Follow PUB on Facebook & Twitter: PUB on Facebook Follow PUB on Twitter Online Version | Visit the PUB Website

Issue 1, September 2014

PUB - Public Understanding of Biotechnology
<< Back to contents
Next article >>
Hero Article Image
Ebola virus: Scanning electron micrograph of Ebola virus (red) budding from the surface of a cell (beige). Image courtesy of NAIAD.

Ebola drugs and vaccines offer new hope

When Peter Piot was in his final year of medicine, in 1973, his academic supervisor at the time told him that there was no future in infectious diseases.

Just three years later, he was part of the team that identified the Ebola virus, one of the deadliest infectious agents ever discovered.

Since then, there have been 24 outbreaks of Ebola, but none has claimed as many lives or spread as far as the one taking place in West Africa right now.

As of mid-September, the numbers looked like this: 5800 cases, more than 2800 deaths, at 120 of which were health workers and five of which were researchers. The epidemic has hit hardest in Guinea, Liberia and Sierra Leone, but there have been several infections in Nigeria and the DRC as well.

And according to Professor Ed Rybicki of the Biopharming Research Unit (BRU) at the University of Cape Town, the outbreak seems to be getting worse. “The case number is still escalating and they don’t have it under control,” he said.

Experimental drug

There is, however, a sliver of hope amid this terrible human tragedy: an experimental cocktail of antibodies known as ZMapp (Mapp Biopharmaceutical Inc.).

Researchers have just published a paper in Nature describing how primates infected with Ebola were cured of the disease when treated with ZMapp. The drug has also been given to seven human volunteers and aid workers infected with Ebola. Two of these subsequently died from the disease, while five made a full recovery.

Hero Article Image Experimental drug: How ZMapp is made in plants. 1) DNA encoding the antibodies is inserted into a bacterium. 2) tobacco plants are inoculated with the bacteria, which delivers the DNA into the plant cells. 3) plant cell machinery reads the DNA and produces antibodies. 4) antibodies are harvested from the plants. 5) antibodies are purified into a form that can be given to humans. 6) Once inside the infected patient, antibodies bind to the Ebola virus and prevents it from doing further damage.
Image by ScienceLink.

The ZMapp case is unusual for two reasons. Firstly, therapeutics of any sort usually go through a complex regulatory process that can take up to 15 years – the ZMapp batch given to humans was actually intended for further animal trials. Secondly, ZMapp was made in tobacco plants.

Click to listen to a clip from The Science Inside radio show:

Rybicki knows all about using plants as medicine factories, since his lab produces a number of therapeutics and vaccine candidates in plants. And he said they’re as safe as any other pharmaceutical.

“There is nothing to suggest that plant-made therapeutics are more dangerous than any other kind, and there is no evidence at all of any harm in any setting, of which I am aware.”

According to him, ZMapp is quite a remarkable achievement in that antibodies are complex proteins made up of four individual amino acid chains, and they require a large amount of processing to form the mature antibody.

Click to listen to a clip from The Science Inside radio show:

An Ebola vaccine in sight

The value of a drug like ZMapp during an Ebola outbreak (if it ultimately proves effective) cannot be overstated, but to really get on top of the disease and prevent another outbreak, a vaccine is needed.

In principle, an Ebola vaccine should not be difficult to make. Rybicki said that the virus is actually quite simple: it’s protective coat is made up of just one protein, which means there is just a single target for a vaccine to recognise.

Many candidates have already been tested, so why is there no vaccine yet? Once again, it’s that pesky regulatory process: getting a vaccine to market requires absolute proof that it doesn’t cause any illness or side-effects, which means it must be tested on a large number of healthy and sick people.

“It’s a good thing that vaccine regulations are as restrictive as they are, because you’re putting it into healthy people and as such it cannot cause harm – that would defeat the purpose entirely,” explains Rybicki.

“On the other hand, when there is a case to be made for emergency-use because there isn’t anything else, then maybe [vaccine-use] should be allowed more quickly.”
Fortunately for those living in West Africa, a number of these candidates have been granted accelerated approval for safety testing during this outbreak.

First up for these safety trials is a vaccine developed by GlaxoSmithKline and the USA’s National Institute of Health, which will be tested in the USA, UK and Gambia. This will be followed in the next few months with testing of two other vaccines developed in Canada and the USA.

As for South Africa’s role in combating Ebola, for now it is limited to sending a specialist team to Sierra Leone, and academic research at one of only nine WHO-certified Ebola diagnostic labs worldwide, located at the National Institute for Communicable Diseases.

Rybicki also notes that there is an agreement between Mapp Biopharmaceutical Inc. and the CSIR, which may result in the production of ZMapp locally.

But since South Africa lacks the proper facilities for human vaccine production, that drug also could only be used for animal testing. For the current outbreak, West African states will have to look to global aid and Western research and development for help.

Professor Ed Rybicki heads up the Biopharming Research Unit at the University of Cape Town. He curates a Virology News feed on, with plenty of up-to-date information on the Ebola outbreak and other virology news:

<< Back to contents
Next article >>

Department of Science and Technology & NRF SAASTA The PUB Programme is an initiative of the Department of Science and Technology and is implemented by SAASTA. The mandate of PUB is to promote a clear, balanced understanding of the potential of biotechnology and to ensure broad public awareness, dialogue and debate about biotechnology and its current and potential applications. For more information visit or contact, Tel: 012 392 9300 or Fax: 012 320 7803.

The articles in this newsletter have been reviewed by independent experts through SAASTA’s Scientific Editorial Process. For more information please visit

The PUB newsletter is an initiative of the Public Understanding of Biotechnology (PUB) programme.
The newsletter is developed by ScienceLink.

NRF | SAASTA Department of Science and Technology