Amyloid arthropathy in chickens

Exposure of embryonating eggs to Enterococcus faecalis and Escherichia coli potentiates E. coli pathogenicity and increases mortality of neonatal chickens

Enterococci and Escherichia coli are opportunistic pathogens of poultry and are associated with embryo and neonatal chick mortality. We have recently demonstrated that 56% of dead broiler chicken embryos in commercial hatcheries in western Canada were due to the coinfection of Enterococcus species and E. coli. The objective of this study was to investigate the host-pathogen interactions of Enterococcus faecalis and E. coli in developing chicken embryos. Embryonating eggs at 12 d of incubation were dipped in a solution of E. faecalis and/or E. coli for 30 s to expose the eggshell to study the migration and colonization of E. faecalis and E. coli in the internal organs of chicken embryos and subsequent neonatal chicken mortality following hatch. A multidrug-resistant E. faecalis isolate from a dead chicken embryo and an E. faecalis isolate from a case of yolk sac infection were able to colonize the internal organs of chicken embryos rapidly compared to an E. faecalis isolate from a healthy chicken without affecting viability or hatchability of embryos. Although E. faecalis colonized internal organs of chicken embryos, no evidence of inflammation of these organs nor the expression of virulence genes of E. faecalis was observed. Although E. faecalis and E. coli alone did not affect the viability of embryos, a significantly high neonatal chicken mortality (27%) was observed following exposure of embryos to both E. faecalis and E. coli. Upregulation of IL-1 and CXCR4 was evident 48 h before peak mortality of neonatal chickens; this could suggest a possible link of cytokine dysregulation to increased mortality in coinfected neonatal chickens. However, further studies are warranted to investigate this issue vis-à-vis coinfection with E. faecalis and E. coli in chicken embryos and neonatal chickens.

Review on skeletal disorders caused by Staphylococcus spp. in poultry

Lameness or leg weakness is the main cause of poor poultry welfare and serious economic losses in meat-type poultry production worldwide. Disorders related to the legs are often associated with multifactorial aetiology which makes diagnosis and proper treatment difficult. Among the infectious agents, bacteria of genus Staphylococcus are one of the most common causes of bone infections in poultry and are some of the oldest bacterial infections described in poultry. Staphylococci readily infect bones and joints and are associated with bacterial chondronecrosis with osteomyelitis (BCO), spondylitis, arthritis, tendinitis, tenosynovitis, osteomyelitis, turkey osteomyelitis complex (TOC), bumblefoot, dyschondroplasia with osteomyelitis and amyloid arthropathy. Overall, 61 staphylococcal species have been described so far, and 56% of them (34/61) have been isolated from clinical cases in poultry. Although Staphylococcus aureus is the principal cause of poultry staphylococcosis, other Staphylococcus species, such as S. agnetis, S. cohnii, S. epidermidis, S. hyicus, S. simulans, have also been isolated from skeletal lesions. Antimicrobial treatment of staphylococcosis is usually ineffective due to the location and type of lesion, as well as the possible occurrence of multidrug-resistant strains. Increasing demand for antibiotic-free farming has contributed to the use of alternatives to antibiotics. Other prevention methods, such as better management strategies, early feed restriction or use of slow growing broilers should be implemented to avoid rapid growth rate, which is associated with locomotor problems. This review aims to summarise and address current knowledge on skeletal disorders associated with Staphylococcus spp. infection in poultry.

Allelic Diversity in the Serum Amyloid A2 Gene and Amyloid A Amyloidosis in a Breeding Colony of Zebra Finches (Taeniopygia guttata)

A high incidence of amyloid A (AA) amyloidosis was observed in the research breeding colony of zebra finches at our institution. Some birds with hepatic AA amyloidosis were asymptomatic for comorbid conditions frequently associated with the development of AA amyloidosis, whereas other birds with comorbid conditions failed to develop AA amyloidosis, suggesting a potential genetic component to the disease. Sequencing the SAA2 gene from 20 birds yielded 18 distinct sequences that coded for 5 isoforms of the protein. Most of the amino acid substitutions are unlikely to affect the protein's structure or function, but 2 changes-R52L and V84M-were predicted to be disruptive. In particular, R52 is highly conserved across vertebrates, with only arginine or lysine found at this position in reported sequences to date. The atypical R52L substitution occurred in 2 otherwise healthy birds with hepatic AA amyloidosis, supporting the idea that this change is pathogenic.

