Single nucleotide variants in innate immune genes associated with Salmonella shedding and colonization in swine on commercial farms

Polymorphisms in Pattern Recognition Receptor Genes Are Associated with Respiratory Disease Severity in Pig Farms

Reduced productivity caused by infections, particularly respiratory diseases, is a serious problem in pig farming. We have previously reported polymorphisms in porcine pattern recognition receptor genes affecting molecular functions and demonstrated that the 2197A/C polymorphism in the nucleotide-binding oligomerization domain containing 2 (NOD2) gene influences porcine circovirus 2-induced mortality. Here, we investigated how these polymorphisms affect respiratory disease-induced lesions, using samples from a slaughterhouse dealing with pigs from two farms. Lung lesions were evaluated using two scoring systems, Goodwin (GW) and slaughterhouse pleuritis evaluation system (SPES), to determine the influence of Mycoplasma hyopneumoniae (Mhp) and Actinobacillus pleuropneumoniae (App), respectively. SPES scores were significantly higher when the 1205T allele of Toll-like receptor 5 (TLR5-1205T), rather than TLR5-1205C, was present. On the farm with more severe Mhp invasion, lower GW lesion scores were significantly associated with the presence of the NOD-like receptor family pyrin domain containing 3 (NLRP3)-2906G allele; where App invasion was worse, lower SPES scores were significantly associated with the presence of the NOD2-2197C allele. Combinations of polymorphisms in pattern recognition receptor genes can therefore be utilized for breeding for resistance against respiratory diseases in pigs. DNA markers of these polymorphisms can thus be used to improve productivity by reducing respiratory diseases due to bacterial pathogens in pig livestock.

Association of natural resistance-associated macrophage protein 1 polymorphisms with Salmonella fecal shedding and hematological traits in pigs

Background and Aim

Natural resistance-associated macrophage protein 1 encoding gene (Nramp1) plays a role in immune response and disease resistance. This study aimed to investigate the polymorphisms of Nramp1 intron 6 concerning Salmonella shedding and hematological traits in pigs.

Materials and Methods

A total of 40 commercial pigs (three-way Large White x Landrace x Duroc cross) were genotyped using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method and analyze the relationship between the polymorphisms of the Nramp1 gene and Salmonella fecal shedding and hematological parameters.

Results

Nramp1 was shown to be polymorphic in these pigs. The Nramp1 gene has two alleles (A and B) and two genotypes (AB and BB). The BB genotype had a higher frequency than the AB genotype. A significant relationship between the BB genotype and the number of Salmonella in feces compared to the AB genotype (p < 0.05) on 7 days post-inoculation (DPI) was revealed in the association analysis. The single-nucleotide polymorphism at intron 6 in the Nramp1 gene was linked to white and red blood cells 2 and 7 DPI (p < 0.05).

Conclusion

The Nramp1 gene was suggested by these findings to be potentially used as a molecular marker for the genetic selection of disease susceptibility in pig breeding.

[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.

Antibody responses to porcine reproductive and respiratory syndrome virus, influenza A virus, and Mycoplasma hyopneumoniae from weaning to the end of the finisher stage in fourteen groups of pigs in Ontario, Canada

Background

Respiratory diseases are among the most important factors affecting swine farm productivity in Canada. The objectives of this study were to investigate antibody responses to porcine reproductive and respiratory syndrome virus (PRRSV), influenza A virus (IAV), and Mycoplasma hyopneumoniae (M. hyopneumoniae) from weaning to the end of the finisher stage on a subset of commercial swine farms in Ontario, Canada, and to examine the association between nursery diet and antibody responses.

