Candidate genes and gene markers for the resistance to porcine pleuropneumonia

Proteomic and immunoproteomic insights into the exoproteome of Actinobacillus pleuropneumoniae, the causative agent of porcine pleuropneumonia

Porcine pleuropneumonia caused by Actinobacillus pleuropneumoniae affects pig health status and the swine industry worldwide. Despite the extensive number of studies focused on A. pleuropneumoniae infection and vaccine development, a thorough analysis of the A. pleuropneumoniae exoproteome is still missing. Using a complementary approach of quantitative proteomics and immunoproteomics we gained an in-depth insight into the A. pleuropneumoniae serotype 2 exoproteome, which provides the basis for future functional studies. Label-free liquid chromatography-tandem mass spectrometry (LC-MS/MS) revealed 593 exoproteins, of which 104 were predicted to be virulence factors. The RTX toxins ApxIIA and ApxIIIA -were found to be the most abundant proteins in the A. pleuropneumoniae serotype 2 exoproteome. Furthermore, the ApxIVA toxin was one of the proteins showing the highest abundance, although ApxIVA is commonly assumed to be expressed exclusively in vivo. Our study revealed several antigens, including proteins with moonlight functions, such as the elongation factor (EF)-Tu, and proteins linked to specific metabolic traits, such as the maltodextrin-binding protein MalE, that warrant future functional characterization and might present potential targets for novel therapeutics and vaccines. Our Ig-classes specific serological proteome analysis (SERPA) approach allowed us to explore the development of the host humoral immune response over the course of the infection. These SERPAs pinpointed proteins that might play a key role in virulence and persistence and showed that the immune response to the different Apx toxins is distinct. For instance, our results indicate that the ApxIIIA toxin has properties of a thymus-independent antigen, which should be studied in more detail.

A genome-wide screen for resilient responses in growing pigs

Background

There is a growing interest to decipher the genetic background of resilience and its possible improvement through selective breeding. The objective of the present study was to provide new insights into the genetic make-up of resilience in growing pigs by identifying genomic regions and candidate genes associated with resilience indicators. Commercial Duroc pigs were challenged with an attenuated Aujeszky vaccine at 12 weeks of age. Two resilience indicators were used: deviation from the expected body weight at 16 weeks of age given the growth curve of non-vaccinated pigs (∆BW) and the increase in acute-phase protein haptoglobin at four days post-vaccination (∆HP). Genome-wide association analyses were carried out on 445 pigs, using genotypes at 41,165 single nucleotide polymorphisms (SNPs) and single-marker and Bayesian multiple-marker regression approaches.

Results

Genomic regions on pig chromosomes 2, 8, 9, 11 (∆BW) and 8, 9, 13 (∆HP) were found to be associated with the resilience indicators and explained high proportions of their genetic variance. The genomic regions that were associated explained 27 and 5% of the genetic variance of ∆BW and ∆HP, respectively. These genomic regions harbour promising candidate genes that are involved in pathways related to immune response, response to stress, or signal transduction (CD6, PTGDR2, IKZF1, RNASEL and MYD88), and growth (GRB10 and LCORL).

Conclusions

Our study identified novel genomic regions that are associated with two resilience indicators (∆BW and ∆HP) in pigs. These associated genomic regions harbour potential candidate genes involved in immune response and growth pathways, which emphasise the strong relationship between resilience and immune response.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12711-022-00739-1.

[Opportunities and risks of the use of genetic resistances to infectious diseases in pigs - an overview]

Demands for health, performance and welfare in pigs, as well as the desire for consumer protection and reduced antibiotic use, require optimal measures in advance of disease development. This includes, in principle, the use of genetically more resistant lines and breeding animals, whose existence has been proven for a wide range of pathogen-host interactions. In addition, attempts are being made to identify the gene variants responsible for disease resistance in order to force the selection of suitable populations, also using modern biotechnical technics. The present work is intended to provide an overview of the research status achieved in this context and to highlight opportunities and risks for the future.The evaluation of the international literature shows that genetic disease resistance exist in many areas of swine diseases. However, polygenic inheritance, lack of animal models and the influence of environmental factors during evaluation render their implementation in practical breeding programs demanding. This is where modern molecular genetic methods, such as Gene Editing, come into play. Both approaches possess their pros and cons, which are discussed in this paper. The most important infectious diseases in pigs, including general diseases and epizootics, diseases of the respiratory and digestive tract and diseases of the immune system are taken into account.

