DETECTION OF REVERSE-TRANSCRIPTASE IN CULTURE-MEDIUM FOR MAMMARY-TUMOR CELL-LINES - A COMPARISON OF AN ESTABLISHED RADIO-LABELING TECHNIQUEAND A CONTEMPORARY NONISOTOPIC TECHNIQUE

Classically, radio-label techniques have been employed to analyse biol ogical samples for reverse transcriptase (RT) activity. More recently, however, non-isotopic kits have been developed for retroviral quantif ication. Nevertheless, until the present investigation it has not been known if these contemporary methods are more sensitive at detecting r everse transcriptase activity. In our study, a non-isotopic ELISA meth od was shown to be considerably more sensitive than the radio-label te chnique at detecting reverse transcriptase in growth medium used to cu lture the murine breast cancer cell line GR/A. Using the ELISA, less r everse transcriptase activity was demonstrated in growth medium from h uman mammary adenocarcinoma MCF-7 cells than the murine source. This E LISA did not detect reverse transcriptase activity from a pure source of Moloney murine leukaemia virus. In light of this, the broad applica bility of this ELISA for reverse transcriptase from different viral so urces must be investigated before it can be used to monitor biological supernatants for the presence of retroviruses.