Journal Article

Coevolutionary Analysis Implicates Toll-Like Receptor 9 in Papillomavirus Restriction

Kraberger, Simona, Gryseels, Sophie, Richet, Cécile, Worobey, Michael, Jackson, Robert, King, Kelly, Harrison, Joseph S., Varsani, Arvind, Van Doorslaer, Koenraad, Larsen, Brendan B.

2022

Overview

Viruses must avoid detection by the innate immune system. In this study, we characterized two new papillomaviruses from bats and used molecular archeology to demonstrate that their genomes altered their nucleotide compositions to avoid detection by TLR9, providing evidence that TLR9 acts as a PRR during papillomavirus infection. Upon infection, DNA viruses can be sensed by pattern recognition receptors (PRRs), leading to the activation of type I and III interferons to block infection. Therefore, viruses must inhibit these signaling pathways, avoid being detected, or both. Papillomavirus virions are trafficked from early endosomes to the Golgi apparatus and wait for the onset of mitosis to complete nuclear entry. This unique subcellular trafficking strategy avoids detection by cytoplasmic PRRs, a property that may contribute to the establishment of infection. However, as the capsid uncoats within acidic endosomal compartments, the viral DNA may be exposed to detection by Toll-like receptor 9 (TLR9). In this study, we characterized two new papillomaviruses from bats and used molecular archeology to demonstrate that their genomes altered their nucleotide compositions to avoid detection by TLR9, providing evidence that TLR9 acts as a PRR during papillomavirus infection. Furthermore, we showed that TLR9, like other components of the innate immune system, is under evolutionary selection in bats, providing the first direct evidence for coevolution between papillomaviruses and their hosts. Finally, we demonstrated that the cancer-associated human papillomaviruses show a reduction in CpG dinucleotides within a TLR9 recognition complex. IMPORTANCE Viruses must avoid detection by the innate immune system. In this study, we characterized two new papillomaviruses from bats and used molecular archeology to demonstrate that their genomes altered their nucleotide compositions to avoid detection by TLR9, providing evidence that TLR9 acts as a PRR during papillomavirus infection. Furthermore, we demonstrated that TLR9, like other components of the innate immune system, is under evolutionary selection in bats, providing the first direct evidence for coevolution between papillomaviruses and their hosts.

• Publisher: American Society for Microbiology
• Subject: Archaeology / Bats / Coevolution / Coronaviruses / CpG islands / Disease transmission / DNA viruses / Endosomes / Evolution / evolutionary biology / Genomes / Golgi apparatus / Human papillomavirus / Humans / Immune response / Immune system / Innate immunity / Mexican free-tailed bat / Mitosis / Mutagenesis / Nucleotides / Papillomaviridae / Papillomaviridae - genetics / Papillomaviridae - metabolism / papillomavirus / Papillomavirus Infections / Pathogens / Pattern recognition receptors / Phylogenetics / Reading / Receptors, Pattern Recognition / Research Article / TLR9 / TLR9 protein / Toll-Like Receptor 9 - genetics / Toll-like receptors / Viral infections / Virions / Virus Diseases / Viruses