A novel adenovirus of Western lowland gorillas (Gorilla gorilla gorilla)

Abstract

Adenoviruses (AdV) broadly infect vertebrate hosts including a variety of primates. We identified a novel AdV in the feces of captive gorillas by isolation in cell culture, electron microscopy and PCR. From the supernatants of infected cultures we amplified DNA polymerase (DPOL), preterminal protein (pTP) and hexon gene sequences with generic pan primate AdV PCR assays. The sequences in-between were amplified by long-distance PCRs of 2-10 kb length, resulting in a final sequence of 15.6 kb. Phylogenetic analysis placed the novel gorilla AdV into a cluster of primate AdVs belonging to the species Human adenovirus B (HAdV-B). Depending on the analyzed gene, its position within the cluster was variable. To further elucidate its origin, feces samples of wild gorillas were analyzed. AdV hexon sequences were detected which are indicative for three distinct and novel gorilla HAdV-B viruses, among them a virus nearly identical to the novel AdV isolated from captive gorillas. This shows that the discovered virus is a member of a group of HAdV-B viruses that naturally infect gorillas. The mixed phylogenetic clusters of gorilla, chimpanzee, bonobo and human AdVs within the HAdV-B species indicate that host switches may have been a component of the evolution of human and non-human primate HAdV-B viruses.

Figure 1

PCR amplification strategy. Above the ruler, the amplified part of the AdV genome is depicted. Below, a schematic visualisation of the positions of the degenerated consensus PCRs (red lines), the long-distance PCRs (black lines) and the resulting contiguous sequence (blue line) is given. In the box, the hexon gene is magnified, and the positions of the hexon loops and the Hex-loop2 PCR (red line) are illustrated.

Figure 2

Simplot analysis of the hexon gene. 2.8 kb of the GgorAdV-B7 hexon gene were compared to the hexon genes of selected chimpanzee (green and red line), gorilla (blue line) and human (yellow and grey line) AdVs. Below the plot, the analysis parameters are listed in blue font. The hexon Loop 1 and Loop 2 regions are indicated at the bottom.

Figure 3

Pairwise sequence alignment of the penton base open reading frame. The penton base gene of GgorAdV-B7 was compared with those of five gorilla-, three chimpanzee- and two human AdVs. The 50-100 percent sequence conservation is represented by the height of each data point along the y axis. The chimpanzee AdV SAdV-29 is highlighted in grey designating the exceptionally high similarity to GgorAdV-B7.

Figure 4

Phylogenetic analysis. The Hexon (A), DPOL (B), pTP (C) and penton (D) sequences of GgorAdV-B7 and those of published NHP and human HAdV-B viruses were aligned and subjected to phylogenetic analysis. Human, chimpanzee, bonobo and gorilla AdVs are in black, blue, green and red font, respectively. AdVs discovered in this study are marked with black dots.

Figure 5

Phylogenetic analysis of the hexon loop 2 region. For details, see legend of Figure 4.