Comparative Neuropathogenesis of Equine Herpesvirus 9 and its Mutant Clone (SP21) Inoculated Intranasally in a Hamster Model.

The neuropathogenesis of equine herpesvirus 9 (EHV-9), a neurotropic herpesvirus, and its mutant clone (SP21) was studied experimentally in a hamster model. EHV-9-infected hamsters showed clinical signs of infection at 3 days post infection (dpi), while infection with SP21 resulted in clinical signs at 4 dpi. Clinical signs were more severe in the EHV-9-infected group than in the SP21-infected group. There was a significant difference in the time of anterograde transmission of EHV-9 and SP21 inside the brain. Viraemia was detected in the EHV-9-infected group at 4-5 dpi, while no viraemia was detected in the SP21-infected group. The serum concentration of tumour necrosis factor-α was significantly higher in EHV-9-infected animals than in those infected by SP21 group at 4-5 dpi, but there was no difference in the serum concentration of interferon-γ. The spatiotemporal profiles of viral replication and virus-associated histopathology were remarkably similar, were high in the olfactory bulb and cerebral hemispheres, and decreased progressively towards the medulla oblongata. The mean group scores of the histopathological changes for the entire brain were significantly higher in the EHV-9 group than in the SP21 group at all time points, starting from 3 dpi. These results suggest that the gene products of the open reading frame (ORF)19 and ORF14 play essential roles in the neuropathogenesis of EHV-9, as the two point-mutations detected in SP21 significantly altered the neuropathogenesis of the virus.

T-cell/Histiocyte-rich Large B-cell Lymphoma of the Larynx in a Juvenile Japanese Macaque (Macaca fuscata).

An 11-month-old female Japanese macaque (Macaca fuscata), born in captivity in a research institute, suddenly died without clinical signs. Necropsy examination revealed a nodular mass protruding from the left ventral aspect of the larynx, compressing the epiglottis anteriorly. Histopathologically, the laryngeal mass was comprised of medium- to large-sized atypical cells. Immunohistochemically, these were positive for CD20 and partially positive for CD79α. Among the atypical cells were CD3+ T cells and CD68+ histiocytes. Based on the findings, this case was diagnosed as T-cell/histiocyte-rich large B-cell lymphoma. Epstein-Barr virus (EBV)-encoded small RNAs were frequently detected in the atypical cells by in-situ hybridization, which was consistent with the finding that the macaque was seropositive for EBV antigen. This is the first report showing the potential association of simian lymphocryptovirus, the simian homologue of EBV, with lymphoma in a juvenile non-human primate.

Uniaxial Magnetization Performance of Textured Fe Nanowire Arrays Electrodeposited by a Pulsed Potential Deposition Technique.

Textured ferromagnetic Fe nanowire arrays were electrodeposited using a rectangular-pulsed potential deposition technique into anodized aluminum oxide nanochannels. During the electrodeposition of Fe nanowire arrays at a cathodic potential of - 1.2 V, the growth rate of the nanowires was ca. 200 nm s-1. The aspect ratio of Fe nanowires with a diameter of 30 ± 5 nm reached ca. 2000. The long axis of Fe nanowires corresponded with the <200> direction when a large overpotential during the on-time pulse was applied, whereas it orientated to the <110> direction under the potentiostatic condition with a small overpotential. By shifting the on-time cathode potential up to - 1.8 V, the texture coefficient for the (200) plane, TC200, reached up to 1.94. Perpendicular magnetization performance was observed in Fe nanowire arrays. With increasing TC200, the squareness of Fe nanowire arrays increased up to 0.95 with the coercivity maintained at 1.4 kOe at room temperature. This research result has opened a novel possibility of Fe nanowire arrays that can be applied for a new permanent magnetic material without rare-earth metals.

Effect of Mouse Strain on Equine Herpesvirus 9 Infection.

