Biology subjects

Tortosa, P.

Publications and source records attributed to Tortosa, P..

13 recordsLinked to original sources

bioRxiv2024

Development of the Incompatible Insect Technique targeting Aedes albopictus: introgression of a wild nuclear background restores the performance of males artificially infected with Wolbachia

The bacterium Wolbachia pipientis is increasingly studied for its potential use in controlling insect vectors or pests due to its ability to induce Cytoplasmic Incompatibility (CI). CI can be exploited by establishing an opportunistic Wolbachia infection in a targeted insect species through trans-infection and then releasing the infected males into the environment as sterilizing agents. Several host life history traits (LHT) have been reported to be negatively affected by artificial Wolbachia infection. Wolbachia is often considered as the causative agent of these detrimental effects, and the importance of the hosts genetic origins in the outcome of trans-infection is generally overlooked. In this study, we investigated the impact of host genetic background using an Aedes albopictus line recently trans-infected with wPip from Culex pipiens mosquito, which exhibited some fitness costs. We measured several LHTs including fecundity, egg hatch rate and male mating competitiveness in the incompatible line after four rounds of introgression aiming at restoring genetic diversity in the nuclear genome. Our results show that introgression with a wild genetic background restored most fitness traits and conferred mating competitiveness comparable to that of wild males. Finally, we show that introgression leads to faster and stronger population suppression under laboratory conditions. Overall, our data support that host genome plays a decisive role in determining the fitness of Wolbachia infected incompatible males. ImportanceThe bacterium Wolbachia pipientis is increasingly used to control insect vectors and pests through the Incompatible Insect Technique (IIT) inducing a form of conditional sterility when a Wolbachia-infected male mates with an uninfected or differently infected female. Wolbachia artificial trans-infection has been repeatedly reported to affect mosquitoes LHTs, which may in turn compromise the efficiency of IIT. Using a tiger mosquito (Aedes albopictus) line recently trans-infected with a Wolbachia strain from Culex pipiens and displaying reduced fitness, we show that restoring genetic diversity through introgression significantly mitigated the fitness costs associated with Wolbachia trans-infection. This was further demonstrated through experimental population suppression, showing that introgression is required to achieve mosquito population suppression under laboratory conditions. These findings are significant for the implementation of IIT programs, as an increase in female fecundity and male performance improves mass rearing productivity as well as the sterilizing capacity of released males.

bioengineering↗

bioRxiv2024

Role of individual and population heterogeneity in shaping dynamics of multi-pathogen excretion in an island endemic bat

Understanding processes driving pathogen transmission in bats is critical to prevent spillovers and emergence events. Although substantial research has addressed this topic, few studies have directly examined shedding dynamics (as opposed to serological studies) and co-infection patterns using fine-scale spatio-temporal datasets. Here, based on the monitoring of 5,714 Reunion free-tailed bats (Mormopterus francoismoutoui) in 17 roosts over 24 months, we studied the co-shedding dynamics of paramyxoviruses (PMV) and Leptospira bacteria (LEPTO) in urine, and herpesviruses (HSV) in saliva. We evidenced all year long shedding with high prevalence of all three infectious agents (37% - 87%), as well as an exceptionally high level of co-shedding (59%), with both positive and negative interactions between infectious agents. Shedding patterns displayed temporal synchrony among roosts, with a peak during summer months, but were not influenced by roost size. Repeated shedding in recaptured bats supports within-host persistence, though underlying mechanisms remain to be identified. Our results also showed rapid HSV infection of juveniles (< 6 months), and suggest longer protection of juveniles by maternal antibodies for PMV and LEPTO. Reproductive individuals (both during the pregnancy and mating) were associated to increased PMV and LEPTO shedding, which can result from tradeoffs between reproduction and infection in both sexes, and/or an age-related bias with the progressive infection of older juveniles during reproductive periods. This study highlights the significance of persistent shedding of multiple pathogens, including bacteria, and their intricate interactions within bat populations. Understanding how human-driven ecological changes may disrupt within-host processes and influence pathogen shedding in bats will help assessing the risk of pathogen spillover from bats to other species, including humans. Author summaryUnderstanding risks of bat-borne pathogen spillover is challenging because of the difficulty in studying shedding dynamics in wild bat populations. Here, we used an original island-endemic bat species to build up a fine-scale spatio-temporal shedding analysis of two viruses (paramyxoviruses and herpesviruses) and a bacterium (Leptospira) at both population- (roost) and individual- (through recaptured bats) levels. Shedding patterns are driven by the age of bats and associated to the reproductive periods in both females and males. Results also suggest that persistence, as well as interactions between infectious agents, are important within-host processes that contribute to the transmission of infections in bat populations. More research is essential to understand how human activities may influence these co-shedding patterns and the risk of cross- species transmission.

