Characterization of a spontaneous cyst-forming strain of Toxoplasma gondii isolated from Tokachi subprefecture in Japan.

Apicomplexan parasite Toxoplasma gondii has three distinct clonal lineages: high, medium and low virulent strains, type I, II and III, respectively. T. gondii avoids the immune response by transforming from fast multiplying tachyzoite to slow multiplying bradyzoite, and establishing a chronic infection. In the present study, we isolated a new strain of T. gondii from cat feces in the Tokachi subprefecture, Hokkaido, Japan and named it as TgCatJpObi1 (Obi1) strain. Genotyping analysis of 12 loci revealed atypical characters close to type II, genotype 4 according to ToxoDB classification. Phenotypically, Obi1 strain shows slow growth rate and the ability of spontaneous cyst formation in both human foreskin fibroblast (HFFs) and mouse peritoneal macrophages in vitro without bradyzoite induction. Parasite virulence was assessed by means of mouse survival upon infection with either Obi1 or ME49 strains. Obi1 strain displayed no mortalities in comparison to type II clonal lineage, ME49 at LD50 to LD100 range (1 × 103-106 tachyzoites). Although virulence of Obi1 strain is significantly lower than that of ME49, nucleotide sequences analyses revealed that genes of virulence factors such as Gra15, Rop5, 16, 17, and 18 in Obi1 strain were 100% identical to those in the type II strain. Thus, characterization of a newly isolated strain, Obi1, is crucial to clarify the development of toxoplasmosis in both humans and animals.

Pilot study on serum C-reactive protein in pet rabbits: clinical usefulness.

OBJECTIVES: The present study was performed to evaluate the usefulness of serum C-reactive protein (CRP) as an acute phase reactive protein in pet rabbits in clinical practice. METHODS: The CRP level using a rabbit CRP ELISA and white blood cell (WBC) count in pet rabbits (30 healthy controls and 62 with various diseases) were measured in the clinical practice setting. The CRP level and WBC count were measured before and after ovariohysterectomy of a healthy rabbit and a rabbit with uterine adenocarcinoma. The association between the CRP level and mortality in rabbits with various diseases was assessed. RESULTS: The CRP level in healthy controls was 0.52±0.82 mg/dl (mean±SD). No age and sex-related differences in neither the CRP level nor WBC count were observed in the healthy control rabbits. The CRP levels in rabbits with gastrointestinal disease (n=22, 11.74±22.89 mg/dl), reproductive and urinary system disease (n=20, 21.19±49.68 mg/dl), dental disease (n=6, 4.87±5.47 mg/dl) and musculoskeletal disease (n=4, 85.66±107.28 mg/dl) were significantly higher than those in healthy controls. The CRP levels in rabbits with neurological disease (n=7, 2.55±1.79 mg/dl) and dermatological disease (n=3, 8.84±7.71 mg/dl) were higher than those in healthy controls, but no significant difference was observed. The WBC counts were not significantly different between rabbits with diseases and healthy controls. Serum samples were collected from two rabbits before and after ovariohysterectomy. In both rabbits, the CRP peaked on postoperative day 1, but no obvious WBC peak was observed. The mortality rate increased as the CRP level increased; the mortality rate was significantly higher in rabbits with a CRP level of ≥100 mg/dl than of <10 mg/dl. CONCLUSIONS: This study indicates that the serum CRP level is useful to determine the disease status, monitor the treatment course and evaluate the prognosis in pet rabbits in clinical practice.

Lissencephaly in a Pekingese.

A 1-year-old neutered male Pekingese was presented for evaluation and further treatment of cluster seizures. The dog had behavioral abnormalities, and a prosencephalic lesion was suspected following neurological examination. The dog showed signs of learning difficulty. Magnetic resonance imaging of the brain revealed a remarkably smooth cerebral cortex with a reduced number of gyri, as well as a cystic lesion associated with the quadrigeminal cistern. A diagnosis of lissencephaly, concurrent with a quadrigeminal cisternal cyst, was made. High-dose and multiple anticonvulsants were necessary to control the seizures. This is the first report of lissencephaly in a Pekingese.

Seroprevalences of Toxoplasma gondii and Neospora caninum in pet rabbits in Japan.

The potential contamination of Toxoplasma gondii and Neospora caninum oocysts in the human environment is a concern from the public health viewpoint. However, estimation of their seroprevalences in humans cannot be performed in a manner that distinguishes between oocysts and tissue cysts as a source of infection. Rabbits are considered popular pet animals in Japan that can acquire natural infections by the aforementioned parasites only through the ingestion of oocysts. Therefore, this study was conducted to estimate the seroprevalences of T. gondii and N. caninum in pet rabbits in Japan as an indicator of the possible oocyst contamination in the environment surrounding human beings. Serum samples of 337 rabbits were examined by different serological methods. Enzyme-linked immunosorbent assays were performed to measure the titer of IgG and IgM antibodies. Samples revealed to be seropositive by ELISA were further analyzed by a latex agglutination test, Western blotting and an indirect immunofluorescence assay. The rates of seropositivity for T. gondii were 0.89% (3/337) and 0.29% (1/337) in IgG and IgM ELISA, respectively. SAG1 and SAG2 were detected as major antigens by the positive rabbit sera in Western blotting associated with strong staining observed by IFA in T. gondii tachyzoites. Regarding N. caninum, none of the serum samples showed a specific reaction in both Western blotting and the IFA. The results of this study indicate low seroprevalences of toxoplasmosis and neosporosis in pet rabbits in Japan, suggesting low oocyst contamination in the human environment.

Chronic progressive polyarthritis in a female cat.

Feline chronic progressive polyarthritis is a rare immune-mediated disease that has only previously been reported in male cats. A one-year-old female cat was presented with anorexia, lassitude and lameness. The tarsal, carpal and elbow joints revealed swelling, pain, stiffness, crepitus and regional lymphadenopathy, and fever was present. The cat was clinically diagnosed with chronic progressive polyarthritis based on the fever, swelling of joints, imaging of erosive proliferative periosteal polyarthritis, positivity for antinuclear antibody, synovial fluid analyses and urinalyses. Both feline leukemia virus antigen and feline immunodeficiency virus antibody were positive. Using hair root DNA, polymerase chain reaction amplification targeting the sex-determining region on the Y chromosome gene amplified the fragment of DNA from a normal male cat, but not amplified from a normal female cat or the present cat. Accordingly, the present cat was classified as genetically female. Cyclosporine treatment was started, and the general condition and movement quickly improved and continued for 8 months post-diagnosis. This is the first report of chronic progressive polyarthritis in a female cat.

Mammary adenocarcinoma in a chipmunk (Tamias sibiricus).

An 8-year-old, female chipmunk (Tamias sibiricus), which had been kept as a pet, was presented with a chief complaint of the gradually enlarging mammary mass and dysuria. The mammary mass was surgically excised and was histopathologically diagnosed as mammary adenocarcinoma. Despite a general improvement in its condition and reduced dysuria after surgery, the chipmunk died on postoperative day 188. Pathological examination revealed that the mammary tumor had metastasized to both the lungs and the pelvic cavity. The metastatic focus in the pelvic cavity involved the left ureter, with ipsilateral hydronephrosis. Immunohistochemically, the tumor cells were stained positive for cytokeratin (CK) AE1/AE3 and partially positive for CK7, but negative for CK20. This is the first report of a mammary tumor in chipmunks.