Egyptian rousette bats maintain long-term protective immunity against Marburg virus infection despite diminished antibody levels

Abstract

Although bats are natural reservoir hosts for numerous zoonotic viruses, little is known about the long-term dynamics of the host immune response following infection and how these viruses are maintained in nature. The Egyptian rousette bat (ERB) is a known reservoir host for Marburg virus (MARV). Following infection of ERBs with MARV, virus-specific IgG antibodies are induced but rapidly wane and by 3 months post-infection the bats are seronegative. To determine whether reinfection of ERBs plays a role in MARV maintenance, we challenge groups of ERBs that were "naturally" or experimentally infected with MARV 17-24 months prior. No bats in either group exhibit evidence of MARV replication or shedding and all bats develop virus-specific secondary immune responses. This study demonstrates that infection of ERBs with MARV induces long-term protective immunity against reinfection and indicates that other factors, such as host population dynamics, drive MARV maintenance in nature.

Figure 1

MARV IgG antibody responses of bats according to group. IgG antibodies were detected by ELISA with purified recombinant nucleoprotein of the Angola strain of MARV expressed in Escherichia coli from blood taken at 0, 7, 14 and 21 DPC. IgG antibody levels are expressed as adjusted sum OD values. The dotted line represents the threshold of the assay (MARV seropositive ≥ 0.95).