Prophylactic and therapeutic neutralizing monoclonal antibody treatment prevents lethal yellow fever infection

Abstract

Yellow fever virus (YFV) infection is fatal in 5%-10% of the 200,000 yearly cases. There is currently no available antiviral treatment. We showed previously that administration of 50 mg/kg of a YFV-specific neutralizing monoclonal antibody (nmAb) at 2 days postinfection (dpi), prior to the onset of severe disease, protected YFV-infected rhesus macaques from death. To further explore the clinical applicability of our nmAb MBL-YFV-01, we treated rhesus macaques with a lower dose (10 mg/kg) of this nmAb prophylactically or therapeutically at 3.5 dpi. We show that a single prophylactic or therapeutic i.v. dose of our nmAb protects rhesus macaques from death following challenge. A comprehensive analysis of 167 inflammatory cytokine and chemokines revealed that protection was associated with significantly reduced expression of 125 of these markers, including type I IFN, IL-6, and CCL2. This study further expands the potential clinical use of our YFV-specific nmAb, which could be used during an outbreak for immediate prophylactic immunity or for patients with measurable serum viremia.

Keywords: Hepatitis; Immunology; Infectious disease; Therapeutics.

Figure 1. Study design for the testing of MBL-YFV-01 in YFV-DakH1279-infected RMs.

Figure 2. Prophylactic and therapeutic administration of MBL-YFV-01 protects RMs from lethal YFV infection.

(A) Longitudinal concentration of MBL-YFV-01 in the plasma of YFV-DakH1279 challenged RMs. (B) Kaplan-Meier survival curves of RMs after challenge with YFV-DakH1279 and treatment with YFV-specific antibodies. P value determined by Mantel-Cox test with Bonferroni correction. (C) Longitudinal serum YFV-DakH1279 loads in RMs. LOQ, 5 × 10³ copies/mL. (D) Longitudinal serum ALT levels in RMs.

Figure 3. YFV RNA expression in the tissues.

(A) Quantification of YFV-DakH1279 RNA by RT-PCR in necropsy tissues. LOQ, 1 × 10² copies/100 ng RNA. Day of necropsy for each animal: RM 1–21 dpi, RM 2-21 dpi, RM 3–21 dpi, RM 4–21 dpi, RM 5–19 dpi, RM 6–19 dpi, RM 7–22 dpi, RM 8–5.5 dpi, RM 9–7 dpi, RM 10–7.5 dpi, RM 11–7.5 dpi, and RM 12–5.5 dpi. (B) RNAscope staining of YFV-DakH1279 RNA in the livers of YFV-DakH1279-infected RMs. Scale bars: 40 μm.

Figure 4. Pathophysiology of YFV-DakH1279 infection in RMs.

(A) Body temperatures. (B) Total bilirubin levels. (C) Blood lymphocyte counts. (D) International normalized ratio measurements.

Figure 5. Inflammatory cytokine/chemokine profiles across treated and untreated RM groups.

(A) Heatmap showing levels of inflammatory cytokines/chemokines in plasma across treatment groups. Rows are clustered via k means. (B) Principal component analysis showing the similarities between the inflammatory cytokine/chemokine profiles for each treatment group.

Figure 6. Plasma proteomics/NULISA differential abundance.

(A) Volcano plot showing baseline-subtracted protein levels upregulated in the therapeutic group in green and upregulated in the untreated group in yellow as an average treatment effect over all time points. (B) Volcano plot showing baseline-subtracted protein levels upregulated in the prophylactic group in blue and upregulated in the untreated group in yellow as an average treatment effect over all time points. (C) Longitudinal expression of CCL2, IFNA1/IFNA13, IFNW1, and IL-6. (D) UpSet plot showing the number of shared (connected black dots) and unique (individual black dots) differentially abundant plasma proteins from the comparisons in A and B.

Figure 7. Top 40 expressed inflammatory cytokines/chemokines in untreated, YFV-DakH1279-infected RMs.