The Vertebrate TLR Supergene Family Evolved Dynamically by Gene Gain/Loss and Positive Selection Revealing a Host-Pathogen Arms Race in Birds

• Type: Article in International Scientific Journal
• Date: 2019

Authors

Khan, I (Author) Other; Maldonado, E (Author) Other; Silva, L (Author) Other; Almeida, D (Author) Other; Johnson, WE (Author) Other; O'Brien, SJ (Author) Other; Zhang, GJ (Author) Other; Jarvis, ED (Author) Other; Gilbert, MTP (Author) Other; Agostinho Antunes (Author) FCUP

Journal

Title: Diversity

Vol. 11

Final page: 131

ISSN: 1424-2818

Publisher: MDPI

Indexing

ISI Web of Knowledge - 22 Citations

Scopus - 24 Citations

Other information

Authenticus ID: P-00Q-YF6

DOI: 10.3390/d11080131

Abstract (EN): The vertebrate toll-like receptor (TLRs) supergene family is a first-line immune defense against viral and non-viral pathogens. Here, comparative evolutionary-genomics of 79 vertebrate species (8 mammals, 48 birds, 11 reptiles, 1 amphibian, and 11 fishes) revealed differential gain/loss of 26 TLRs, including 6 (TLR3, TLR7, TLR8, TLR14, TLR21, and TLR22) that originated early in vertebrate evolution before the diversification of Agnatha and Gnathostomata. Subsequent dynamic gene gain/loss led to lineage-specific diversification with TLR repertoires ranging from 8 subfamilies in birds to 20 in fishes. Lineage-specific loss of TLR8-9 and TLR13 in birds and gains of TLR6 and TLR10-12 in mammals and TLR19-20 and TLR23-27 in fishes. Among avian species, 5-10% of the sites were under positive selection (PS) (omega 1.5-2.5) with radical amino-acid changes likely affecting TLR structure/functionality. In non-viral TLR4 the 20 PS sites (posterior probability PP > 0.99) likely increased ability to cope with diversified ligands (e.g., lipopolysaccharide and lipoteichoic). For viral TLR7, 23 PS sites (PP > 0.99) possibly improved recognition of highly variable viral ssRNAs. Rapid evolution of the TLR supergene family reflects the host-pathogen arms race and the coevolution of ligands/receptors, which follows the premise that birds have been important vectors of zoonotic pathogens and reservoirs for viruses.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 25