PED & Vaccine Update

Strict adherence to bio-security and sanitation protocols remains the chief defence against PED, even with the release in June of a vaccine developed to control the virus, says an Alberta veterinarian.

Red Deer-based swine specialist Egan Brockhoff joined Hank Harris and Joel Harris of Iowa-based Harris Vaccines Inc. on July 31 for a telephone town hall sponsored by Alberta Pork. The phone-in conference was the latest in a series created by the organization to update producers and industry representatives on efforts to prevent and control porcine epidemic diarrhea and similar coronaviruses, including transmissible gastroenteritis (TGE) and swine coronavirus (SCV).
Alberta’s bio-security measures have so far been highly effective in keeping PED out of Alberta farms, including vigorous testing of key sites and shipments, said Brockhoff.

It is now clear that imports of porcine plasma have been the primary source of outbreaks in Ontario, where the first infected pigs were found late in January, he said.

Alberta continues to conduct regular tests for the virus at key sites, including processors and assembly yards. Of more than 3,200 samples tested by the last week in July, there had been only one positive sample, found in a batch of porcine plasma. The shipment was destroyed and none of the product made it to any farms, said Brockhoff.

While they are not suggesting that the additive be banned outright, he and other swine veterinarians in Canada continue to caution producers about feeding porcine plasma. Those who want to continue using it must ensure that they know the source of the additive and are confident that it has been processed and handled correctly, he said.

In a straw poll taken by Alberta Pork from among producers taking part in the town hall, 83 per cent had already stopped using the additive.
Another poll conducted during the same teleconference found that 93 per cent of those producers had upgraded their bio-security systems and protocols during the last year.

Producers, processors, shippers and others who handle pigs and inputs must continue the vigilance they have shown to date to prevent the virus from coming into more herds, said Brockhoff.

For those farms where the virus has crept in, the vaccine developed at Harris Vaccines has proven to be an effect tool for keeping it under control, he said.
Guest speakers from the company explained for the teleconference how the vaccine was developed and the way veterinarians are recommending that it be used on farms in three categories: Newly infected (acute), relapsed and chronic.
Joel Harris, head of sales and marketing, explained that the vaccine is made from a different technology than what is typically used. Rather than using the entire virus, the company has developed and patented a process to isolate and replicate the genetic sequence. It then engineers a vaccine from that sequence. The process allows rapid development and manufacture of vaccine.

Harris Vaccine went to work when the first outbreaks occurred in the U.S. during the spring of 2013 and a first generation vaccine was released in August of that year.
However, tests showed that the animals treated with the vaccine were not developing as many antibodies as the company would have liked to see, said Harris.
“In January of this year we released our second generation PED vaccine, which really just included a larger gene sequence of the PED virus, and that is what subsequently got USDA approval in June,” he said.

Harris Vaccines was granted a temporary licence by the US Department of Agriculture and, shortly afterward, the Canadian Food Inspection Agency agreed to issue permits for emergency purposes.

About 200,000 doses have been shipped to Canada so far, mainly to Ontario, and the company is working with the CFIA for further approvals, beyond the emergency permits, said veterinarian Hank Harris, founder and president of the company.
“You have to go through your local veterinarian and you have to apply through CFIA, and we can help assist in that,” said Harris.

The vaccine is generally administered to sows that were previously infected, seven to 10 days before they are due to give birth to provide maximum protection for their piglets. It is also being administered to condition gilts as they go into barns where the infection has been present, he said.

Data are still being collected to determine how many doses should be administered and at what intervals in different situations, including barns where the disease had become chronic.

It is clear that exposure to the disease does not allow the sow to develop enough antibodies on her own to protect future litters. There are also still some questions about how long the vaccine will remain effective. Data so far have shown that the protection developed by treated sows is passed on to their piglets in serum, colostrum and milk, said Harris.

Expanding on Brockhoff’s discussion of two different strains of PED, he said the differences between the two are minimal and the gene sequence used to make the vaccine is almost identical, so the vaccine is effective against both strains.
Brockhoff said Harris Vaccines is the only company so far that has developed an effective vaccine for local markets.

“There are no other vaccines that are close to being introduced to the market in Canada or potentially North America. We’re months and months away from anything else,” he said.

A number of vaccines are being developed in Asia, but none of them are likely to come here, said Brockhoff.
He warned that producers should use the vaccine only in barns that have already been infected. There is no gain to be had from introducing the vaccine into a clean barn, he said.

In all regions, and especially in those where the disease has not yet emerged, the combination of sanitation and bio-security is still the best defence, said Brockhoff.
“I’m very confident that bio-security is really going to be king for us for keeping disease out,” he said.

“I’m really encouraged. Our pork producers and our industry people have really done a great job in Alberta.”
Prospects of new infections will rise as the fall approaches with shorter days and cooler weather, said Brockhoff.

“We’ve just got to keep doing all the little things right and we’re really going to have another successful fall,” he said.

Producers and other industry partners can visit to find updates on PED in Canada and the US. Audio recordings of the town hall discussions are also available on the site. •

— By Brenda Kossowan