Luis Gustavo Corbellini

Otimização da imunoistoquímica para detecção de herpesvírus bovino tipo 5 (BHV-5) em tecidos do sistema nervoso central fixados com formaldeído

In order to optimize immunohistochemical technique (IHC) for detection of Bovine herpesvirus type 5 (BHV-5) on formalin-fixed sections of central nervous system, different methods of enzymatic digestion, use of different antibodies and products for blocking of nonspecific reactivity were evaluated. The reactions showed the highest intensity of specific coloration and the minimum amounts of background when protease from Streptomyces griseus (0.1%) or proteinase K from Tritirachium album limber (0.05%) were used, incubating for 15 minutes at 37°C. Only two of the tested monoclonal antibodies specifically labelled BHV-5 antigen. The nonspecific reactions were blocked through incubation of tissues with casein (0.5%) for five minutes or powdered milk (2.5%) for 60 minutes or equine serum (2.5%) for 60 minutes. The optimized immunohistochemical method allowed the detection of BHV-5 antigen in histopathological archives.

Neosporosis as a cause of abortion in dairy cattle in Rio Grande do Sul, southern Brazil

Forty-six aborted bovine fetuses submitted to the Faculty of Veterinary, Department of Clinical Pathology, Universidade Federal do Rio Grande do Sul, were examined histopathologically. Non-suppurative inflammation was observed mainly in the brain and heart of 22 fetuses. Brain lesions consisted primarily of mononuclear inflammatory cell infiltrates with occasional foci of necrosis. Protozoa that reacted with Neospora caninum antisera were seen in 18 of the 22 (81.8%) brain specimens from fetuses with encephalitis. Blood samples collected from 223 Holstein cows on five dairy herds were tested for N. caninum antibodies by an immunofluorescent antibody technique. These samples were obtained from aborting cattle and normally calving cattle (control group). Overall, 11.2% of cows sampled had N. caninum antibodies at a dilution of 1:200. Seroprevalence was higher (P = 0.0053) in aborting (23.3%) than in non-aborting cows (8.3%). Association between seropositivity to N. caninum and abortion was found, with seropositive cows being 3.3 times more likely to abort than seronegative cows (OR = 3.33; 95% CI: 1.38, 8.062). Additionally, N. caninum antibodies were detected in sera from seven cows that had aborted fetuses with lesions suggestive of protozoal infection. These results suggest that N. caninum is an important cause of abortion in dairy cattle in Rio Grande do Sul State, Brazil.

Granulomatous encephalitis in a neurologically impaired goat kid associated with degeneration of Neospora caninum tissue cysts.

Congenital Neospora caninum infection was diagnosed in a Saanen goat from a farm in southern Brazil. The kid was unable to nurse and had difficulty rising, ataxia, and opistothotonos. The neurologic signs became more severe 3 days after birth, when it was euthanized. No gross lesions were observed at necropsy. Multifocal infiltrates primarily of mononuclear cells, nodular microgliosis, and perivascular cuffs of lymphocytes, plasma cells, and few neutrophils were observed in the brain, mostly in the cortex and adjacent to ventricles. Rare multinucleate giant cells were observed adjacent to inflammatory foci. Several tissue cysts with a thick wall that reacted strongly with polyclonal antiserum to N. caninum were in the cerebral cortex and medulla oblongata. Lesions were also present in heart, lungs, and liver, but N. caninum tachyzoites were not found. Distinguishing features in this goat kid included neurologic impairment resulting from congenital infection with N. caninum and the presence of granulomatous inflammation with rare giant cells associated with degeneration of tissue cysts.

Typing of canine parvovirus strains circulating in Brazil between 2008 and 2010.

Abstract Detection and characterisation of the canine parvovirus (CPV-2) strains that are currently circulating are essential for the understanding of viral evolution and the development of measures to control its spread. In the present study, stool samples from 144 dogs were analysed by polymerase chain reaction (PCR) for CPV-2, and 29.2% (42/144) of them were positive. From the 42 positive strains, 71.4% (30) of the dogs had signs of haemorrhagic gastroenteritis. The sequencing of the 583bp fragment of the VP2 gene from the positive strains identified 78.6% (33/42) of them as type 2c, 19% (8/42) as type 2b and 2.4% (1/42) as type 2a. A phylogenetic analysis of the variants circulating in the canine population of Brazil showed that they are very similar to those found in other countries and type 2c has become the predominant type circulating in Brazil.

