The approval by the Medicines Control Council (MCC) of the first human trials of a candidate HIV vaccine in South Africa has scientists at UCT - and elsewhere in the country and the world - cautiously hopeful.
The Medical Research Council (MRC) announced on June 18 that phase one human clinical trials of the AlphaVax replicon Vector (ArVTM) vaccine, earmarked for the HIV subtype-C strain that predominates in southern Africa, would begin shortly in South Africa and the United States. The phase one trial - a safety trial to confirm that the test vaccine does not produce significant side effects in humans - is the first to be approved in South Africa and the first in the world to test a clade-C vaccine.
A number of UCT scientists - Professor Carolyn Williamson of the UCT Institute for Infectious Disease and Molecular Medicine (IIDMM), along with Dr Joanne van Harmelen and PhD student Robin Thomas - have a vested interest in the trials, having done some of the initial groundwork for ArV. The trio worked with Dr Ron Swanstrom of the University of North Carolina and Dr Lynn Morris of the National Institute for Communicable Diseases (NICD) in Johannesburg to select the clade-C HIV genes that would eventually go into the vaccine.
"Because of the high variation in the HI virus, it was thought that we would increase our chances of success if we matched up the vaccine with the strain of virus being targeted," explained Williamson.
AlphaVax's vaccine blends a select portion of HIV genetic material (the so-called "gag gene"), cloned from the HIV gene sequence isolated by the UCT team, with parts of an attenuated (weakened) strain of the Venezuelan equine encephalitis (VEE) virus, a pathogen normally associated with a disease that affects horses and mules in South and North America. The virus-like HIV particles are toted via the "coat" of the VEE virus into the body, where it will then hopefully induce an immune response against HIV.
ArV has been designed specifically not to include the genetic elements needed to activate live HIV or trigger the VEE virus, and so will not infect volunteers with either of the two viruses.
The vaccine will be trialled under the auspices of the HIV Vaccine Trials Network (HVTN), funded by the US's National Institutes of Health (NIH), at two sites in South Africa - the Perinatal HIV Research Unit at the Chris Hani Baragwanath Hospital in Soweto and the South African AIDS Vaccine Initiative (SAAVI) Vaccine Research Unit at the MRC in Durban. John Hopkins University, Columbia University, the University of Rochester and Vanderbilt University will act as the US sites.
The vaccine, which was developed in partnership with the International AIDS Vaccine Initiative (IAVI), has successfully negotiated the laborious lab and animal trials. The HVTN will now test the vaccine on 96 volunteers across the two countries - 48 in each - with the blessings of the South African MCC, the US Food and Drug Administration (FDA) and a slate of ethics committees in South Africa and the US that have reviewed and approved the phase one protocols.
As welcome as the trials are, anticipation is tempered by discretion - a signed-and-certified vaccine, ready for administration and circulation, is still some way off, Williamson cautioned. Firstly, the volunteers - all healthy HIV-negative adults, suitably vetted and counselled - will receive three injections at four-weekly intervals.
They will then be monitored closely for local (redness or swelling around the site of the shot), systemic (fevers, fatigue) or allergic reactions over a 12-month period. Following this, scientists in SA and the US will analyse data from the trials, which is expected to take about two years.
And should the vaccine pass the phase one trials, it will then have to go through extensive phase two (does it stimulate an immune response to the HIV?) and three (does it actually prevent HIV infection?) trials, which should gobble up another couple of years. "One always hopes that things will more forward without hurdles, especially when it comes to producing a vaccine against HIV, but it's a very long path," noted a guarded Williamson.
But while the bubbly has not quite been uncorked and the backslapping has been prudently deferred, the upcoming trials are a significant stride in the pursuit of a vaccine against HIV, she added.
"It's a big step getting the vaccine into the phase one trials. Scientists around the world all contribute to the global knowledge, so even if what you do is not the ultimate answer, it does contribute to existing knowledge and, hopefully, lead to the improvement of vaccine technology.
"So everyone is pleased and excited because it means that we in South Africa have actually started the journey."