The infectivity of equine herpesvirus (EHV)-9 has been studied in different animal models including immunocompromised animals. The current study focused on the infectivity of EHV-9 in different mouse strains (C3H, C57BL, DBA, BALB/c-nu/nu, BALB/c and ICR) by intranasal inoculation of 2 × 106 plaque forming units (PFU). Various organs, including head and lungs, were collected 7 days post infection (dpi) to investigate microscopical lesions and the distribution of EHV-9 antigen. Immunopositivity of tissue sections was scored using ImageJ software. Open reading frame (ORF) 30 expression in lung tissues was quantified using quantitative reverse transcriptase polymerase chain reaction. Pathological examination revealed different degrees of rhinitis in the different mouse strains. Severe rhinitis was detected in C3H and BALB/c-nu/nu strains, moderate rhinitis was observed in C57BL and DBA strains and no lesions were detected in BALB/c mice. Immunopositivity for EHV-9 antigens was detected in the olfactory epithelium of C3H and BALB/c-nu/nu strains. Compared with C57BL, DBA, BALB/c-nu/nu, ICR and BALB/c strains, the C3H strain showed greater expression of EHV-9 antigens in the brain. The proportion of areas with high positive to positive immunoreactivity for EHV-9 were 7.57, 3.42, 3.12, 2.51, 1.79 and 0.03% for C3H, C57BL, DBA, BALB/c-nu/nu, ICR and BALB/c strains, respectively. The proportions of areas with low positive to negative immunoreactivity were 92.42, 96.70, 96.87, 97.48, 98.16 and 99.96%, respectively. The highest relative expression levels for EHV-9 ORF30 in the lungs were in C3H mice. No significant differences in the expression of ORF30 were observed in other strains. In conclusion, of the strains examined, C3H, C57BL, DBA, BALB/c-nu/nu and ICR were the most susceptible to EHV-9 infection, and the BALB/c strain was less susceptible.

Overexpression of Peroxiredoxin 6 Protects Neoplastic Cells against Apoptosis in Canine Haemangiosarcoma.

Canine haemangiosarcoma (HSA), like human angiosarcoma, is an uncommon malignant vascular endothelial cell tumour associated with a poor prognosis. The peroxiredoxin (PRDX) family of peroxidases, which comprises six members in mammals (PRDX1-6), might contribute to cancer cell survival in the face of oxidative stress as these proteins exhibit frequent upregulation in cancer cells. In this study, we investigated the expression levels of PRDX6 in spontaneously arising primary canine HSAs by immunohistochemical analysis, identifying marked expression of this protein. Both PRDX6 mRNA and protein were overexpressed in HSA cell lines compared with normal canine endothelial cells, although some variation was observed between the different HSA cell lines. Small interfering RNA-induced downregulation of PRDX6 promoted apoptosis in the HSA cell lines. The observation that PRDX6 suppression increased the cytotoxicity of these cells suggests that PRDX6 might play an important cytoprotective role.

Immunohistochemical analysis of CD146 expression in canine skin tumours.

CD146, a cell adhesion molecule, is overexpressed in a variety of carcinomas, including melanoma, prostate cancer, epithelial ovarian cancer, and breast cancer. The level of expression is directly correlated with tumour progression and metastatic potential. The most commonly affected organ for both neoplastic and non-neoplastic tumours is the skin. The objective of this study is to investigate the immunohistochemical expression of CD146 in canine skin tumours of epidermal or follicular origin in 53 squamous cell carcinomas (SCCs), 9 squamous papillomas, 7 infundibular keratinizing acanthomas (IKA), 21 trichoepitheliomas, 13 trichoblastomas, and 3 pilomatricomas. Immunohistochemical results showed that SCCs (90.6%), squamous papilloma (33.3%), IKA (85.7%), trichoepithelioma (85.9%), trichoblastoma (30.8%) and pilomatricoma (100%), respectively, were positive for CD146. The significant expression of CD146 in SCCs supports its importance as a useful treatment target. CD146 could also be used in differentiation of trichoepithelioma and trichoblastoma.

Immunohistochemical Detection of Urokinase Plasminogen Activator and Urokinase Plasminogen Activator Receptor in Canine Vascular Endothelial Tumours.

Immunohistochemistry was used to assess the expression of urokinase plasminogen activator (uPA) and uPA receptor (uPAR) in 57 canine primary haemangiosarcomas (HSAs), 26 canine cutaneous haemangiomas (HAs) and in control sections of canine cutaneous granulation tissue. The correlation between uPA/uPAR expression and the Ki67 labelling index (LI) was estimated in the HSA and HA tissues. uPA was expressed by 73.2% and 75.0% of splenic HSAs and non-splenic HSAs, respectively. All HSA tissues tested expressed uPAR. Expression of both molecules was significantly higher in HSAs than in cutaneous HAs (3.8% for uPA and 30.7% for uPAR). The average Ki67 LI of the uPA(+)/uPAR(+) HSAs was significantly higher than that of uPA(-)/uPAR(+) HSAs and HA tissues (mean ± SDs 32.8 ± 15.3, 15.2 ± 7.2 and 2.1 ± 0.7, respectively; P <0.05). These results suggest that uPA and uPAR play a significant role in the malignant proliferation of canine HSA, regardless of the primary origin of the tumour.

