Biology subjects

Leroy, E. M.

Publications and source records attributed to Leroy, E. M..

7 recordsLinked to original sources

bioRxiv2025

A global serosurvey of RNA virus-reactive antibodies in bats and rodents reveals the enzootic presence of flavi- and paramyxoviruses in African Pteropodidae

Bats and rodents have been identified as reservoir hosts of diverse RNA viruses that pose potential risks to humans. However, overall virus prevalence in wildlife and underlying factors determining the zoonotic potential of reservoir-borne viruses remain poorly characterized. Virus detection often relies on the identification of viral nucleotide sequences and may therefore be limited by variable virus concentration, tissue tropism, sample quality, and duration of infection. In this study, we applied a multiplex immunofluorescence assay to examine bat and rodent seroprevalence against 14 different human pathogenic RNA viruses spanning seven virus families (Coronaviridae, Flaviviridae, Hantaviridae, Paramyxoviridae, Phenuiviridae, Pneumoviridae, Togaviridae). We retrospectively analyzed 1,135 bat (16 species) and 454 rodent (15 species) blood or transudate specimens collected at 63 sites in seven countries. Tropical bats exhibited notably high rates of seropositivity against certain virus families (Flaviviridae: 42.8%; Paramyxoviridae: 60.4%; Togaviridae: 7.5%). Multivariable logistic regression models were created to evaluate the association of tropical bat characteristics with seropositivity. Preliminary findings indicate that large colony size, found among species such as Eidolon helvum and Rousettus aegyptiacus, is a risk factor for orthoflavi- and orthorubulavirus infection, consistent with the communal spread of bat-adapted viruses. Author SummaryMany animal populations carry viruses that have the potential to spill over to humans and cause severe disease. Despite surveillance efforts, it is logistically challenging to detect virus infections in wildlife, as viruses may have a short duration of infection or unknown routes of transmission. In this study, we examined blood and transudate samples from rodents and bats around the world for antibodies against 14 different viruses known to cause disease in humans. We analyzed the samples via a mosaic chip-based immunofluorescence test, which has the advantage of detecting antibodies against whole-virus antigen. This method allows for broad surveillance, as we would also expect to uncover evidence of past infection with bat- and rodent-adapted viruses that are related, but not identical, to known human pathogens. We detected antibodies against all seven virus families we examined, with especially high detection rates of antibodies in tropical bats. We used the results to construct multivariable logistic regression models of tropical bat seroprevalence to examine potential associations between tropical bat characteristics and previous infection by certain virus families. Bats with large colony sizes, such as Eidolon helvum and Rousettus aegyptiacus, were apparently at increased risk of infection with orthoflavi- and orthorubulaviruses compared to other tropical bat species.

microbiology↗

bioRxiv2024

Toxoplasma gondii from Gabonese forest, Central Africa: first report of an African wild population

The protozoan Toxoplasma gondii is a ubiquitous and highly prevalent parasite that can theoretically infect all warm-blooded vertebrates. In humans, toxoplasmosis causes infections in both immunodeficient and immunocompetent patients, congenital toxoplasmosis, and ocular lesions. These manifestations have different degrees of severity. Clinical severity is determined by multiple factors, including the genotype of the T. gondii strain involved in the infection. T. gondii exhibits remarkable genetic diversity, which varies according to geography and ecotype (domestic or wild). Previous studies have demonstrated that wild strains of T. gondii are of particular epidemiological interest, as they have been associated with more severe forms of toxoplasmosis in different regions of the world. However, no data on wild strains of T. gondii are available from Africa. In this study, we describe for the first time a wild T. gondii population from Africa. Wild animals from the forest environment of Gabon, Central Africa, were screened for chronic infection with T. gondii using quantitative PCR. The infecting T. gondii strains were genotyped whenever possible by the analysis of 15 microsatellite markers and by whole-genome sequencing. A new genotype was identified and was found to be highly divergent from previously described T. gondii populations worldwide, including those from the domestic environment in Gabon. Whole genome-based analyses indicated that this strain was genetically closer to a wild Pan-American population than to domestic African populations. This discovery marks the first description of a wild T. gondii population in Africa. The role of wild T. gondii strains in the incidence of severe toxoplasmosis in Africa remains unclear and requires further investigation. Author SummaryThe emergence of new pathogens from wildlife is today a well-recognized health threat. Studying these infectious agents has proven to be challenging due to the difficulty in accessing to samples from wild animals. In the present study, we took advantage of a recent survey on the viral carriage of wild animals from Gabon, Central Africa, to screen animal samples for the presence of the zoonotic protozoan Toxoplasma gondii, a ubiquitous and highly prevalent parasite that can theoretically infect all warm-blooded vertebrates, including humans. This parasite is the etiological agent of toxoplasmosis, a disease causing a substantial public health burden worldwide through different clinical manifestations and varying degrees of severity. A novel genotype was identified and found to be highly divergent from previously described T. gondii populations worldwide, including those from the domestic environment in Gabon. This discovery marks the first description of a wild T. gondii population in Africa. It has been shown that wild strains of T. gondii are of significant epidemiological relevance, as they have been associated with more severe forms of toxoplasmosis in different regions of the world. The implications of wild T. gondii strains in the incidence of severe toxoplasmosis in Africa remain unclear and merit further investigation.

