Inclusion Body Disease Research Articles

Clinical and genetic analysis of a patient with Neuronal intranuclear inclusion body disease characterized by cortical enhancement in the posterior brain region

To explore the clinical, imaging, and genetic characteristics of an adult patient with sporadic Neuronal intranuclear inclusion disease (NIID). A patient who had visited the First People's Hospital of Chenzhou on August 6, 2023 was selected as the study subject. Results of clinical examination, neuroimaging, and genetic testing were retrospectively analyzed along with a literature review. The number of GGC trinucleotide repeats in the 5'-untranslated region of the NOTCH2NLC gene was determined by GC-PCR. The patient had presented with episodic encephalopathy, with enhanced magnetic resonance imaging showing enhancement features of the posterior cerebral cortex during the period of acute episode. Genetic testing revealed an increased number of GGC repeats (n = 97) in the 5'- untranslated region of the NOTCH2NLC gene, which confirmed the diagnosis of NIID. Clinical attention should be paid to the enhanced MRI findings of patients with adult-onset NIID, for whom posterior cortical enhancement may be characteristic manifestation during the acute phase of encephalopathy-like episode.

A Multiplex RT-PCR Method for the Detection of Reptarenavirus Infection.

Reptarenaviruses cause Boid Inclusion Body Disease (BIBD), a fatal disease of boid snakes with an economic and ecological impact, as it affects both captive and wild constrictor snakes. The clinical picture of BIBD is highly variable but often only limited. Intracytoplasmic inclusion bodies (IB), which develop in most cell types including blood cells, are the pathognomonic hallmark of BIBD; their detection represents the diagnostic gold standard of the disease. However, IBs are not consistently present in clinically healthy reptarenavirus carriers, which can, if undetected, lead to and maintain the spread of the disease within and between snake populations. Sensitive viral detection tools are required for screening and control purposes; however, the genetic diversity of reptarenaviruses hampers the reverse transcription (RT) PCR-based diagnostics. Here, we describe a multiplex RT-PCR approach for the molecular diagnosis of reptarenavirus infection in blood samples. The method allows the detection of a wide range of reptarenaviruses with the detection limit reaching 40 copies per microliter of blood. Using 245 blood samples with a reference RT-PCR result, we show that the technique performs as well as the segment-specific RT-PCRs in our earlier studies. It can identify virus carriers and serve to limit reptarenavirus spreading in captive snake collections.

Molecular characterization of a reptarenavirus detected in a Colombian Red-Tailed Boa (Boa constrictor imperator)

The global decline in biodiversity is a matter of great concern for members of the class Reptilia. Reptarenaviruses infect snakes, and have been linked to various clinical conditions, such as Boid Inclusion Body Disease (BIBD) in snakes belonging to the families Boidae and Pythonidae. However, there is a scarcity of information regarding reptarenaviruses found in snakes in both the United States and globally. This study aimed to contribute to the understanding of reptarenavirus diversity by molecularly characterizing a reptarenavirus detected in a Colombian Red-Tailed Boa (Boa constrictor imperator). Using a metagenomics approach, we successfully identified, and de novo assembled the whole genomic sequences of a reptarenavirus in a Colombian Red-Tailed Boa manifesting clinically relevant symptoms consistent with BIBD. The analysis showed that the Colombian Red-Tailed Boa in this study carried the University of Giessen virus (UGV-1) S or S6 (UGV/S6) segment and L genotype 7. The prevalence of the UGV/S6 genotype, in line with prior research findings, implies that this genotype may possess specific advantageous characteristics or adaptations that give it a competitive edge over other genotypes in the host population. This research underscores the importance of monitoring and characterizing viral pathogens in captive and wild snake populations. Knowledge of such viruses is crucial for the development of effective diagnostic methods, potential intervention strategies, and the conservation of vulnerable reptilian species. Additionally, our study provides valuable insights for future studies focusing on the evolutionary history, molecular epidemiology, and biological properties of reptarenaviruses in boas and other snake species.

Background and roles: myosin in autoimmune diseases.

