Transfected Babesia bovis Expressing a Tick GST as a Live Vector Vaccine

The Rhipicephalus microplus tick is a notorious blood-feeding ectoparasite of livestock, especially cattle, responsible for massive losses in animal production. It is the main vector for transmission of pathogenic bacteria and parasites, including Babesia bovis, an intraerythrocytic apicomplexan protozoan parasite responsible for bovine Babesiosis. This study describes the development and testing of a live B. bovis vaccine expressing the protective tick antigen glutathione-S-transferase from Haemaphysalis longicornis (HlGST). The B. bovis S74-T3B parasites were electroporated with a plasmid containing the bidirectional Ef-1α (elongation factor 1 alpha) promoter of B. bovis controlling expression of two independent genes, the selectable marker GFP-BSD (green fluorescent protein–blasticidin deaminase), and HlGST fused to the MSA-1 (merozoite surface antigen 1) signal peptide from B. bovis. Electroporation followed by blasticidin selection resulted in the emergence of a mixed B. bovis transfected line (termed HlGST) in in vitro cultures, containing parasites with distinct patterns of insertion of both exogenous genes, either in or outside the Ef-1α locus. A B. bovis clonal line termed HlGST-Cln expressing intracellular GFP and HlGST in the surface of merozoites was then derived from the mixed parasite line HlGST using a fluorescent activated cell sorter. Two independent calf immunization trials were performed via intravenous inoculation of the HlGST-Cln and a previously described control consisting of an irrelevant transfected clonal line of B. bovis designated GFP-Cln. The control GFP-Cln line contains a copy of the GFP-BSD gene inserted into the Ef-1α locus of B. bovis in an identical fashion as the HIGST-Cln parasites. All animals inoculated with the HlGST-Cln and GFP-Cln transfected parasites developed mild babesiosis. Tick egg fertility and fully engorged female tick weight was reduced significantly in R. microplus feeding on HlGST-Cln-immunized calves. Collectively, these data show the efficacy of a transfected HlGST-Cln B. bovis parasite to induce detectable anti-glutathione-S-transferase antibodies and a reduction in tick size and fecundity of R. microplus feeding in experimentally inoculated animals.

The cattle tick Rhipicephalus microplus is a hematophagous ectoparasite, responsible for the transmission of lethal parasites such as Babesia sp, limiting cattle production in tropical and subtropical regions of the world. There is an urgent emerging need for improved methods of control for these currently neglected tick and tick borne diseases. It is hypothesized that a dual attenuated-live vector vaccine containing a stably transfected tick antigen elicits protective immune responses against the parasite and the tick vector in vaccinated cattle. Live Babesia vaccines based on attenuated parasites are the only effective method available for preventing acute babesiosis. On the other hand, glutathione-S-transferase from Haemaphysalis longicornis (HlGST) is a known effective antigen against Rhipicephalus microplus, the most common vector for B. bovis. This study describes the development and testing of a transfected, B. bovis vaccine expressing HlGST against the tick R. microplus. A B. bovis clonal line designated HlGST-Cln expressing HlGST and GFP/BSD, and separately a control transfected B. bovis clonal line expressing only GFP/BSD was used to vaccinate calves in two independent experiments. All immunized calves developed mild babesiosis, and only calves immunized with the HlGST-Cln parasite line generated anti-HlGST antibodies. Tick egg fertility and fully engorged female tick weight were reduced significantly in R. microplus feeding on HlGST-Cln-vaccinated calves. Taken together, these data demonstrates the ability of transfected B. bovis to elicit antibodies against a heterologous tick antigen in cattle and to induce partial protection in the vaccinated animals against the cattle tick for the first time, representing a step toward the goal to produce a live vector anti-tick vaccine.

