Casas, I. | bioRxiv Science

bioRxiv2020

Phylodynamics of SARS-CoV-2 transmission in Spain

ObjectivesSARS-CoV-2 whole-genome analysis has identified three large clades spreading worldwide, designated G, V and S. This study aims to analyze the diffusion of SARS-CoV-2 in Spain/Europe. MethodsMaximum likelihood phylogenetic and Bayesian phylodynamic analyses have been performed to estimate the most probable temporal and geographic origin of different phylogenetic clusters and the diffusion pathways of SARS-CoV-2. ResultsPhylogenetic analyses of the first 28 SARS-CoV-2 whole genome sequences obtained from patients in Spain revealed that most of them are distributed in G and S clades (13 sequences in each) with the remaining two sequences branching in the V clade. Eleven of the Spanish viruses of the S clade and six of the G clade grouped in two different monophyletic clusters (S-Spain and G-Spain, respectively), with the S-Spain cluster also comprising 8 sequences from 6 other countries from Europe and the Americas. The most recent common ancestor (MRCA) of the SARS-CoV-2 pandemic was estimated in the city of Wuhan, China, around November 24, 2019, with a 95% highest posterior density (HPD) interval from October 30-December 17, 2019. The origin of S-Spain and G-Spain clusters were estimated in Spain around February 14 and 18, 2020, respectively, with a possible ancestry of S-Spain in Shanghai. ConclusionsMultiple SARS-CoV-2 introductions have been detected in Spain and at least two resulted in the emergence of locally transmitted clusters, with further dissemination of one of them to at least 6 other countries. These results highlight the extraordinary potential of SARS-CoV-2 for rapid and widespread geographic dissemination.

microbiology↗

bioRxiv2019

Mating strategy is determinant of Adenovirus prevalence in European bats

Adenoviruses are double-strained DNA viruses found in a great number of vertebrates, including humans. In order to understand their transmission dynamics, it is crucial, even from a human health perspective, to investigate how host traits influence their prevalence. Bats are important reservoirs for Adenoviruses, and here we use the results of recent screenings in Western Europe to evaluate the association between characteristic traits of bat species and their probability of hosting Adenoviruses, taking into account their phylogenetic relationships. Across species, we found an important phylogenetic component in the presence of Adenoviruses and mating strategy as the most determinant factor conditioning the prevalence of Adenoviruses across bat species. Contrary to other more stable mating strategies (e.g. harems), swarming could hinder transmission of Adenoviruses since this strategy implies that contacts between individuals are too short. Alternatively, bat species with more promiscuous behavior may develop a stronger immune system. Outstandingly high prevalence of Adenoviruses was reported for the Iberian species Pipistrellus pygmaeus, P. kuhlii and Nyctalus lasiopterus and we found that in the latter, males were more likely to be infected by Adenoviruses than females, due to the immunosuppressing consequence of testosterone during the mating season. As a general trend across species, we found that the number of Adenoviruses positive individuals was different across localities and that the difference in prevalence between populations was correlated with their geographic distances (P. pygmaeus). These results increase our knowledge about the transmission mechanisms of Adenoviruses.\n\nAuthor SummaryAdenoviruses are DNA viruses with a wide range of vertebrate hosts, including humans, causing ocular, respiratory and gastrointestinal diseases. Here, we focus on the prevalence of Adenoviruses in bats, which are known to be natural reservoir of many viruses, using the results of recent screenings for prevalence of these viruses in 33 European bat species. Our aim is to find association between Adenoviruses prevalence and biological and behavioral host traits, considering the heterogeneity both between and within species in order to have a deeper understanding of mechanisms of viral transmission.\n\nOur results highlight the importance of mating strategy: bats species using swarming as mating strategy are less likely to be infected by Adenoviruses. Moreover, we found that locality of capture can explain a higher prevalence of Adenovirus within species. However, no general pattern has been found in the analysis at individual level, suggesting a strong species specificity and complex viral transmission dynamics.

ecology↗