Antibody Responses to Marburg Virus in Egyptian Rousette Bats and Their Role in Protection against Infection.

Nadia Storm,Janusz Paweska,Petrus Jansen Van Vuren,Wanda Markotter

doi:10.3390/v10020073

Nadia Storm, Janusz Paweska + Show 2 more

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https://doi.org/10.3390/v10020073

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Abstract

Egyptian rousette bats (ERBs) are reservoir hosts for the Marburg virus (MARV). The immune dynamics and responses to MARV infection in ERBs are poorly understood, and limited information exists on the role of antibodies in protection of ERBs against MARV infection. Here, we determine the duration of maternal immunity to MARV in juvenile ERBs, and evaluate the duration of the antibody response to MARV in bats naturally or experimentally infected with the virus. We further explore whether antibodies in previously naturally exposed bats is fully protective against experimental reinfection with MARV. Maternal immunity was lost in juvenile ERBs by 5 months of age. Antibodies to MARV remained detectable in 67% of experimentally infected bats approximately 4 months post inoculation (p.i.), while antibodies to MARV remained present in 84% of naturally exposed bats at least 11 months after capture. Reinfection of seropositive ERBs with MARV produced an anamnestic response from day 5 p.i. Although PCR-defined viremia was present in 73.3% of reinfected ERBs, replicating virus was recovered from the serum of only one bat on day 3 p.i. The negative PCR results in the salivary glands, intestines, bladders and reproductive tracts of reinfected bats, and the apparent absence of MARV in the majority of swabs collected from these bats suggest that reinfection may only play a minor role in the transmission and maintenance of MARV amongst ERBs in nature.

Highlights

Marburg virus (MARV) is a member of the family Filoviridae and is the causative agent of severe and often fatal hemorrhagic fever in humans and non-human primates [1]
All wild-caught juveniles tested in this study were born to dams previously naturally infected with MARV as evidenced by the presence of MARV-specific maternal immunoglobulin G (IgG) antibodies in the juveniles
At approximately 5 months after birth, maternal IgG antibodies to MARV could only be antibodiesdetected to MARV

Summary

Introduction

Marburg virus (MARV) is a member of the family Filoviridae and is the causative agent of severe and often fatal hemorrhagic fever in humans and non-human primates [1]. The Egyptian rousette bat (ERB), Rousettus aegyptiacus, has been recognized as a reservoir host for MARV based on repeated isolation of the virus from naturally infected bats [10,11,12] as well as the absence of clinical disease following experimental inoculation [13,14,15,16]. Spillover of MARV into human and animal populations often coincides with periods of increased viral shedding from ERBs [11], but the mechanisms driving the transmission and maintenance of MARV remain to be described. Three hypotheses for MARV transmission dynamics in ERB populations exist: (1) bats may obtain lifelong immunity following recovery from a primary infection, and new outbreaks of the virus only occur when the pool of susceptible bats is replenished by weaned juveniles that have lost maternal immunity; (2) immunity to MARV in bats may be transient, with the virus being able to persist through fluctuating herd immunity; or (3) bats may be persistently infected with MARV, shedding virus periodically due to physiological or environmental stress factors [19]

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