Encouraging kids to express themselves seems like a good idea…until they actually do it. Gene expression, on the other hand, is all upside without the downside, and is key to success in applying genomics to improve disease resilience and sustainability in Canadian pork production.
“When the information stored in our DNA is converted into instructions for making proteins or other molecules, it is called gene expression,” said Dr. Kyu-Sang Lim, Post-doctoral Research Associate, Department of Animal Science at Iowa State University.
Express for success
“The main focus of my work in the project is to investigate the gene expression profile in the blood of young healthy pigs as an early indicator of disease resilience,” said Dr. Lim. “I have made substantial progress in my research over the last 3 years. I have been evaluating a novel globin blocking method to make gene expression profiling in blood based on sequencing more efficient. As well, I am developing analysis pipelines and conducting statistical and genetic analyses on the level of gene expressions on over 900 pigs.”
Gene expression from the blood of young healthy pigs, measurable in the nucleus breeding herds, can provide indicators for selection of pigs for disease resilience. It may provide disease-related biological processes and can point researchers to key gene targets for selection, management and/or treatments.
“The transcription-based drug discovery approach for sickle cell anemia in humans, targeting the activation of γ-globin transcription, is a good example of the application of gene expression analysis in disease studies.”
In search of resilience
In the current study, healthy cross-bred pigs from multiplication units were moved to an experimental facility and the level of expression of several genes in blood, collected prior to exposing pigs to the disease challenge, showed significant associations with disease resilience traits that were recorded during the challenge. Most significant associations between gene expressions and resilience traits were found for mortality, including in combination with the number of health treatments received, as well as feed conversion ratio. Pigs that showed a higher expression of genes that were related to immune response in their blood prior to the challenge tended to have poorer performance, both before and during the challenge.
Though experienced scientists are rarely surprised by their findings, the pig genome project produced some interesting results around PRRS (porcine reproductive and respiratory syndrome).
“Some people may have heard of the gene-edited CD163 knockout pigs that are completely resistant to the infection of the PRRS virus. Although none of these pigs were included in our study, we found that pigs with a higher expression of the CD163 gene in their blood prior to a challenge were more likely to die in the disease challenge, which included exposure to the PRRS virus. This suggests that there is a natural variation in the CD163 gene that affects resistance to PRRS.”
Regardless of the disease, boosting resilience can go a long way towards enhancing pig health, improving animal welfare, lowering costs and reducing the use of antibiotics. Given the power of gene expression to help predict that resilience, it is a topic worthy of closer scrutiny.
“This study should provide an insight into the biological basis behind gene expression patterns of young, healthy pigs and how this is associated with their future disease resilience,” said Dr. Lim. “In addition, the significant associations between gene expressions and resilience traits may warrant their use as an early disease resilience indicator in pig breeding.”