Germs produce novel HIV drug

Two models for the way HIV enters and
infects a body cell. In the global fusion
model at top the virus forms an entry
claw, then the virus progressively fuses
with the cell across its width, merging the
contents of the viral membrane with the
cellular membrane. In the local fusion
model below, after the viral claw is
formed it creates a local pore in the cell
membrane, through which the viral core
enters the cell.
(Image: PLoS Pathogens)

• CSIR Biosciences
Fanie Marais
+27 12 841 2325
Dr Maureen Louw
+27 12 841 2167
General enquiries
+27 12 841 3260
• Cape Biotech
+27 21 442 3780

Mary Alexander

South African researchers have genetically engineered a strain of bacteria to produce large and affordable quantities of a novel and highly effective treatment for HIV, the virus that causes Aids.

The Council for Scientific and Industrial Research (CSIR) recently received backing from Cape Biotech, a government-funded biotechnology investment company, to develop a bio-manufacturing process for the antiretroviral Enfuvirtide. A peptide, or amino acid molecule, Enfuvirtide helps slow down the spread of HIV in the body by blocking the virus’s entry into uninfected cells.

It’s one of the most effective treatments for HIV, used in combination with other drugs, but until now so expensive it is beyond the means of most South Africans.

“Clinical data have confirmed Enfuvirtide’s role in decreasing viral roads,” says Fanie Marais, CSIR research and development outcomes manager. “But the estimated R19 300 (US$2 600) treatment cost per patient, per month, is likely to forever prevent its pervasive use.”

The project leader is the CSIR’s Dr Maureen Louw, a molecular biologist with extensive experience in genetically engineering bacteria.

“We have genetically modified a microorganism so as to harness the organism’s natural ability for protein secretion and to channel it into over-expressing the peptide we need,” she says on the CSIR website.

The current chemical process of producing Enfuvirtide requires 106 chemical steps and 44 ingredients, making it exorbitantly expensive to produce. The new bio-manufacturing process instead makes the bacteria do the work.

“We will use fermentation processes to multiply the recombinant bacteria, and therefore increase the yield of peptides obtained,” Louw says.

“The aim is to achieve this in a more cost effective manner than the chemical process behind the commercial product on the market.”

Having developed the process, the CSIR is now looking at the cost-effectiveness of the technology. According to Louw, if producing the therapy in large quantities at low cost proves economically viable, it will be a boon for South Africa, and an enormous scientific achievement.

“To put a highly effective antiretroviral treatment within the reach of our HIV-positive population would be a career highlight for all of the scientists on the project,” she says.

“Every scientist wants his/her work to move from the laboratory into a real life application. This investment by Cape Biotech brings us one step closer to this ideal.”

South Africa has one of the highest HIV infection rates in the world. According to Statistics South Africa’s mid-year population estimates for 2009 (PDF), some 10.6% of the population, or 5.21-million people, is HIV positive.

According to the CSIR, if all these people received treatment, South Africa would likely make up almost 40% of the global antiretroviral market. A cheap, abundant and locally produced source of highly effective HIV therapy would be a huge help in reining in the country’s infection rate.

The initiative also has the promise of developing South Africa’s pharmaceutical industry. Fred van der Post of Cape Biotech says that if the project’s concept is successfully proven, the technology will be licensed to either an existing local enterprise or a new public-private partnership.

Developed at North Carolina’s Duke University in 1996, Enfuvirtide was the first of a new class of antiretroviral drugs known as entry or fusion inhibitors – inhibiting the HI virus’s fusion with or entry into healthy cells. It is currently used in combination therapy to treat HIV-positive people who have developed resistance to other drugs.

A peptide, or polymer formed by linked amino acids, Enfuvirtide mimics the machinery the virus uses to attach itself to a cell, effectively preventing the virus from creating an entry pore through the cell’s membrane.

It is considered to be effective only against HIV-1, the most globally widespread and virulent form of HIV.