CD56+ B-cell Neurolymphomatosis in a Cat.

A 16-year-old male Russian blue cat was presented with acute onset of paraparesis of the forelimbs that progressed to tetraparesis. Neurological examination revealed non-ambulatory tetraparesis with decreased postural reactions in all four limbs. Magnetic resonance imaging revealed multifocal nerve root swelling on the right at C6/C7 and C7/T1, while ultrasonography demonstrated swelling of the right brachial plexus. To understand the cause of the nerve swelling, the right musculocutaneous nerve arising from the brachial plexus and the pectoralis muscle were biopsied. Histologically, there was evidence of neurolymphomatosis (neurotropic lymphoma) with Wallerian degeneration and denervation atrophy of myofibres. The neoplastic lymphoid cells expressed CD79a, CD20 and CD56. Based on these findings, a diagnosis of B-cell neurolymphomatosis was made. Expression of CD56, synonymous with neural cell adhesion molecule, is rare in B-cell lymphomas and has not been reported in feline B-cell lymphomas or feline neurolymphomatosis. CD56 expression was suspected to have played an important role in neurotropism of the neoplastic cells in this case.

Different intestinal tropism of the G2b Taiwan porcine epidemic diarrhea virus-Pintung 52 strain in conventional 7-day-old piglets.

The group 2b (G2b) porcine epidemic diarrhea virus (PEDV) that emerged in 2013 has since caused devastating diseases and economic loss. The full-length genome of the G2b Taiwan PEDV-Pintung 52 (PEDV-PT) strain and its intestinal tropism by evaluating the pathological changes in the original PEDV-PT infected field piglet and orally inoculation of either 10, 103, or 105 50% tissue culture infective dose/mL (TCID50/mL) of the plaque-purified PEDV-PT-Passage 5 (P5) in 7-day-old conventional piglets were analyzed. Phylogenetic analysis of the full-length genome indicated that the G2b Taiwan PEDV-PT strain was closely related to the North American G2b PEDV strains. Some pathological features of the G2b Taiwan PEDV-PT infection, including the absence of lesions and antigen signal in the crypt epithelial cells of the jejunum and ileum and in the villus enterocytes of the duodenum and colon, were different from those of infections by the North American G2b PEDV strains. This difference in the intestinal tropism of the G2b Taiwan PEDV-PT strain highlights the importance of studying the pathogenicities of different PEDV variants. Moreover, similar distributions of PEDV antigens and lesions in the G2b Taiwan PEDV-PT infected field piglet and its plaque-purified isolate, PEDV-PT-P5, inoculated piglets indicating that the plaque-purified PEDV-PT-P5 viral stock could facilitate the preclinical evaluation of vaccines and other interventions aimed at preventing the G2b PEDV infection.

Diffuse-type Gastric Mucinous and Signet Ring Cell Adenocarcinoma in a Captive California King Snake (Lampropeltis getula californiae).

An adult female California king snake (Lampropeltis getula californiae) housed in Taipei Zoo was presented with a 2-week history of anorexia, fatigue and abdominal swelling. Exploratory laparotomy revealed a gastric mass with two circular perforations and multiple mottled white to beige protuberances along the mucosal surface. Histologically, the gastric mass showed an invasive, transmural growth of epithelial cells arranged in nests, lobules, acini and sheets in the mucosa and submucosa that progressively transformed into signet ring cells in the muscularis externa and subserosa. All of the neoplastic cells expressed pan-cytokeratin immunohistochemically. Based on the World Health Organization histological criteria, a diagnosis of diffuse-type gastric mucinous and signet ring cell adenocarcinoma was made.

Phylogenetic Analysis of the Spike (S) Gene of the New Variants of Porcine Epidemic Diarrhoea Virus in Taiwan.

New variants of porcine epidemic diarrhoea virus (PEDV), which emerged in Taiwan in late 2013, have caused a high morbidity and mortality in neonatal piglets. To investigate the molecular characteristics of the spike (S) gene of the emerging Taiwan PEDV strains for a better understanding of the genetic diversity and relationship among the Taiwan new variants and the global PEDVs, full-length S genes of PEDVs from nine 1-7 day-old piglets from three pig farms in the central and southern Taiwan were sequenced and analysed. The result of phylogenetic analysis of the S gene showed that all the Taiwan PEDV strains were closely related to the non-S INDEL strains from US, Canada and China, suggesting a common ancestor for these strains. As compared with the historic PEDVs and CV777-based vaccine strains, the nine Taiwan PEDV variants shared almost the same genetic signatures as the global non-S INDEL strains, including a series of insertions, deletions and mutations in the amino terminal as well as identical mutations in the neutralizing epitopes of the S gene. The high similarity of the S protein among the Taiwan and the globally emerged non-S INDEL PEDV strains suggests that the Taiwan new variants may share similar pathogenesis and immunogenicity as the global outbreak variants. The development of a novel vaccine based on the Taiwan or the global non-S INDEL strains may be contributive to the control of the current global porcine epidemic diarrhoea outbreaks.