microbiology↗

bioRxiv2023

Evidence for circulation of Rift Valley fever virus in wildlife and domestic animals in a forest environment in Gabon, Central Africa

Rift Valley fever (RVF) is a mosquito-borne viral zoonosis caused by the RVF virus (RVFV) that can infect domestic and wild animals. Although the RVFV transmission cycle has been well documented across Africa in savanna ecosystems, little is known about its transmission in tropical rainforest settings, particularly in Central Africa. We therefore conducted a survey in northeastern Gabon to assess RVFV circulation among wild and domestic animals. Among 163 wildlife samples tested using RVFV-specific RT-qPCR, four ruminants belonging to subfamily Cephalophinae were detected positive. The phylogenetic analysis revealed that the four RVFV sequences clustered together with a virus isolated in Namibia within the well-structured Egyptian clade. A cross-sectional survey conducted on sheep, goats and dogs living in villages within the same area determined the IgG RVFV-specific antibody prevalence using cELISA. Out of the 306 small ruminants tested (214 goats, 92 sheep), an overall antibody prevalence of 15.4% (95% CI [11.5-19.9]) was observed with a higher rate in goats than in sheep (20.1% versus 3.3%). RVFV-specific antibodies were detected in a single dog out 26 tested. Neither age, sex of domestic animals nor season was found to be significant risk factors of RVFV occurrence. Our findings highlight sylvatic circulation of RVFV for the first time in Gabon. These results stress the need to develop adequate surveillance plan measures to better control the public health threat of RVFV. Author summaryRift Valley fever (RVF) is a mosquito-borne viral zoonosis caused by the RVF virus (RVFV) that can affect wild and domestic animals. Although the RVFV transmission cycle has been well documented across Africa in savanna ecosystems, little is known about its transmission in tropical rainforests, especially in Central Africa. We thus conducted a survey in northeastern Gabon to assess RVFV circulation among wild and domestic animals. In this study, we demonstrated for the first time in Gabon the presence of the RVFV in two wildlife species (Peters duiker Cephalophus callipygus and the blue duiker Philantomba monticola). In addition, we detected RVFV-specific antibodies in small domestic ruminants (sheep and goats) with an overall antibody prevalence of 15.4%, with a much higher seroprevalence rate in goats than sheep (20.1% versus 3.3%). Furthermore, RVFV-specific antibodies were also observed in a single (hunting) dog out of the 26 tested. These results stress the need to develop adequate surveillance plan measures to better control the public health threat of RVFV.

microbiology↗

bioRxiv2022

A large-scale serological survey in pets from October 2020 through June 2021 in France shows significantly higher exposure to SARS-CoV-2 in cats

