Susantha Gomis, principal investigator and head and graduate chair of veterinary pathology at the at the University of Saskatchewan’s Western College of Veterinary Medicine, has developed a new aerosol based process using synthetic bacterial DNA (CpG-ODN) to spur the immune system of newly hatched chickens to better protect them from bacterial infections in the early period post-hatching.
“The birds are really vulnerable when they hatch, especially the first week of life, they get infections (and) it causes high mortality,” he told FeedNavigator. “Not all the birds die, but some of the birds do.” And early infections can have a lasting effect on the birds that survive, as disease can alter their size and development.
His team, which includes researchers from the University of Waterloo, was recently awarded $400,000 by the Western Economic Diversification Canada to continue research into the non-antibiotic aerosol.
The current project isn’t the first time that Gomis has worked on triggering an immune response — he started testing CpG-ODN about ten years ago, he said.
Originally, it was given as an injection, but that delivery method wasn’t practical. Now he’s focused on making the delivery system an aerosol that birds breathe before they’re set to leave the hatchery, he said.
“(We are) giving the small piece of synthetic bacterial DNA and it mimics a viral infection for the bird,” said the professor. “It sends out a false signal so it the immune system is really alert and activated (and it) happens in the hatchery, so when they’re moved they’re ready.”
Promotion of good bacteria
“The immune system is incredibly complex, so when people talk about stimulating the immune system they’re talking about a small part,” said Doug Korver, professor of poultry nutrition at the University of Alberta, who is working with a team to improve gut health in birds by promoting the growth of good or even neutral bacteria in the digestive tract using yeast derived supplements.
The abundance of positive bacteria prevents the types of bacteria linked to disease from gaining a hold on the lining of the digestive system, he said.
“The reason we feed antibiotic replacements is we’re trying to deliver the products where the bacteria are actually a problem, and to interrupt the relation between the pathogen and the bird,” said the researcher.
Currently, the research is in the early stage and has involved feeding the supplements to the birds and checking their fecal matter to see what bacterial reaction occurs, he said. Though initial results show an increase in helpful bacteria and a decrease in disease causing varieties, further testing will be needed before more definitive claims can be made.
Removal of Category 1 antibiotics
The Canadian poultry industry reportedly includes more than 25 hatcheries, 2,700 farmers and 185 producers. It contributes about $6.5 billion to the country’s annual GDP.
But, as elsewhere, there is growing pressure on the poultry sector to migrate away from antibiotics due to societal concerns the use of such drugs in animal production is linked to antibiotic resistance in humans. Since May 2014, Canadian poultry producers have eliminated the preventative use of Category I antibiotics – those drugs important for human medicine – on their flocks.
However, Korver said, antibiotics have been a type of blunt tool to treat and prevent illness, so several kinds of treatments used in synergy will likely be needed to gain similar reactions.
“People have come to realize that it’s going to be a combination of replacements, and we’re looking at different mechanisms, different approaches,” he said. “Each one that has a specific function, a specific target, and when you look at them together we may be able to get back to the same overall effect of antibiotics, but without the whole concern of resistance, or transfer of resistance, or some of the concerns that people have about antibiotics currently.”
In terms of next steps for the aerosol project, Gomis said the government funding will allow the research team to start testing the product in the field using larger numbers of birds.
“We’ve done enough experiments over the years at the lab scale,” he said. “We’re going to do experiments in the field before we go to commercialization.”
The research is set to take place in two different Canadian provinces, British Columbia and Saskatchewan, during different seasons to test the effectiveness when combined with different external conditions, he said. The goal is to gain a better understanding of how the three conditions – the bird, its environment and the pathogen – work together outside of a laboratory setting.
Additionally, when working in the lab, there are different mortality rates for birds who don’t receive treatment when compared to birds on a farm, said the professor. The goal is to see in practical experiments if the mortality rate can be lowered.
Past research using CpG-ODN
Gomis said he has done several trials with CpG-ODN looking at its effect in different laboratory settings. One such early study tested the immune response of 200 chickens using CpG-ODN applied either intramuscularly or subcutaneously. Birds were dosed at day 22 post hatching with CpG-ODN and three days later were exposed to a virulent strain of E. coli through an infected scratch. The birds were observed for 10 days after the infection.
The survival rate for birds control group birds that received no treatment was 15% while the rate for the birds receiving the highest amount of synthetic bacteria subcutaneously was 80% and the group getting the same amount intramuscularly was about 45%.
Source: Infection and Immunity
Doi: DOI: 10.1128/IAI.71.2.857–863.2003
Title: Protection of Chickens against Escherichia coli Infections by DNA Containing CpG Motifs
Authors: Susantha Gomis, Lorne Babiuk, Dale L. Godson, Brenda Allan, Tannis Thrush, Hugh Townsend, Philip Willson, Edwin Waters, Rolf Hecker, and Andrew Potter