Colostral transmission of maedi visna virus: sites of viral entry in lambs born from experimentally infected ewes.

Maedi visna virus (MVV) vertical transmission in sheep via infected colostrums is a very important route of infection in lambs. To verify colostral transmission and to study early viral entry in lambs, colostrum samples, and small intestine and mesenteric lymph nodes of lambs born from experimentally infected ewes were examined by histopathology, immunohistochemistry (IHC) and in situ hybridisation (ISH) studies. In particular, newborn lambs were naturally fed maternal colostrum and humanely killed at 10, 24, 48, 72, 96 h and 7 and 10 days after birth; two caesarian-derived lambs served as uninfected controls. No lesions suggestive of MVV infection were found, but marked immunoreactions for MVV capsid antigen (CA, p28) were detected in lambs fed maternal colostrum and in macrophages cultured from colostrum. IHC results in lambs suggest an initial viral absorption by intestinal epithelial cells at the tip of the villi, passage to mononuclear cells in the lamina propria and involvement of ileum Peyers' patches and mesenteric lymph nodes, with different staining patterns depending on infection times. ISH on intestinal sections of the 72 h lamb revealed the presence of proviral DNA in epithelial cells at the tip of the villi, suggesting a role for these cells in early MVV replication. The results contribute to knowledge about the pathogenesis of ovine lentivirus infection suggesting that the small intestine and mesenteric nodes are the sites of entry and propagation of MVV in lambs fed colostrums from infected ewes.

Association of Maedi Visna virus with Brucella ovis infection in rams.

Maedi Visna Virus (MVV) is the etiological agent of a systemic disease of sheep, which causes lesions in lungs, the central nervous system, joints, and mammary glands. It has been speculated that the association with Brucella ovis may lead to the venereal shedding of the virus. In this work, samples of epididymis from ten rams positive for MVV and infected experimentally with Brucella ovis, were subjected to liquid-phase PCR, immunohistochemistry (IHC) and in situ PCR tests, aimed at identifying the pathogens in a tissue context. IHC was carried out using a monoclonal antibody raised against p28 MVV protein and a polyclonal antibody to B. ovis. Liquid phase- and in situ PCR were designed to amplify a portion of MVV proviral DNA Pol sequence. In the animals showing B. ovis-related histopathological changes, IHC clearly demonstrated a positivity for B. ovis and MVV in interstitial and epithelial ductal cells. In situ PCR assessed the presence of MVV proviral DNA in macrophages and elements inside the epithelium. The unaffected and reagent control samples constantly gave negative results. Taken together, these data demonstrate that MVV may affect ovine epididymis, apparently taking advantage of the concurrent infection by B. ovis. The tropism of MVV for the epididymal epithelial cells, may be responsible for its excretion with the semen.

Experimental Maedi Visna Virus Infection in sheep: a morphological, immunohistochemical and PCR study after three years of infection.

A morphological, immunohistochemical and polymerase chain reaction (PCR) study was performed on eight ewes experimentally infected with an Italian strain of Maedi-Visna Virus (MVV) in order to evaluate the lesions and the viral distribution after three years of infection. At the moment of euthanasia, seven sheep were seropositive for MVV, while one sheep in poor body conditions was seronegative since one year. Lungs, pulmonary lymph nodes, udder, supramammary lymph nodes, carpal joints, the CNS, spleen and bone marrow of the eight infected sheep were collected for histology, for immunohistochemical detection of the MVV core protein p28 and for PCR amplification of a 218 bp viral DNA sequence of the pol region. The most common histological findings consisted of interstitial lymphoproliferative pneumonia and lymphoproliferative mastitis of different severity, while no lesions were observed in the CNS. MVV p28 antigen was immunohistochemically labelled in lungs, udder, pulmonary lymph nodes, spleen and bone marrow but not in the CNS of all the eight infected sheep. A 218 bp sequence of MVV pol region was detected in lung of a seropositive and of the seroconverted negative sheep. The results suggest that (i) MVV causes heterogeneous lesions in homogeneously reared ewes, (ii) MVV p28 antigen is detectable not only in inflammed target organs, but also in pulmonary lymph nodes, spleen and bone marrow, and (iii) immunohistochemistry and PCR are useful methods for Maedi-Visna diagnosis in suspected cases, also when serological tests are negative.

