Report on the 14th Symposium of the Swine and Poultry Infectious Disease Research Center (CRIPA)

The 14th CRIPA Symposium was held on December 8, 2023 and consisted of 15 hybrid conferences and a scientific poster session. This event highlighted crucial themes, in particular antibiotic resistance in swine and poultry medicine. Invited experts addressed key topics such as necrotic enteritis, avian reoviruses, organic breeding, multi-drug resistance plasmids as well as the microbiota and pig productivity. The presentations revealed innovative avenues to respond to these challenges, demonstrating the scientific community's commitment to sustainable solutions in the context of animal health.

Innovative strategies to combat necrotic enteritis: the research of Dr. Wade Abbott

Dr. Wade Abbott (Agriculture and Agri-Food Canada), presented an overview of his team's research work aimed at improving strategies to combat necrotic enteritis in chickens, induced by the bacteria Clostridium perfringens. A crucial phase of the experiment focused on mucus erosion associated with colonization, where respiratory and intestinal mucus layers were identified as critical barriers against colonization and infection.

« With necrotic enteritis, we believe that the mucus layer is being eroded during inflammation, so a combination of pathogen and host activities is responsible for the formation of necrotic lesions » 

• Dr. Wade Abbott, Agriculture and Agri-Food Canada

With this understanding, the research team set out to explore new approaches, including enzyme inhibition, to prevent colonization of C. perfringens in the chicken gut. Extensive testing of commercially available inhibitors was carried out, with selection of the best candidate to assess its ability to hinder bacterial growth.

At the same time, the team set about developing methods aimed at purifying the oligosaccharides present in milk and dairy residues, thus considering the valorization of dairy waste as a means of intervention against necrotic enteritis. Finally, aware that animal stress can play a role in the appearance of necrotic enteritis, the team explored the transplantation of microbiota from healthy birds as an alternative strategy. The promising results revealed a significant reduction in necrotic lesions in many animals after transplantation. This research opens up innovative perspectives for the development of effective solutions against necrotic enteritis without the use of antibiotics.

In-Depth Analysis of Avian Reoviruses: A Close Review by Dr. Steven Conrad

Dr. Steven Conrad (USDA) presented an overview of avian reoviruses conducted at the USDA in the United States. The main goal of their research was to clarify the host-pathogen interactions of viral diseases associated with poultry production and to produce new vaccines for chickens and turkeys.

Dr. Conrad highlighted the challenges faced by his team, including the development of viral manipulation techniques for the quantification of avian reoviruses (ARVs). Their research identified CaptoCore technology as the most efficient approach for purifying ARVs before sequencing their entire genome. This method, allowing small DNA fragments to enter the CaptoCore while trapping variants outside, demonstrated exceptional genome coverage and mapping, with economical use of resources.

An important research focus of the laboratory was the use of antigen display technologies such as the use of lactic acid bacteria particles to display the avian reovirus σC (Sigma C) antigen for vaccine delivery at the mucous membranes.

« We can use this approach to analyse other proteins because right know the only protein ARV known to be protective is σC, that doesn’t mean that other proteins might not be worthy choices for vaccines as well »

• Dr. Steven Conrad, USDA

Finally, as 99% of existing work on avian reoviruses mainly focuses on the σC protein, Dr. Conrad concluded by emphasizing the importance of exploring other proteins to broaden the prospects for solutions in this area.

Antibiotic resistance on organic farms: insights from Dr. Paul George

Then, Dr. Paul George (Université Laval), in collaboration with Martine Boulianne (Université de Montréal) and several partners, including the Swine and Poultry Infectious Disease Research Center, the Fédération des producteurs d'œufs du Québec and the Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST), presented research on resistance to antibiotics, heavy metals and azoles in organic farms.

« Antibiotics free doesn’t necessarily mean antimicrobial resistance free »

• Dr. Paul George, Université Laval

He highlighted the critical importance of managing resistance even in antibiotic-free environments. He mentioned that heavy metals are important key nutrients that we all need to keep our bodies functioning, but they can become toxic in high doses. The defense mechanisms that bacteria use to eliminate heavy metal pollution are often the same methods and mechanisms that they use to defend against antimicrobial agents, including antibiotics. In Quebec and across Canada, heavy metal pollution is a problem. Some countries allow their use as growth promoters.