Intracranial Transitional Meningioma in a Cat

Background: Meningioma is a tumor that is usually attached to the dura mater. It typically arises from the meningothelial cell of the arachnoid or pia mater. Considered an extra-axial tumor of the central nervous system which can occur on any region of the meninges. The biological behavior tends to be benign and usually is not infiltrative allowing surgical indication, conferring to the patient a better prognosis. Geriatric patients are the most affected and there is no breed predisposition. This paper describes the clinical signs, pathological findings, and immunohistochemical features of a case of transitional meningioma in a cat.Case: A 14-year-old, neutered male mongrel cat was referred to the Veterinary Clinic Hospital. The history was that the cat had anorexia and disorientation. On the day of admission, lethargy and blindness were observed. Full complete blood counts showed leukopenia and lymphopenia. The serum biochemistry tests were unspecific. Thoracic and skull radiographs and ultrasound examination revealed no abnormalities. The cat was hospitalized and the main treatment was based on antibiotics and corticosteroids. The cat tested negative for FIV and FeLV. Toxoplasma gondii serum antibodies were not detected using indirect fluorescent antibody test performed with a commercial kit. The clinical signs progressed to walking in circles, stumbling, wandering, anisocoria, and stupor. On the eleventh day the cat died during hospitalization. The cat was submitted for routine post-mortem examination revealing a rounded mass involving the right occipital cortex and the cerebellum, easily separable from the brain parenchyma. In the brainstem there were moderate diffuse congestion, perivascular edema, and moderate multifocal areas of necrosis, and hemorrhage. Histological examination revealed neoplastic cells sit in tight little whorled clusters, sometimes elongated with abundant collagen intermingled. Sections from the tumor underwent immunohistochemical evaluation for glial fibrillary acidic protein (GFAP), S100, cytokeratin, and vimentin. There was immunoexpression only of vimentin. The diagnosis of transitional meningioma was established from the pathologic features and confirmed by positive staining of vimentin antibody.Discussion: The animals affected by brain tumors present a series of poorly defined or mild neurological signs. Unfortunately, evaluation of cerebrospinal fluid is neither sensitive nor specific test for the diagnosis of meningiomas in dogs and cats. Computed tomography and magnetic resonance imaging are considered the main diagnostic tools available for ante-mortem investigation of several types of brain tumors, but they are also expensive and difficult to obtain in veterinary medicine. The neurosurgery related morbidity and mortality limits the biopsy and surgical treatment to veterinary centers with highly qualified and advanced anesthesia techniques and critical care. In Brazil, there is no report of transitional meningiomas in cats and there are a few controlled studies to better insight into the biological behavior of intracranial neoplasms, prognosis and therapeutic procedures in cats. The meningioma should be included in the differential diagnosis of patients with clinical signs of intracranial diseases. However, as the difficulty of performing imaging tests specific prevents the antemortem diagnosis, definitive diagnosis is restricted, in most cases, to necropsy and histopathology.Keywords: brain tumor, feline, intracranial tumor.

Autochthonous Canine Visceral Leishmaniasis in Urban Area of Porto Alegre, RS, Brazil

Background: Leishmaniasis is a chronic infectious disease caused by intracellular protozoan Leishmania that affects canine and human. The visceral leishmaniasis (VL) is caused by the Leishmania donovani complex, in which canines are the main reservoir for human VL. In Southern Brazil, case reports of this disease have increased, especially when canines are infected in endemic areas in the country. Canines usually present a systemic disease, characterized by cutaneous lesions, weight loss, generalized lymphadenopathy, hepatomegaly and splenomegaly. This report aims to describe the clinicalpathological features of a case of autochthonous VL in a canine of an urban area of Porto Alegre.Case: A male, mixed breed, dog , 7 year-old, resident at the East Side of Porto Alegre, living together with two other canines, presented at clinical examination progressive weight loss, associated with hyporexia and hyperthermia, evolving to lateral recumbency, paralisys, and death. At necropsy, the dog was cachectic with diffusely pale mucosae. Gross findings included liver enlarged, with multifocal firm brownish areas, spleen enlarged, showing multifocal firm round dark-red areas, and kidneys diffusely pale with evidentiated tranversal striations on cortical zone. At microscopic examination, there was on the spleen diffuse inflammatory infiltrate of macrophages with large cytoplasm containing multiple amastigotes. The liver, exhibited atrophy of hepatocytes and moderate multifocal inflammatory infiltrate in sinusoids of macrophages containing multiple amastigotes. These features were also observed moderately on lymph nodes and lamina propria of large intestine. Immunohistochemistry examination showed marked positive staining for Leishmania spp. in amastigotes located whitin the cytoplasm of macrophages of spleen, liver, lymph nodes and large intestine.Discussion: Canine leishmaniasis is a disease that affects both internal organs and skin. However, the condition is called VL mostly because it is associated with the same species that cause the visceral form in humans. In this case the canine presented liver, spleen and lymph node lesions; however no skin lesion was observed during the clinical examination. A serological evaluation of canids in East Side of Porto Alegre performed in 2005 showed that 3.5% of these dogs were positive for Leishmania; yet neither of these animals presented clinical signs. This demonstrates that the agent was already present, however only 3-10% of the canines infected develop clinical disease. In non-endemic areas VL is related to the migration of canids from endemic areas, where VL is common. However the canine here described was born, raised, and was living in Porto Alegre. Lutzomyia longipalpis is the main vector of VL and despite its wide distribution it was identified only in 2009 in Rio Grande do Sul State. Autochthonous cases of VL were reported in canines and humans in this state, confirming the hypothesis that the vector was widely distributed and it is now present in Porto Alegre, keeping the epidemiological cycle of that disease active. Canine VL occurs prior in humans, since canines are the main domestic reservoirs and are critical for the maintenance of this disease cycle. This is the first autochthonous VL in a canine of an urban area of Porto Alegre; therefore authorities should be alert, and new control measures must be taken to avoid the canine leishmaniasis outbreak due to its potential for zoonotic transmission.Keywords: leishmaniasis, canine, protozoan, immunohistochemistry.