Histopathological and immunohistochemical features of atypical epithelial tumours of the gland of the third eyelid in seven dogs.

This report documents the histopathological and immunohistochemical features of atypical epithelial tumours of the gland of the third eyelid (GTE) in seven dogs. Cases 1 and 2 were diagnosed as myoepithelioma, comprising of compressive proliferations of interlacing bundles of neoplastic spindle cells expressing cytokeratin 14, p63, calponin and α-smooth muscle actin. Cases 3, 4 and 5 were diagnosed as complex carcinomas comprising of atypical glandular cells expressing cytokeratin 8/18, together with spindle-shaped or round neoplastic cells expressing cytokeratin 14, p63, calponin and α-smooth muscle actin. Cases 6 and 7 were diagnosed as basal cell adenocarcinomas (BCACs) comprising of a mixed proliferation of glandular and basal-type cells expressing cytokeratin 14 and p63. Therefore, in addition to glandular components, these tumours may include neoplastic cells with a myoepithelial or basal cell phenotype. Hence, there is diversity in the features of epithelial neoplasia of the GTE in dogs, similar to tumours in human salivary and lacrimal glands.

Sarcocystis chloropusae (protozoa: Sarcocystidae) n. sp. from the common moorhen (Gallinula chloropus) from Egypt.

A new name Sarcocystis chloropusae is proposed for a parasite previously found in two of 25 common moorhen (Gallinula chloropus) from Brolos Lake, Egypt. Sarcocysts were microscopic, up to 650 µm long, the cyst wall was up to 4.5 µm thick, and contained villar protrusions that were up to 4 µm long and up to 2 µm wide. The villar protrusions were crowded, contained vesicles but lacked microtubules. The ground substance layer was smooth. The bradyzoites were up to 12 µm long and up to 2 µm wide. Molecular characterization and phylogenetic analysis of the (ITS-1) supported the conclusion that the Sarcocystis in G. chloropus is a distinct species.

Analysis of genomic mutation and immunohistochemistry of platelet-derived growth factor receptors in canine vascular tumours.

We examined whether mutation of the platelet-derived growth factor receptor protein tyrosine kinase (PDGFR)-α and PDGFR-ß genes contributes to their overexpression in canine vascular tumours. Genomic sequences of trans- or juxtamembrane regions of PDGFR-α and PDGFR-ß were analysed with immunohistochemical staining and polymerase chain reaction-direct sequencing using DNA from paraffin-embedded neoplastic tissues of 27 hemangiosarcomas (HSAs) and 20 hemangiomas (HAs). Immunohistochemically, 75% of the HA cases were positive for PDGFR-α and almost most of the HA cases were negative for PDGFR-ß. Of the HSA cases, 55.6% were negative for PDGFR-α and 63% were strongly positive for PDGFR-ß. Among the HA cases, 1 missense mutation was detected in PDGFR-α exon 18 and 1 in PDGFR-ß exon 17. Two HSA cases had missense mutations in exon 14 and 1 in exon 17 of PDGFR-ß. Thus, genomic mutation of trans- or juxtamembrane regions of PDGFRs was not the main mechanism driving the activation of receptors in HSA and HA.

Characterization of spontaneous malignant lymphomas in Japanese macaques (Macaca fuscata).