Additionally, Dr. George shed light on azole resistance, emphasizing its vital role as an antifungal compound widely used in Europe and Asia. In 2016, in the United States, approximately 3,000 tons of azoles were used in agriculture each year. In Canada, it's hard to get numbers, but it's not used as much.

As organic farms gain popularity in Canada, with approximately 4% of Quebec egg farms certified organic, CRIPA is launching two new initiatives aimed at establishing a baseline on pathogen diversity and disease risks, as well as 'to assess the risks of exposure to fungi and mycotoxins in bioaerosols from free-range egg farms in Quebec.

The first stages of this project involved sampling air, litter/soil, and eggs from three organic and three non-organic producers, with results pending, but promising to provide crucial data on the bacterial biomass and fungal and bacterial biodiversity.

Controlling the spread of multi-resistance plasmids: the conclusions of the study by Dr. Vincent Burrus

Dr. Vincent Burrus (University of Sherbrooke) revealed the results of his study on IncC conjugative plasmids, epidemic vectors carrying antibiotic resistance genes. He mentioned that IncC conjugative plasmids have a wide host range. They are present in many Vibrionaceae and Enterobacteriaceae and are referred to as epidemic, meaning they can spread very efficiently through a large number of different strains and species. They carry a large number of resistance genes and are globally prevalent in pathogens infecting humans and animals. Exploring the interference of the ctiC gene in relaxosome assembly, his team identified its specific action on IncC plasmids.

« To test this hypothesis, we are trying to see if there is interaction between two proteins and we can see as an output the formation of the expression of the lacZ gene that we can monitor »

• Dr. Vincent Burrus, Université de Sherbrooke

When Dr. Burrus' team used different proteins for their test, the results demonstrated significant competition between the CtiC and Mobl proteins, suggesting the possibility of using a CtiC-mimicking peptide to disrupt this interaction and target relaxosome assembly. These findings open promising perspectives for controlling the fertility of IncC plasmids and reducing the spread of resistance genes.

Exploring the links between nutrition, microbiota and pig productivity: observations from Dr. Marie Lewis

Finally, Dr. Marie Lewis (University of Reading, UK) shared significant findings on the long-term impact of environmental and nutritional changes on the pig microbiota and the development of the immune system. Highlighting the importance of iron in the diet of pigs, she demonstrated that iron deficiency, beginning a few days after birth, induces an increased susceptibility to anemia in these animals. Dr. Lewis explained the magnitude of the microbiome by revealing that 2kg of our body weight is microbial bacteria and 60% of dry fecal matter is made up of bacteria.

First, she discussed what happens when we give iron to pigs from birth. Thus, the first group was composed of controlled pigs which did not have any iron supplement, the second group received an iron injection, the third group received iron orally and the fourth group received at the both an iron injection and oral iron. The results demonstrated that untreated piglets quickly developed anemia, while those receiving any form of iron supplement had normal blood iron levels and normal metabolic rate at 28 days of age regardless. the type of iron they received. Anemic piglets and those receiving oral iron, with or without intramuscular iron injection, were significantly smaller and weighed approximately 0.5 kg less.

« Giving them oral iron during the preweaning period significantly reduces their weight gain, which is really important in terms of productivity as they are half a kilogram lighter by 28 days »

• Dr. Marie Lewis, University of Reading, UK

Dr. Lewis and her team believed it was linked to the reduction of Lachnospiraceae bacteria in the gut, because this link was also observed in a study of adult humans.

The second part of their research concerned what happens if oral iron is given to piglets during the post-weaning period. His team had five different groups. Group 1 was to give oral iron and zinc, group 2 oral iron without zinc, group 3 oral iron given on day 37 (without zinc), group 4 an iron injection intramuscular on day 28 (low oral iron and no zinc) and group 5 with a negative control (low iron and no zinc). The results did not reveal significant differences in productivity between the groups.

However, it is important to note that reducing the amount of oral iron in the diet is linked to positive changes in microbiota composition and could reduce the risk of diarrhea after weaning.

These findings call for a deeper understanding of the interactions between nutrition, microbiota and productivity.

In light of the various conferences, all agree on the need for a collaborative approach to resolve the challenges of antibiotic resistance and animal health in a context of sustainable development. We hope that the symposium will have inspired all participants to persevere in their efforts, because it is together that we will find solutions.