Long-term Prophylaxis Against Aerosolized Marburg Virus in Nonhuman Primates With an Afucosylated Monoclonal Antibody

Abstract

Marburg virus (MARV) causes a hemorrhagic fever disease in human and nonhuman primates with high levels of morbidity and mortality. Concerns about weaponization of aerosolized MARV have spurred the development of nonhuman primate (NHP) models of aerosol exposure. To address the potential threat of aerosol exposure, a monoclonal antibody that binds MARV glycoprotein was tested, MR186YTE, for its efficacy as a prophylactic. MR186YTE was administered intramuscularly to NHPs at 15 or 5 mg/kg 1 month prior to MARV aerosol challenge. Seventy-five percent (3/4) of the 15 mg/kg dose group and 50% (2/4) of the 5 mg/kg dose group survived. Serum analyses showed that the NHP dosed with 15 mg/kg that succumbed to infection developed an antidrug antibody response and therefore had no detectable MR186YTE at the time of challenge. These results suggest that intramuscular dosing of mAbs may be a clinically useful prophylaxis for MARV aerosol exposure.

Keywords: Marburg virus; aerosol; antibody; monoclonal.

Figure 1.

Comparison of MR186_LS and MR186_YTE in a guinea pig model of aerosol MARV exposure. Guinea pigs (n = 6 per group) were dosed intraperitoneally 1 day prior to challenge with 10 mg/kg of monoclonal antibody. On the day of challenge, animals were exposed to a guinea pig-adapted MARV aerosol with a target exposure of 1000 PFU. A, Survival. P < .005 for the treatment groups compared to the control by Mantel-Cox. B, Plasma viral load by plaque assay. Limit of detection = 25 PFU/mL and is indicated by a horizontal dashed line. Mean is indicated by the horizontal bar. C, Plasma viral load by qRT-PCR. Limit of detection = 10³ copies/mL, indicated by a horizontal dashed line. Mean is indicated by the horizontal bar. Abbreviations: MARV, Marburg virus; PFU, plaque-forming unit; qRT-PCR, quantitative reverse transcription polymerase chain reaction.

Figure 2.

Serum pharmacokinetics of MR186_YTE in nonhuman primates. Groups of 3 cynomolgus macaques were administered a single intramuscular 15 or 5 mg/kg dose of MR186_YTE. Serum concentration of MR186_YTE as determined by enzyme-linked immunosorbent assay (ELISA).

Figure 3.

Efficacy in NHPs against aerosol exposure 28 days after MR186_YTE IM dosing. NHPs were administered a dose of either 15 or 5 mg/kg IM (n = 4 per group). After 28 days, NHPs were exposed to an aerosol target challenge of 1000 PFU of MARV Angola. A, Survival. The historic control group (n = 3) includes the single contemporaneous control and 2 controls from prior studies challenged with the same viral stock by the same route. B, Viral titer by qRT-PCR. The limit of detection is depicted by a dashed horizontal line. C, Viral titer by plaque assay. The limit of detection is depicted by a dashed horizontal line. D, Clinical scores. The horizontal dashed line (clinical score = 9) is the threshold score for euthanasia. B–D, The dashed lines for individual animals indicate that the animal succumbed to MVD. Abbreviations: IM, intramuscular; MARV, Marburg virus; NHP, nonhuman primate; PFU, plaque-forming unit; qRT-PCR, quantitative reverse transcription polymerase chain reaction.

Figure 4.

IHC of bronchial and alveolar tissues from NHP 9 (control) that succumbed to infection on day 9 (A and C) and NHP 3 that survived to day 35 (B and D). The black and white arrows in A indicate respiratory epithelia and underlying inflammation positive for viral antigen by IHC, respectively. The black and white arrows in C indicate histiocytes and alveolar macrophages/intraseptal histiocytes positive for viral antigen by IHC, respectively. Abbreviations: IHC, immunohistochemistry; NHP, nonhuman primate.

Figure 5.

A, MR186_YTE serum concentration in NHPs. Serum samples prior to aerosol challenge were assayed via antigen capture ELISA. Dashed lines indicate NHPs that did not survive. B, Survival outcome versus MR186_YTE serum concentration in NHPs. C, Anti-MR186_YTE reactivity in NHP serum. Serum samples from NHPs were tested by ELISA for binding activity to MR186_YTE. D, NHP serum reactivity against different human mAbs. Sera (day −3 with respect to aerosol challenge) from the NHP with an ADA response (NHP 1) and from an NHP in the same dose group without an ADA response (NHP 4) were tested by ELISA for reactivity with a panel of mAbs. MR232 is a human IgG_1/κ anti-MARV GP mAb; DA349 is a human IgG_1/λ anti–Ebola virus GP mAb; DA348 is a human IgG_1/κ anti-RSV gF mAb. Error bars indicate standard deviation. Abbreviations: ADA, antidrug antibody; mAb, monoclonal antibody; MARV, Marburg virus; NHP, nonhuman primate.