Fossil rhabdoviral sequences integrated into arthropod genomes: ontogeny, evolution, and potential functionality.

Autor(es): Fort Philippe; Albertini Aurélie; Van-Hua Aurélie; Berthomieu Arnaud; Roche Stéphane; Delsuc Frédéric; Pasteur Nicole; Capy Pierre; Gaudin Yves; Weill Mylène

Resumo: Retroelements represent a considerable fraction of many eukaryotic genomes and are considered major drives for adaptive genetic innovations. Recent discoveries showed that despite not normally using DNA intermediates like retroviruses do, Mononegaviruses (i.e., viruses with nonsegmented, negative-sense RNA genomes) can integrate gene fragments into the genomes of their hosts. This was shown for Bornaviridae and Filoviridae, the sequences of which have been found integrated into the germ line cells of many vertebrate hosts. Here, we show that Rhabdoviridae sequences, the major Mononegavirales family, have integrated only into the genomes of arthropod species. We identified 185 integrated rhabdoviral elements (IREs) coding for nucleoproteins, glycoproteins, or RNA-dependent RNA polymerases; they were mostly found in the genomes of the mosquito Aedes aegypti and the blacklegged tick Ixodes scapularis. Phylogenetic analyses showed that most IREs in A. aegypti derived from multiple independent integration events. Since RNA viruses are submitted to much higher substitution rates as compared with their hosts, IREs thus represent fossil traces of the diversity of extinct Rhabdoviruses. Furthermore, analyses of orthologous IREs in A. aegypti field mosquitoes sampled worldwide identified an integrated polymerase IRE fragment that appeared under purifying selection within several million years, which supports a functional role in the host's biology. These results show that A. aegypti was subjected to repeated Rhabdovirus infectious episodes during its evolution history, which led to the accumulation of many integrated sequences. They also suggest that like retroviruses, integrated rhabdoviral sequences may participate actively in the evolution of their hosts.

Palavras-Chave: Genetic Evolution; Molecular Gene Transfer; Horizontal Genome; Insect Phylogeny Rhabdoviridae

Imprenta: Molecular Biology and Evolution, v. 29, n. 1, p. 381-390, 2012

Identificador do objeto digital: 10.1093/molbev/msr226

Descritores: Aedes aegypti - Cell ; Aedes aegypti - DNA ; Aedes aegypti - Genome ; Aedes aegypti - Pathogenesis ; Aedes aegypti - RNA ; Aedes aegypti - Virus ; Aedes aegypti - Public health

Data de publicação: 2012