What goes in an Ebola vaccine?

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On my last post, I talked about the current state of Ebola vaccines and how close we are to getting them into patients. Today, I'll chat a little bit about how the Ebola vaccine actually works! Let's focus on one of the two vaccines in Phase I clinical trials right now, produced by a company known as NewLink Genetics and the Canadian National Microbiology Laboratory.

Figure 1: Professor Adrian Hill, Director of the Jenner Institute, and Chief Investigator of the trials, holds a phial containing the Ebola vaccine at the Oxford Vaccine Group Centre for Clinical Vaccinology and Tropical Medicine (CCVTM)

Figure 1: Professor Adrian Hill, Director of the Jenner Institute, and Chief Investigator of the trials, holds a phial containing the Ebola vaccine at the Oxford Vaccine Group Centre for Clinical Vaccinology and Tropical Medicine (CCVTM)

In general, the purpose of a vaccine is to prepare your immune system to respond to a particular virus. Your body has the incredible ability to remember pathogens (any infectious agent) that it has encountered in the past, so by giving your immune system a "heads up", it's ability to knock down the virus goes way up.

There are a few ways to accomplish this. Some vaccines are inactivated vaccines, which means that the virus is completely killed before it is introduced into a person. The viruses for rabies, smallpox, and the flu are made in this way. Some vaccines are also attenuated, which means that the virus is live, but was raised in a way that disables its ability to become virulent. Lastly, a vaccine may feature a protein subunit of the virus in question, but not the entire virus. This would be the equivalent of giving a bloodhound a piece of a criminals clothing. It's not the actual criminal, but it's close enough for the purposes of recognition!

The NewLink Ebola vaccine (known as VSV-EBOV) is a combination of the last two types of vaccines. It features an attenuated virus, although it is NOT the Ebola virus. Instead, the scientists used a virus known as vesicular stomatitis virus (VSV), which causes flu like symptoms in farm animals. This virus has been genetically engineered to express one of the Ebola proteins, thus giving your immune system a chance to recognize what Ebola looks like and produce the antibodies that will eventually fight if off. Clever, right?

So far, the safety of this vaccine is being tested in humans, with hopes of ramping up production and sending the vaccines into West Africa!