Application of the MISTEACHING(S) disease susceptibility framework to Actinobacillus pleuropneumoniae to identify research gaps: an exemplar of a veterinary pathogen

Historically, the MISTEACHING (microbiome, immunity, sex, temperature, environment, age, chance, history, inoculum, nutrition, genetics) framework to describe the outcome of host-pathogen interaction, has been applied to human pathogens. Here, we show, using Actinobacillus pleuropneumoniae as an exemplar, that the MISTEACHING framework can be applied to a strict veterinary pathogen, enabling the identification of major research gaps, the formulation of hypotheses whose study will lead to a greater understanding of pathogenic mechanisms, and/or improved prevention/therapeutic measures. We also suggest that the MISTEACHING framework should be extended with the inclusion of a 'strain' category, to become MISTEACHINGS. We conclude that the MISTEACHINGS framework can be applied to veterinary pathogens, whether they be bacteria, fungi, viruses, or parasites, and hope to stimulate others to use it to identify research gaps and to formulate hypotheses worthy of study with their own pathogens.

The effects of boar on susceptibility to swine inflammation and necrosis syndrome in piglets

Inflammation and necrosis can appear in pigs in several parts of the body simultaneously. The signs can affect newborns, suckling piglets and older pigs, and recent studies suggest that the syndrome is primarily endogenous. Inflammation and necrosis indicate impaired animal welfare, and thus should be controlled in pig production. This can be achieved by improving husbandry conditions. However, the variation in signs also appears to have a genetic component. The aim of the present study was therefore to test the effects of different boars from the Duroc and Pietrain breeds on the prevalence of swine inflammation and necrosis syndrome in their offspring. For this purpose, 646 suckling pigs from 39 sows (two herds) and 19 boars were made available. On the third day of life, the piglets were examined for clinical signs of inflammation and necrosis at tail base, tail tip, ears, face, teats, navel and claws. For the evaluation, we included the boar within the breed and the breed as fixed effects and the sow within the herd as random effects. More than 70% of the piglets were affected at the tail base, ears, coronary bands and heels. Bristle loss, swelling, redness, venous congestion and claw wall bleeding occurred most frequently. Exudation and necrosis affected fewer piglets. None of the piglets was completely free from signs of SINS. Offspring from Duroc boars had significantly lower SINS scores (4.87 ± 0.44) than offspring from Pietrain boars (10.13 ± 0.12). Within the Pietrain breed, significant effects of the boar were observed on inflammation and necrosis levels. Under the present study conditions, using Duroc boars instead of Pietrain boars resulted in a 59% reduction in the SINS scores of their offspring. The SINS score in the offspring of the most favourable Pietrain boar was almost 40% lower than that of offspring in the least favourable. These findings confirm considerable genetic effects on the outcome of SINS under a given husbandry. Further studies are necessary to characterise the genetic effects in detail and to make them useful to combat the syndrome.

Genes and SNPs Involved with Scrotal and Umbilical Hernia in Pigs

Hernia is one of the most common defects in pigs. The most prevalent are the scrotal (SH), inguinal (IH) and umbilical (UH) hernias. We compared the inguinal ring transcriptome of normal and SH-affected pigs with the umbilical ring transcriptome of normal and UH-affected pigs to discover genes and pathways involved with the development of both types of hernia. A total of 13,307 transcripts was expressed in the inguinal and 13,302 in the umbilical ring tissues with 94.91% of them present in both tissues. From those, 35 genes were differentially expressed in both groups, participating in 108 biological processes. A total of 67 polymorphisms was identified in the inguinal ring and 76 in the umbilical ring tissue, of which 11 and 14 were novel, respectively. A single nucleotide polymorphism (SNP) with deleterious function was identified in the integrin α M (ITGAM) gene. The microtubule associated protein 1 light chain 3 γ (MAP1LC3C), vitrin (VIT), aggrecan (ACAN), alkaline ceramidase 2 (ACER2), potassium calcium-activated channel subfamily M α 1 (KCNMA1) and synaptopodin 2 (SYNPO2) genes are highlighted as candidates to trigger both types of hernia. We generated the first comparative study of the pig umbilical and inguinal ring transcriptomes, contributing to the understanding of the genetic mechanism involved with these two types of hernia in pigs and probably in other mammals.