Microstructural differences in the osteochondral unit of terrestrial and aquatic mammals

During evolution, animals have returned from land to water, adapting with morphological modifications to life in an aquatic environment. We compared the osteochondral units of the humeral head of marine and terrestrial mammals across species spanning a wide range of body weights, focusing on microstructural organization and biomechanical performance. Aquatic mammals feature cartilage with essentially random collagen fiber configuration, lacking the depth-dependent, arcade-like organization characteristic of terrestrial mammalian species. They have a less stiff articular cartilage at equilibrium with a significantly lower peak modulus, and at the osteochondral interface do not have a calcified cartilage layer, displaying only a thin, highly porous subchondral bone plate. This totally different constitution of the osteochondral unit in aquatic mammals reflects that accommodation of loading is the primordial function of the osteochondral unit. Recognizing the crucial importance of the microarchitecture-function relationship is pivotal for understanding articular biology and, hence, for the development of durable functional regenerative approaches for treatment of joint damage, which are thus far lacking.

Genomic comparison of mecC-carrying methicillin-resistant Staphylococcus aureus from hedgehogs and humans in the Netherlands

OBJECTIVES

MRSA carrying the mecC gene (mecC-MRSA) have been found in humans and animals worldwide. A high carriage rate of mecC-MRSA has been described among hedgehogs in different countries. We performed genomic comparison of mecC-MRSA from hedgehogs and humans using next-generation sequencing (NGS) to investigate possible zoonotic transmission in the Netherlands.

METHODS

Nasal swabs from hedgehogs (n = 105) were cultured using pre-enrichment and selective plates. Isolates were sequenced using Illumina NGS platforms. These data were compared with sequence data of mecC-MRSA (n = 62) from the Dutch national MRSA surveillance in humans.

RESULTS

Fifty hedgehogs were found to be MRSA positive, of which 48 carried mecC. A total of 60 mecC-MRSA isolates derived from 50 hedgehogs were compared with the human isolates. Fifty-nine mecC-MRSA from hedgehogs and all but one isolate from humans belonged to clonal complexes CC130 and CC1943. The mecC gene was located within the SCCmec XI element. Most mecC-MRSA did not carry other resistance genes besides mecC and blaZ. Two human isolates carried erm(C). Isolates differed in the presence of various virulence genes, which were linked to distinct STs and clonal complexes. Some isolates had up to 17 virulence genes, which underlines their pathogenic potential. No genetic clusters of hedgehog and human isolates were found.

CONCLUSIONS

mecC-MRSA from hedgehogs and humans mainly belonged to the same two clonal complexes, indicating a common source. No firm evidence for recent zoonotic transmission was found. Further studies are needed to investigate the role of hedgehogs in the occurrence of mecC-MRSA in humans.

Diversity of Hepatozoon species in wild mammals and ticks in Europe

BACKGROUND

Hepatozoon spp. are tick-borne parasites causing subclinical to clinical disease in wild and domestic animals. Aim of this study was to determine Hepatozoon prevalence and species distribution among wild mammals and ticks in Europe.

METHODS

Samples of wild mammals and ticks, originating from Austria, Bosnia and Herzegovina, Croatia, Belgium and the Netherlands, were tested with PCR to amplify a ~ 670-bp fragment of the small subunit ribosomal RNA gene.

RESULTS

Of the 2801 mammal samples that were used for this study, 370 (13.2%) tested positive. Hepatozoon canis was detected in samples of 178 animals (3 Artiodactyla, 173 Carnivora, 1 Eulipotyphia, 1 Lagomorpha), H. martis in 125 (3 Artiodactyla, 122 Carnivora), H. sciuri in 13 (all Rodentia), Hepatozoon sp. in 47 (among which Hepatozoon sp. Vole isolate, all Rodentia) and H. ayorgbor in 4 (all Rodentia). Regarding origin, 2.9% (6/208) tested positive from Austria, 2.8% (1/36) from Bosnia and Herzegovina, 14.6% (173/1186) from Croatia and 13.9% (190/1371) from Belgium/the Netherlands. Of the 754 ticks collected, 0.0% (0/35) Hyalomma sp., 16.0% (4/25) Dermacentor spp., 0.0% (0/23) Haemaphysalis spp., 5.3% (24/50) Ixodes and 1.4% (3/221) Rhipicephalus spp. tested positive for Hepatozoon (4.2%; 32/754), most often H. canis (n = 22).

