Porcine Reproductive and Respiratory Syndrome Virus (PRRSV) is one of the pathogensthat is most dangerous to the swine sector. In addition to affecting the reproductive system in breeding sows and young animals' respiratory tracts, it is often associated with other secondary diseases, which is why it has become the health problem that inflicts the greatest economic losses in the swine industry worldwide.
A new study by the Animal Pathology group at the University of Cordoba (UCO), led by researcher Librado Carrasco, has identified the role of three key molecules in the immune defense against this pathogen in three target organs of the pig: the lung, the thymus and the tracheobronchial lymph node, which are fundamental tothe triggering of the immune response, and those in which the virus replicates the most once it comes into contact with the organism.
For this purpose, the research work analyzed these organs of 70 pigs in three differentiated groups, one of them not infected by this pathogen, which functions as a control group, and two other groups infected with two strains of varying virulence of the virus. Specifically, the study focused on what are known as Viral Transcription Factors, molecules that regulate the differentiation of cells involved in the immune system.
As researcher Inés Ruedas-Torres, one of the main authors of the study, emphasizes, the results indicate that three of these molecules (T-BET, FOXP3 and EOMES) are expressed more intensely and earlier in the most virulent strain analyzed.
The immune response: a balance between several factors
"Immune defense is not based on a single response, but rather on the sum of several elements," emphasizes Irene Rodríguez-Gómez, another of the researchers who participated in the study. Along these lines, as the study shows, each of the three proteins that the research has revealed to be fundamental to the immune response plays a different role in the body's defense. While the first of the three molecules analyzed (T-BET) is related to the activation of the macrophages that phagocytize the virus, the second (FOXP3) prevents, among other functions, the inflammatory response of the infected organism from being too intense. The third molecule (EOMES) is responsible for the activation of lymphocytes responsible for inducing the death of virus-infected cells.
"Apart from the fact that this study analyzes a series of aspects related to basic science," explains Jaime Gómez-Laguna, another of the authors involved in the study, "these results allow us to identifyfactors key to the immunopathology of this disease in order to continue studying them in more detail, and to develop certain strategies in the future."
There are currently several types of commercial vaccines against PRRSV, but none of them, the researcher stresses, prevents secondary infections or offers complete protection, due to the high mutation of the virus. The long-term objective, therefore, is to develop new vaccine candidates that offer total immunity against the different strains of the pathogen.
References
Ruedas-Torres, Inés & Gómez-Laguna, Jaime & Sánchez-Carvajal, José &Larenas-Muñoz, Fernanda &Barranco, Inmaculada &Pallarés, Francisco & Carrasco, Librado& Rodríguez-Gómez, Irene. (2021). Activation of T-bet, FOXP3, and EOMES in Target Organs From Piglets Infected With the Virulent PRRSV-1 Lena Strain. Frontiers in Immunology. 12. 773146. 10.3389/fimmu.2021.773146.