Bovine Mastitis due to Prototheca zopfii: Clinical, Epidemiological and Pathological Aspects in a Brazilian Dairy Herd

The clinical, epidemiological and pathological aspects of protothecal mastitis in a Brazilian dairy herd are described. Prototheca zopfii infection was diagnosed in 11 of 121 milking cows. Clinical mastitis refractory to usual therapy was observed in 7 cows. Several environmental conditions conducive to the growth of Prototheca spp., such as wetness, muddiness and the presence of organic material, were present in the dairy. Improper milking practices and insanitary infusion of the intramammary antibiotics were also observed. Six cows with protothecal mastitis were slaughtered and the affected quarters of each cow were examined by histology and immunohistochemical staining for bovine keratin and P. zopfii. The histological lesions were characterized by interstitial infiltrates of macrophages, plasma cells and lymphocytes; algae were seen in the alveolar lumen and interstitium. The lack of a positive reaction with an antiserum against bovine keratin in the mammary alveolar epithelial layer in some affected areas suggests destruction of milk-producing tissues, which may be related to the low milk production observed. The algal organisms stained positively with a polyclonal antibody against P. zopfii.

Herd-level risk factors for bovine viral diarrhea virus infection in dairy herds from Southern Brazil.

A cross-sectional study was carried out to identify risk factors for bovine viral diarrhea virus (BVDV) infection in 300 randomly selected dairy herds which were tested for antibodies in bulk tank milk (BTM) using a commercial indirect ELISA kit (SVANOVA). Results from the analysis were interpreted according to the Swedish BVDV control scheme. The testing revealed 129 (43%) BTM BVDV antibody-positive herds. Use of artificial insemination (AI) and herd size were significantly associated with BVDV serological status (P<0.05). Dairy herds that use AI had 2.82 increased odds of BVDV-seropositivity (95% CI: 1.02-7.24). Since the semen used in the studied population come from known selected sires, it was hypothesized that AI technicians should represent an important risk factor because the increasing number of visitors in the farm can introduce the virus through the clothes, shoes and contaminated equipment.

Longitudinal dissemination of Salmonella enterica clonal groups through the slaughter process of Salmonella-positive pig batches.

This study was conducted to assess the dissemination of Salmonella clonal groups in slaughterhouses that received batches of Salmonella -positive pigs and used different routine processing procedures. Eight serial sampling sessions were conducted in three slaughterhouses (A, B, and C). Blood was collected randomly (n = 25) from each batch of pigs and processed for serology. Carcasses (n = 12) were identified and sampled after dehairing, after singeing, after evisceration, and before chilling. A section of cecum also was collected. Salmonella isolates were submitted to pulsed-field gel electrophoresis. The overall seroprevalence of Salmonella was 80.6% (316 of 392 samples), and cecal contents were positive for Salmonella in 23.8% (26 of 109) of the pigs sampled. Carcasses after dehairing had a significantly higher prevalence of Salmonella (P = 0.004) and the highest Salmonella levels (median = 0.26 log CFU/300 cm(2)). The singeing step significantly affected the Salmonella status of the carcasses (P = 0.001); however, the efficacy of singeing differed among slaughterhouses. In the prechilling step, 14.7% (16 of 109) of the carcasses were positive for Salmonella. Salmonella pulsotypes found on the prechill carcasses were also found in the lairage, in the cecal contents, and on carcasses after dehairing, suggesting that the main source of contamination was the slaughter process before singeing. Slaughterhouse C was the most likely (odds ration [OR] = 6.51) to have pigs carrying Salmonella in the gut, and slaughterhouse B was the most likely (OR = 14.66) to have contaminated carcasses at the prechilling step. These findings indicate that the procedures adopted in slaughterhouse B contributed to the spread of Salmonella strains. In contrast, in slaughterhouse C the Salmonella strains carried by the pigs or found in the lairage were not recovered from prechilled carcasses, validating the effectiveness of the slaughterhouse interventions. These results indicate that an effective slaughter process can help decrease the number of Salmonella-positive carcasses in slaughterhouses that receive Salmonella-positive pig batches.