The myosin superfamily is a group of molecular motors. Autoimmune diseases are characterized by dysregulation or deficiency of the immune tolerance mechanism, resulting in an immune response to the human body itself. The link between myosin and autoimmune diseases is much more complex than scientists had hoped. Myosin itself immunization can induce experimental autoimmune diseases of animals, and myosins were abnormally expressed in a number of autoimmune diseases. Additionally, myosin takes part in the pathological process of multiple sclerosis, Alzheimer's disease, Parkinson's disease, autoimmune myocarditis, myositis, hemopathy, inclusion body diseases, etc. However, research on myosin and its involvement in the occurrence and development of diseases is still in its infancy, and the underlying pathological mechanisms are not well understood. We can reasonably predict that myosin might play a role in new treatments of autoimmune diseases.

Reptarenavirus S Segment RNA Levels Correlate with the Presence of Inclusion Bodies and the Number of L Segments in Snakes with Reptarenavirus Infection-Lessons Learned from a Large Breeding Colony.

Reptarenaviruses cause boid inclusion body disease (BIBD), a fatal disease particularly impacting captive boa constrictor collections. The development of cytoplasmic inclusion bodies (IBs) comprising reptarenavirus nucleoprotein (NP) in many cell types of affected snakes is characteristic of BIBD. However, snakes can harbor reptarenaviruses without showing IBs, hence representing carriers and a potential source of transmission. The RNA genome of reptarenaviruses comprises a small (S) and a large (L) segment, and the snakes with BIBD commonly carry a swarm of reptarenavirus segments. To design sensitive and reliable tools for the diagnosis of reptarenavirus infection in snake colonies, we used metatranscriptomics to determine the reptarenavirus segments present in a large boa constrictor breeding colony. The analysis identified one reptarenavirus S segment and three L segments in the colony. The sequence data served to design real-time reverse transcription-PCR (RT-PCR) targeting the found S segment. This allowed us to identify all infected animals and to quantify the S segment RNA levels, which we found to correlate with the presence of IBs. We further found a positive correlation between the number of L segments and the S segment RNA level, which could suggest that L segment excess also contributes to the IB formation. Information on cohousing of the snakes showed a clear association of reptarenavirus infection with cohousing in general and cohousing with infected animals. Information on breeding and offspring confirmed that vertical transmission occurred. Furthermore, our data suggest that some animals might be able to clear the infection or at least exhibit transient or intermittent viremia. IMPORTANCE Boid inclusion body disease (BIBD) is caused by reptarenavirus infection, and while reptarenavirus nucleoprotein is the main component of the inclusion bodies (IBs) characteristic of BIBD, not all reptarenavirus-infected snakes demonstrate IBs in their cells. Identification of infected individuals is critical for controlling the spread of the disease; however, the genetic divergence of reptarenaviruses complicates reverse transcription-PCR (RT-PCR)-based diagnostics. Here, we tested a next-generation-sequencing-based approach to establish a tailored "colony-specific" set of diagnostic tools for the detection of reptarenavirus small (S) and large (L) genome segments. With this approach, we could demonstrate that an S-segment-specific RT-PCR is highly effective in identifying the infected individuals. We further found the S segment RNA level to positively correlate with the presence of IBs and the number of L segments, which could direct future studies to identify the BIBD pathogenetic mechanisms.

Clinical Features and Classification of Neuronal Intranuclear Inclusion Disease.

Neuronal intranuclear inclusion body disease (NIID) is a neurodegenerative disease with highly heterogeneous clinical manifestations. The present study aimed to characterize clinical features and propose a classification system based on a large cohort of NIID in China. The Chinese NIID registry was launched from 2017, and participants' demographics and clinical features were recorded. Brain MRI, skin pathologies, and the number of GGC repeat expansions in the 5' untranslated region of the NOTCH2NLC gene were evaluated in all patients. In total, 223 patients (64.6% female) were recruited; the mean (SD) onset age was 56.7 (10.3) years. The most common manifestations were cognitive impairment (78.5%) and autonomic dysfunction (70.9%), followed by episodic symptoms (51.1%), movement disorders (50.7%), and muscle weakness (25.6%). Imaging markers included hyperintensity signals along the corticomedullary junction on diffusion-weighted imaging (96.6%), white matter lesions (98.1%), paravermis (55.0%), and focal cortical lesions (10.1%). The median size of the expanded GGC repeats in these patients was 115 (range, 70-525), with 2 patients carrying >300 GGC repeats. A larger number of GGC repeats was associated with younger age at onset (r = -0.329, p < 0.0001). According to the proposed clinical classification based on the most prominent manifestations, the patients were designated into 5 distinct types: cognitive impairment-dominant type (34.1%, n = 76), episodic neurogenic event-dominant type (32.3%, n = 72), movement disorder-dominant type (17.5%, n = 39), autonomic dysfunction-dominant type (8.5%, n = 19), and neuromuscular disease-dominant type (7.6%, n = 17). Notably, 32.3% of the episodic neurogenic event-dominant type of NIID has characteristic focal cortical lesions on brain MRI presenting localized cortical edema or atrophy. The mean onset age of the neuromuscular disease-dominant type was 47.2 (17.6) years, younger than the other types (p < 0.001). There was no significant difference in the sizes of GGC repeats among the patients in the 5 types (p = 0.547, Kruskal-Wallis test). This observational study of NIID establishes an overall picture of the disease regarding clinical, imaging, and genetic characteristics. The proposed clinical classification of NIID based on the most prominent manifestation divides patients into 5 types.