Entamoeba invadens myositis in a common water monitor lizard (Varanus salvator).

Amoebiasis is one of the most common protozoal diseases of reptiles, but amoebic myositis has not been reported in any animal species. An 11-year-old, male common water monitor lizard (Varanus salvator) was found dead with several subacute ulcerated skin wounds. Gross examination revealed multiple discrete to coalescing, white-yellow to gray, caseous foci scattered in the skeletal muscles and liver. The mucosa of small intestine was thickened, red, and contained many variably sized, dark red ulcers, with depressed and hemorrhagic centers. Histopathologic examination revealed severe necrotizing and granulomatous myositis, hepatitis, and enteritis accompanied by large numbers of intralesional, 10-20-microm diameter, periodic acid-Schiff-positive, amoeboid protozoa. Gene sequence analysis of a 136-bp region of the 18S ribosomal RNA amplified by polymerase chain reaction revealed 98-100% similarity with Entamoeba invadens. Aside from intestinal and hepatic involvement, no other internal organs were affected. The muscular infection by E. invadens likely resulted from a combination of direct invasion of trophozoites via skin wounds and hematogenous spread.

Amyloid-producing odontogenic tumor and its immunohistochemical characterization in a Shih Tzu dog.

A 10-year-old, male, Shih-Tzu dog presented with swelling of the right lower jaw caused by a mass arising from the right mandibular gingiva. Radiographic examination revealed bone lysis of the right wing of the mandible. Histopathologically, the growth was characterized by indistinctly lobulated nests, islands, and strands of proliferating odontogenic and squamous epithelial cells, intermingled in close association with large numbers of irregular extracellular deposits of amyloid and amorphous calcified substance. Immunohistochemically, both epithelial components stained strongly positive for cytokeratin (AE1/AE3); the squamous epithelial cells also reacted strongly with neuron-specific enolase (NSE) and S-100 protein, whereas the odontogenic epithelial cells displayed weak immunoreactivity to NSE and partial reactivity to S-100 protein. The amyloid deposits were AE1/AE3-negative. The growth was diagnosed as an amyloid-producing odontogenic tumor.

Vaccine-associated rhabdomyosarcoma with spinal epidural invasion and pulmonary metastasis in a cat.

A 7-year-old, female, domestic medium-haired cat had a recurrent deep dermal mass in the interscapular region after initial surgical removal 3 months earlier. The cat had received a killed rabies vaccine and a five-in-one vaccine in the same area about 2 months prior to the first surgery. The relapsed mass was diagnosed as vaccine-associated sarcoma. The cat was euthanized 2 months later because of hind limb paralysis. At necropsy, multiple, poorly demarcated, nodular masses were seen in the muscles around the shoulders, neck, and thoracic vertebrae. Pulmonary metastasis and spinal epidural invasion at T1-T3 with regional cord compression and malacia were observed. Microscopically, the masses consisted of interwoven bundles of spindle cells with prominent multinucleated giant cell formation. The neoplastic cells stained strongly positive for myoglobin, and moderately but variably positive for vimentin, desmin, and alpha- smooth muscle actin. Phosphotungstic acid-hematoxylin staining revealed cytoplasmic striations in scattered tumor cells. The tumor was considered a vaccine-associated rhabdomyosarcoma.

Hydatidosis in a Chapman's zebra (Equus burchelli antiquorum).

A 14-year-old male Chapman's zebra had been treated for a cervical granulomatous cellulitis for 3 months prior to sudden death associated with myocardial fibrosis. Incidental findings at necropsy included multiple 3-8-cm unilocular cysts in the liver and lungs. Cysts contained either a clear fluid with or without hydatid sand or a gelatinous substance with foci of mineralization. Light and scanning electron microscopic examination of the hydatid sand revealed free protoscolices as well as intact and ruptured brood capsules with protoscolices attached to the germinal membrane. The protoscolices had 2 rows of 36-38 rostellar hooks with a length of 25-30 microm. The cyst wall consisted of inner germinal, intermediate laminated, and outer adventitial layers. Hydatidosis caused by Echinococcus granulosus was diagnosed based on the unilocular cysts, multiple protoscolices formed in a brood capsule, typical trilayered cyst wall, and herbivorous intermediate host. This is the first reported case of animal hydatidosis in Taiwan. The infection is thought to have been established 12 years ago in South Africa prior to importation.

