When the phrase African Swine Fever comes up, it makes people in the pig industry and certain government officials who know what’s at stake shudder. That is why research institutes and organizations are working hard to come up with a vaccine that will work to combat the dreaded disease killing millions of pigs in its path.
VIDO-InterVac hopes to be ready to begin testing new approaches for dealing with African Swine Fever on animals this year.
In 2013 the Vaccine and Infectious Disease Organization-International Vaccine Centre received clearance to work with level 3 pathogens and, in the fall of 2019, it received the clearance to work with African Swine Fever.
Dr. Volker Gerdts, the Director and CEO of VIDO-InterVac, said VIDO is working with level three diseases, both human and animal, referred to in the animal sector as level three ag.
“They’re the most significant diseases like African Swine Fever, Classical Swine Fever, and so on,” said Dr. Gerdts. “However, many of these diseases are also foreign to Canada or North America and considered foreign animal diseases restricting the research to government labs. The significance, I think, is the recognition that VIDO has one of the most advanced high containment facilities in the world right here in Saskatoon.”
He said it’s a 150 million dollar facility funded by the Government of Canada, Province of Saskatchewan, and the City of Saskatoon specifically designed to work with level three pathogens.
“That means built to prevent any pathogens from ever getting out of this facility, including all fluids, solid, and all animal materials and destroyed to ensure that no pathogen will ever get out,” said Gerdts.
ASF is a large and complex virus with 170 different proteins compared to the Ebola virus that kills people, which has seven proteins and many genotypes. It has multiple life cycles in different hosts, both in the warthog and the domestic pig.
“It’s just overall very, very difficult to control with work restricted to a handful of labs in the world, which makes it very challenging in working together and getting quick results,” he said. “Until the recent outbreak in China, mostly a neglected disease in terms of funding and efforts with few accomplishments. Several labs are pursuing three different vaccine technologies — the most common one at the moment, live-attenuated vaccines. Here we use what is called gene deletion, making mutants that lack a few genes and attenuated, meaning they don’t cause disease by themselves. Our colleagues in the U.S., and in Spain, and recently in China at the Harbin Institute are developing them. They recently announced this in China where they have this new double deletion mutant virus that is a live-attenuated vaccine. Other technologies that include safer vaccines for example, to use what we call subunit vaccines. These are only if you want parts of the virus that are being used as a vaccine. However, their ability to induce a good immune response is much weaker than what you would have if you had a live virus.”
Dr. Gerdts said unfortunately, there is no promising vaccine coming up.
He thinks it will be the most successful one where they are working with partners in Africa by using viral vectors.
“You put a gene of the ASF, or a number of them if you want, into another virus used to deliver; this other virus is safe. Pigs don’t get sick from it, and the advantage is that the immune response you’re stimulating is very good, but you don’t use live African Swine Fever virus,” he said. “So it’s a safe vaccine, and we never introduce the virus into the herd. The issue with live-attenuated vaccines is to find the right dose, or if you don’t give enough vaccine virus, you’re not getting a good response. If you give too much, you’re even making your pigs sick and cause disease with your vaccine virus. So from a safety profile, they are the lowest. There is a big concern that the vaccine virus then will transmit to other animals, will shed and potentially even get in wild reservoirs, like wild boars and so on. So really live-attenuated vaccines are really the only option you have if you have nothing else. And that’s what we’re seeing in China right now, in parts of Asia. In Canada, we will not use any live-attenuated vaccines, unless suddenly the whole industry is battling ASF at the same time. Canada, more likely, if they’re ever going to use a vaccine, will be using a safe vaccine.”
Dr. Gerdts said everybody’s asking the question for ASF when, where and how will there be a safe and effective vaccine.
“We haven’t been successful yet in developing a vaccine, so we’re working in partnership with South Africa and Kenya on a new ASF vaccine using adenoviruses for delivery. And so we generated several different vaccine candidates, and in partnership with Winnipeg, the CFIA lab there, we’re testing those together. Out recent approval at VIDO, is work with ASF in vitro at the moment, and diagnostics, looking at antivirals instead of using vaccines. So come up with different strategies of how we detect and prevent the virus otherwise.”
Dr. Gerdts’ parting comment, “Hopefully as soon as possible. Really, for African Swine Fever, we’re all trying to develop something that works as quickly as possible.” •
— By Harry Siemens

Volker Gerdts was recently a speaker of a breakout session at Banff Pork Seminar, breakout session 3, Vaccines & Health.