CONCLUSIONS

Hepatozoon canis is most present in mammals (especially in Carnivora such as gray wolves and golden jackals) and ticks, followed by H. martis, which was found merely in stone martens and pine martens. None of the rodent-associated Hepatozoon spp. were detected in the ticks, suggesting the possible implication of other arthropod species or non-vectorial routes in the transmission cycle of the hemoprotozoans in rodents. Our findings of H. canis in ticks other than R. sanguineus add to the observation that other ticks are also involved in the life cycle of Hepatozoon. Now that presence of Hepatozoon has been demonstrated in red foxes, gray wolves, mustelids and rodents from the Netherlands and/or Belgium, veterinary clinicians should be aware of the possibility of spill-over to domestic animals, such as dogs.

Zoonotic Mutation of Highly Pathogenic Avian Influenza H5N1 Virus Identified in the Brain of Multiple Wild Carnivore Species

Wild carnivore species infected with highly pathogenic avian influenza (HPAI) virus subtype H5N1 during the 2021-2022 outbreak in the Netherlands included red fox (Vulpes vulpes), polecat (Mustela putorius), otter (Lutra lutra), and badger (Meles meles). Most of the animals were submitted for testing because they showed neurological signs. In this study, the HPAI H5N1 virus was detected by PCR and/or immunohistochemistry in 11 animals and was primarily present in brain tissue, often associated with a (meningo) encephalitis in the cerebrum. In contrast, the virus was rarely detected in the respiratory tract and intestinal tract and associated lesions were minimal. Full genome sequencing followed by phylogenetic analysis demonstrated that these carnivore viruses were related to viruses detected in wild birds in the Netherlands. The carnivore viruses themselves were not closely related, and the infected carnivores did not cluster geographically, suggesting that they were infected separately. The mutation PB2-E627K was identified in most carnivore virus genomes, providing evidence for mammalian adaptation. This study showed that brain samples should be included in wild life surveillance programs for the reliable detection of the HPAI H5N1 virus in mammals. Surveillance of the wild carnivore population and notification to the Veterinary Authority are important from a one-heath perspective, and instrumental to pandemic preparedness.

Highly Pathogenic Avian Influenza A(H5N1) Virus in Wild Red Foxes, the Netherlands, 2021

We detected infection with highly pathogenic avian influenza A(H5N1) virus clade 2.3.4.4b in 2 red fox (Vulpes vulpes) cubs found in the wild with neurologic signs in the Netherlands. The virus is related to avian influenza viruses found in wild birds in the same area.

Pathology and Pathogenesis of Eurasian Blackbirds (Turdus merula) Naturally Infected with Usutu Virus

The Usutu virus (USUV) is a mosquito-borne zoonotic flavivirus. Despite its continuous circulation in Europe, knowledge on the pathology, cellular and tissue tropism and pathogenetic potential of different circulating viral lineages is still fragmentary. Here, macroscopic and microscopic evaluations are performed in association with the study of cell and tissue tropism and comparison of lesion severity of two circulating virus lineages (Europe 3; Africa 3) in 160 Eurasian blackbirds (Turdus merula) in the Netherlands. Results confirm hepatosplenomegaly, coagulative necrosis and lymphoplasmacytic inflammation as major patterns of lesions and, for the first time, vasculitis as a novel virus-associated lesion. A USUV and Plasmodium spp. co-infection was commonly identified. The virus was associated with lesions by immunohistochemistry and was reported most commonly in endothelial cells and blood circulating and tissue mononucleated cells, suggesting them as a major route of entry and spread. A tropism for mononuclear phagocytes cells was further supported by viral labeling in multinucleated giant cells. The involvement of ganglionic neurons and epithelial cells of the gastrointestinal tract suggests a possible role of oral transmission, while the involvement of feather follicle shafts and bulbs suggests their use as a diagnostic sample for live bird testing. Finally, results suggest similar pathogenicity for the two circulating lineages.

Fatal Chlamydia avium Infection in Captive Picazuro Pigeons, the Netherlands

In 2016, an outbreak of Chlamydia avium infection occurred among Picazuro pigeons (Patagioenas picazuro) living in an aviary in the Netherlands. Molecular typing revealed a unique strain of C. avium. Our findings show that C. avium infection, which usually causes subclinical infection, can cause fatal disease in pigeons.

