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Rats (n=40) aged 8 weeks were infected, either by oronasal inoculation or by contact, with one of two different myocardial strains of encephalomyocarditis virus (EMCV), namely, the Greek strain 424/90 and the Belgian strain B279/95. The animals were killed at 11-62 days post-infection (dpi) and samples of brain, heart, pancreas, kidney, Peyer's patches, spleen, lung and thymus were processed for virological, histopathological and immunohistochemical evaluation. This experimental infection was inapparent, but virus was isolated from faeces and several organs of all animals. The main histopathological changes were focal interstitial pancreatitis, degeneration and necrosis of pancreatic acinar cells, depletion of thymus and Peyer's patches, and interstitial pneumonia. EMCV antigen was detected in the cytoplasm of cardiac muscle cells, pancreatic acinar cells and hepatic epithelial cells, and in macrophages of the spleen, lung and thymus. In the heart (the target organ of EMCV in pigs), the presence of EMCV in cardiac muscle cells without lesions lends support to the hypothesis that the rat is a natural reservoir host species of EMCV. The persistence of virus in the macrophages of the thymus may represent a mechanism of perpetuation and reactivation, under immunosuppressive conditions, of the infection.

Summary Histopathological and immunohistochemical examinations were performed on the brain and spinal cord of 37 goats from two Greek herds in which scrapie had been reported. Of the 37 animals, 18 were from a herd consisting only of goats and 19 were from a herd of goats mixed with sheep. The goats studied were grouped on the basis of the presence or absence of clinical signs. Distinctive lesions and PrP sc (PrP, prion protein) deposition were found in the central nervous system (CNS) of eight clinically affected animals and six symptomless animals. The lesion profile and PrP sc distribution varied both between and within groups, variation being particularly pronounced in the symptomless goats. The results concerning the latter group suggested a poor correlation between the intensity of lesions, the amount of PrP sc in the CNS, and the manifestation of clinical signs. Immunohistochemical examination revealed 10 different PrP sc types, four of which are reported for the first time in goats. All scrapie-affected animals carried the VV 21 II 142 HH 143 RR 154 genotype, with the exception of two goats that carried the HR 143 dimorphism and had detectable PrP sc deposits. The results suggest that the histopathological and immunohistochemical profile of the natural disease in goats is influenced by the PrP genotype and age of the animals but may not be directly associated with the presence or otherwise of clinical signs.

Six piglets aged 20 days were inoculated oranasally with 5 ml of a suspension (106 TCID50/ml) of a Greek myocardial strain of encephalomyocarditis virus (EMCV). The animals either died (n=2) or were killed for examination on days 1,2 or 3 post-inoculation (pi). EMCV was isolated from virtually all organs examined (heart, tonsils, palatine glands, pancreas, spleen, small intestine and mesenteric lymph nodes). Histopathologically, interstitial myocarditis, necrosis of cardiac muscle cells and Purkinje fibres, and necrotizing tonsillitis were detected in all inoculated piglets. Focal interstitial pancreatitis, necrosis of pancreatic acinar cells and Langerhans islet cells, and necrosis of germinal centre lymphocytes of the lymph nodes and Peyer's patches were detected in two piglets that died or were killed on day 3 pi. Immunohistochemically, viral antigen was detected in epithelial cells of all organs examined, including the tonsils, palatine glands, pancreatic interlobular ducts and small intestine. This suggests that EMCV is epitheliotropic, in addition to its known myocardial tropism. The frequent presence of intracytoplasmic EMCV in macrophages of the tonsils and spleen supports the hypothesis that macrophages play a role in viral replication and dissemination in the body.

