Oral Presentation 64th International Conference of the Wildlife Disease Association 2015

Experimental inoculation of Egyptian rousette bats (Rousettus aegyptiacus) with five different ebolaviruses, and comparison with Marburg virus (#64)

Megan EB Jones 1 2 3 , Amy J Schuh 1 , Brian R Amman 1 , Tara K Sealy 1 , Sherif R Zaki 4 , Stuart T Nichol 1 , Jonathan S Towner 1
  1. Viral Special Pathogens Branch, Centers for Disease Control and Prevention, Atlanta, GA, USA
  2. Department of Pathology, College of Veterinary Medicine, University of Georgia, Athens, GA, USA
  3. Current address: Wildlife Disease Laboratories, Institute for Conservation Research, San Diego Zoo Global, San Diego, CA, USA
  4. Infectious Diseases Pathology Branch, Centers for Disease Control and Prevention, Atlanta, GA, USA

Ebolaviruses and marburgviruses (Filoviridae) cause sporadic outbreaks of hemorrhagic fever in humans and non-human primates, with case fatality rates up to 90%. The Egyptian rousette bat (Rousettus aegyptiacus) has been identified as a natural reservoir for marburgviruses and a source of virus spillover to humans. Cumulative evidence suggests various fruit bat species also play a role in the transmission cycle of ebolaviruses. Through a two-part experimental infection study, we investigated the susceptibility of Egyptian rousettes to viruses representing each of the five ebolavirus species (Sudan, Ebola, Bundibugyo, Taï Forest, and Reston viruses), and compared findings with Marburg virus.  In a 10-day pilot study, groups of four juvenile, captive-bred bats were inoculated with a low-passage stock of one of the ebolaviruses, or with Marburg virus. There were no mortalities and no significant hematologic or histopathologic abnormalities. In ebolavirus groups, viral RNA distribution in tissues was limited, and no bat became viremic. In the Sudan virus group, viral RNA was more widespread, and liver and spleen were PCR-positive at day 5 post-inoculation. In contrast, Marburg virus RNA was widely disseminated, with evidence of viremia, oral and rectal viral shedding, and antigen in spleen and liver. In a second, 15-day serial euthanasia study, 15 bats were inoculated with Sudan virus. Viral RNA was found in multiple tissues, especially at early time points, but tissue viral loads were low, with no detected viremia or viral shedding. This is the first reported experimental infection study comparing tissue tropism, potential for viral shedding, and clinical and pathologic effects of six different filoviruses in the Egyptian rousette, a known marburgvirus reservoir. Our results suggest that Egyptian rousettes are unlikely sources for ebolaviruses in nature, and lend support to a possible single filovirus – single bat host relationship, analogous to that of hantaviruses in rodent reservoirs.