Anesthetic Management of an Orange-Spined-Hairy-Dwarf-Porcupine (Sphiggurus villosus) Undergoing Myelography

 Background: The orange-spined hairy dwarf porcupine (Sphiggurus villosus) is a mammal that belongs to the rodentia order. Accidents involving this porcupine and dogs have become usual in some cities of Brazil. Dog bites may eventually result in spinal injuries. When there is clinical evidence of spinal cord injury, a myelography under general anesthesia may be required to allow identification of the exact location of the injury. To the authors’ knowledge, there is only one case report about anesthesia in Sphiggurus villosus where dissociative anesthesia was employed. This paper describes one case report of inhalation anesthesia with isoflurane in a Sphiggurus villosus undergoing myelography.Case: A 1.6 kg orange-spined hairy dwarf porcupine, with a history of dog bite was referred to the Veterinary Hospital of the University. On clinical examination, the patient was in good physical condition, alert, with an approximately 1-cm injury near the 10th and 11th thoracic vertebrae. Nociception in pelvic limbs was present whereas proprioception was absent. Radiographic examinations were suggestive of vertebral dislocation and fracture between the 10th and 11th thoracic verte­brae. A myelography was then requested by the responsible veterinarian. The porcupine received intramuscular midazolam (0.5 mg/kg) in combination with meperidine (10 mg/kg) as premedication. Anesthesia was induced and maintained with isoflurane in 100% oxygen via a face mask connected to a non-rebreathing circuit. Monitored variables at 5-min intervals included: pulse rate (PR) and systolic arterial blood pressure (SAP) measured by a Doppler ultrasound with its probe positioned at the palmar metacarpal artery; pulse oximetry (SpO2) measured by a sensor positioned at the tarsus; rectal temperature; and respiratory rate (RR). During the myelography, the range of values for the above mentioned variables were: PR, 189-206 beats/min; SAP, 90-130 mmHg; SpO2, 94-96%; RR, 32-40 breaths/min; and rectal temperature decreased by 0.5oC. Anesthetic recovery was uneventful. Postoperative pain relief was achieved with intramuscular tramadol (5 mg/kg).Discussion: To the authors’ knowledge, this is the first case report of inhalation anesthesia in a Sphiggurus villosus speci­men. In a previous case report, other authors described anesthesia for myelography in a porcupine with IM tiletamine/ zolazepam (5 mg/kg). In the case reported here, dissociative anesthetics, such as tiletamine, were avoided because these agents may increase intracranial pressure, cerebral blood flow and cerebrospinal fluid pressure, which are undesirable in patients with spinal trauma. Although physiologic variables were considered to be stable during anesthesia with isoflurane in this report, these findings have to be interpreted carefully. First, normal range of values for physiologic variables has not been reported for porcupines. Second, accuracy of the measurement techniques used (e.g. noninvasive measurement of SAP) has not been validated. Under the conditions reported in this case report, premedication with meperidine and mid­azolam was effective to induce good muscle relaxation and allowed anesthetic induction with isoflurane via a face mask. This anesthetic protocol provided adequate conditions for performing the myelography in a porcupine and physiologic variables remained stable throughout the procedure.Keywords: rodents, anesthesia, spinal trauma.