Iron Regulation in Elderly Asian Elephants (Elephas maximus) Chronically Infected With Mycobacterium tuberculosis

Restriction of nutrients to pathogens (nutritional immunity) is a critical innate immune response mechanism that operates when pathogens such as Mycobacterium tuberculosis have the potential to evade humoral immunity. Tuberculosis is of growing concern for zoological collections worldwide and is well-illustrated by infections of Asian and African elephants, where tuberculosis is difficult to diagnose. Here, we investigated hematological parameters and iron deposition in liver, lung, and spleen of three Asian elephants (Elephas maximus) infected with Mycobacterium tuberculosis. For reference purposes, we analyzed tissue samples from control M. tuberculosis-negative elephants with and without evidence of inflammation and/or chronic disease. Molecular analyses of bacterial lesions of post mortally collected tissues confirmed M. tuberculosis infection in three elephants. DNA sequencing of the bacterial cultures demonstrated a single source of infection, most likely of human origin. In these elephants, we observed moderate microcytic anemia as well as liver (mild), lung (moderate) and spleen (severe) iron accumulation, the latter mainly occurring in macrophages. Macrophage iron sequestration in response to infection and inflammation is caused by inhibition of iron export via hepcidin-dependent and independent mechanisms. The hepatic mRNA levels of the iron-regulating hormone hepcidin were increased in only one control elephant suffering from chronic inflammation without mycobacterial infection. By contrast, all three tuberculosis-infected elephants showed low hepcidin mRNA levels in the liver and low serum hepcidin concentrations. In addition, hepatic ferroportin mRNA expression was high. This suggests that the hepcidin/ferroportin regulatory system aims to counteract iron restriction in splenic macrophages in M. tuberculosis infected elephants to provide iron for erythropoiesis and to limit iron availability for a pathogen that predominantly proliferates in macrophages. Tuberculosis infections appear to have lingered for more than 30 years in the three infected elephants, and decreased iron availability for mycobacterial proliferation may have forced the bacteria into a persistent, non-proliferative state. As a result, therapeutic iron substitution may not have been beneficial in these elephants, as this therapy may have enhanced progression of the infection.

The nocturnal leopard gecko (Eublepharis macularius) uses UVb radiation for vitamin D3 synthesis

Vitamin D is an important regulator of calcium and phosphorus homeostasis in animals. It can be acquired from the diet or synthesised de novo when skin is exposed to UVb. Vitamin D deficiency can lead to a complex of diseases collectively called metabolic bone disease (MBD). Diurnal lizards without access to UVb are prone to develop vitamin D deficiency, even when dietary vitamin D₃ is provided. A trial was conducted to determine whether juvenile nocturnal lizards require access to UVb to prevent vitamin D deficiency. All leopard geckos (Eublepharis macularius) were supplemented with dietary vitamin D₃. One group was exposed to low level UVb radiation (33-51 μW/cm²) from hatching until 6 months of age and a second group remained unexposed. Animals were fed ad libitum and their growth and weight gain compared with non-exposed controls. At the end of the trial, blood samples were analysed for vitamin D₃ metabolites. The concentration of the vitamin D₃ metabolite, 25(OH)D₃, was higher in UVb exposed animals (61 ± 20 vs. 38 ± 8 nmol/L), confirming cutaneous synthesis with UVb exposure. Growth and weight gain were similar in both groups, and this, together with the absence of clinical symptoms, suggests that dietary vitamin D₃ alone can meet the vitamin D requirements for growth of this nocturnal gecko, during the first six months of life. It remains to be investigated whether the higher vitamin D metabolite levels holds other health benefits for this species, such as improved bone density or immune response.

Lack of evidence for the presence of leprosy bacilli in red squirrels from North-West Europe

Leprosy is a human infectious disease caused by Mycobacterium leprae or Mycobacterium lepromatosis that can also occur in animals and even manifest as zoonosis. Recently, both mycobacteria were detected in red squirrels (Sciurus vulgaris) from the British Isles. To further explore the presence of leprosy bacilli in North-West Europe, we screened Belgian and Dutch squirrels. Tissue samples from 115 animals tested by qPCR were negative for both pathogens. No molecular or pathological evidence was found of the presence of these zoonotic pathogens in North-West Europe.