Lymphomas are common spontaneous tumors in nonhuman primates but remain poorly characterized in Japanese macaques (Macaca fuscata). This study examined 5 cases of spontaneous malignant lymphoma in Japanese macaques, focusing on the immunophenotypes and presence of simian lymphocryptoviruses, which are Epstein-Barr virus-related herpesviruses in nonhuman primates. The macaques with lymphoma were 5 to 28 years old, indicating that lymphomas develop over a wide age range. The common macroscopic findings were splenomegaly and enlargement of lymph nodes. Histologic and immunohistochemical analyses revealed that all cases were non-Hodgkin type and exhibited a T-cell phenotype, positive for CD3 but negative for CD20 and CD79α. The lymphomas exhibited diverse cellular morphologies and were subdivided into 3 types according to the World Health Organization classification. These included 3 cases of peripheral T-cell lymphoma, not otherwise specified; 1 case of T-cell prolymphocytic leukemia; and 1 case of an unclassifiable T-cell lymphoma. Positive signals were detected by in situ hybridization in 2 of the 4 examined cases using probes for the Epstein-Barr virus-encoded small RNA (EBER). Furthermore, the presence of M. fuscata lymphocryptovirus 2, a macaque homolog of Epstein-Barr virus, was demonstrated in EBER-positive cases by polymerase chain reaction amplification followed by direct sequencing. Immunohistochemistry using antibody to the Epstein-Barr virus-encoded nuclear antigen 2 was negative, even in the EBER-positive cases. The present study suggests that T-cell lymphoma is more common than B-cell lymphoma in Japanese macaques and that M. fuscata lymphocryptovirus 2 is present in some cases.

Pathological findings in equine herpesvirus 9-induced abortion in rats.

Pregnant rats were infected experimentally with equine herpesvirus (EHV)-9, a new neurotropic equine herpesvirus serologically similar to EHV-1, during the first and third trimesters. The inoculated dams had mild to severe neurological signs and gave birth to dead fetuses or undersized pups. Rats inoculated during the first and last trimesters had varying degrees of encephalitis as well as abnormalities of the placentas in the form of marked dilation of maternal blood sinusoids and varying degrees of atrophy and necrosis of the trophoblast cells of the labyrinth, the spongiotrophoblasts and the giant cell layer. Virus antigen was detected by immunohistochemistry in the brain and the trophoblast cells of labyrinth, the spongiotrophoblasts and giant cell layer of the placenta in rats inoculated during the first trimester. Virus antigen was detected in fetuses from rats inoculated in the first and last trimesters. Virus DNA was amplified by polymerase chain reaction from the placenta and fetuses of inoculated rats. EHV-9 may induce fetal death and abortion in pregnant dams, possibly caused by direct EHV-9 infection of the placenta and/or fetus as well as the secondary effect of vascular injury.

Mycobacterium marinum infection in Japanese forest green tree frogs (Rhacophorus arboreus).

Four Japanese forest green tree frogs (Rhacophorus arboreus) were presented with emaciation, abdominal distention and ulcerative and nodular cutaneous lesions affecting the brisket, limbs, digits and ventral abdomen. Another three frogs had been found dead in the same tank 1 year previously. Necropsy examination of these seven frogs revealed splenomegaly and hepatomegaly, with multiple tan-yellow nodular foci present in the liver, spleen, heart, lungs, ovaries and kidneys. Microscopically, five frogs had necrosis and surrounding granulomatous inflammation in the liver, spleen, kidneys, lungs, intestine and ovaries, with numerous acid-fast bacilli in the areas of necrosis. Two frogs had granulomatous lesions in the lungs, liver, spleen, heart, coelomic membrane, stomach and intestinal wall. These lesions had no or minimal necrosis and few acid-fast bacilli. Mycobacterium spp. was cultured from three frogs and identified as Mycobacterium marinum by colony growth rate and photochromogenicity and DNA sequencing. This is the first report of M. marinum infection in Japanese forest green tree frogs.

Elevated receptor for activated C kinase 1 expression is involved in intracellular Ca2+ influx and potentially associated with compromised regulatory T cell function in patients with asthma.

