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Abstract: Three new polyoma viruses have been recently identified; two of them, the KI et WU viruses are present in nasopharyngeal aspirates during the course of acute respiratory infections. The incidence of these viruses is low compared to other respiratory viruses and the disease has not shown a high severity of clinical signs. The physiopathology of the diseases and the mode of cultivation of these viruses remain unknown. The third virus was discovered from cutaneous biopsies of Merkel tumours with a higher incidence than in tissue from healthy patients. Its mode of transmission and its role in the cancerogenesis need more studies. However, as the virus can integrate into the cellular DNA, it signifies that the virus may have a role in various human tumors. [Copyright &y& Elsevier]

Abstract: Transmissible spongiform encephalopathies (TSEs), are fatal neurodegenerative diseases caused by unconventional agents, the prions. They are characterised by the accumulation in infected tissues of an abnormally folded form of the host-encoded prion protein (PrP). This pathological form is partially resistant to protease digestion, leading to the production of so-called PrPres fragments. Different isolates from the same host species may show different eletrophoretic profiles, reflecting the existence of different prion strains. The active surveillance of ruminant TSEs implemented in European countries, based on a large-scale biochemical testing of brain tissue samples from carcasses, has revealed PrPres profiles unnoticed so far. Experimental transmission of these atypical cases to various transgenic mouse lines has led to the recognition of a novel scrapie strain in sheep and goats, called Nor98, and of two variant strains of spongiform encephalopathy in cattle. This review is aimed at summarising the current knowledge on these newly recognised forms of ruminants TSEs, and at discussing their possible origin and potential implications in terms of animal and human health. [Copyright &y& Elsevier]

To assess risk for cattle-to-human transmission of prions that cause uncommon forms of bovine spongiform encephalopathy (BSE), we inoculated mice expressing human PrP Met129 with field isolates. Unlike classical BSE agent, L-type prions appeared to propagate in these mice with no obvious transmission barrier. H-type prions failed to infect the mice. [ABSTRACT FROM AUTHOR]

The sedimentation coefficient and buoyant density of hog cholera, bovine viral diarrhea and Border disease viruses, have been compared with those of representative members of the family togaviridae. It appears that the pestivirus genus is a homogeneous group which is not only antigenically but also structurally, unrelated to the other genera of the togavirus family. [ABSTRACT FROM AUTHOR]

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The summer-dormancy period among collections of Phalaris tuberosa L. from the eastern Mediterranean region when grown at Davis, California, ranged from 30 to 127 days. Plants from the more arid sites of origin tended to exhibit the longer dormancy. There were exceptions, however, and these, together with the diversity of behaviour in this material, suggest that genotypes with a potential for increased summer growth may be selected for use on rangelands. [ABSTRACT FROM AUTHOR]

Because variant Creutzfeldt-Jakob disease (vCJD) in humans probably results from consumption of products contaminated with tissue from animals with bovine spongiform encephalopathy, whether infectious prion protein is present in ruminant muscles is a crucial question. Here we show that experimentally and naturally scrapie-affected sheep accumulate the prion protein PrPSc in a myocyte subset. In naturally infected sheep, PrPSc is detectable in muscle several months before clinical disease onset. The relative amounts of PrPSc suggest a 5,000-fold lower infectivity for muscle as compared to brain. [ABSTRACT FROM AUTHOR]