The outcome of hepatitis C virus infection is predicted by escape mutations in epitopes targeted by cytotoxic T lymphocytes

CD8(+) cytotoxic T lymphocytes (CTL) are thought to control hepatitis C virus (HCV) replication and so we investigated why this response fails in persistently infected individuals. The HCV quasispecies in three persistently infected chimpanzees acquired mutations in multiple epitopes that impaired class I MHC binding and/or CTL recognition. Most escape mutations appeared during acute infection and remained fixed in the quasispecies for years without further diversification. A statistically significant increase in the amino acid replacement rate was observed in epitopes versus adjacent regions of HCV proteins. In contrast, most epitopes were intact when hepatitis C resolved spontaneously. We conclude that CTL exert positive selection pressure against the HCV quasispecies and the outcome of infection is predicted by mutations in class I MHC restricted epitopes.

[New possibilities in oral immunoprophylaxis of newborn diarrhea in calves--a field study using specific egg antibodies]

To investigate the effect of oral immunoprophylaxis in diarrhea of newborn calves egg powder with antibodies specific to E. coli K99 (ETEC) and rotavirus were used in a field trial in south west Germany. Fourteen farms with a total of 105 calves were selected. Egg powder (21 g per day) was fed as a supplement to the regular diet for the first 14 days after birth. Animals of the control group received egg powder derived from hens not immunized with the antigens. Frequency, duration and severity of diarrhea, fecal dry matter and weight gain were examined in order to evaluate the influence of the specific egg powder. Using a Lactovac test kit pathogens were detected in the feces of 76.2% of the calves, with 24.7% infected with E. coli K99, 39.1% with rotavirus, 19.0% with coronavirus and 32.4% with cryptosporidia. An overall reduction in diarrhea frequency from 68.5% to 52.9% was observed in calves fed with specific antibodies. Animals with an E. coli K99 infection showed a reduction from 92.3% to 30.7% and those infected exclusively with E. coli K99 from 83.3% to 0%. The duration of diarrhea was significantly reduced (42 h) in animals fed with specific antibodies in comparison to the control animals (60 h). With the exception of animals infected with coronavirus a marked reduction in the severity of diarrhea was observed in antibody treated calves. During the first 14 days after birth antibody treated calves showed a weight gain of 5.6 kg on average in comparison with 3.5 kg in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Infective endocarditis due to Fusobacterium nucleatum: case report and review of the literature

Endocarditis caused by Fusobacterium nucleatum is exceedingly rare. We report a case of F. nucleatum right-sided endocarditis in a patient with no known intravenous drug abuse. A detailed computer and manual search of the literature using Med-Line and Index Medicus, respectively, revealed a total of five cases of endocarditis due to this species. The clinical characteristics and the patient's hospital course are summarized and reviewed.