evolutionary biology↗

bioRxiv2023

Effect of habitat degradation on hantavirus infection among introduced and endemic small mammals of Madagascar

Hantaviruses are globally distributed zoonotic pathogens capable of causing fatal disease in humans. Rodents and other small mammals are the typical reservoirs of hantaviruses, though the particular host varies regionally. Addressing the risk of hantavirus spillover from animal reservoirs to humans requires identifying the local mammal reservoirs and the predictors of infection in those animals, such as their population density and habitat characteristics. We screened native and non-native small mammals and bats in northeastern Madagascar for hantavirus infection to investigate the influence of habitat, including effects of human land use on viral prevalence. We trapped 227 bats and 1663 small mammals over 5 successive years in and around Marojejy National Park across a range of habitat types including villages, agricultural fields, regrowth areas, and secondary and semi-intact forests. Animals sampled included endemic tenrecs (Tenrecidae), rodents (Nesomyidae) and bats (6 families), along with non-native rodents (Muridae) and shrews (Soricidae). A hantavirus closely related to the previously described Anjozorobe virus infected 9.5% of Rattus rattus sampled. We did not detect hantaviruses in any other species. Habitat degradation had a complex impact on hantavirus prevalence in our study system: more intensive land use increase the abundance of R. rattus. The average body size of individuals varied between agricultural and non-agricultural land-use types, which in turn affected infection prevalence. Smaller R.rattus had lower probability of infection and were captured more commonly in villages and forests. Thus, infection prevalence was highest in agricultural areas. These findings provide new insights to the gradients of hantavirus exposure risk for humans in areas undergoing rapid land use transformations associated with agricultural practices.

zoology↗

bioRxiv2023

Stuck on a small tropical island: wide in-situ diversification of an urban-dwelling bat

Bats are often the only mammals naturally colonizing isolated islands and are thus an excellent model to study evolutionary processes of insular ecosystems. Here, we studied the Reunion free-tailed bat (Mormopterus francoismoutoui), an endemic species to Reunion Island that has adapted to urban settings. At regional scale, we investigated the evolutionary history of Mormopterus species, as well as on Reunion Island sex-specific and seasonal patterns of genetic structure. We used an extensive spatio-temporal sampling including 1,136 individuals from 18 roosts and three biological seasons (non-reproductive/winter, pregnancy/summer, and mating), with additional samples from Mormopterus species from neighbouring islands (M. jugularis of Madagascar and M. acetabulosus of Mauritius). Complementary information gathered from both microsatellite and mitochondrial markers revealed a high genetic diversity but no signal of spatial genetic structure and weak evidence of female philopatry. Regional analysis suggests a single colonization event for M. francoismoutoui, dated around 175,000 years ago, and followed by in-situ diversification and the evolution of divergent ancestral lineages, which today form a large metapopulation. Population expansion was relatively ancient (55,000 years ago) and thus not linked to human colonization of the island and the availability of new anthropic day-roost sites. Discordant structure between mitochondrial and microsatellite markers suggests the presence of yet-unknown mating sites, or the recent evolution of putative ecological adaptations. Our study illustrates how understanding mechanisms involved in speciation can be challenging and the importance of both mitochondrial and nuclear DNA in resolving the wide in-situ diversification of an urban-dwelling bat, endemic to a small island.

genetics↗

bioRxiv2023

Virome analysis of New Zealand's bats reveals cross-species viral transmission among the Coronaviridae

1.The lesser short-tailed bat (Mystacina tuberculata) and the long-tailed bat (Chalinolobus tuberculatus) are Aotearoa New Zealands only native extant terrestrial mammals and are believed to have migrated from Australia. Long-tailed bats arrived in New Zealand an estimated two million years ago and are closely related to other Australian bat species. Lesser short-tailed bats, in contrast, are the only extant species within the Mystacinidae and are estimated to have been living in isolation in New Zealand for the past 16-18 million years. Throughout this period of isolation, lesser short-tailed bats have become one of the most terrestrial bats in the world. Through a metatranscriptomic analysis of guano samples from eight locations across New Zealand we aimed to characterise the viromes of New Zealands bats and determine whether viruses have jumped between these species over the past two million years. High viral richness was observed among long-tailed bats with viruses spanning seven different viral families. In contrast, no bat-specific viruses were identified in lesser short-tailed bats. Both bat species harboured an abundance of likely dietary- and environmental-associated viruses. We also identified alphacoronaviruses in long-tailed bat guano that had previously been identified in lesser short-tailed bats, suggesting that these viruses had jumped the species barrier after long-tailed bats migrated to New Zealand. Of note, an alphacoronavirus species discovered here possessed a complete genome of only 22,416 nucleotides with entire deletions or truncations of several non-structural proteins, thereby representing what is possibly the shortest genome within the Coronaviridae identified to date. Overall, this study has revealed a diverse range of novel viruses harboured by New Zealands only native terrestrial mammals, in turn expanding our understanding of bat viral dynamics and evolution globally.