Afoxolaner (NexGard®) in pet snakes for the treatment and control of Ophionyssus natricis (Mesostigmata: Macronyssidae)

BackgroundOphionyssus natricis is the main species of mite that infests captive reptiles. High infestations may result in the host experiencing general discomfort and deleterious effects, even death. Moreover, O. natricis is an important vector of reptile vector-borne diseases and is considered to be the putative vector of the Reptarenavirus, the causal agent of the inclusion body disease. Despite the cosmopolitan distribution of O. natricis in captive reptiles, treatment options are limited. The aim of the present study was to assess the efficacy of afoxolaner (NexGard®; Boehringer Ingelheim, Ingelheim, Germany) in heavily infested, privately owned snakes, evaluate the prevalence of mites and drug availability in the plasma of treated snakes (pharmacokinetics) and perform a clinical examination of animals.MethodsThe study was conducted in two snake breeding facilities, where many snakes were infested with mites. Each animal was clinically examined and weighed, and mite infestations were assessed on the animals and in their enclosures (environment). Animals were treated with a dose of 2.5 mg afoxolaner per kilogram body weight (2.5 mg/kg) administered orally. All animals were examined pre-treatment (T0) and at various time points post-treatment (T1, 6 h; T2, 24 h; T3, 14 days; T4, 28 days). The collected mites were morphologically identified at the species level and the species identity also confirmed molecularly.ResultsOverall, 81 snakes from the two participating facilities (i.e. 70 from site 1 and 11 from site 2) were screened, and 31 (38.3%) snakes were found to have at least one mite. All mites were identified morphologically and molecularly as O. natricis. Lampropeltis was the genus of snakes with highest number of infested individuals. Mites were found to be alive on snakes at T1, but at T2 only dead mites were observed, and at T3 and T4 mites were no longer present on the animals or in their environment. No side effects were observed in the treated snakes.ConclusionsA single oral administration of afoxolaner at 2.5 mg/kg was a safe treatment for snakes and 100% effective for the eradication of natural O. natricis infestation without the need to treat the environment of the snake.Graphical

Inclusion Body Disease and Columbid Alphaherpesvirus 1 Infection in a Eurasian Eagle-Owl (Bubo bubo) of Central Italy.

Hepatosplenitis or inclusion body disease is a fatal disease in owls caused by Columbid alphaherpesvirus 1 (CoHV-1). A few old case reports describe it worldwide. In Italy, knowledge regarding virus circulation and disease development is lacking. Four Eurasian eagle-owls (Bubo bubo), two adults and two juveniles, were submitted for postmortem examination showing aspecific clinical signs a few hours before death. Grossly disseminated petechial hemorrhages on serosal surfaces (n = 4), hepatic and splenic necrosis (n = 3), bilateral and symmetric necrosis of pharyngeal tonsils (n = 2), and diffuse and bilateral dark-red discoloration and firmness in lungs (n = 2) were seen. Tissues were sampled for histology, bacteriology, molecular testing, and transmission electron microscopy (TEM). On histology, disseminated petechial hemorrhages (n = 4) and necrosis of liver (n = 3) and spleen (n = 3) were seen, as well as lympho-histiocytic interstitial pneumonia and meningoencephalitis (n = 2). Intranuclear inclusion bodies (INIBs) were detected in one case. A panherpesviral PCR led to positive results in one case, identified in sequencing as CoHV-1. On TEM, intranuclear and intracytoplasmic virions with herpesviral morphology were seen in the same case. For the other three birds, the lack of PCR positivity, INIBs, and TEM detection could be linked to a possible reduction of the virus to undetectable levels. Death possibly occurred secondarily to bacterial infections, supposedly established during the acute phase of CoHV-1 infection. This paper reports the presence of CoHV-1in Italy and the development of a fatal form of the disease in a Eurasian eagle-owl.