The brain and spinal cord of 48 goats from two Greek herds in which scrapie had been reported were examined. All animals were symptomless at the time of euthanasia. Notably, no lesions were observed either at the level of the obex or at other regions of the brain and spinal cord. Immunohistochemical examination revealed PrPsc labelling of the linear and fine punctuate types, mainly in the cerebral cortices, of 36 goats. Twenty-seven of them were negative by ELISA (designed to detect proteinase-resistant PrP) at the level of the obex but positive in a pooled brain sample, and the majority carried PrP genotypes associated with scrapie susceptibility. Surprisingly, in 16 of the 27 animals, PrPsc deposits were detected only in the rostral parts of the brain. In addition, nine animals which were ELISA-positive at the level of the obex exhibited positive immunoreactivity, but not in the dorsal vagal nucleus. The findings indicate that this unusual scrapie type may have been underdiagnosed previously and may be of importance in scrapie surveillance programmes.

Rats (n=40) aged 8 weeks were infected, either by oronasal inoculation or by contact, with one of two different myocardial strains of encephalomyocarditis virus (EMCV), namely, the Greek strain 424/90 and the Belgian strain B279/95. The animals were killed at 11-62 days post-infection (dpi) and samples of brain, heart, pancreas, kidney, Peyer's patches, spleen, lung and thymus were processed for virological, histopathological and immunohistochemical evaluation. This experimental infection was inapparent, but virus was isolated from faeces and several organs of all animals. The main histopathological changes were focal interstitial pancreatitis, degeneration and necrosis of pancreatic acinar cells, depletion of thymus and Peyer's patches, and interstitial pneumonia. EMCV antigen was detected in the cytoplasm of cardiac muscle cells, pancreatic acinar cells and hepatic epithelial cells, and in macrophages of the spleen, lung and thymus. In the heart (the target organ of EMCV in pigs), the presence of EMCV in cardiac muscle cells without lesions lends support to the hypothesis that the rat is a natural reservoir host species of EMCV. The persistence of virus in the macrophages of the thymus may represent a mechanism of perpetuation and reactivation, under immunosuppressive conditions, of the infection.

Seven 40-day-old piglets were inoculated with encephalomyocarditis virus (EMCV) strain 424/90, isolated from an outbreak of the myocardial form of the disease in Greece. Two non-infected animals were used as controls. Of the seven inoculated piglets, five died suddenly on day 1·5, 2 (two piglets), 2·5 or 4 post-inoculation (p.i.). The remaining two and the control piglets were killed on day 8 p.i. EMCV antigen was detected immunohistochemically in endothelial cells of capillaries from 1·5 to 2·5 days p.i. only, but was found in cardiac muscle cells, Purkinje fibres and macrophages on all occasions up to day 8 p.i. In endothelial cells and macrophages, EMCV antigen was detected intracytoplasmically, but in cardiac muscle cells and Purkinje fibres it was observed intracytoplasmically or intranuclearly, or both. The frequent presence of EMCV antigen in Purkinje fibres suggests an explanation for the sudden death of the piglets.

ENZOOTIC NASAL TUMOUR OF GOATS IN GREECE P. Loukopoulos, N.D. Giadinis, V. Psychas, C.I. Dovas and E. Kaldrymidou Faculty of Veterinary Medicine, Aristotle University, Greece Introduction: The enzootic nasal tumour (ENT) of goats arises from secretory epithelial cells of the ethmoid turbinate and follows infection by ENTV-2, an exogenous retrovirus. The geographical distribution of the disease is believed to be wide, but this has not been studied comprehensively. Materials and Methods: Intranasal tumours of goats that were included in the study were retrieved from the archives or were recruited as part of an ongoing prospective study. The tumours were examined grossly and microscopically and a selected number of tumour samples was analyzed by PCR and sequencing. Results: Fifty-four intranasal tumours were examined, the first of which was initially examined in 1984. Although no metastases were observed, a small number of cases were locally aggressive. Histologically, most cases were low-grade adenocarcinomas. The cases originated from four geographical regions in Greece (Thrace, Macedonia, Thessaly and central Greece). PCR detected ENTV-2 proviral DNA within the tumours examined. Sequencing and phylogenetic analysis demonstrated clustering of these isolates with the ENTV-2 prototypes in a branch distinct from ENTV-1, JSRV and SERV representatives. Conclusions: ENT of goats is present and appears to have widespread geographical distribution in Greece. Further examination and monitoring of the disease status is warranted. P1