All attempts in the lab to force such viruses to regain the ability to replicate have failed. Even if this did happen in the body, the resulting virus would resemble HIV, as the hybrid contains no Ebola genes - and HIV cannot infect lung cells. If it did get into the blood, where normal HIV thrives, such a virus would not replicate as efficiently as wild-type HIV. While the patient might suffer, the virus could never reach high enough levels in the body to infect others, Pickles says.
The biggest risk is that if a patient becomes infected with wild-type HIV, the wild-type virus and the hybrid could somehow merge, but such recombination has never been observed in HIV.
Despite his confidence that the hybrid will be safe, Pickles has abandoned similar research as he fears opposition from a fearful public will prevent the method ever being used. Another problem with Kobinger's approach is that patients will require repeated treatments, because the added gene ends up in surface cells that die off after a few months. Other teams are trying to find ways of targeting the progenitor cells that give rise to the surface cells.