Boid Inclusion Body Disease Is Also a Disease of Wild Boa Constrictors.

ABSTRACTReptarenaviruses cause boid inclusion body disease (BIBD), a potentially fatal disease, occurring in captive constrictor snakes boas and pythons worldwide. Classical BIBD, characterized by the formation of pathognomonic cytoplasmic inclusion bodies (IBs), occurs mainly in boas, whereas in pythons, for example, reptarenavirus infection most often manifests as central nervous system signs with limited IB formation. The natural hosts of reptarenaviruses are unknown, although free-ranging/wild constrictor snakes are among the suspects. Here, we report BIBD with reptarenavirus infection in indigenous captive and wild boid snakes in Costa Rica using histology, immunohistology, transmission electron microscopy, and next-generation sequencing (NGS). The snakes studied represented diagnostic postmortem cases of captive and wild-caught snakes since 1989. The results from NGS on archival paraffin blocks confirm that reptarenaviruses were already present in wild boa constrictors in Costa Rica in the 1980s. Continuous sequences that were de novo assembled from the low-quality RNA obtained from paraffin-embedded tissue allowed the identification of a distinct pair of reptarenavirus S and L segments in all studied animals; in most cases, reference assembly could recover almost complete segments. Sampling of three prospective cases in 2018 allowed an examination of fresh blood or tissues and resulted in the identification of additional reptarenavirus segments and hartmanivirus coinfection. Our results show that BIBD is not only a disease of captive snakes but also occurs in indigenous wild constrictor snakes in Costa Rica, suggesting boa constrictors to play a role in natural reptarenavirus circulation.IMPORTANCE The literature describes cases of boid inclusion body disease (BIBD) in captive snakes since the 1970s, and in the 2010s, others and ourselves identified reptarenaviruses as the causative agent. BIBD affects captive snakes globally, but the origin and the natural host of reptarenaviruses remain unknown. In this report, we show BIBD and reptarenavirus infections in two native Costa Rican constrictor snake species, and by studying archival samples, we show that both the viruses and the disease have been present in free-ranging/wild snakes in Costa Rica at least since the 1980s. The diagnosis of BIBD in wild boa constrictors suggests that this species plays a role in the circulation of reptarenaviruses. Additional sample collection and analysis would help to clarify this role further and the possibility of, e.g., vector transmission from an arthropod host.

Persistent Reptarenavirus and Hartmanivirus Infection in Cultured Boid Cells.

ABSTRACTMammarenaviruses establish a persistent infection in their rodent and bat hosts, and the evidence suggests that reptarenaviruses and hartmaniviruses found in captive snakes act similarly. In snakes, reptarenaviruses cause boid inclusion body disease (BIBD), which is often associated with secondary infections. Snakes with BIBD usually carry more than a single pair of reptarenavirus S and L segments and occasionally demonstrate hartmanivirus coinfection. Here, we reported the generation of cell lines persistently infected with a single or two reptarenavirus(es) and a cell line with persistent reptarenavirus-hartmanivirus coinfection. By RT-PCR we demonstrated that the amount of viral RNA within the persistently infected cells remains at levels similar to those observed following initial infection. Using antibodies against the glycoproteins (GPs) and nucleoprotein (NP) of reptarenaviruses, we studied the levels of viral protein in cells passaged 10 times after the original inoculation and observed that the expression of GPs declines dramatically during persistent infection, unlike the expression of NP. Immunofluorescence (IF) staining served to demonstrate differences in the distribution of NP within the persistently infected compared to freshly infected cells. IF staining of cells inoculated with the viruses secreted from the persistently infected cell lines produced similar NP staining compared to cells infected with a traditionally passaged virus, suggesting that the altered NP expression pattern of persistently infected cells does not relate to changes in the virus. The cell cultures described herein can serve as tools for studying the coinfection and superinfection interplay between reptarenaviruses and studying the BIBD pathogenesis mechanisms.IMPORTANCE Mammarenaviruses cause a persistent infection in their natural rodent and bat hosts. Reptarenaviruses cause boid inclusion body disease (BIBD) in constrictor snakes, but it is unclear whether snakes are the natural host of these viruses. In this study, we showed that reptarenaviruses established a persistent infection in cultured Boa constrictor cells and that the persistently infected cells continued to produce infectious virus. Our results showed that persistent infection results from subsequent passaging of cells inoculated with a single reptarenavirus, two reptarenaviruses, or even when inoculating the cells with reptarenavirus and hartmanivirus (another arenavirus genus). The results further suggested that coinfection would not result in overt competition between the different reptarenaviruses, thus helping to explain the frequent reptarenavirus coinfections in snakes with BIBD. The established cell culture models of persistent infection could help to elucidate the role of coinfection and superinfection and potential immunosuppression as the pathogenic mechanisms behind BIBD.