A peritoneal mesothelioma in a captive aardwolf (Proteles cristatus).

A 10-year-old male aardwolf (Proteles cristatus) was presented abdominal distention and emaciation for 3 months. Physical examination revealed firm abdominal masses with effusions. Cytologic assessment of the effusion showed uniform round tumor cells with a surface brush border. Necropsy showed white velvety masses covering the peritoneal surface of the liver, gall bladder, stomach, omentum, mesentery, spleen, intestine, abdominal wall and diaphragm. Histologic examination demonstrated papillary projections, lined with cuboidal tumor cells supported by fibrous connective tissue cores, arising from the serosa of visceral organs. Cytoplasmic vacuolation and a surface brush border were evident on some cells under light microscopy. Tumor cells stained positive for both cytokeratin (AE1/AE3) and vimentin. Electron microscopy showed prominent surface microvilli, rough endoplasmic reticulum, mitochondria and desmosomes in tumor cells. This may be the first reported case of peritoneal mesothelioma in a captive wild aardwolf.

Effects of cartap on isolated mouse phrenic nerve diaphragm and its related mechanism.

Cartap, a nereistoxin analogue pesticide, is reported to have no irritation to eyes in rabbits. However, we have demonstrated recently that cartap could actually cause acute death in rabbits via ocular exposure. Our preliminary study with isolated mouse phrenic nerve diaphragms has shown that instead of neuromuscular blockade, cartap caused muscular contracture. The objective of the study was to examine the effect of cartap on the neuromuscular junction in more detail and to investigate its possible underlying mechanism with isolated mouse phrenic nerve diaphragms and sarcoplasmic reticulum (SR) vesicles. Cartap or nereistoxin at various concentrations was added in the organ bath with isolated mouse phrenic nerve diaphragm and both nerve- and muscle-evoked twitches were recorded. Instead of blocking the neuromuscular transmission as nereistoxin did, cartap caused contracture in stimulated or quiescent isolated mouse phrenic nerve diaphragm. Both the cartap-induced muscular contracture force and the time interval to initiate the contracture were dose-dependent. The contracture induced by cartap was not affected by the pretreatment of the diaphragm with the acetylcholine receptor blocker alpha-bungarotoxin; the Na(+) channel blocker tetrodotoxin; or various Ca(2+) channel blockers, NiCl(2), verapamil, and nifedipine. On the contrary, the contracture was significantly inhibited when the diaphragm was pretreated with ryanodine or EGTA containing Ca(2+)-free Krebs solution or in combination. This suggested that both internal and extracellular Ca(2+) might participate in cartap-induced skeletal muscle contracture. Moreover, cartap inhibited the [(3)H]-ryanodine binding to the Ca(2+) release channel of SR in a dose-dependent manner. Additionally, cartap could induce a significant reduction in Ca(2+)-ATPase activity of SR vesicles at a relatively high dose. The results suggested that cartap might cause the influx of extracellular Ca(2+) and the release of internal Ca(2+), with subsequent induction of muscular contracture in the isolated mouse phrenic nerve diaphragm. Based on these findings, we propose that the acute death of rabbits following ocular exposure to cartap might have resulted from respiratory failure secondary to diaphragm contracture.

Effects of porcine reproductive and respiratory syndrome virus (isolate tw91) on porcine alveolar macrophages in vitro.

To verify the role of porcine reproductive and respiratory syndrome virus (PRRSV) infection on pulmonary defense mechanisms, alterations in the viability, morphology, and various functions of porcine alveolar macrophages (AMs) were evaluated in vitro for 2-72 h after exposure to a Taiwan isolate, tw91, at a multiplicity of infection (MOI) of 0.1. A low but constant rate of infection, around 5%, was seen in AMs from the PRRSV-infected group throughout the study. When compared with a mock-infected group, AMs from the PRRSV-infected group had a significantly lower viability at 18-72 h post-infection (HPI) as determined by trypan blue dye exclusion. Also during this time period, the cells showed morphological changes, including rounding, bleb formation, and rupture. The phagocytic and microbicidal capacity of AMs against Candida albicans was significantly inhibited after 6 HPI. Although the total amount of superoxide anion (O2-) and hydrogen peroxide (H2O2) produced by the AMs was reduced after 18 and 12 HPI, respectively, the amount of production was enhanced in both reactive oxygen species on a per viable cell basis after 12 HPI. In contrast, the level of bioactive tumor necrosis factor alpha (TNF-alpha) secretion, either total or on a per viable cell basis, was markedly reduced soon after PRRSV infection, up to 36 HPI, followed by a rebound thereafter. Prostaglandin E2 (PGE2) production was enhanced, both in total and on a per viable cell basis, in the first 6 h of infection, especially at 2 HPI. However, it became lower than that of the control after 36 HPI. The results indicated that PRRSV infection could cause, directly and/or indirectly, not only death of AMs but also adverse alterations in their morphology and function, although some of the effects seemed to be reversible. Because AMs are crucial to the host against airborne pathogens, PRRSV infection may potentially predispose pigs to secondary pulmonary infections.