BACKGROUND: Regulatory T cells (T(regs)) are activated during anergy in response to T cell receptor (TCR) activation and functional immune suppression. Anergy of paediatric T(regs) is partially dependent on intracellular calcium mobility; following TCR activation, T(regs) do not exhibit increased intracellular Ca(2+) concentration ([Ca(2+) ](i)). OBJECTIVE: We determined whether [Ca(2+) ](i) in adult T(regs) defined their anergy, if intracellular Ca(2+) movement was linked to regulatory functions, whether [Ca(2+)](i) was indicative of asthma pathology, and the potential molecular mechanism responsible for Ca(2+) movement in T(regs). METHODS: T(regs) were purified by the magnetic bead method, and their regulatory functions were assessed by monitoring carboxyfluorescein succinimidyl ester-labelled responder T cell proliferation. The Ca(2+) response of Fura-2-labelled cells was measured using a video image analysis system. To analyse the functions of T(regs) at the molecular level, we generated Jurkat Tet-On(®) clones with doxycycline (Dox)-induced forkhead box P3 (FOXP3) protein expression. RESULTS: CD4(+) CD25(+) CD127(-/low) T(regs) from participants without asthma did not elicit Ca(2+) influx in response to TCR activation, exhibited little proliferation and suppressed proliferation of CD4(+) CD25(-) T cells. In contrast, under similar conditions, T(regs) from patients with asthma exhibited increased [Ca(2+)](i) and robust proliferation with partial loss of regulatory functions. FOXP3 protein levels in Tet-On(®) clones were high after both 2- and 5-day Dox treatment; however, 5-day cells were comparable with T(regs) from patients with asthma, whereas 2-day cells were similar to T(regs) from participants without asthma. Increasing [Ca(2+)](i) induced a high level of receptor for activated C kinase 1 (RACK1) expression in 5-day cells. CONCLUSIONS AND CLINICAL RELEVANCE: We confirmed that T(regs) in patients with asthma are functionally impaired and that the abnormal regulatory functions of these cells can be analysed by [Ca(2+)](i) following TCR engagement. Furthermore, the impaired functioning of T(regs) evident in patients with asthma may be due to a high level of RACK1.

Susceptibility of BALB/c-nu/nu mice and BALB/c mice to equine herpesvirus 9 infection.

This study aimed to clarify the timing and infectivity of equine herpesvirus 9 (EHV-9) infection in BALB/c-nu/nu mice and their immunocompetent counterpart (BALB/c). Following intranasal inoculation with 10(5) PFU of EHV-9, specimens from 8 mice per group were collected at different times postinoculation (PI) and assessed using histopathology, immunohistochemistry for viral antigen, and quantitative real-time polymerase chain reaction for ORF30 gene expression. In BALB/c-nu/nu mice, EHV-9 antigen was abundant in olfactory epithelia of all inoculated animals, and in the olfactory bulb of 1 animal. In contrast, only 1 BALB/c mouse per time point had rhinitis, with mild to moderate immunopositivity starting from 12 to 48 h PI, followed by a gradual virus clearance at 72 h PI. Statistically, significant differences were noted in the immunohistochemistry reactions between the 2 mouse strains, indicating that BALB/c-nu/nu is more susceptible to infection. Relative expression levels of ORF30 gene in olfactory epithelia were significantly different between the 2 groups, with the exception of 12 h PI, when BALB/c-nu/nu animals showed dramatic increases in ORF30 gene expression level until 48 h PI, followed by a decline in expression level until the end of experiment. In contrast, the expression level in brains showed no differences between mouse strain except at 96 h PI. In both strains, the highest messenger RNA expression was detected at 48 h PI, followed by a decline in BALB/c mice, proving a rapid clearance of virus in BALB/c and a gradual slowing down of the increased expression levels in BALB/c-nu/nu.

AA amyloidosis in vaccinated growing chickens.

Systemic amyloid-A (AA) amyloidosis in birds occurs most frequently in waterfowl such as Pekin ducks. In chickens, AA amyloidosis is observed as amyloid arthropathy. Outbreaks of systemic amyloidosis in flocks of layers are known to be induced by repeated inflammatory stimulation, such as those resulting from multiple vaccinations with oil-emulsified bacterins. Outbreaks of fatal AA amyloidosis were observed in growing chickens in a large scale poultry farm within 3 weeks of vaccination with multiple co-administered vaccines. This study documents the histopathological changes in tissues from these birds. Amyloid deposits were also observed at a high rate in the tissues of apparently healthy chickens. Vaccination should therefore be considered as a potential risk factor for the development of AA amyloidosis in poultry.

Validity of Three-Dimensional Photonic Scanning Technique for Estimating Percent Body Fat.

BACKGROUND: Three-dimensional photonic scanning (3DPS) was recently developed to measure dimensions of a human body surface. OBJECTIVE: The purpose of this study was to explore the validity of body volume measured by 3DPS for estimating the percent body fat (%fat). Design, setting, participants, and measurement: The body volumes were determined by 3DPS in 52 women. The body volume was corrected for residual lung volume. The %fat was estimated from body density and compared with the corresponding reference value determined by the dual-energy x-ray absorptiometry (DXA). RESULTS: No significant difference was found for the mean values of %fat obtained by 3DPS (22.2 ± 7.6%) and DXA (23.5 ± 4.9%). The root mean square error of %fat between 3DPS and reference technique was 6.0%. For each body segment, there was a significant positive correlation between 3DPS- and DXA-values, although the corresponding value for the head was slightly larger in 3DPS than in DXA. Residual lung volume was negatively correlated with the estimated error in %fat. CONCLUSIONS: The body volume determined with 3DPS is potentially useful for estimating %fat. A possible strategy for enhancing the measurement accuracy of %fat might be to refine the protocol for preparing the subject's hair prior to scanning and to improve the accuracy in the measurement of residual lung volume.

