How far are we from discovering an Ebola cure?

Ebola continues to kill people across West Africa, and there is still no cure. Available treatments only alleviate the symptoms of the disease. People who suffer from Ebola have only support available, such as intravenous fluids to prevent dehydration caused by bleeding, vomiting and diarrhea.

Several potential drugs and vaccines are currently being tested on animals and are being clinically tested, but progress is very slow. It is almost impossible to conduct on-site testing, mainly because epidemics in Africa are sporadic and unpredictable.

“It’s very difficult to conduct conventional clinical trials,” said Thomas Geisbert of the University of Texas, which develops vaccines and therapies.

Stopping duplication

The only form of treatment that has come to testing in humans works using a technique called RNA interference. The approach uses RNA molecules – which can prevent DNA from producing proteins – to prevent the Ebola virus from multiplying.

The drug, called TCM-Ebola, protected the monkeys when given to them within 30 minutes of the virus being injected. Safety tests on human volunteers have been suspended, however, until the manufacturer receives more information on how the immune system responds to high doses.

Another approach is to inhibit a viral enzyme that is vital for microbial survival. The compound that seems to do this is called BCX4430, and is currently being tested on animals infected with Ebola.

A virus vaccine would be best. Perhaps the most promising are vaccines made from relatively harmless microbes called vesicular stomatitis virus (VSV). VSV has been genetically modified so that the protein on its surface is replaced by a single Ebolin protein. This deceives the human immune system into thinking that it has seen Ebola and stimulates the production of antibodies against the virus. The idea is that if the immune system later encounters the real virus, it will be prepared and ready to attack.

Vaccine as medicine

The vaccine could also be used as a medicine after a person has been exposed to Ebola, in the same way as rabies vaccines are used. This is because these viruses are incubated for a few days until the first symptoms, so there is time for the vaccine to work.

Indeed, in 2009, a vaccine based on VSV was given to a German researcher who accidentally stabbed herself in the finger with a needle that carried the virus. She survived the incident, but there is no way to know if the virus really entered her body.

Such a strategy requires that the vaccine be given as soon as possible, after exposure. “If someone comes in with complete symptoms of the hemorrhagic virus, then they don’t have more than 24 to 48 hours to live,” says Geisbert.

Unfortunately, none of these approaches are even close to obtaining regulatory permits – or passing the first phase of human testing – to be used in Africa now. They may be ready for some next epidemic, Geisbert says.

Gallery

1 / 3 Photo: Shutterstock

Ebola continues to kill people across West Africa, and there is still no cure. Available treatments only alleviate the symptoms of the disease. People who suffer from Ebola have only support available, such as intravenous fluids to prevent dehydration caused by bleeding, vomiting and diarrhea.

Several potential drugs and vaccines are currently being tested on animals and are being clinically tested, but progress is very slow. It is almost impossible to conduct on-site testing, mainly because epidemics in Africa are sporadic and unpredictable.

“It’s very difficult to conduct conventional clinical trials,” said Thomas Geisbert of the University of Texas, which develops vaccines and therapies.

Stopping duplication

The only form of treatment that has come to testing in humans works using a technique called RNA interference. The approach uses RNA molecules – which can prevent DNA from producing proteins – to prevent the Ebola virus from multiplying.

The drug, called TCM-Ebola, protected the monkeys when given to them within 30 minutes of the virus being injected. Safety tests on human volunteers have been suspended, however, until the manufacturer receives more information on how the immune system responds to high doses.

Another approach is to inhibit a viral enzyme that is vital for microbial survival. The compound that seems to do this is called BCX4430, and is currently being tested on animals infected with Ebola.

A virus vaccine would be best. Perhaps the most promising are vaccines made from relatively harmless microbes called vesicular stomatitis virus (VSV). VSV has been genetically modified so that the protein on its surface is replaced by a single Ebolin protein. This deceives the human immune system into thinking that it has seen Ebola and stimulates the production of antibodies against the virus. The idea is that if the immune system later encounters the real virus, it will be prepared and ready to attack.

Vaccine as medicine

The vaccine could also be used as a medicine after a person has been exposed to Ebola, in the same way as rabies vaccines are used. This is because these viruses are incubated for a few days until the first symptoms, so there is time for the vaccine to work.

Indeed, in 2009, a vaccine based on VSV was given to a German researcher who accidentally stabbed herself in the finger with a needle that carried the virus. She survived the incident, but there is no way to know if the virus really entered her body.

Such a strategy requires that the vaccine be given as soon as possible, after exposure. “If someone comes in with complete symptoms of the hemorrhagic virus, then they don’t have more than 24 to 48 hours to live,” says Geisbert.

Unfortunately, none of these approaches are even close to obtaining regulatory permits – or passing the first phase of human testing – to be used in Africa now. They may be ready for some next epidemic, Geisbert says.

Gallery

1 / 3 Photo: Shutterstock