Effects of body mass on microstructural features of the osteochondral unit: A comparative analysis of 37 mammalian species

Since Galileo's days the effect of size on the anatomical characteristics of the structural elements of the body has been a subject of interest. However, the effects of scaling at tissue level have received little interest and virtually no data exist on the subject with respect to the osteochondral unit in the joint, despite this being one of the most lesion-prone and clinically relevant parts of the musculoskeletal system. Imaging techniques, including Fourier transform infrared imaging, polarized light microscopy and micro computed tomography, were combined to study the response to increasing body mass of the osteochondral unit. We analyzed the effect of scaling on structural characteristics of articular cartilage, subchondral plate and the supporting trabecular bone, across a wide range of mammals at microscopic level. We demonstrated that, while total cartilage thickness scales to body mass in a negative allometric fashion, thickness of different cartilage layers did not. Cartilage tissue layers were found to adapt to increasing loads principally in the deep zone with the superficial layers becoming relatively thinner. Subchondral plate thickness was found to have no correlation to body mass, nor did bone volume fraction. The underlying trabecular bone was found to have thicker trabeculae (r=0.75, p<0.001), as expected since this structure carries most loads and plays a role in force mitigation. The results of this study suggest that the osteochondral tissue structure has remained remarkably preserved across mammalian species during evolution, and that in particular, the trabecular bone carries the adaptation to the increasing body mass.

Towards high quality real-time whole genome sequencing during outbreaks using Usutu virus as example

Recently, protocols for amplicon based whole genome sequencing using Nanopore technology have been described for Ebola virus, Zika virus, yellow fever virus and West Nile virus. However, there is some debate regarding reliability of sequencing using this technology, which is important for applications beyond diagnosis such as linking lineages to outbreaks, tracking transmission pathways and pockets of circulation, or mapping specific markers. To our knowledge, no in depth analyses of the required read coverage to compensate for the error profile in Nanopore sequencing have been described. Here, we describe the validation of a protocol for whole genome sequencing of USUV using Nanopore sequencing by direct comparison to Illumina sequencing. To that point we selected brain tissue samples with high viral loads, typical for birds which died from USUV infection. We conclude that the low-cost MinION Nanopore sequencing platform can be used for characterization and tracking of Usutu virus outbreaks.

Phylogeographic Distribution of Human and Hare Francisella Tularensis Subsp. Holarctica Strains in the Netherlands and Its Pathology in European Brown Hares (Lepus Europaeus)

Sequence-based typing of Francisella tularensis has led to insights in the evolutionary developments of tularemia. In Europe, two major basal clades of F. tularensis subsp. holarctica exist, with a distinct geographical distribution. Basal clade B.6 is primarily found in Western Europe, while basal clade B.12 occurs predominantly in the central and eastern parts of Europe. There are indications that tularemia is geographically expanding and that strains from the two clades might differ in pathogenicity, with basal clade B.6 strains being potentially more virulent than basal clade B.12. This study provides information on genotypes detected in the Netherlands during 2011–2017. Data are presented for seven autochthonous human cases and for 29 European brown hares (Lepus europaeus) with laboratory confirmed tularemia. Associated disease patterns are described for 25 European brown hares which underwent post-mortem examination. The basal clades B.6 and B.12 are present both in humans and in European brown hares in the Netherlands, with a patchy geographical distribution. For both genotypes the main pathological findings in hares associated with tularemia were severe (sub)acute necrotizing hepatitis and splenitis as well as necrotizing lesions and hemorrhages in several other organs. Pneumonia was significantly more common in the B.6 than in the B.12 cases. In conclusion, the two major basal clades present in different parts in Europe are both present in the Netherlands. In hares found dead, both genotypes were associated with severe acute disease affecting multiple organs. Hepatitis and splenitis were common pathological findings in hares infected with either genotype, but pneumonia occurred significantly more frequently in hares infected with the B.6 genotype compared to hares infected with the B.12 genotype.

