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.