A sensitive fluorescence in situ hybridization technique for detection of porcine reproductive and respiratory syndrome virus.

A sensitive fluorescence in situ hybridization (ISH) for detecting porcine reproductive and respiratory syndrome virus (PRRSV) RNA in viral infected tissue was developed using digoxigenin-labeled RNA probes targeted on the nucleocapsid gene of PRRSV. In situ RNA/RNA hybrids were detected with an anti-digoxigenin antibody alkaline phosphatase conjugate and further revealed with Fast Red TR salt/naphthol AS-MX phosphate using a fluorescent microscope. Viral nucleic acid was readily demonstrated within macrophages, known to be the major target of PRRSV. In addition, positively stained cells were found in the salivary gland and skin tissues which have not been reported to contain PRRSV infected cells before. In conclusion, the fluorescence ISH used in this study provides a fast and sensitive means for screening virus-infected tissues in which relatively few cells are affected. This advantage will be especially beneficial for studying viral persistence and for routine diagnosis of PRRSV infection.

Evidence for CD8+ antiviral activity in cats infected with feline immunodeficiency virus.

Human immunodeficiency virus (HIV) causes a long, asymptomatic infection characterized by normal to elevated numbers of circulating CD8+ cells and a progressive decline in CD4+ cells. It has been speculated that HIV-specific antiviral activity driven by CD8+ T cells may control viral replication during this period and maintain the clinically asymptomatic stage of disease. The disease induced in cats by feline immunodeficiency virus (FIV) is similar to HIV in that it is characterized by a long asymptomatic stage with a progressive decline in CD4+ cells, culminating in AIDS. In the present study, we demonstrate that FIV is more readily isolated from CD8+ T-cell-depleted peripheral blood mononuclear cells (PBMC) of FIV-infected cats than from unfractionated PBMC cultures. In addition, CD8+ T cells isolated from FIV-positive cats demonstrating anti-FIV activity in PBMC cultures inhibit FIV infection of FCD4E cells in vitro. Anti-FIV activity is not found in FIV- negative cats and is not characteristic of cats acutely infected with FIV but is present in the majority of chronically infected, clinically asymptomatic and symptomatic cats. Decreases in plasma and cell-associated viremia during the acute-stage FIV infection appears to precede the appearance of CD8+ anti-FIV cells in the circulation. In summary, this study demonstrates a population(s) of CD8+ T cells in chronically FIV-infected cats capable of suppressing FIV replication in cultured PBMC. The significance of anti-FIV CD8+ cells in the immunopathogenesis of the infection and disease progression has yet to be determined.

Lymphocyte population changes in cats naturally infected with feline immunodeficiency virus.

Feline immunodeficiency virus (FIV) is associated with feline acquired immunodeficiency syndrome (FAIDS) and has been suggested as a model for HIV-induced human AIDS. The most obvious immunological defect in HIV infection is a reduction in CD4+ cell numbers and an inversion of the CD4:CD8 ratio. To determine whether the same is true in FIV infection, we analyzed by flow cytometry using a panel of monoclonal antibodies to feline lymphocyte populations the CD4:CD8 ratios in cats naturally infected with the virus. We report that 13 of 19 FIV-infected cats had ratios below the 5th percentile of normal cats (0.57, established from analysis of 39 normal cats) and 18 of 19 had ratios below 1. Repeated analyses over a period of several months revealed the inverted ratios to be consistent. Analysis of lymphocyte numbers in FIV-infected cats shows that the inverted ratios are due to a decrease in CD4+ T cells, while CD8+ T and B cells remain relatively normal in number. Analysis of a group of cats with a variety of other chronic diseases, including feline leukemia virus (FeLV) infections, revealed a near-normal distribution of CD4:CD8 ratios. These findings are similar to those in HIV infections and indicate that, like HIV, FIV causes a selective reduction in CD4+ cells and should be an excellent model for studying retrovirus-induced AIDS.