Widespread activity of multiple lineages of Usutu virus, western Europe, 2016

In the summer of 2016, Belgium, France, Germany and the Netherlands reported widespread Usutu virus (USUV) activity based on live and dead bird surveillance. The causative USUV strains represented four lineages, of which two putative novel lineages were most likely recently introduced into Germany and spread to other western European countries. The spatial extent of the outbreak area corresponded with R₀ values > 1. The occurrence of the outbreak, the largest USUV epizootic registered so far in Europe, allowed us to gain insight in how a recently introduced arbovirus with potential public health implications can spread and become a resident pathogen in a naïve environment. Understanding the ecological and epidemiological factors that drive the emergence or re-emergence of USUV is critical to develop and implement timely surveillance strategies for adequate preventive and control measures. Public health authorities, blood transfusion services and clinicians in countries where USUV was detected should be aware of the risk of possible USUV infection in humans, including in patients with unexplained encephalitis or other neurological impairments, especially during late summer when mosquito densities peak.

Comparative Genomics of Campylobacter iguaniorum to Unravel Genetic Regions Associated with Reptilian Hosts

Campylobacter iguaniorum is most closely related to the species C. fetus, C. hyointestinalis, and C. lanienae. Reptiles, chelonians and lizards in particular, appear to be a primary reservoir of this Campylobacter species. Here we report the genome comparison of C. iguaniorum strain 1485E, isolated from a bearded dragon (Pogona vitticeps), and strain 2463D, isolated from a green iguana (Iguana iguana), with the genomes of closely related taxa, in particular with reptile-associated C. fetus subsp. testudinum. In contrast to C. fetus, C. iguaniorum is lacking an S-layer encoding region. Furthermore, a defined lipooligosaccharide biosynthesis locus, encoding multiple glycosyltransferases and bounded by waa genes, is absent from C. iguaniorum. Instead, multiple predicted glycosylation regions were identified in C. iguaniorum. One of these regions is > 50 kb with deviant G + C content, suggesting acquisition via lateral transfer. These similar, but non-homologous glycosylation regions were located at the same position on the genome in both strains. Multiple genes encoding respiratory enzymes not identified to date within the C. fetus clade were present. C. iguaniorum shared highest homology with C. hyointestinalis and C. fetus. As in reptile-associated C. fetus subsp. testudinum, a putative tricarballylate catabolism locus was identified. However, despite colonizing a shared host, no recent recombination between both taxa was detected. This genomic study provides a better understanding of host adaptation, virulence, phylogeny, and evolution of C. iguaniorum and related Campylobacter taxa.

Identification of a novel gammaherpesvirus associated with (muco)cutaneous lesions in harbour porpoises (Phocoena phocoena)

Herpesviruses infect a wide range of vertebrates, including toothed whales of the order Cetacea. One of the smallest toothed whales is the harbour porpoise (Phocoena phocoena), which is widespread in the coastal waters of the northern hemisphere, including the North Sea. Here, we describe the detection and phylogenetic analysis of a novel gammaherpesvirus associated with mucocutaneous and skin lesions in stranded harbour porpoises along the Dutch coast, tentatively designated phocoenid herpesvirus 1 (PhoHV1). Phylogenetically, PhoHV1 forms a monophyletic clade with all other gammaherpesviruses described in toothed whales (Odontoceti) to date, suggesting a common evolutionary origin.

Campylobacter iguaniorum sp. nov., isolated from reptiles

During sampling of reptiles for members of the class Epsilonproteobacteria, strains representing a member of the genus Campylobacter not belonging to any of the established taxa were isolated from lizards and chelonians. Initial amplified fragment length polymorphism, PCR and 16S rRNA sequence analysis showed that these strains were most closely related to Campylobacter fetus and Campylobacter hyointestinalis. A polyphasic study was undertaken to determine the taxonomic position of five strains. The strains were characterized by 16S rRNA and atpA sequence analysis, matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry and conventional phenotypic testing. Whole-genome sequences were determined for strains 1485E(T) and 2463D, and the average nucleotide and amino acid identities were determined for these strains. The strains formed a robust phylogenetic clade, divergent from all other species of the genus Campylobacter. In contrast to most currently known members of the genus Campylobacter, the strains showed growth at ambient temperatures, which might be an adaptation to their reptilian hosts. The results of this study clearly show that these strains isolated from reptiles represent a novel species within the genus Campylobacter, for which the name Campylobacter iguaniorum sp. nov. is proposed. The type strain is 1485E(T) ( = LMG 28143(T) = CCUG 66346(T)).

