sample where grouped by serostatus and time since symptom onset and PCA computed in R using the FactoMineR package. Fatal Lassa fever (black circles), Non-fatal Lassa fever (red squares). Post Lassa fever—acute illness (dark blue triangles). Post-Lassa fever—non-acute illness (light blue triangles). Febrile non-Lassa illness (green diamonds).</p

Cluster analysis of serum metabolites in subjects with different outcomes following Lassa virus infection, survivors of Lassa virus infection and febrile controls.

<p>Heat map representing levels of 24 putatively identified platelet activating factor (PAF) or PAF-like molecules, 18 miscellaneous molecules, 34 peptides and 153 lipids (no PAFs included) in subjects with different Lassa virus serostatus. Panel A: Platelet activating factor (PAF) and PAF-like molecules. PAFs and PAF-like molecules are listed in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0005943#pntd.0005943.s002" target="_blank">S2 Table</a>. Panel B: Miscellaneous molecules. Metabolites are listed in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0005943#pntd.0005943.s003" target="_blank">S3 Table</a>. Panel C: Peptides. Peptides are listed in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0005943#pntd.0005943.s004" target="_blank">S4 Table</a>. Panel D: Lipids (no PAFs included). Lipids are listed in <a href="http://www.plosntds.org/article/info:doi/10.1371/journal.pntd.0005943#pntd.0005943.s005" target="_blank">S5 Table</a>.</p

Diagnostic sensitivity and specificity of top biomarkers comparing fatal Lassa fever versus non Lassa febrile illness patients.

<p>Diagnostic sensitivity and specificity of top biomarkers comparing fatal Lassa fever versus non Lassa febrile illness patients.</p

Serostatus of febrile patients presenting to the Kenema Government Hospital Viral Hemorrhagic Fever Ward.

<p>Subjects meeting the case definition for possible viral hemorrhagic fever were tested for the presence of LASV in the blood by RT-PCR or antigen-capture ELISA. The presence of anti-LASV IgM or IgG was assessed by recombinant antigen ELISA.</p

Extracted ion chromatograms of selected metabolites that differ in the serum of subjects with fatal and nonfatal Lassa fever.

<p>Intensity versus retention time plots for selected metabolites that are present in different levels in the serum of subjects with fatal Lassa fever and subjects that presented with a non-Lassa febrile illness. Panel A: PC(O-16:1(11Z)/2:0)Na⁺ PAF4. Panel B: PC(O-18:2(9Z,12Z)/2:0)H⁺ PAF7. Panel C: D-Urobilinogen/I-Urobilin M12. Panel D: 7-Methylinosine M18. Red: Acute Lassa fever—fatal. Black: non-Lassa febrile illness.</p