Cutaneous haemangiosarcoma in a sheep: morphological, histopathological and immunohistochemical observations.

Haemangiosarcomas of animals are reported mainly in the dog and cat and less commonly in the cow, horse, pig and goat, but no cases have been reported in sheep. These tumours occur more commonly in internal sites than in the subcutis. A large mass in the right flank of a 6-year-old Sardinian sheep showed histopathological features of a haemangiosarcoma. The antibodies anti-Factor VIII-related antigen (FVIII-RAg) and anti-CD31 did not react immunohistochemically with either the normal or the neoplastic endothelial cells, whereas endothelin-1 strongly labelled both the normal and the neoplastic cells at different stages of differentiation. The results emphasize the usefulness of endothelin-1 as a vascular marker in sheep, particularly in the immunohistochemical detection of neoplastic endothelial cells.

A conventional beagle dog model for acute and chronic infection with Helicobacter pylori.

Helicobacter pylori has been widely recognized as an important human pathogen responsible for chronic gastritis, peptic ulcers, gastric cancer, and mucosa-associated lymphoid tissue (MALT) lymphoma. Little is known about the natural history of this infection since patients are usually recognized as having the infection only after years or decades of chronic disease. Several animal models of H. pylori infection, including those with different species of rodents, nonhuman primates, and germ-free animals, have been developed. Here we describe a new animal model in which the clinical, pathological, microbiological, and immunological aspects of human acute and chronic infection are mimicked and which allows us to monitor these aspects of infection within the same individuals. Conventional Beagle dogs were infected orally with a mouse-adapted strain of H. pylori and monitored for up to 24 weeks. Acute infection caused vomiting and diarrhea. The acute phase was followed by polymorphonuclear cell infiltration, interleukin 8 induction, mononuclear cell recruitment, and the appearance of a specific antibody response against H. pylori. The chronic phase was characterized by gastritis, epithelial alterations, superficial erosions, and the appearance of the typical macroscopic follicles that in humans are considered possible precursors of MALT lymphoma. In conclusion, infection in this model mimics closely human infection and allows us to study those phases that cannot be studied in humans. This new model can be a unique tool for learning more about the disease and for developing strategies for treatment and prevention.

Mortality in black siskins (Carduelis atrata) with systemic coccidiosis.

Ninety-five (97%) of 98 black siskins (Carduelis atrata) died within 2 months of arrival in Italy from South America with the following clinical sings: rapid weight loss, breast muscle atrophy, congested and distended abdomen, diarrhea, and lethargy. Macroscopically we observed hepato-splenomegaly, pulmonary congestion, and thickening of the interstinal wall. Histologically, lymphomonocytic transmural enteritis, interstitial mononuclear cell infiltrates in the lungs and in the liver, as well as activation of splenic follicles were common features. Large numbers of protozoa belonging to Isospora sp. were observed in various stages of their life-cycle in the intestinal epithelium, and some zoites were found in the extra-intestinal cellular infiltrate as well. No viral or bacterial pathogens were found.

Lead poisoning in domestic and wild ducks.

The results of clinical, radiological, hematological, histomorphological and toxicological research carried out on experimental lead poisoning of domestic and Wild ducks are reported and discussed. Radiological, histological and toxicological investigations were aimed at determining the most characteristic features for diagnosis. These experiments support previous research on spontaneous lead poisoning of ducks kept in private reserves (Del Bono, 1970) and toxicological researches carried out recently (Sivieri, Buggiani and Rindi, 1972) on many breeds of migratory birds and confirm the serious consequences of this disease on many breeds of wild birds in Italy.