An ocular infection model using suckling hamsters inoculated with equine herpesvirus 9 (EHV-9): kinetics of the virus and time-course pathogenesis of EHV-9-induced encephalitis via the eyes.

By using a new member of the neurotropic equine herpesviruses, EHV-9, which induced encephalitis in various species via various routes, an ocular infection model was developed in suckling hamsters. The suckling hamsters were inoculated with EHV-9 via the conjunctival route and were sacrificed after 6, 12, 24, 36, 48, 72, 96, 120, and 144 hours (h) post inoculation (PI). Three horizontal sections of the brains, including the eyes and cranial cavity, were examined histologically to assess the viral kinetics and time-course neuropathological alterations using a panoramic view. At 6 to 24 h PI, there were various degrees of necrosis in the conjunctival epithelial cells, as well as frequent mononuclear cell infiltrations in the lamina propria and the tarsus of the eyelid, and frequent myositis of the eyelid muscles. At 96 h PI, encephalitis was observed in the brainstem at the level of the pons and cerebellum. EHV-9 antigen immunoreactivity was detected in the macrophages circulating in the eyelid and around the fine nerve endings supplying the eyelid, the nerves of the extraocular muscles, and the lacrimal glands from 6 h to 144 h PI. At 96 h PI, the viral antigen immunoreactivity was detected in the brainstem at the level of the pons and cerebellum. These results suggest that EHV-9 invaded the brain via the trigeminal nerve in addition to the abducent, oculomotor, and facial nerves. This conjunctival EHV-9 suckling hamster model may be useful in assessing the neuronal spread of neuropathogenic viruses via the eyes to the brain.

The class A macrophage scavenger receptor CD204 is a useful immunohistochemical marker of canine histiocytic sarcoma.

The immunohistochemical expression of the class A macrophage scavenger receptor CD204, was investigated in 50 canine histiocytic sarcomas (HSs) and compared with that of CD18, CD163, CD11d and class II molecules of the major histocompatibility complex (MHC). Expression of CD204 was also determined in 81 canine round cell tumours and pleomorphic sarcomas including T- and B-cell lymphomas, mast cell tumours, extramedullary plasmacytomas, cutaneous histiocytomas, transmissible venereal tumours, pigmented or amelanotic melanomas, poorly differentiated haemangiosarcomas and rhabdomyosarcomas. All of the 50 HSs expressed CD204, CD18 and MHC class II; 27 were positive for CD163 and seven expressed CD11d. All of the round cell tumours, except for one grade III mast cell tumour, were negative for CD204; however, they showed varying immunoreactivity patterns for CD18 and MHC class II. None of the pleomorphic sarcomas were immunoreactive for CD204. CD204 would appear to be a useful marker for canine HS.

Spontaneous T/NK-cell lymphoma associated with simian lymphocryptovirus in a Japanese macaque (Macaca fuscata).

A 5-year-old female Japanese macaque (Macaca fuscata) was humanely destroyed because of severe anaemia with poor response to treatment. At necropsy examination, marked splenomegaly and systemic enlargement of lymph nodes were observed. Microscopical examination revealed diffuse proliferation of neoplastic lymphoid cells in the spleen and lymph nodes with infiltration of the liver, lung, gastrointestinal tract, kidney and bone marrow. Immunohistochemically, the neoplastic cells expressed CD3 and CD4, but not CD20, CD79α or CD8, consistent with a T helper phenotype. A portion of neoplastic cells expressed the natural killer (NK) cell marker CD56. In-situ hybridization detected Epstein-Barr virus (EBV)-encoded small RNAs in the neoplastic cells, indicating the involvement of simian lymphocryptovirus (LCV). This is the first report of simian LCV-associated T/NK-cell lymphoma with the predominant expression of T-cell antigens in non-human primates.