Abstracts (first author)


Novel papillomaviruses in free-ranging Iberian bats challenge the dogmas: interspecies transmission, no virus-host coevolution and evidences for recombination


Author(s): Bravo IG, Wibbelt G, Vázquez-Morón S, Ibáñez C, Echevarría JE, Juste J, García-Pérez R


Papillomaviridae are a wide and divergent family of small, non-encapsulated dsDNA viruses that infect most vertebrates. Animal PV diversity is poorly sampled, and thence most of our hypotheses about PV evolution are biased because of the clinical focus on PV research. We communicate here the sequencing and cloning of five new PVs isolated from different bat species: Eidolon helvum PV type 1 (EhelPV1), Rhinolophus ferrumequinum PV type 1 (RferPV1), Eptesicus serotinus PV type 1 (EserPV1), Eptesicus serotinus PV type 2 (EserPV2) and Eptesicus serotinus PV type 3 (EserPV3). These novel PVs were isolated from three different bat families: Pteropodidae, Rhinolophidae y Vespertilionidae, respectively. Phylogenetic relationships within Papillomaviridae were inferred by means of maximum likelihood, Bayesian, and supernetwork analyses. Further, we have studied the prevalence of EserPV1, 2 and 3 in a number of E. serotinus and E. isabellinus bat colonies in the Iberian peninsula. There are currently nine bat PVs, and they are not monophyletic: five of them belong to the Lamda+Mu PVs crowngroup, one to the Alpha+Omicron PVs crowngroup, and three of them are close to root and their precise phylogenetic positions cannot be inferred with certainty. The increased sampling of the Lambda+Mu PV crowngroup is welcome, as it hosts viruses infecting diverse hosts (carnivores, chiroptera, primates, rodents and lagomorpha), with diverse tropisms (cutaneous and mucosal) and with divergent clinical manifestations of the infections (asymptomatic, benign proliferations and malignant tumours). Our results question once again the old assumption of virus-host coevolution for the PVs and reinforce the hypothesis of a biphasic evolution in the story of the PVs: an initial adaptive radiation linked to the definition of new niches during the evolution of mammalian skin that generated the ancestral PV crowngroups, followed by a limited co-especiation between viruses and hosts.

Abstracts (coauthor)


Horizontal gene transfer is a powerful mechanism by which antibiotic resistance spread among species. However, the maintenance of a horizontally transferred antibiotic resistance gene is not granted, because of its low level of adaptation to the receiving organism. In particular, transferred genes usually have codon preferences that differ from the ones of the receiving genome. This leads to translation errors, low translation rates and finally to low activity of the transferred gene and energetic costs for the receiving cell. It is theoretically predicted that a deoptimized codon usage gene will undergo an amelioration process - i.e. its sequence will evolve towards a codon usage similar to the host one - and a fine tuning of its expression and of the expression of interacting genes. To test these predictions, three synonymous versions of the Chloramphenicol Acetyl Transferase with different codon preferences were designed and transfected in Escherichia coli. After verifying that unadapted codon usage induced a fitness cost, we experimentally evolved these populations for 1000 generations. At the phenotypic level, the cost of codon usage deadaptation was totally compensated. However, at the genotypic level, no amelioration process was observed but various genetic changes occurred ranging from mutations in the promoter to gene loss to plasmid copy number reduction and to genetic changes in the bacteria chromosome. At the proteome level, the presence of a codon usage biased gene and the posterior evolution affected the expression of a high number of proteins. Our results suggest that the presence of horizontally transferred gene with a different codon usage induces selection pressures leading to a refactorization of the bacterial functioning. Horizontal transfer of antibiotic resistance gene thus reveals itself, not only as a spreading highway for these genes but also as a powerful mechanism pushing bacteria to explore new ways of functioning.


Chairman: Octávio S. Paulo
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XIV Congress of the European Society for Evolutionary Biology

Organization Team
Department of Animal Biology (DBA)
Faculty of Sciences of the University of Lisbon
P-1749-016 Lisbon


Computational Biology & Population Genomics Group