A post we made last week suggested a new vaccine can protect macaques against the monkey equivalent of HIV, however the vaccine using the common virus cytomegalovirus (CMV) as the vector or container of proteins from the simian immunodeficiency virus (SIV) protected none of a group of 24 rhesus macaques from infection. But in 13 of the monkeys vaccinated, it did produce infections characterised by an undetectable viral load.
This profound viral suppression led to an apparent decline in the number of SIV-infected cells over a period of two years after infection to the point that SIV-infected cells were undetectable in 72% of monkeys with controlled viremia. Despite this, there was no apparent waning of immune responses to SIV in the all-important effector-memory CD8 and CD4 lymphocytes over this time in twelve of the 13 monkeys.
The researchers comment that their vaccine seems to have produced “an unprecedented level of SIV control and even the possibility of progressive clearance of SIV infection over time.”
The question now is how to make a safe analogue of this vaccine for use in humans.