microbiology↗

bioRxiv2023

What can New Zealand bats tell us about Coronaviruses?

The current Covid-19 pandemic emphasizes the dramatic consequences of emerging zoonotic pathogens and stimulates the need for an assessment of the evolution and natural cycle of such microbes in a One Health framework. A number of recent studies have revealed an astonishing diversity of bat-borne Coronaviruses, including in insular environments, which can be considered as simplified biological systems suited for the exploration of the transmission cycles of these viruses in nature. In this work, we present two new lineages of alpha Coronaviruses detected by screening the only two extant New Zealand bat species: the lesser short-tailed bat (Mystacina tuberculata) and the long-tailed bat (Chalinolobus tuberculatus). Infection prevalence reaching 60% in long-tailed bats makes this host-pathogen model relevant for the investigation of maintenance mechanisms in a bat reservoir with peculiar physiological adaptations to temperate climates. A phylogenetic analysis shows that these viral lineages do cluster with Coronaviruses hosted by bat sister species from Australia, supporting co-diversification processes and confirming that the evolution of these viruses is tightly linked to that of their hosts. These patterns provide an interesting framework for further research aiming at elucidating the natural history and biological cycles of these economically-devastating zoonotic viruses.

ecology↗

bioRxiv2022

Identification of the onchocerciasis vector in the Kakoi-Koda focus of the Democratic Republic of Congo

BackgroundThe objective of this study was to characterise the vector in a small hyper-endemic focus of onchocerciasis (the Kakoi-Koda focus) which has recently been discovered on the western slopes of the rift valley above Lake Albert. Methodology/Principal FindingsAquatic stages of blackflies were collected by hand from streams and rivers, and anthropophilic adult females were collected by human landing catches. Using a combination of morphotaxonomy and DNA barcoding, the blackflies collected biting humans within the focus were identified as Simulium dentulosum and S. vorax, which were also found breeding in local streams and rivers. Simulium damnosum s.l., S. neavei and S. albivirgulatum were not found (except for a single site in 2009 where crabs were carrying S. neavei). Anthropophilic specimens from the focus were screened for Onchocerca DNA using discriminant qualitative real-time triplex PCR. One specimen of S. vorax was positive for Onchocerca volvulus in the body, and out of 155 S. dentulosum, 30% and 11% were infected and infective (respectively). Conclusions/SignificanceSimulium dentulosum currently appears to be the main vector of human onchocerciasis within the Kakoi-Koda focus, and S. vorax may be a secondary vector. It remains possible that S. neavei was the main (or only) vector in the past having now become rare as a result of the removal of tree-cover and land-use changes. Simulium vorax has previously been shown to support the development of O. volvulus in the laboratory, but this is the first time that S. dentulosum has been implicated as a vector of onchocerciasis, and this raises the possibility that other blackfly species which are not generally considered to be anthropophilic vectors might become vectors under suitable conditions. Because S. dentulosum is not a vector in endemic areas surrounding the Kakoi-Koda focus, it is probable that the Kakoi-Koda focus is significantly isolated. AUTHOR SUMMARYRiver blindness (=onchocerciasis) is a severely debilitating disease caused by the nematode parasite Onchocerca volvulus, and in Africa it is known to be transmitted from person to person by blood-sucking blackflies (Diptera: Simuliidae) of the Simulium damnosum complex, the S. neavei group and (rarely) by S. albivirgulatum. Using classical morphological characteristics and DNA analysis we have unexpectedly identified the vector blackfly as S. dentulosum (and possibly S. vorax) in a small endemic area (the Kakoi-Koda focus) which has been recently discovered on the western slopes of the rift valley in the Democratic Republic of Congo above Lake Albert. In the surrounding endemic areas, the vectors are S. damnosum complex and/or S. neavei (as normally expected), and because S. dentulosum is not a vector in these surrounding areas, it follows that this focus is entomologically isolated from immigrant blackfly species which might otherwise have carried new infections into the Kakoi-Koda focus (and vice-versa). This is of local importance, because it makes elimination of the parasite easier, but our findings have wider significance across Africa, because they raise the possibility that under the right conditions, other common and widely-distributed blackfly species might unexpectedly become man-biters and significant vectors.

