In a second experiment they added BRU's lymph node cells to a stimulated culture of lymphocytes from a healthy blood donor.

In this co-culture, they also found reverse transcriptase activity. This was interpreted as proof for the transmission and isolation of a retrovirus.

In yet another experiment cell-free fluids from the co-culture were added to cultures of umbilical cord T-cells.

In this culture they found:

1. RT activity
2. "typical type-C" retroviral particles

These findings were interpreted as proof that the retrovirus from BRU was transmitted to the donors T-cells and then to the umbilical cord T-cells.