Genetic characterisation of a novel reptarenavirus detected in a dead pet red-tailed boa (Boa constrictor).

Boid inclusion body disease (BIBD) is a severe and transmissible disease of snakes worldwide. Reptarenaviruses have been identified as the aetiological agents of BIBD. We determined the almost complete genome sequence of an arenavirus detected in a female red-tailed boa that had succumbed in a private collection in Hungary. We used a combination of next generation sequencing and Sanger sequencing methods. Based on the analysis of the obtained sequence data, the virus, tentatively named Coldvalley virus, seemed to belong to the Reptarenavirus genus of the Arenaviridae family. This classification was confirmed by the genome structure (bisegmented single-stranded RNA) characteristic of the genera Mammarenavirus and Reptarenavirus. The pairwise comparison of the nucleotide and amino acid sequences, as well as the topology of the maximum likelihood phylogenetic trees, suggested that the newly-characterised Coldvalley virus can be classified into the species Rotterdam reptarenavirus.

Boid Inclusion Body Disease (BIBD) is Associated with Altered Haematological Parameters and Immune Functions in Captive Boa Constrictor

Boid Inclusion Body Disease (BIBD) is Associated with Altered Haematological Parameters and Immune Functions in Captive Boa Constrictor

Arenavirus Nucleoprotein Targeting Host Mitochondria: A Novel Aspect of Boid Inclusion Body Disease Pathogenesis?

Arenavirus Nucleoprotein Targeting Host Mitochondria: A Novel Aspect of Boid Inclusion Body Disease Pathogenesis?

Boid Inclusion Body Disease and Reptarenavirus Infection: A Diagnostic Challenge in Snake Colonies

Boid Inclusion Body Disease and Reptarenavirus Infection: A Diagnostic Challenge in Snake Colonies

A subpopulation of arenavirus nucleoprotein localizes to mitochondria

Viruses need cells for their replication and, therefore, ways to hijack cellular functions. Mitochondria play fundamental roles within the cell in metabolism, immunity and regulation of homeostasis due to which some viruses aim to alter mitochondrial functions. Herein we show that the nucleoprotein (NP) of arenaviruses enters the mitochondria of infected cells, affecting the mitochondrial morphology. Reptarenaviruses cause boid inclusion body disease (BIBD) that is characterized, especially in boas, by the formation of cytoplasmic inclusion bodies (IBs) comprising reptarenavirus NP within the infected cells. We initiated this study after observing electron-dense material reminiscent of IBs within the mitochondria of reptarenavirus infected boid cell cultures in an ultrastructural study. We employed immuno-electron microscopy to confirm that the mitochondrial inclusions indeed contain reptarenavirus NP. Mutations to a putative N-terminal mitochondrial targeting signal (MTS), identified via software predictions in both mamm- and reptarenavirus NPs, did not affect the mitochondrial localization of NP, suggesting that it occurs independently of MTS. In support of MTS-independent translocation, we did not detect cleavage of the putative MTSs of arenavirus NPs in reptilian or mammalian cells. Furthermore, in vitro translated NPs could not enter isolated mitochondria, suggesting that the translocation requires cellular factors or conditions. Our findings suggest that MTS-independent mitochondrial translocation of NP is a shared feature among arenaviruses. We speculate that by targeting the mitochondria arenaviruses aim to alter mitochondrial metabolism and homeostasis or affect the cellular defense.

Experimental Reptarenavirus Infection of Boa constrictor and Python regius.

