Georeferenced date on caught animals.

In 2021, a patient died from Marburg virus (MARV) disease in Guinea and it was the first confirmed case in West Africa. The origin of the outbreak has not been identified. It was revealed that the patient didn’t travel anywhere before the illness. Prior to outbreak, MARV had been found in bats in the neighboring Sierra Leone, but never in Guinea. Therefore, the origin of infection is unclear: was it an autochthonous case with spillover from a local population of bats or an imported case with spillover from fruit bats foraging/migrating from Sierra Leone? In this paper, we studied Rousettus aegyptiacus in Guinea as the possible source of MARV infection caused the patient death in 2021 in Guinea. We caught bats in 32 sites of Guéckédou prefecture, including seven caves and 25 locations of the flight path. A total of 501 fruit bats (Pteropodidae) were captured, including 66 R. aegyptiacus. The PCR screening showed three positive MARV R. aegyptiacus, roosting in two caves discovered in Guéckédou prefecture. After Sanger sequencing and phylogenetic analyses it was shown that found MARV belongs to the Angola-like lineage but it is not identical to the isolate obtained during the outbreak of 2021.</div

Sampling locations depicting the caves where PCR-positive MARV bats were caught.

Map A shows the sampling locations in Guéckédou prefecture (Guinea) indicating the Koema cave in Sierra Leone where MARV-positive bats were previously found [2]. Map B shows an overview of the sampling area and Guinea. Map C focuses on the area around Legon Tyo Cave and Temessadou M’bokét village. Map D zooms on the area around the Kokongoa cave. Elevation contours on maps C and D are shown for altitudes over 440 m with an interval of 20 m. The base vector layer of the map was downloaded from Natural Earth (https://www.naturalearthdata.com/downloads/10m-physical-vectors/).</p

The Legon Tyo cave.

Panel A: The entrance to the Legon Tyo cave (view from below). The cave is located on a wooded slope surrounded with tall trees that block the view and prevent taking a general view photo. Therefore, the picture of the cave entrance was taken at close range. The entrance to the cave hangs from above with a cornice (The growth direction of the tree in the right corner of the photo helps to understand the orientation of the photo). Panel B: General view of a similar cave located on the opposite (southern) slope of Mount Legon Tyo. This cave has a similar entrance structure, but unlike the Legon Tyo cave, here the slope is not covered with trees and therefore it is clearly visible that the entrance is located high on a steep slope and a person cannot get inside without special equipment.</p

Detailed data on MARV-positive <i>Rousettus aegyptiacus</i>.

Detailed data on MARV-positive Rousettus aegyptiacus.</p

Phylogenetic tree, distances, and alignment comparing the relationship of the MARV sequence of sample ERB-79 to other marburgviruses.

The sequences from Guinea generated during this study are indicated with asterisks. A: Maximum-likelihood tree (Tamura 3-parameter model with 1000 pseudoreplicates) of partial marburgvirus nucleoprotein gene fragments (92 bp). Scale bar indicates the mean number of nucleotide substitutions per site. The sequences in bold were used in the alignment presented below. The tree is midpoint rooted and the root position is verified by the Ravn virus (DQ447649) outgroup. B: Phylogenetic distances between sample ERB-79 and MARV sequences of different phylogenetic groups that were available in GenBank (35 sequences of Ozolin group, 8 sequences of Musoke group, 6 sequences of Angola-like ERB group, and 13 sequences of Angola human group). Distance is shown as the number of substitutions (on the 92 bp fragment of the NP gene). Solid line represents the median, box shows interquartile range (IQR), whiskers represent 1.5 × IQR, and the circles indicate outliers (values exceeded 1.5 × IQR). C: Aligned fragments (92 bp) of the MARV nucleoprotein gene with highlighted variable sites.</p

Maximum-likelihood phylogeny of 64 partial Marburg virus polymerase gene (L gene) fragments with a total length of 1262 bp.

Tree was constructed using the best-fit nucleotide substitution model (T93+G). Sequences in brown were obtained from ERB, and sequences in black come from human and nonhuman primate samples. The sequence from R. aegyptiacus ID ERB-452 generated in this study is indicated with an asterisk and bold text. Scale bar indicates the mean number of nucleotide substitutions per site. The filled circles on branches indicate bootstrap values greater than 0.9.</p

Primers used for sequencing of qRT-PCR positive samples.

Primers used for sequencing of qRT-PCR positive samples.</p

<i>Rousettus aegyptiacus</i> trapping data with the results of PCR screening on MARV.

Rousettus aegyptiacus trapping data with the results of PCR screening on MARV.</p

Phylogenetic trees of four different fragments of Marburg virus.

Phylogenetic trees of four different fragments of Marburg virus.</p