Results

Overall, older pigs were more likely to test seropositive for PRRSV and less likely to test seropositive for M. hyopneumoniae (p <  0.001). Pigs were more likely to test seropositive for IAV at weaning and the end of the grower and finisher stages compared to the end of nursery (p <  0.001). Pigs that were seropositive for IAV were more likely to test seropositive for both PRRSV and M. hyopneumoniae (p <  0.001). Two, 9, and 4 groups that had more than 20% of pigs seropositive to PRRSV, IAV, and M. hyopneumoniae, respectively, from the end of nursery to the end of finisher were classified as seropositive. Pigs fed a plant-based (low complexity) diet during nursery were more likely to be seropositive for PRRSV (p <  0.001) but there were no significant differences in seropositivity to IAV or M. hyopneumoniae due to nursery diet complexity.

Conclusions

This study provides information regarding changes in serum antibody in pigs across different stages of production and highlights periods of vulnerability. Additionally, these findings may encourage further research into the effects of nursery diet complexity on disease susceptibility and immune response.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-021-02756-6.

C-Type Lectins in Veterinary Species: Recent Advancements and Applications

C-type lectins (CTLs), a superfamily of glycan-binding receptors, play a pivotal role in the host defense against pathogens and the maintenance of immune homeostasis of higher animals and humans. CTLs in innate immunity serve as pattern recognition receptors and often bind to glycan structures in damage- and pathogen-associated molecular patterns. While CTLs are found throughout the whole animal kingdom, their ligand specificities and downstream signaling have mainly been studied in humans and in model organisms such as mice. In this review, recent advancements in CTL research in veterinary species as well as potential applications of CTL targeting in veterinary medicine are outlined.

Identification of single-nucleotide variants associated with susceptibility to Salmonella in pigs using a genome-wide association approach

BACKGROUND

Salmonella enterica serovars are a major cause of foodborne illness and have a substantial impact on global human health. In Canada, Salmonella is commonly found on swine farms and the increasing concern about drug use and antimicrobial resistance associated with Salmonella has promoted research into alternative control methods, including selecting for pig genotypes associated with resistance to Salmonella. The objective of this study was to identify single-nucleotide variants in the pig genome associated with Salmonella susceptibility using a genome-wide association approach. Repeated blood and fecal samples were collected from 809 pigs in 14 groups on farms and tonsils and lymph nodes were collected at slaughter. Sera were analyzed for Salmonella IgG antibodies by ELISA and feces and tissues were cultured for Salmonella. Pig DNA was genotyped using a custom 54 K single-nucleotide variant oligo array and logistic mixed-models used to identify SNVs associated with IgG seropositivity, shedding, and tissue colonization.

RESULTS

Variants in/near PTPRJ (p = 0.0000066), ST6GALNAC3 (p = 0.0000099), and DCDC2C (n = 3, p < 0.0000086) were associated with susceptibility to Salmonella, while variants near AKAP12 (n = 3, p < 0.0000358) and in RALGAPA2 (p = 0.0000760) may be associated with susceptibility.

CONCLUSIONS

Further study of the variants and genes identified may improve our understanding of neutrophil recruitment, intracellular killing of bacteria, and/or susceptibility to Salmonella and may help future efforts to reduce Salmonella on-farm through genetic approaches.

Infection, colonization and shedding of Campylobacter and Salmonella in animals and their contribution to human disease: A review

Livestock meat and offal contribute significantly to human nutrition as sources of high-quality protein and micronutrients. Livestock products are increasingly in demand, particularly in low- and middle-income settings where economies are growing and meat is increasingly seen as an affordable and desirable food item. Demand is also driving intensification of livestock keeping and processing. An unintended consequence of intensification is increased exposure to zoonotic agents, and a contemporary emerging problem is infection with Campylobacter and Salmonella spp. from livestock (avian and mammalian), which can lead to disease, malabsorption and undernutrition through acute and chronic diarrhoea. This can occur at the farm, in households or through the food chain. Direct infection occurs when handling livestock and through bacteria shed into the environment, on food preparation surfaces or around the house and surroundings. This manuscript critically reviews Campylobacter and Salmonella infections in animals, examines the factors affecting colonization and faecal shedding of bacteria of these two genera as well as risk factors for human acquisition of the infection from infected animals or environment and analyses priority areas for preventive actions with a focus on resource-poor settings.