ecology↗

bioRxiv2021

Co-evolution of Leptospira and Tenrecidae (Afrotheria) on Madagascar

Leptospirosis is a bacterial zoonosis caused by pathogenic Leptospira that are maintained in the kidney lumen of infected animals acting as reservoirs and contaminating the environment via infected urine. The investigation of leptospirosis through a One Health framework has been stimulated by notable genetic diversity of pathogenic Leptospira together with a high infection prevalence in certain animal reservoirs. Studies of Madagascars native mammal fauna have revealed a diversity of Leptospira with high levels of host-specificity. Native rodents, tenrecids, and bats shelter several distinct lineages and species of Leptospira, some of which have also been detected in acute human cases. Specifically, Leptospira mayottensis, first discovered in humans on Mayotte, an island neighboring Madagascar, was subsequently identified in a few species of Malagasy tenrecids, an endemic family of small mammals. Distinct L. mayottensis lineages were identified in shrew tenrecs (Microgale cowani and Nesogale dobsoni) on Madagascar, and later in spiny tenrecs (Tenrec ecaudatus) on Mayotte. These findings suggest that L. mayottensis (i) has co-radiated with tenrecids on Madagascar, and (ii) has recently emerged in human populations on Mayotte following the introduction of T. ecaudatus from Madagascar. Hitherto, L. mayottensis has not been detected in spiny tenrecs on Madagascar. In the present study, we broaden the investigation of Malagasy tenrecids and describe the presence of L. mayottensis in Malagasy T. ecaudatus and M. thomasi. These results confirm the hypothesis that L. mayottensis was introduced to Mayotte, presumably via T. ecaudatus, and provide additional data on the co-radiation of Leptospira and Tenrecidae.

evolutionary biology↗

bioRxiv2021

Tracking animal reservoirs of pathogenic Leptospira: the right test for the right claim.

Leptospirosis, caused by a pathogenic Leptospira bacteria, is the most prevalent zoonosis worldwide and in this context has been extensively investigated through a One Health framework. Diagnosis of human leptospirosis includes molecular and serological tools, with serological Microscopic Agglutination Test (MAT) still being considered as a gold standard. Mammals considered as biological reservoirs include species or populations that are able to maintain chronic infection and shed the bacteria via their urine in the environment. Leptospira bacteria are often investigated using the same diagnosis tool, serological MAT. However, MAT testing of putative animal reservoirs can lead to mis-interpretations as it can signal previous infection and not necessarily bring in robust information regarding the capacity of such sero-positive animals to maintain chronic infection. We use previously published data and present new results on introduced and endemic small mammals to show that MAT should not be used for the identification of reservoirs. By contrast, serological data are informative on the level of exposure of animals occupying a specific environment. Finally, we present a sequential methodology to investigate human leptospirosis in a One Health framework that associates molecular detection in humans and animals, together with MAT of human samples using Leptospira isolates obtained from reservoir animals occurring in the same environment.

microbiology↗

bioRxiv2019

The potential for a released autosomal X-shredder becoming a driving-Y chromosome and invasively suppressing wild populations of malaria mosquitoes

Synthetic sex-ratio distorters based on X-chromosome shredding are predicted to be more efficient than sterile males for population suppression of malaria mosquitoes using genetic control. X-chromosome shredding operates through the targeted elimination of X-chromosome-bearing gametes during male spermatogenesis, resulting in males that have a high fraction of male offspring. Strains harboring autosomal constructs containing a modified endonuclease I-PpoI have now been developed in the malaria mosquito Anopheles gambiae, resulting in strong sex-ratio distortion towards males. Data are being gathered for these strains for submission of regulatory dossiers for contained use and subsequent field release in West Africa. Since autosomal X-shredders are transmitted in a Mendelian fashion and can be selected against their frequency in the population is expected to decline once releases are halted. However, any unintended transfer of the X-shredder to the Y-chromosome could theoretically change these dynamics: This could lead to 100% transmission of the newly Y-linked X-shredder to the predominant male-biased offspring and its insulation from negative selection in females, resulting in its potential spread in the population and ultimately to suppression. Here, we analyze plausible mechanisms whereby an autosomal X-shredder could become linked to the Y-chromosome after release and provide data regarding its potential for activity should it become linked to the Y-chromosome. Our results strongly suggest that Y-chromosome linkage through remobilization of the transposon used for the initial genetic transformation is unlikely, and that, in the unexpected event that the X-shredder becomes linked to the Y-chromosome, expression and activity of the X-shredder would likely be inhibited by meiotic sex chromosome inactivation. We conclude that a functioning X-shredding-based Y-drive resulting from a naturally induced transposition or translocation of the transgene onto the Y-chromosome is unlikely.