Fatal Ichthyocotylurus erraticus infestation in Inca terns (Larosterna inca) in a zoological collection

In a breeding group of Inca terns (Larosterna inca), 14 birds died without antemortem signs of illness. Other than a poor body condition and a bloody cloaca, no symptoms were observed. Gross necropsy revealed severe segmental hemorrhagic enteritis with intralesional trematodes in most birds. Histopathologic examination revealed infiltration of lymphocytes, plasma cells, and granulocytes in the lamina propria of the duodenum and cross-sections of trematodes in the lumen. The parasites were identified as Ichthyocotylurus erraticus, a trematode of fish-eating birds. The cause of the infestation most likely was the feeding of unfrozen fresh fish. We describe the first case of a lethal I. erraticus infestation in Inca terns.

Occurrence, diversity, and host association of intestinal Campylobacter, Arcobacter, and Helicobacter in reptiles

Campylobacter, Arcobacter, and Helicobacter species have been isolated from many vertebrate hosts, including birds, mammals, and reptiles. Multiple studies have focused on the prevalence of these Epsilonproteobacteria genera in avian and mammalian species. However, little focus has been given to the presence within reptiles, and their potential zoonotic and pathogenic roles. In this study, occurrence, diversity, and host association of intestinal Epsilonproteobacteria were determined for a large variety of reptiles. From 2011 to 2013, 444 cloacal swabs and fecal samples originating from 417 predominantly captive-held reptiles were screened for Epsilonproteobacteria. Campylobacter, Arcobacter, and Helicobacter genus specific PCRs were performed directly on all samples. All samples were also cultured on selective media and screened for the presence of Epsilonproteobacteria. Using a tiered approach of AFLP, atpA, and 16S rRNA sequencing, 432 Epsilonproteobacteria isolates were characterized at the species level. Based on PCR, Campylobacter, Arcobacter, and Helicobacter were detected in 69.3% of the reptiles; 82.5% of the chelonians, 63.8% of the lizards, and 58.0% of the snakes were positive for one or more of these genera. Epsilonproteobacteria were isolated from 22.1% of the reptiles and were isolated most frequently from chelonians (37.0%), followed by lizards (19.6%) and snakes (3.0%). The most commonly isolated taxa were Arcobacter butzleri, Arcobacter skirrowii, reptile-associated Campylobacter fetus subsp. testudinum, and a putative novel Campylobacter taxon. Furthermore, a clade of seven related putative novel Helicobacter taxa was isolated from lizards and chelonians. This study shows that reptiles carry various intestinal Epsilonproteobacteria taxa, including several putative novel taxa.

Tularaemia in a brown hare (Lepus europaeus) in 2013: first case in the Netherlands in 60 years

Tularaemia has not been reported in Dutch wildlife since 1953. To enhance detection, as of July 2011, brown hares (Lepus europaeus) submitted for postmortem examination in the context of non-targeted wildlife disease surveillance, were routinely tested for tularaemia by polymerase chain reaction (PCR). Francisella tularensis subspecies holarctica infection was confirmed in a hare submitted in May 2013. The case occurred in Limburg, near the site of the 1953 case. Further surveillance should clarify the significance of this finding.

Rapid enigmatic decline drives the fire salamander (Salamandra salamandra) to the edge of extinction in the Netherlands

In the Netherlands, the fire salamander (Salamandra salamandra) is at the edge of its geographic range and is restricted to three small populations in the extreme south of the country. Despite the species being listed as ‘Endangered’ on the national Red List, the situation was considered to be stable. However, from 2008 onwards dead individuals were seen on more than one occasion. A sharp decline in numbers has been observed since 2010 (96%; ), but we were unable to attribute this to any known cause of amphibian decline, such as chytridiomycosis, ranavirus or habitat degradation. The present work describes this enigmatic decline, and we discuss these results in the context of possible causes.

Vestibular syndrome due to a choroid plexus papilloma in a ferret

A 6-year-old, castrated male ferret (Mustela putorius furo) was presented with progressive neurological signs consisting of a right-sided head tilt and ataxia. Neurological examination revealed hemiparesis and absence of proprioception on the right side, consistent with central vestibular syndrome. Measurement of blood glucose excluded hypoglycemia due to insulinoma. Contrast-enhanced computed tomography revealed the presence of an intracranial mass, consistent with either granuloma or neoplasia. Palliative treatment with prednisolone yielded no improvement. At postmortem examination, a final diagnosis of a choroid plexus papilloma originating from the fourth ventricle was made. This is the first report of such a tumor in a ferret.

