A gag‐env Hybrid Protein of Human T‐cell Leukemia Virus Type I and Its Application to Serum Diagnosis

A fused gene of the gag and env sequences of human T‐cell leukemia virus type I (HTLV‐I), the causative agent of adult T‐cell leukemia, was constructed in vitro and expressed in Escherichia coli. The gag‐env hybrid protein accumulated as insoluble granules with a yield of approximately 12% of the total proteins. In an enzyme‐linked immunosorbent assay done with the use of the gag‐env hybrid protein, all 57 seropositive sera gave positive signals, and none of the sera from normal persons did. This system can produce large quantities of the gag‐env hybrid protein, which can be used for mass screening of human sera for HTLV‐I infection.