Boid inclusion body disease (BIBD) causes losses in captive snake populations globally. BIBD is associated with the formation of cytoplasmic inclusion bodies (IBs), which mainly comprise reptarenavirus nucleoprotein (NP). In 2017, BIBD was reproduced by cardiac injection of boas and pythons with reptarenaviruses, thus demonstrating a causative link between reptarenavirus infection and the disease. Here, we report experimental infections of Python regius (n = 16) and Boa constrictor (n = 16) with three reptarenavirus isolates. First, we used pythons (n = 8) to test two virus delivery routes: intraperitoneal injection and tracheal instillation. Viral RNAs but no IBs were detected in brains and lungs at 2 weeks postinoculation. Next, we inoculated pythons (n = 8) via the trachea. During the 4 months following infection, snakes showed transient central nervous system (CNS) signs but lacked detectable IBs at the time of euthanasia. One of the snakes developed severe CNS signs; we succeeded in reisolating the virus from the brain of this individual and could demonstrate viral antigen in neurons. In a third attempt, we tested cohousing, vaccination, and sequential infection with multiple reptarenavirus isolates on boas (n = 16). At 10 months postinoculation, all but one snake tested positive for viral RNA in lung, brain, and/or blood, but none exhibited the characteristic IBs. Three of the four vaccinated snakes seemed to sustain challenge with the same reptarenavirus; however, neither of the two snakes rechallenged with different reptarenaviruses remained uninfected. Comparison of the antibody responses in experimentally versus naturally reptarenavirus-infected animals indicated differences in the responses.IMPORTANCE In the present study, we experimentally infected pythons and boas with reptarenavirus via either intraperitoneal injection or tracheal instillation. The aims were to experimentally induce boid inclusion body disease (BIBD) and to develop an animal model for studying disease transmission and pathogenesis. Both virus delivery routes resulted in infection, and infection via the trachea could reflect the natural route of infection. In the experimentally infected snakes, we did not find evidence of inclusion body (IB) formation, characteristic of BIBD, in pythons or boas. Most of the boas (11/12) remained reptarenavirus infected after 10 months, which suggests that they developed a persistent infection that could eventually have led to BIBD. We demonstrated that vaccination using recombinant protein or an inactivated virus preparation prevented infection by a homologous virus in three of four snakes. Comparison of the antibody responses of experimentally and naturally reptarenavirus-infected snakes revealed differences that merit further studies.

PROTEIN ELECTROPHORESIS OF PLASMA SAMPLES FROM BOA CONSTRICTORS WITH AND WITHOUT REPTARENAVIRUS INFECTION.

Reptarenaviruses infect a variety of boid and pythonid snake species worldwide and have been shown to be the cause of inclusion body disease (IBD). Little is known about the correlations between virus infection and clinical disease, as well as the effects of viral infection on the immune system and the blood protein fractions. The goal of this study was to examine the differences in the plasma protein fractions in reptarenavirus reverse transcription polymerase chain reaction (RT-PCR)-negative and -positive tested snakes with and without clinical signs of disease. Blood from a total of 111 boa constrictors (Boa constrictor) was evaluated. Reverse transcription PCRs and H&E staining for inclusion bodies were carried out on each sample for the detection of reptarenavirus, and the plasma protein fractions were evaluated by capillary zone electrophoresis (CZE). Thirty four of the 111 evaluated snakes were positive by RT-PCR and 19 of the 34 showed clinical signs of disease. In comparison with IBD-negative healthy boa constrictors, the positive snakes with clinical signs had significantly lower albumin levels (P = 0.0052), lower A: G ratios (P = 0.0037), and lower α-globulin levels (P = 0.0073), while their γ-globulin levels were significantly higher (P = 0.0004). In the same comparison, clinically healthy arenavirus-positive boas showed only significantly lower α-globulin (P = 0.0124) and higher γ-globulin levels (P = 0.0394). The results of the present study indicate that reptarenavirus infection may influence plasma protein fractions in boa constrictors.

Identification of Reptarenaviruses, Hartmaniviruses, and a Novel Chuvirus in Captive Native Brazilian Boa Constrictors with Boid Inclusion Body Disease.