TP53 gene mutations in canine osteosarcoma

OBJECTIVE

To investigate mutations of the TP53 gene in canine osteosarcoma (OS).

STUDY DESIGN

Clinical historic cohort study.

ANIMALS

Client-owned dogs.

METHODS

OS (n=59) were screened for mutations of the complete TP53 gene using polymerase chain reaction and the mutation was analyzed by single-strand conformational polymorphism. Clinical outcome of dogs with TP53-mutated OS were compared with dogs with OS without a mutation after complete surgical excision of the primary tumor.

RESULTS

TP53 gene mutations were observed in 24 of 59 (40.7%) OS; 3 mutated OS had 2 mutations. The alterations consisted mainly of point mutations (74%). Dogs with mutated OS had a significantly shorter survival time (ST) after surgery than dogs with normal tumor TP53 gene expression (P=.03). Other significant prognosticators for ST and disease-free interval included elevated serum alkaline phosphatase (P<.01) and tumor grade (P=.01).

CONCLUSION

TP53 genetic mutations are common in canine OS and may have a prognostic value.

CLINICAL RELEVANCE

Mutations of the TP53 gene may influence survival and should be considered when evaluating canine OS.

Giant Cell Tumor of the Bone in a Scarlet Macaw (Ara macao)

A 6-mo-old female scarlet macaw (Ara macao) was presented after a 2-mo period of anorexia and weakness. The bird was reluctant to fly 1 wk before referral due to a painful left wing. Physical examination revealed a firm swelling around the left shoulder. On radiographs, the diaphysis and proximal metaphysis of the left scapula were radiolucent. Computer tomography revealed an osteolytic process, suggestive of a bone tumor, affecting the left scapula. Cytology of a fine needle aspiration biopsy of the mass showed erythrocytes, a proliferation of spindle-shaped mesenchymal cells, and multinucleated giant cells (osteoclasts) suggestive of a giant cell tumor. The left wing, including the scapula, was amputated. The bird showed a fast recovery but died 1 hr later. Findings during the pathological examination were compatible with shock due to blood loss. The shoulder process was characterized as a giant cell tumor. To our knowledge, this is the first complete report of a giant cell tumor of the bone in a bird.

[Recurrent skin problems in a manatee: the diagnostic approach]

A 40-year-old manatee was referred with recurrent vesicular and ulcerative dermatosis for the past 15 years. During this period the animal was anorectic and lost weight. Differential diagnoses were formulated on the basis of the history and clinical signs. Skin scrapings, bacterial and fungal culture, cytological examination, blood examination, and histopathological examination of skin biopsies narrowed this list down to autoimmune dermatosis. Despite corticosteroid therapy the symptoms recurred and the animal died. Histopathological examination of post-mortem skin biopsies showed again autoimmune dermatosis, more specifically subepidermal bullous autoimmune dermatosis, as the most probable cause of the skin lesions. Post-mortem examination showed cardiac decompensation and chronic nephritis. It was impossible to estimate the possible contribution of the chronic dermatosis to the cause of death. The purpose of this case report is to show the importance of a systematic work-up of disease in exotic animals.

Lobaplatin as an adjuvant chemotherapy to surgery in canine appendicular osteosarcoma: a phase II evaluation

Canine osteosarcoma, the most common bone tumor in dogs, is a well-established, naturally-occurring animal model for human OS. The aim of this study was to evaluate the clinical and hematological side-effects and to assess the efficacy of lobaplatin chemotherapy in dogs with appendicular osteosarcoma as an adjuvant therapy to surgical resection. Twenty-eight dogs without systemic signs of disease were treated with surgical resection of the tumor and adjuvant lobaplatin chemotherapy at a dose of 35 mg/m2, i.v., once every three weeks, for a maximum of 4 doses. Clinical signs of toxicosis were uncommon and consisted mainly of vomiting and depression. Hematological signs of toxicoses were common 7 to 10 days after lobaplatin chemotherapy and consisted of thrombocytopenia, leukopenia and neutropenia. All the signs were transient and most disappeared within three weeks of lobaplatin administration. A one-year disease-free fraction of 21.8% and a one-year survival fraction of 31.8% were calculated. Multivariate Cox regression analyses showed that a high histological tumor grade and presence of metastasis in the tumor vessels were associated with significantly shorter disease-free interval and survival time. Also, an increased pretreatment plasma alkaline phosphatase level at first presentation and a high histological level of tumor necrosis were associated with a shorter survival interval. Lobaplatin was easy to administer as an i.v. bolus injection at a three-week interval in dogs without the need for pretreatment infusions.

