Multi-clade vaccine trial launched in Massachusetts
In April, scientists at the University of Massachusetts Medical School (US) started recruiting 36 healthy, HIV-uninfected volunteers for a Phase I trial of a preventive AIDS vaccine strategy. The vaccines being tested are a DNA vaccine and a recombinant gp120 protein vaccine. Both of the candidates were developed by Dr. Shan Lu, associate professor of medicine and the head of the HIV vaccine effort at UMMS, in collaboration with Advanced Bioscience Laboratories. They are being tested in a “prime boost” strategy which uses two different vaccines given at different times.
Both of the vaccines are based on genetic material from four different versions, or clades, of HIV. This material is produced in a laboratory and cannot cause HIV. Clades are genetically-related families of HIV viruses. Different clades are found in different regions of the world.
It is not yet known whether it will be possible to make a single “universal” vaccine against all versions of HIV, or whether it will be necessary to make many different vaccines, each based on the most common versions of HIV in a given region. Data from this and other trials of “multi-clade” vaccines will increase understanding of how HIV genetic diversity affects vaccine design.
In an early Phase I trial, scientists will be able to conduct laboratory tests on volunteers’ blood samples to see whether or not the immune responses produced by the vaccines control different versions of HIV. These tests will not provide a final answer but they will provide useful information about whether it is possible to generate “cross-clade” protection with a single vaccine.