World's largest HIV vaccine study expands

The world's largest ongoing HIV vaccine study has been expanded to consider various ways a vaccine might boost immune response to the AIDS virus.
The HVTN 505 study has been underway since June 2009 and is funded by the National Institutes of Health, Voice of America reports. HVTN stands for the HIV Vaccine Trials Network.
“The trial is being expanded both in terms of the number of participants, as well as what the trial is looking to answer,” Mitchell Warren, the head of the AIDS Vaccine Advocacy Coalition, said, according to Voice of America.
Enrollment for the study is increasing from around 1,300 to 2,200 participants. The study originally focused on whether the vaccine regimen could lower the amount of HIV in the blood if people were to become infected after being vaccinated. It will now add a focus on whether the vaccine could actually prevent infection.
The change is partly because of encouraging results in 2009 of the RV-144 vaccine trial in Thailand that proved that protection is possible, though the effectiveness was too low to go to market.
“Because of the Thai trial, what we saw in that vaccine actually preventing infection was, wow, we really need to then look differently at HVTN 505 and expand its ability to look at the question: could this vaccine actually also prevent infection, prevent acquisition of HIV?" Warren said, according to Voice of America.
With little success in getting vaccine candidates to give a protective effect in the 1980s and 1990s, emphasis was switched to whether vaccines could mitigate the infection.
“We have the antibody response, or the humoral immunity, which conceptually is the part of the body that could help prevent infection," Warren said, according to  Voice of America. "And then we have what’s called cell mediated immunity, which is the part of the immune system that will help modulate the disease if one were to be infected."
The HVTN 505 study will now attempt to activate both of those symptoms.
“It uses a prime boost combination of two different vaccines," Warren said, according to Voice of America. "One is a DNA vaccine that has snippets of HIV that can’t cause HIV at all, but is meant to kind of prime the immune system. And then it has an Adeno 5 vaccine boost."
While Adeno 5 is a common cold virus, it is used as a vector or means of delivering the vaccine. The HVTN 505 study is currently being conducted in 12 U.S. cities.

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