Spontaneous nephroblastoma with oncocytic differentiation in a Japanese White rabbit.

Spontaneous nephroblastoma is an uncommon tumor in laboratory rabbits. We recently encountered this tumor, and we describe its histological characteristics in this report. A male 3-year-old Japanese White rabbit (JW/kbs), maintained as a stock animal, suddenly showed poor condition and was found dead a few days later. At necropsy, a large mass was found that extended from one side of the renal pelvis. The cut surface of the mass was dark red in color and velvety to the touch. The kidney on the contralateral side was normal. Microscopically, the tumor mass consisted of biphasic components, which consisted of epithelial (tubular and glomerular) and blastemal (nodular) elements. No sarcomatous proliferation was observed. In addition, some of the tubules were lined by cells with a large amount of eosinophilic cytoplasm. The cells were confirmed as oncocytes by immunohistochemical and electron microscopic examinations. The present case was therefore diagnosed as a nephroblastoma with oncocytic differentiation.

Magnetic resonance imaging, computed tomography, and gross anatomy of forelimb joints in New Zealand rabbit (Oryctolagus cuniculus L.).

The present study aimed to define the anatomical structures by comparing the transversal computed tomography (CT) and magnetic resonance (MR) images of the forelimb joints of the rabbits with the cross-sectional plastinated images. A total of 14 (seven females, seven males) one-year-old adult New Zealand rabbits were used in the study. After the CT and MR imaging procedures were completed, the forelimbs were removed from the body. The forelimbs were plastinated using the silicone plastination method and sectioned transversal. Cross-sectional plastinates were evaluated and correlated anatomically with conjugate CT and MR images. Joint and surrounding anatomical structures were defined in sections. Cross-sectional plastinated samples were highly correlated with CT and MR images in terms of bone and soft tissue, respectively. It is thought that the anatomical and radiological data obtained from the forelimb joints of rabbits will provide a basis for scientists who are involved in both experimental surgical interventions and clinical anatomy education.

Prevalence of Hepatitis E Virus Infection among Laboratory Rabbits in China.

Hepatitis E virus (HEV) is zoonotic and the leading cause of acute viral hepatitis worldwide. Rabbit HEV can infect humans and is prevalent globally. It is reported that laboratory rabbits are also naturally infected with HEV. Therefore, it is important to investigate in a large scale the prevalence of HEV in laboratory rabbits. Serum samples were collected from 649 laboratory rabbits of 13 different commercial vendors in Beijing, China, from 2017 to 2019, and anti-HEV and HEV antigen (Ag) were tested. Fecal samples were collected from 50 laboratory rabbits from one of the vendors for HEV RNA detection. Six laboratory rabbits with natural HEV infection were euthanized and their liver, kidney, bile and urine samples were collected for HEV RNA quantification. Liver tissues were subjected to histopathology analysis. The overall positive rates of anti-HEV antibodies and HEV-Ag are 2.6% (15/588) and 7.9% (51/649), respectively. HEV RNA was detected in 12.0% (6/50) of the rabbits. High viral load of HEV RNA was detected in liver and bile samples. Liver inflammation was observed. HEV is circulating in laboratory rabbit population in China. Strict screening is crucial to ensure experimental accuracy and prevent zoonotic transmission to research personnel.

Rabbit colony infected with a bovine-like G6P[11] rotavirus strain.

Group A rotaviruses (RVAs) are the main etiological agent of infantile diarrhea in both humans and animals worldwide. A limited number of studies have investigated the molecular characteristics of RVA strains in stool specimens of rabbits, with only a few lapine RVA strains isolated and (partially) characterized to date. The most common G/P-genotype combinations found in rabbits are G3P[14] and G3P[22]. In this study a RVA strain was isolated from the small intestine of a 9-week-old rabbit from an infected laboratory rabbit colony. The RVA strain RVA/Rabbit-tc/NLD/K1130027/2011/G6P[11] was shown to possess the typical bovine G6 and P[11] genotypes. The complete genome of this unusual lapine strain was sequenced and characterized. Phylogenetic analyses of all 11 gene segments revealed the following genotype constellation: G6-P[11]-I2-R2-C2-M2-A13-N2-T6-E2-H3. The VP1, VP2, VP3, VP6, NSP2 and NSP4 genes all belonged to DS-1-like genotype 2, but clustered more closely to bovine RVA strains than to lapine RVA strains. The NSP1 genotype A13 is typically associated with bovine RVAs, while the NSP3 genotype T6 and the NSP5 genotype H3 have been found in a wide variety of species. However, the isolated strain clustered within bovine(-like) T6 and H3 subclusters. Overall, the data indicate that the RVA strain is most closely related to bovine-like RVA strains and most likely represents a direct interspecies transmission from a cow to a rabbit. Altogether, these findings indicate that a RVA strain with an entirely bovine genome constellation was able to infect and spread in a laboratory rabbit colony.