genetics↗

bioRxiv2019

Bat coronavirus phylogeography in the western Indian Ocean

Bats provide key ecosystem services such as crop pest regulation, pollination, seed dispersal, and soil fertilization. Bats are also major hosts for biological agents responsible for zoonoses, such as coronaviruses (CoVs). The islands of the Western Indian Ocean are identified as a major biodiversity hotspot, with more than 50 bat species. In this study, we tested 1,013 bats belonging to 36 species from Mozambique, Madagascar, Mauritius, Mayotte, Reunion Island and Seychelles, based on molecular screening and partial sequencing of the RNA-dependent RNA polymerase gene. In total, 88 bats (8.7%) tested positive for coronaviruses, with higher prevalence in Mozambican bats (20.5% {+/-} 4.9%) as compared to those sampled on islands (4.5% {+/-} 1.5%). Phylogenetic analyses revealed a large diversity of - and {beta}-CoVs and a strong signal of co-evolution between CoVs and their bat host species, with limited evidence for host-switching, except for bat species sharing day roost sites. ImportanceThis is the first study to report the presence of coronaviruses (CoVs) in bats in Mayotte, Mozambique and Reunion Island, and in insectivorous bats in Madagascar. Eight percent of the tested bats were positive for CoVs, with higher prevalence in continental Africa than on islands. A high genetic diversity of - and {beta}-CoVs was found, with strong association between bat host and virus phylogenies, supporting a long history of co-evolution between bats and their associated CoVs in the Western Indian Ocean. These results highlight that strong variation between islands does exist and is associated with the composition of the bat species community on each island. Future studies should investigate whether CoVs detected in these bats have a potential for spillover in other hosts.

evolutionary biology↗

bioRxiv2019

Exploring the infection dynamics of a bacterial pathogen on a remote oceanic island reveals annual epizootics impacting an albatross population

Oceanic islands with reduced species richness provide an opportunity to investigate the emergence, maintenance and transmission of infectious diseases threatening wildlife. On Amsterdam Island, in the southern Indian Ocean, massive and recurrent mortality of the nestlings of Indian yellow-nosed albatross (Thalassarche carteri) has been attributed to avian cholera caused by Pasteurella multocida, a bacterial pathogen of likely human introduction. To understand the annual dynamics of pathogen prevalence, we measured the shedding of bacterial DNA by the albatrosses during four successive breeding seasons. The screening of 583 bird swabs by Real-Time PCR revealed an intense circulation of P. multocida during each study year, with a steady increase of infection prevalence across the breeding season. In the three years of highest pathogen prevalence, the epizootics were associated with massive die-offs of nestlings, inducing low annual fledging success (< 20%). These findings and developed PCR protocol have crucial applications for refining wildlife conservation plans aiming at controlling this disease.

ecology↗

bioRxiv2018

Construction of a Genetic Sexing Strain for Aedes albopictus: a promising tool for the development of sterilizing insect control strategies targeting the tiger mosquito

BackgroundAedes albopictus is an invasive mosquito species of global medical concern as its distribution has recently expanded to Africa, the Americas and Europe. In the absence of prophylaxis protecting human populations from emerging arboviruses transmitted by this mosquito species, the most straightforward control measures rely on the suppression or manipulation of vector natural populations. A number of environmental-friendly methods using innundative releases of sterilizing males are currently under development. However, these strategies are still lacking an efficient sexing method required for mass production of males.\n\nResultsWe present the first Genetic Sexing Strain (GSS) in Ae. albopictus, hereafter referred as TiCoq, obtained by sex linkage of rdl gene conferring dieldrin resistance. Hatching rate, larval survival and sex ratio were followed during twelve generations. The use of dieldrin at third larval stage allowed selecting 98% of males on average.\n\nConclusionA good production rate of TiCoq males makes this GSS suitable for any control method based on mass production of Ae. albopictus sterilizing males. Despite limitations resulting from affected egg hatch as well as the nature of the used insecticide, the construction of this GSS paves the way for industrial sex separation of Ae. albopictus.

genetics↗