cDNA probes for the diagnosis of bovine torovirus (Breda virus) infection.

A genomic cDNA library of RNA from Breda virus (BRV), a bovine torovirus, was prepared. The nucleotide sequence of the 3' end of the genome was found to be highly conserved (93% identical) between BRV and Berne virus, the torovirus prototype. Cross-hybridization experiments were performed to select Berne virus cDNA clones for use as probes in a dot hybridization assay; the objective was to detect heterologous torovirus RNA in fecal material. A rapid RNA extraction method was employed to make the test applicable for routine diagnosis. Samples from calves after experimental and natural infection with BRV were assayed to establish the sensitivity and specificity of the test and to compare the test with the enzyme-linked immunosorbent assay (ELISA) for antigen detection. For this purpose, 53 samples from seven infected calves were tested with both methods. In the ELISA, BRV was detected in six fecal samples from three inoculated calves. By use of the hybridization test, 16 samples from seven calves reacted positively. With one exception, only postinoculation samples were found positive in hybridization. No signal was seen in feces from uninoculated calves or from calves infected with rotavirus or coronavirus.     

Risk groups for clinical complications of norovirus infections: an outbreak investigation

Norovirus infections have been described as self-limiting diseases of short duration. An investigation of a norovirus outbreak in a university hospital provided evidence for severe clinical features in patients with several underlying diseases. Clinical outcomes of norovirus infection were defined. Risk-factor analysis targeting underlying diseases and medication was performed using multivariate analyses. In five outbreak wards, 84 patients and 60 nurses were infected (an overall attack rate of 32% in patients, and 76% in nurses). The causative agent was the new variant Grimsby virus. Severe clinical features, including acute renal failure, arrhythmia and signs of acute graft organ rejection in renal transplant patients, were observed in seven (8.3%) patients. In multivariate analyses, cardiovascular disease (OR 17.1, 95% CI 2.17-403) and renal transplant (OR 13.0, 95% CI 1.63-281) were risk-factors for a potassium decrease of >20%. Age >65 years (OR 11.6, 95% CI 1.89-224) was a risk-factor for diarrhoea lasting >2 days. Immunosuppression (OR 5.7, 95% CI 1.78-20.1) was a risk-factor for a creatinine increase of >10%. Norovirus infections in patients with underlying conditions such as cardiovascular disease, renal transplant and immunosuppressive therapy may lead to severe consequences typified by decreased potassium levels, increased levels of C-reactive protein and creatine phosphokinase. In the elderly, norovirus infection may lead to an increased duration of diarrhoea. Therefore patients at risk should be hospitalised early and monitored frequently. Strict preventional measures should be implemented as early as possible to minimise the risk of nosocomial outbreaks.