Even if Montagnier had proof for the existence of a retrovirus in his umbilical cord lymphocytes, the retrovirus could not have originated in BRU. There are two very good reasons for this:

1. All cells, infected or not, release retrovirus particles in cultures, especially when the culture conditions are those used by Montagnier et al. As far back as 1976, eminent retrovirologist wrote, "the failure to isolate endogenous viruses from certain species may reflect the limitations of in vitro cocultivation techniques". In other words, given sufficient time and ingenuity, a researcher can produce retroviral particles from any cell.

According to all HIV experts, for the HIV particles to be infectious, gp120 is absolutely necessary.

gp120 is present only in the particles knobs.

However: To date, nobody, not even Hans Gelderblom, has found proof for the existence of these knobs in the cell-free HIV particles.

Since, into the umbilical cord lymphocyte culture Montagnier and his colleagues introduced cell-free fluids from the co-culture. It means that even if the cell-free fluids contain particles they could not have been infectious.