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A vaccine for HIV is getting closer

The results of a Phase II therapeutic clinical trial in South Africa with an advanced HIV vaccine candidate developed using FIT Biotech’s Gene Transport Unit (GTU®) vector delivery platform have shown that the vaccine reduces the HIV virus load in people infected with the disease.

More than 5.5 million people in South Africa are infected with HIV, with close to a third of women presenting at public antenatal clinics infected. Many other countries in Africa are also facing major problems with the disease.

While most HIV vaccine efforts to date have been aimed at developing a preventive HIV vaccine to protect non-infected individuals against future exposure, therapeutic vaccination of individuals already infected offers the best hope for chronically infected individuals not eligible for antiretroviral therapy. This is especially important in South Africa, since access to antiretroviral therapy through public-sector health care there is limited to individuals with a CD4 cell count of < 200 cells/mm³, which occurs relatively late in the progression of the disease to full-blown AIDS.

A vaccine that can modify the course of the infection and its progression towards the disease by maintaining a low viral load and high or constant CD4 cell counts is needed to do this. Developing one, however, is complicated by the ability of the virus to mutate rapidly, resulting in a high variation between different HIV subtypes (Clades A-K).

Meeting the challenge

FIT Biotech has addressed this challenge by designing an antigenic artificial protein, known as MultiHIV, composed of sequences from six HIV genes and incorporating antigens from the A, B, C, and FGH HIV clades. MultiHIV has been estimated to cover more than 95% of the theoretical antigenic variability within HIV strains – and lies at the core of FIT Biotech’s lead HIV vaccine candidate, which is a DNA plasmid using the company’s proprietary GTU® vector technology.

A Phase II therapeutic clinical trial of the vaccine with 60 treatment-naïve HIV-infected individuals in Soweto was completed by the University of Witwatersrand’s Perinatal HIV Research Unit in 2009 – and showed a significant reduction in viral load and an increase in CD4 cell counts in vaccinated individuals. FIT Biotech is now following this success up with clinical trials in Europe and the US.

Phase II therapeutic trials have started in Britain and France with people infected with HIV and already on medication for the disease, while Phase I trials are due to start soon in the US with people who are not infected.

Better gene expression

FIT Biotech’s GTU® technology is based around a special DNA plasmid capable of delivering selected genes to human cells. In addition to providing up to 100 times stronger and more persistent gene expression than other standard plasmids – due to the enhanced transcriptional activity of the nuclear anchoring protein – it also offers versatility, cost-efficient production opportunities, and freedom from the safety risks commonly associated with viral vectors.

> Kalevi Reijonen
(Published in HighTech Finland 2010)