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can infect many animals, including pets such as dogs and cats. Many studies have documented infection in companion animals by bio-molecular and serological methods. However, only a few have compared seroprevalence in cats and dogs from the general population, and these studies were limited by small sample sizes and collections over short periods. Our goal was to obtain a more accurate evaluation of seroprevalence in companion animals in France and to determine whether cats and dogs differ in their exposure to SARS-CoV-2. For this purpose, we conducted an extensive SARS-CoV-2 cross-sectional serological survey of 2036 cats and 3577 dogs sampled by veterinarians during medical examinations in clinics throughout France. Sampling was carried out from October 2020 through June 2021, a period encompassing the second and third waves of SARS-CoV-2 infections in humans in the country. Using a microsphere immunoassay targeting the receptor binding domain and trimeric spike protein, we found 7.1% seroprevalence in pets. In a subset of 308 seropositive samples, 26.3% had neutralizing antibodies. We found that cats were significantly more likely to test positive than dogs, with seropositivity rates of 9.3% and 5.9% in cats and dogs, respectively. Finally, data for both species showed that seroprevalence was lower in older animals and was not associated with the date of sampling or the sex of the animal. Our results show that cats are significantly more sensitive to SARS-CoV-2 than dogs, in line with experimental studies. Our large sample size provides for a reliable, statistically robust estimate of the frequency of infection of pets from their owners and offers strong support for the notion that cats are more sensitive to SARS-CoV-2 than dogs. Our findings emphasise the importance of a One-Health approach to the SARS-CoV-2 pandemic and raise the question of whether companion animals in close contact with humans should be vaccinated.

microbiology↗

bioRxiv2021

New detection of SARS-CoV-2 in two cats height months after COVID-19 outbreak appearance in France

Although there are several reports in the literature of SARS-CoV-2 infection in cats, few SARS-CoV-2 sequences from infected cats have been published. In this report, SARS-CoV-2 infection was evaluated in two cats by clinical observation, molecular biology (qPCR and NGS), and serology (Microsphere immunoassay and seroneutralization). Following the observation of symptomatic SARS-CoV-2-infection in two cats, infection status was confirmed by RT-qPCR and, in one cat, serological analysis for antibodies against N-protein and S-protein, as well as neutralizing antibodies. Comparative analysis of five SARS-CoV-2 sequence-fragments obtained from one of the cats showed that this infection was not with one of the three recently emerged variants of SARS-CoV-2. This study provides additional information on the clinical, molecular, and serological aspects of SARS-CoV-2 infection in cats.

microbiology↗

bioRxiv2021

Myocarditis in naturally infected pets with the British variant of COVID-19

Domestic pets can contract SARS-CoV-2 infection but, based on the limited information available to date, it is unknown whether the new British B.1.1.7 variant can more easily infect certain animal species or increase the possibility of human-to-animal transmission. In this study, we report the first cases of infection of domestic cats and dogs by the British B.1.1.7 variant of SARS-CoV-2 diagnosed at a specialist veterinary hospital in the South-East of England. Furthermore, we discovered that many owners and handlers of these pets had developed Covid-19 respiratory symptoms 3-6 weeks before their pets became ill and had also tested PCR positive for Covid-19. Interestingly, all these B.1.1.7 infected pets developed atypical clinical manifestations, including severe cardiac abnormalities secondary to myocarditis and a profound impairment of the general health status of the patient but without any primary respiratory signs. Together, our findings demonstrate for the first time the ability for companion animals to be infected by the B.1.1.7 variant of SARS-CoV-2 and raise questions regarding its pathogenicity in these animals. Moreover, given the enhanced infectivity and transmissibility of B.1.1.7 variant for humans, these findings also highlights more than ever the risk that companion animals may potentially play a significant role in SARS-CoV-2 outbreak dynamics than previously appreciated.

microbiology↗

bioRxiv2020

High prevalence of SARS-CoV-2 antibodies in pets from COVID-19+ households

In a survey of household cats and dogs of laboratory-confirmed COVID-19 patients, we found a high seroprevalence of SARS-CoV-2 antibodies, ranging from 21% to 53%, depending on the positivity criteria chosen. Seropositivity was significantly greater among pets from COVID-19+ households compared to those with owners of unknown status. Our results highlight the potential role of pets in the spread of the epidemic.

microbiology↗