Boid inclusion body disease (BIBD) is a transmissible viral disease of captive snakes that causes severe losses in snake collections worldwide. It is caused by reptarenavirus infection, which can persist over several years without overt signs but is generally associated with the eventual death of the affected snakes. Thus far, reports have confirmed the existence of reptarenaviruses in captive snakes in North America, Europe, Asia, and Australia, but there is no evidence that it also occurs in wild snakes. BIBD affects boa species within the subfamily Boinae and pythons in the family Pythonidae, the habitats of which do not naturally overlap. Here, we studied Brazilian captive snakes with BIBD using a metatranscriptomic approach, and we report the identification of novel reptarenaviruses, hartmaniviruses, and a new species in the family Chuviridae The reptarenavirus L segments identified are divergent enough to represent six novel species, while we found only a single novel reptarenavirus S segment. Until now, hartmaniviruses had been identified only in European captive boas with BIBD, and the present results increase the number of known hartmaniviruses from four to six. The newly identified chuvirus showed 38.4%, 40.9%, and 48.1% amino acid identity to the nucleoprotein, glycoprotein, and RNA-dependent RNA polymerase, respectively, of its closest relative, Guangdong red-banded snake chuvirus-like virus. Although we cannot rule out the possibility that the found viruses originated from imported snakes, the results suggest that the viruses could circulate in indigenous snake populations.IMPORTANCE Boid inclusion body disease (BIBD), caused by reptarenavirus infection, affects captive snake populations worldwide, but the reservoir hosts of reptarenaviruses remain unknown. Here, we report the identification of novel reptarenaviruses, hartmaniviruses, and a chuvirus in captive Brazilian boas with BIBD. Three of the four snakes studied showed coinfection with all three viruses, and one of the snakes harbored three novel reptarenavirus L segments and one novel S segment. The samples originated from collections with Brazilian indigenous snakes only, which could indicate that these viruses circulate in wild snakes. The findings could further indicate that boid snakes are the natural reservoir of reptarena- and hartmaniviruses commonly found in captive snakes. The snakes infected with the novel chuvirus all suffered from BIBD; it is therefore not possible to comment on its potential pathogenicity and contribution to the observed changes in the present case material.

Differences in Tissue and Species Tropism of Reptarenavirus Species Studied by Vesicular Stomatitis Virus Pseudotypes.

Reptarenaviruses cause Boid Inclusion Body Disease (BIBD), and co-infections by several reptarenaviruses are common in affected snakes. Reptarenaviruses have only been found in captive snakes, and their reservoir hosts remain unknown. In affected animals, reptarenaviruses appear to replicate in most cell types, but their complete host range, as well as tissue and cell tropism are unknown. As with other enveloped viruses, the glycoproteins (GPs) present on the virion’s surface mediate reptarenavirus cell entry, and therefore, the GPs play a critical role in the virus cell and tissue tropism. Herein, we employed single cycle replication, GP deficient, recombinant vesicular stomatitis virus (VSV) expressing the enhanced green fluorescent protein (scrVSV∆G-eGFP) pseudotyped with different reptarenavirus GPs to study the virus cell tropism. We found that scrVSV∆G-eGFPs pseudotyped with reptarenavirus GPs readily entered mammalian cell lines, and some mammalian cell lines exhibited higher, compared to snake cell lines, susceptibility to reptarenavirus GP-mediated infection. Mammarenavirus GPs used as controls also mediated efficient entry into several snake cell lines. Our results confirm an important role of the virus surface GP in reptarenavirus cell tropism and that mamma-and reptarenaviruses exhibit high cross-species transmission potential.

Viral diseases of reptiles in clinical practice

Viruses are the cause of several important diseases in reptiles. In recent years, numerous novel reptile-infecting viruses have been discovered. There are also an increasing number of tests available for detecting viral infections in these animals. This review offers an overview of common and important viral infections in reptiles, the associated diseases as well as their diagnosis. Specific viruses presented include those infecting reptiles commonly kept as pets, specifically squamates (snakes and lizards), turtles, and tortoises. In this context, the review includes the adenoviruses, which are particularly common in bearded dragons (Pogona vitticeps). The paramyxoviruses and tobaniviruses (also known as nidoviruses or serpentoviruses) are likewise discussed, both of which may cause severe respiratory disease foremost in various snake species. Reptarenaviruses, the causative agents of inclusion body disease (IBD) in boas and pythons are discussed as well. The squamate viruses listed also encompass the iridoviruses including the ranaviruses, invertebrate iridoviruses, and hemocytiviruses, all of which are, amongst others, found in various lizard species. For the chelonians, herpesviruses of tortoises and turtles are discussed separately, followed by the ranaviruses and picornaviruses, all of which have been associated with upper respiratory and upper digestive tract disease, but can also cause other clinical signs, such as picornavirus-induced severe softening of the shell in juvenile tortoises.