Perdas reprodutivas associadas com infecção por Toxoplasma gondii em caprinos no sul do Brasil

Toxoplasma gondii was implicated with reproductive losses in a goat herd in Rio Grande do Sul, Brazil. Gross changes were present in 2 out of 6 fetuses/offsprings submitted for diagnosis and included enlarged, pale mesenteric lymph nodes, and edematous, mottled red and tan lungs. Microscopic changes were observed in most fetuses and were especially characterized by lymphoplasmacytic infiltration in the brain and lungs. Other histological changes included lymphoplasmacytic interstitial nephritis, necrotizing lymphadenitis and periportal lymphoplasmacytic cell infiltrates. While bacteriological and direct immunofluorescent antibody tests for Leptospira sp. were negative in samples from all cases, immunohistochemical and PCR procedures for Toxoplasma gondii reacted positively in most of them. Antibody titles against T. gondii varying from 1:512 to 1:2048 were detected in serum samples from the mother goats of these aborted (1), stillborn (3) or dead newborn (2) kids. This paper describes the clinical, pathological, serological, molecular and immunohistochemical findings of a Toxoplasma gondii-infected goat flock.

Co-infection of Pneumocystis carinii f. sp. suis and porcine circovirus-2 (PCV2) in pig lungs obtained from slaughterhouses in southern and midwestern regions of Brazil.

EDNA M. CAVALLINI SANCHES, MAURO R. BORBA, ANDRÉIA SPANAMBERG, CAROLINE PESCADOR, LUÍS G. CORBELLINI, ANA P. RAVAZZOLO, DAVID DRIEMEIER and LAERTE FERREIRO Sections of Veterinary Mycology, Departamento de Patologia Clı́nica Veterinária, Faculdade de Veterinária, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9090, 90540-000, Porto Alegre, RS, Brazil, and Sections of Pathology, Departamento de Patologia Clı́nica Veterinária, Faculdade de Veterinária, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9090, 90540-000, Porto Alegre, RS, Brazil, and Sections of Immunology, Departamento de Patologia Clı́nica Veterinária, Faculdade de Veterinária, Universidade Federal do Rio Grande do Sul (UFRGS), Av. Bento Gonçalves 9090, 90540-000, Porto Alegre, RS, Brazil

Bovine digital dermatitis in southern Brazil

near the heel bulbs (WVeaver and others 1981, Blowey and Sharp 1988, Read 1994). The disease was first described in Italy by Cheli and Mortellaro (1974). Since then, digital dermatitis and a similar condition named papillomatous digital dermatitis have beeni reported worldwide (Peterse 1986, Blowey and Sharp 1988, Van Amstel and others 1991, Read and others 1992, Rodriguez-Lainz and others 1999). Lately, both designations appear to represent the same disease complex, which in the USA is also known as footwarts, hairy footwarts, heel warts and strawberry foot disease (Read 1994, Read and Walker 1998). The rapid therapeutic response following topical treatment with antibiotics in most affected animals supports the involvement of bacterial species in the development of the disease (Read and others 1992, Read and Walker 1998). In addition, several bacterial agents, including spirochaetes related to human treponemes (Blowey and others 1992, Read and others 1992, Walker and others 1995, Dopfer and others 1997), Bacteroides species (Peterse 1986, Blowey and Sharp 1988) and Catinpylobacter species (Dopfer and others 1997, Ohya and others 1999), have been implicated in the aetiology of digital dermatitis. Outbreaks of the disease have mainly been reported in housed cattle (Peterse 1986, Blowey and Sharp 1988, Bassett and others 1990, Bergsten and others 1998, Read and Walker 1998, Rodriguez-Lain7z and others 1999) suggesting that environmental or biological factors associated with those systems of managenment may be important risk factors (RodriguezLainz and others 1996, 1999). Typical lesions have been described as red in colour, circular to oval in shape, alopecic, prone to bleeding, moist and painful to the touch. Larger ulcerative lesions or characteristic raised proliferative processes are associated with later stages of the disease (Blowey and Sharp 1988, Bassett and oth-