Aldoheptose Biosynthesis. Previously, a novobiocin-hypersensitive mutant of Escherichia coli K-12 carrying a cysE-pyrE linked mutation, designated rfaD, which specifically affects the synthesis of the aldoheptose, L-glycero-D-mannoheptose, has been isolated and genetically characterized. Recently, we have cloned a 2.5 kilobase fragment carrying the rfaD gene into several high copy plasmids. The rfaD gene has been expressed in several expression systems, and further characterization of the rfaD gene product is in progress. Hepatitis Non-A, NonB. Hepatitis non-A, nonB (HNANB) is a world-wide problem, and 90% of the transfusion-related hepatitis cases in the United States (and 80-90% in several other countries) are diagnosed as HNANB. Approximately 50% of all acute HNANB patients develop chronic HNANB (an estimate of 4 million persons). They remain as potential sources of infection. Recent publications suggest a correlation between certain hepatocellular carinomas and chronic HNANB infections. Based on biochemical, immunological, and morphological evidence, we suggested that the HNANB agent is a mammalian type C retrovirus. Recently, using an in vitro focus-induction assay developed for mammalian type C viruses, we observed that pelleted material from HNANB sera (transfusion-related) induced foci formation. This result is consistent with the presence of a mammalian type C virus in HNANB sera.
