The in vitro effect of partially purified lysed leukocyte ultrafiltrate (LLU) on LAV 1 strain of the human immuno-deficiency virus (HIV) was investigated. Decrease of virus production as a function of LLU concentration was observed while the phenotype of cultured lymphocytes has remained unchanged. We observed the same depletion of helper-inducer T-cells in samples treated with LLU as well as in infected controls. LLU did not influence significantly the growth of cultured lymphocytes. Following the effect of LLU on RNA-dependent DNA polymerase, inhibition of the LAV 1 reverse transcriptase by LLU was observed. This inhibition was shown to be LLU dose-dependent, considering its content of proteins and orcinol-reactive material. Kinetic studies revealed that inhibition is reversible and competitive with the substrate (3HTTP) but not with template-primer (poly rA-oligo dT).
