Biology subjects

Dervas, E.

Publications and source records attributed to Dervas, E..

3 recordsLinked to original sources

bioRxiv2026

Histopathological and virus-associated features of Boid Inclusion Body Disease in Boa constrictor

Boid inclusion body disease (BIBD) is a reptarenavirus-induced fatal disease of boid snakes that, while diagnosed with ease due to the pathognomonic intracytoplasmic inclusion bodies (IB), is not yet fully characterized pathomorphologically and with regards to its pathogenesis. The present study retrospectively investigated a random cohort of 50 captive male and female boa constrictors of variable age (neonate to 25 years) for histopathological changes and in situ viral protein (nucleoprotein, NP, and glycoprotein 2, GP2) expression patterns. IB formation and NP expression were scored semiquantitatively. The vast majority of snakes (42/50; 84%) exhibited histopathological changes; these mainly (39/42; 93%) represented inflammatory processes that most frequently affected the gastrointestinal tract. Overall, IB and NP scores were significantly higher in the more recent cases (2020-2025) compared to the older cases (2000-2003). NP scores did not differ between age groups or sex, but were lower in animals with clinical signs and higher in those with histopathological changes. No statistically significant association was found between NP scores and inflammatory processes, neither in general nor in individual organs. GP2 expression, as an indicator of virion assembly, was less consistent than NP expression and generally restricted to individual cells with and without IBs. There was no histological evidence of overt damage in infected cells. Jointly, the results indicate different phases of restrictive and systemic viral replication that are not directly associated with pathological processes and/or clinical signs.

pathology↗

bioRxiv2024

Haemolymphatic tissues of captive boa constrictor (Boa constrictor): morphological features in healthy individuals and with Boid Inclusion Body Disease

Knowledge on the structure and composition of the haematopoietic tissue (HT) is essential to understand the basic immune functions of the immune system in any species. For reptiles, it is extremely limited, hence we undertook an in-depth in situ investigation of the HT (bone marrow, thymus, spleen, lymphatic tissue of the alimentary tract) in the common boa (Boa constrictor). We also assessed age- and disease-related changes, with a special focus on Boid Inclusion Body Disease, a highly relevant reptarenavirus-associated disease in boid snakes. The HT was subjected to gross, histological and ultrastructural examination, including special stains, immunohistochemistry, in situ hybridization and morphometric analyses. In general, the HT was dominated by T cells and lacked a clear structural organization, such as follicle formation. BIBD was associated with significantly higher cellularity and a granulomatous response in the spleen, and the presence of virus-infected haematopoietic cells in the bone marrow, suggesting the latter as a persistent source of viremia. HighlightsO_LILymphatic tissues of B. constrictor lack organization and are dominated by T cells C_LIO_LIThe thymus of B. constrictor shows slow age-related involution C_LIO_LIBIBD-positive boas show a granulomatous response in the spleen C_LIO_LIReptarenaviruses infect haematopoietic cells in the bone marrow C_LIO_LIReptarenavirus infected bone marrow cells might represent a source of viremia C_LI

pathology↗

bioRxiv2020

Python nidoviruses, more than respiratory pathogens

In recent years nidoviruses have emerged as an important respiratory pathogen of reptiles, affecting especially captive python populations. In pythons, nidovirus infection induces an inflammation of the upper respiratory and alimentary tract which can develop into a severe and often fatal proliferative pneumonia. We observed pyogranulomatous and fibrinonecrotic lesions in organ systems other than the respiratory tract during full post mortem examinations on 30 nidovirus RT-PCR positive pythons of varying species originating from Switzerland and Spain. The observations prompted us to study whether the atypical tissue tropism associates with previously unknown nidoviruses or changes in the nidovirus genome. RT-PCR and inoculation of Morelia viridis cell cultures served to recruit the cases and to obtain virus isolates. Immunohistochemistry and immunofluorescence staining against nidovirus nucleoprotein demonstrated that the virus not only infects a broad spectrum of epithelial (respiratory and alimentary epithelium, hepatocytes, renal tubules, pancreatic ducts etc.), but also intravascular monocytes, intralesional macrophages and endothelial cells. By next-generation sequencing we obtained full length genome for a novel nidovirus species circulating in Switzerland. Analysis of viral genomes recovered from pythons showing nidovirus infection-associated respiratory or systemic disease did not explain the observed phenotypes. The results indicate that python nidoviruses have a broad cell and tissue tropism, further suggesting that the course of infection could vary and involve lesions in a broad spectrum of tissues and organ systems as a consequence of monocyte-mediated systemic spread of the virus. IMPORTANCEDuring the last years, python nidoviruses have become a primary cause of fatal disease in pythons. Nidoviruses represent a threat to captive snake collections, as they spread rapidly and can be associated with high morbidity and mortality. Our study indicates that, different from previously evidence, the viruses do not only affect the respiratory tract, but can spread in the entire body with blood monocytes, have a broad spectrum of target cells, and can induce a variety of lesions. Nidovirales is an order of animal and human viruses that compromise important zoonotic pathogens such as MERS-CoV and SARS-CoV, as well as the recently emerged SARS-CoV-2. Python nidoviruses belong to the same subfamily as the mentioned human viruses and show similar characteristics (rapid spread, respiratory and gastrointestinal tropism, etc.). The present study confirms the relevance of natural animal diseases to better understand the complexity of viruses of the order nidovirales.

pathology↗