Attempted experimental reproduction of porcine periweaning-failure-to-thrive syndrome using tissue homogenates

Dynamics of the Enteric Virome in a Swine Herd Affected by Non-PCV2/PRRSV Postweaning Wasting Syndrome

A commercial pig farm with no history of porcine circovirus 2 (PCV2) or porcine reproductive and respiratory syndrome virus (PRRSV) repeatedly reported a significant reduction in body weight gain and wasting symptoms in approximately 20–30% of the pigs in the period between three and six weeks after weaning. As standard clinical interventions failed to tackle symptomatology, viral metagenomics were used to describe and monitor the enteric virome at birth, 3 weeks, 4 weeks, 6 weeks, and 9 weeks of age. The latter four sampling points were 7 days, 3 weeks, and 6 weeks post weaning, respectively. Fourteen distinct enteric viruses were identified within the herd, which all have previously been linked to enteric diseases. Here we show that wasting is associated with alterations in the enteric virome of the pigs, characterized by: (1) the presence of enterovirus G at 3 weeks of age, followed by a higher prevalence of the virus in wasting pigs at 6 weeks after weaning; (2) rotaviruses at 3 weeks of age; and (3) porcine sapovirus one week after weaning. However, the data do not provide a causal link between specific viral infections and the postweaning clinical problems on the farm. Together, our results offer evidence that disturbances in the enteric virome at the preweaning stage and early after weaning have a determining role in the development of intestinal barrier dysfunctions and nutrient uptake in the postweaning growth phase. Moreover, we show that the enteric viral load sharply increases in the week after weaning in both healthy and wasting pigs. This study is also the first to report the dynamics and co-infection of porcine rotavirus species and porcine astrovirus genetic lineages during the first 9 weeks of the life of domestic pigs.

Unusual histopathologic features in thymic corpuscles associated with porcine periweaning failure-to-thrive syndrome

Six, 5-6-wk-old pigs, from 3 farms of the same company, with significant loss of body condition were submitted for postmortem evaluation. Macroscopically, the main lesion observed in all of the pigs was thymic atrophy. Microscopically, all of the pigs had thymic atrophy, superficial lymphocytic fundic gastritis, atrophic enteritis, superficial colitis, and neutrophilic and lymphocytic rhinitis, leading to a diagnosis of porcine periweaning failure-to-thrive syndrome. In the pigs from 2 of the farms, many of the thymic corpuscles had infiltrates of neutrophils and degenerate cells, in some cases infiltrating the surrounding parenchyma.

Genomic investigation of porcine periweaning failure to thrive syndrome (PFTS)

Porcine periweaning failure to thrive syndrome (PFTS) can be defined by anorexia, lethargy, progressive debilitation and compulsive behaviours that occur in seemingly healthy pigs within two to threeweeks of weaning in the absence of any known infectious, nutritional, management or environmental factors. A genetic component has been hypothesised for this syndrome. In the present study, 119 commercial pigs (80 cases and 39 controls) were genotyped with the porcine 80K single nucleotide polymorphism-chip and were analysed with logistic regression and two Fixation Index-based approaches. The analyses revealed several regions on chromosomes 1, 3, 6 and 11 with moderate divergence between cases and controls, particularly three haplotypes on SSC3 and 11. The gene-based analyses of the candidate regions revealed the presence of genes that have been reported to be associated with phenotypes like PFST including depression (PDE10A) and intestinal villous atrophy (CUL4A). It is important to increase the effort of collecting more samples to improve the power of these analyses.

Genome-wide association study of periweaning failure-to-thrive syndrome (PFTS) in pigs

Porcine periweaning-failure-to-thrive syndrome (PFTS) is a condition that affects newly weaned piglets. It is characterised by a progressive debilitation leading to death, in the absence of infectious, nutritional, management or environmental factors. In this study, we present the first report of PFTS in South America and the results of a genome-wide association study to identify the genetic markers associated with the appearance of this condition in a crossbred swine population. Four chromosomal regions were associated with PFTS predisposition, one located on SSCX, one on SSC8, and the two other regions on SSC14. Regions on SSC8 and SSC14 harbour important functional candidate genes involved in human depression and might have an important role in PFTS. Our findings contribute to the increasing knowledge about this syndrome, which has been investigated since 2007, and to the identification of the aetiology of this disease.

Real-Time Reverse Transcription Polymerase Chain Reaction for Rapid Detection of Transmissible Gastroenteritis Virus

Transmissible gastroenteritis (TGE) is a highly contagious disease of pigs caused by the TGE virus (TGEV). Rapid detection of the virus in the affected pigs’ feces is critical for controlling the disease outbreaks. The real-time RT-PCR assay described in this chapter can quickly detect the presence of TGEV in fecal samples with high sensitivity and specificity.

Evidence that periweaning failure-to-thrive syndrome (PFTS) has a genetic predisposition

Genetic susceptibility or resistance to diseases is currently drawing increasing attention. This work describes two different breeding herds showing signs of periweaning failure-to-thrive syndrome (PFTS), an emergent swine disease. The disease was diagnosed based on clinical picture and confirmed by histopathology. The possibility of main infectious pathogens was ruled out by immunohistochemistry and PCR. In a simple approach, sires of the affected piglets have been determined using microsatellite paternity analysis, including a healthy group in each case. In each of the two farms, a single boar was found to have sired 45-50 per cent sick animals. Removal of this sire from two farms resulted in a significant decrease in the prevalence of the disease among the offspring, in accordance with other two cases diagnosed, although without including a control group. Since the analysed animals belonged to three different genetic lines, these findings point to the existence of individual genetic susceptibility to this syndrome.