In a prospective study 19 adult patients with nephropathia epidemica were examined in the acute phase of disease with computed tomography (CT) of the lungs and conventional chest radiography. Infiltrates and/or pleural effusions were seen in ten of 19 patients. In two of the patients, abnormalities were disclosed only by CT. Patients with pathologic radiography findings had a more pronounced inflammatory response, as measured by C-reactive protein and leukocyte count, than did those with normal radiography findings. It is concluded that radiological evidence of pulmonary involvement is a common finding early in the course of nephropathia epidemica. The possibility that the lung may be a site of viral replication merits further investigation.

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PubMedDate not supplied

Increased production of nitric oxide in patients with hemorrhagic fever with renal syndrome--relation to arterial hypotension and tumor necrosis factor.

In 15 consecutive subjects hospitalized with nephropathia epidemica, a European form of hemorrhagic fever with renal syndrome, the plasma concentrations of nitrate plus nitrite, stable metabolites of nitric oxide, were determined. From day 3 of onset of disease the concentrations increased, peak levels being reached on days 5 to 7. Maximal plasma concentrations of nitrate plus nitrite were correlated to the degree of hypotension (r = -0.64, p = 0.02) and levels of tumor necrosis factor (TNF)-alpha (r = 0.51, p = 0.05) and soluble TNF receptors p55 and p75 (r = 0.58, p = 0.03 and r = 0.54, p = 0.04, respectively) but not to levels of interferon-gamma or interleukin-10 (p > 0.05). The results are compatible with the well-known capacity of TNF-alpha to enhance production of nitric oxide, and suggest that nitric oxide may be of physiologic importance in hemorrhagic fever with renal syndrome.

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PubMedDate not supplied

Immunization of mice with an attenuated Salmonella typhimurium strain expressing a membrane protein of Francisella tularensis. A model for identification of bacterial determinants relevant to the host defence against tularemia.

A 17-kilodalton (kDA) protein of the facultative intracellular bacterium Francisella tularensis is one of several membrane proteins that induce an in vitro response in T cells from F. tularensis-primed humans. A DNA fragment containing two genes, one of which encodes the 17-kDa protein, was cloned into an attenuated Salmonella typhimurium strain. Mice orally immunized with the recombinant S. typhimurium strain showed lower viable counts in livers and spleens after challenge with F. tularensis LVS (live vaccine strain) than did animals immunized with the non-recombinant strain. Cyclosporin A neutralized the protective effect of the recombinant S. typhimurium strain.

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PubMedDate not supplied

Nature of protective immunity to Francisella tularensis.

Tularemia is caused by the facultative intracellular bacterium Francisella tularensis. Attenuated live vaccines, such as F. tularensis LVS (live vaccine strain), afford good--although not complete--protection; how to judge the degree of this protection has long been a problem. Both natural infection and vaccination result in immunospecific and long-lasting humoral and cell-mediated immunity. The latter is the crucial protective mechanism, whereas the humoral response protects only against strains of reduced virulence, such as those used in the vaccines. Immune serum has been used to screen for structures of F. tularensis with the ability to induce a protective immune response. This immune serum is, however, primarily directed toward antigens different from those involved in cell-mediated immunity. Serum antibodies from primed individuals recognize carbohydrate capsule antigens of F. tularensis, whereas T lymphocytes recognize membrane polypeptides of the organism. The preparation of membrane polypeptides from F. tularensis is now facilitated by the availability of a capsule-deficient mutant of F. tularensis LVS. In vitro, several membrane polypeptides of the mutant stimulate T lymphocytes from vaccinees and from naturally infected individuals. Further studies of the mechanisms of induction of protective immunity should focus on these membrane polypeptides.

Animals↗