Biology subjects

Chaval, Y.

Publications and source records attributed to Chaval, Y..

4 recordsLinked to original sources

bioRxiv2025

Likely circulation of a coronavirus in roe deer (Capreolus capreolus) populations suggested by SARS-CoV-2 serological investigation in France

The risk of viral transmissions from domestic/wild animals to humans is a major public health concern. Humans can also transmit viruses back to domestic and wild animals, acting as reservoir for virus maintenance and sources of epidemic diseases re-emergence. The SARS-CoV-2, causing COVID-19, likely originated from wildlife and has been evidenced to transmit from humans to captive, domestic and wild animals. White-tailed deer (Odocoileus virginianus) show high SARS-CoV-2 prevalence following human contamination, suggesting they could act as an emerging virus reservoir. We completed recent research on European cervid species by investigating whether SARS-CoV-2 had emerged in longitudinally-monitored European roe deer (Capreolus capreolus) populations in direct contact with humans in France. We performed indirect tests (serological ELISAs and seroneutralization) on sera collected before and after the virus emergence in humans, and direct RT-PCR tests on nasal swabs collected in 2022. We also investigated the virus exposure and prevalence in three other cervid species. ELISA tests were positive for 2.20% of sera, pre- and post-pandemic, but seroneutralization and PCR tests were negative. Although one population showed increased seroprevalence post-2020, results suggest that SARS-CoV-2 has not emerged in those populations, and that ELISA cross-reaction with one or several unidentified circulating coronaviruses is possible.

immunology↗

bioRxiv2025

Effects of host sex, age and behaviour on co-infection patterns in a wild ungulate

Recent zoonotic disease emergences reveal the importance of studying wildlife parasite communities. As wild hosts frequently harbour diverse parasite species, understanding the drivers of multiple infection patterns in free-ranging hosts is critical for elucidating the ecological and epidemiological dynamics of parasite communities. In this study, we analysed co-infection patterns in European roe deer (Capreolus capreolus) inhabiting a fragmented rural landscape in southwestern France. Using data from 130 GPS-tracked roe deer, we examined the influence of proximity to livestock, host activity levels, age, sex, and between-parasite interactions on the presence of 11 parasitic taxa. Hierarchical modelling of species communities (HMSC) revealed that proximity to livestock significantly increased the likelihood of infection with orofecally transmitted parasites (Toxoplasma gondii, gastrointestinal parasites). Sex and age were other key predictors, with males and juveniles exhibiting a higher frequency of parasite presence, likely influenced by hormonal and immune system differences. Activity levels showed distinct age-related effects, with higher activity levels being positively associated with increased parasite prevalence in yearlings, but not in adults. In contrast, parasite association patterns within individual hosts were weak, suggesting minimal interactions between parasite species. Our findings highlight the interplay between exposure and susceptibility in shaping co-infection patterns and underscore the value of hierarchical modelling approaches in multi-parasite systems. Key FindingsO_LIParasite communities, studied in 130 GPS monitored roe deer, revealed frequent co-infection. C_LIO_LIProximity to livestock increased the risk of infection by parasite taxa shared with domestic animals. C_LIO_LIFor several parasitic taxa, males and younger roe deer had a higher probability of infection. C_LIO_LIThe effect of host activity on parasite infection was dependent on roe deer age. C_LIO_LIOnly slight between-parasite interactions were detected within individual hosts. C_LI

ecology↗

bioRxiv2023

Reproductive tactics, birth timing and the trade-off between risk avoidance and foraging in an income breeder

The behavioural trade-off between foraging and risk avoidance is expected to be particularly acute during gestation and lactation, when the energetic demands of reproduction peak. We investigated how female roe deer, an income breeding ungulate, adjust their management of this trade-off during the birth period in terms of foraging activity and habitat use. We showed that activity levels of reproductive females more than doubled immediately following parturition, when energy demand is highest. Moreover, reproductive females increased their use of open habitat during daytime and ranged closer to roads, but slightly further from refuge woodland, compared to non-reproductive females. However, these post-partum modifications in behaviour were particularly pronounced in late-parturient females who adopted a more risk prone tactic, presumably to compensate for the fitness handicap of their late-born offspring. In income breeders, individuals that give birth late may be forced to trade risk avoidance for resource acquisition during peak allocation to reproduction, likely with significant fitness consequences.

animal behavior and cognition↗

bioRxiv2018

Fluctuating pathogen-mediated selection drives the maintenance of innate immune gene polymorphism in a widespread wild ungulate

Toll-like Receptors (TLR) play a central role in recognition and host frontline defence against a wide range of pathogens. A number of recent studies have shown that TLR genes (Tlrs) often exhibit a large polymorphism in natural populations. Yet, there is little knowledge on how this polymorphism is maintained and how it influences disease susceptibility in the wild. In a previous work, we showed that some Tlrs exhibit similarly high levels of genetic diversity than Mhc and contemporary signatures of balancing selection in roe deer (Capreolus capreolus), an abundant and widespread ungulate in Europe. Here, we tested whether Mhc-Drb or Tlr (Tlr2, Tlr4 and Tlr5) diversity is driven by pathogen-mediated selection. We examined the relationships between their genotype (heterozygosity status and presence of specific alleles) and infections with Toxoplasma and Chlamydia, two intracellular pathogens known to cause reproductive failure in ungulates. We showed that Toxoplasma and Chlamydia exposures vary significantly across year and landscape structure with few co-infection events detected, and that the two pathogens act antagonistically on Tlr2 polymorphism. By contrast, we found no evidence of association with Mhc-Drb and a limited support for Tlr heterozygosity advantage. Our study confirmed the importance of looking beyond Mhc genes in wildlife immunogenetic studies. It also emphasized the necessity to consider multiple pathogen challenges and their spatiotemporal variation to improve our understanding of vertebrate defence evolution against pathogens.

evolutionary biology↗