Marburg virus infection detected in a common African bat

Abstract

Marburg and Ebola viruses can cause large hemorrhagic fever (HF) outbreaks with high case fatality (80-90%) in human and great apes. Identification of the natural reservoir of these viruses is one of the most important topics in this field and a fundamental key to understanding their natural history. Despite the discovery of this virus family almost 40 years ago, the search for the natural reservoir of these lethal pathogens remains an enigma despite numerous ecological studies. Here, we report the discovery of Marburg virus in a common species of fruit bat (Rousettus aegyptiacus) in Gabon as shown by finding virus-specific RNA and IgG antibody in individual bats. These Marburg virus positive bats represent the first naturally infected non-primate animals identified. Furthermore, this is the first report of Marburg virus being present in this area of Africa, thus extending the known range of the virus. These data imply that more areas are at risk for MHF outbreaks than previously realized and correspond well with a recently published report in which three species of fruit bats were demonstrated to be likely reservoirs for Ebola virus.

Figure 1. Animal collection sites in Gabon and Republic of Congo.

Animal trap locations in Gabon and Republic of Congo (expansion) are indicated by yellow circles. Also indicated are the locations of the four PCR positive bats (by arrows) and the dates and locations of all known origins of previous Marburg virus outbreaks (red circles).

Figure 2. Phylogenetic analyses and nucleotide sequence alignments of NP and VP35 sequences derived from bat tissues.

A) Maximum likelihood analysis of the concatenated NP (464 nt) and VP35 (302 nt) sequence fragments obtained from each bat specimen and 18 MBG virus isolates. Bootstrap support values are indicated at the nodes. Abbreviations of historical isolates are Rav = Ravn, Ozo = Ozolin, Pop = Popp and Mus = Musoke. B-C) Nucleotide alignment of the sequences in (A) in which the lineages from the Angola 2005 outbreak are singly represented by Ang1379c.

Figure 3. Marburg antibody testing in bats collected at locations where PCR positive bats were found.

A.) Corrected OD values from bat sera diluted 1∶100 that are greater than the threshold value of 0.13 (solid horizontal bar) which was calculated as the average corrected OD of the negative control group (E. franqueti, N = 47) plus 3 standard deviations. The numbers of sera specimens used to calculate the values are shown to the right of the corresponding symbol. OD values from nested-PCR positive bats 1448, 2296 (§§) and 1631 (§) are also noted. B.) Antibody titers of sera specimens with corrected OD values greater than 0.13. The numbers of serum specimens used to calculate the values are shown to the right of the corresponding symbol.

Figure 4. Geographic distribution (green shade) of Rousettus aegyptiacus in Africa.

Red dots indicate the locations of all previous known Marburg virus outbreaks, as indicated in Figure 1, in addition to the locations of the Marburg-positive bats.