Prognostic significance of a new histologic grading system for canine osteosarcoma

Histologic grade is an important determinant in clinical outcome of human osteosarcoma (OS). In this study, the histologic characteristics of primary and metastatic canine OS were evaluated using a new classification system. Histologic characteristics were classified in 166 primary and 34 metastatic canine OS. Prognostic variables for clinical outcome were determined using multivariate analysis. Most OS were histologically characterized by severe to extreme cellular pleomorphism, a variable number of mitoses, small to moderate amounts of matrix, a high percentage of tumor cells, and minimal to moderate amounts of necrosis. Tumor invasion into vessels was present in 117/152 (71%) tumors, and 12/50 (24%) of the regional lymph nodes had evidence of metastasis. Classification of the 166 tumors resulted in seven (4%) grade 1, 34 (21%) grade II, and 125 (75%) grade III OS. In the multivariate analysis, histologic grade III OS and elevated pretreatment plasma alkaline phosphatase (AP) levels were independent predictors of clinical outcome. Dogs with high-grade tumors and elevated AP should be carefully evaluated for the presence of metastatic disease before starting adjunctive therapy protocols.

Unexpected Bw4 and Bw6 reactivity patterns in new alleles

The Bw4 and Bw6 epitopes were the first HLA-B differences to be recognized by serological methods. Since then 44 serological groups have been identified and more than 250 alleles assigned by molecular typing methods. In general each serological HLA-B group is associated with the presence of either the Bw4 or the Bw6 epitope. There are several exceptions to this rule. Four alleles, B*4601, *7301, *5503 and *1806, show no serological reactivity with either Bw4 or Bw6. Although the Bw6 motif at residues 77-83 is present in these alleles the Bw6 epitope is modified by a valine at residue 76. One or more alleles from the B8, B40 and B62 groups are identified as Bw4 positive, whereas all others are Bw6 positive. In the groups B27, B44 and B47 several alleles are found to be Bw6 positive, while the majority is Bw4 positive. Histocompatibility testing of dialysis patients and their families revealed the serological presence of an unexpected Bw4 epitope associated with B18 in one patient and B56 in another. Allele-specific amplification and sequencing of exons 2 and 3 of these HLA-B alleles revealed the presence of the Bw4 sequence motif for both. The new alleles were assigned B*1809 and B*5607, respectively. In 2 other patients the presence of a new B*07 allele was determined by sequence based typing. Although the new allele, B*0715, showed the Bw6 sequence motif at positions 77 to 83, a substitution of amino acid 76 from glutamic acid to valine was identified. This change resulted in an aberrant Bw6 serological reaction pattern.

Actin cytoskeletal lesions in differentiated human colon carcinoma Caco-2 cells after exposure to soybean agglutinin

We have investigated the effects of soybean agglutinin on the cytoskeletal element actin in differentiated Caco-2 cells. The actin cytoskeleton of the cells was visualized by fluorescence microscopy using 7-nitrobenz-2-oxa-1, 3-diazole phallacidin as a specific marker for F-actin. Compared with control Caco-2 cells no changes in the fluorescence pattern were observed after incubation with soybean agglutinin. However, using the deoxyribonuclease-I inhibition assay a dose-related response was noted in the increase of intracellular G-actin after a 2-hour incubation period with soybean agglutinin. Already after exposure for 15 min to soybean agglutinin a decrease in intracellular F-actin was demonstrable. This apparent depolymerization could be prevented by incubating the Caco-2 cells with soybean agglutinin and the appropriate monosaccharide simultaneously. The increase in the amount of G-actin appeared to be correlated with a shortening of microvilli on the Caco-2 cells.