Chicken embryo lethality assay for determining the lethal dose and virulence of Enterococcus faecalis

Enterococcus faecalis is the major pathogen found in field cases of amyloid arthropathy in chickens. Given the need for a better understanding of the virulence mechanisms of the causative strains, the embryo lethality assay (ELA) is proposed in the present study as a model to evaluate the virulence of E. faecalis strains, specifically the pathogenic avian strain K923/96, which was previously related with amyloid arthropathy. Hence, 0.2 ml of five doses of the cited strain (from 2.5 to 2500 colony-forming units (CFU) per ml) were inoculated into the allantoic cavity of 10-day-old embryos. The embryo mortality rate (EMR) was determined by daily candling of the eggs over a period of seven days and based on this information the median lethal dose (LD₅₀) was calculated. The ELA was repeated four times on a sample of 3443 eggs. The infectious dose showed a significant effect on the EMR. The EMR with the doses of 2.5, 5, 25, 250 and 2500 CFU/ml was 43%, 45%, 63%, 90% and 93%, respectively. The estimated dose at LD₅₀ was 6.6 CFU/ml. As expected, the higher the infectious dose, the greater the EMR and the lower the embryo survival time. The highest EMR was recorded after three and four days post-inoculation in all doses. In conclusion, these results can be used as a basis for further researches on the E. faecalis virulence. In order to corroborate its model capacity to predict the virulence of this bacterium, more ELAs with different E. faecalis strains are required.

Longitudinal study of transmission of Escherichia coli from broiler breeders to broilers

Escherichia coli is of major importance in industrial broiler production as the main cause of salpingitis and peritonitis in broiler breeders. Furthermore E. coli is the most common cause of first week mortality in broiler chickens. The aim of the present study was to investigate the transmission of E. coli, isolated from broiler breeders with salpingitis, to the progeny and the possibility of subsequent first week mortality. Four parent flocks were followed during the whole production period (20-60 weeks) by post mortem and bacteriological examination of randomly selected dead birds. Newly hatched chickens from each flock were swabbed in the cloaca on four occasions (parent age 30, 40, 50, 60 weeks) and E. coli was isolated. Causes of first week mortality were determined pathologically and bacteriologically. E. coli isolates from parents, newly hatched chickens and first week mortality were selected for Pulsed-Field-Gel-Electrophoresis (PFGE) and Multi-Locus-Sequence-Typing (MLST) to determine their clonal relationships. E. coli was the main cause of both salpingitis in parents and first week mortality in broilers, and E. coli dominated the bacterial flora of the cloaca of newly hatched chickens. PFGE of E. coli showed identical band patterns in isolates from the three different sources indicating a transmission of E. coli from parent birds to chickens. In conclusion, E. coli isolated from salpingitis in broiler parents were found to be transmitted to broilers in which some sequence types contributed to the first week mortality.

Experimental induction of chicken amyloid A amyloidosis in white layer chickens by inoculation with inactivated vaccines

We investigated the amyloidogenic potential of inactivated vaccines and the localized production of serum amyloid A (SAA) at the injection site in white layer chickens. Hens in the treated group were injected intramuscularly three times with high doses of inactivated oil-emulsion Salmonella Enteritidis vaccine and multivalent viral and bacterial inactivated oil-emulsion vaccines at two-week intervals. Chickens in the control group did not receive any inoculum. In the treated group, emaciation and granulomas were present, while several chickens died between 4 and 6 weeks after the first injection. Hepatomegaly was seen at necropsy, and the liver parenchyma showed inconsistent discolouration with patchy green to yellowish-brown areas, or sometimes red-brown areas with haemorrhage. Amyloid deposition in the liver, spleen, duodenum, and at injection sites was demonstrated using haematoxylin and eosin staining, Congo red, and immunohistochemistry. The incidence of chicken amyloid A (AA) amyloidosis was 47% (28 of 60) in the treated group. In addition, RT-PCR was used to identify chicken SAA mRNA expression in the liver and at the injection sites. Furthermore, SAA mRNA was detected by in situ hybridization in fibroblasts at the injection sites, and also in hepatocytes. We believe that this is the first report of the experimental induction of systemic AA amyloidosis in white layer chickens following repeated inoculation with inactivated vaccines without the administration of amyloid fibrils or other amyloid-enhancing factors.

Systemic Clinical and Metabolic Diseases

Like other animals pet and companion birds are also prone to systemic illness. This is presented in the form of certain clinical signs and symptoms which is known as “ sick-bird syndrome.”

Intrinsic Stability, Oligomerization, and Amyloidogenicity of HDL-Free Serum Amyloid A

Serum amyloid A (SAA) is an acute-phase reactant protein predominantly bound to high-density lipoprotein in serum and presumed to play various biological and pathological roles. Upon tissue trauma or infection, hepatic expression of SAA increases up to 1,000 times the basal levels. Prolonged increased levels of SAA may lead to amyloid A (AA) amyloidosis, a usually fatal systemic disease in which the amyloid deposits are mostly comprised of the N-terminal 1-76 fragment of SAA. SAA isoforms may differ across species in their ability to cause AA amyloidosis, and the mechanism of pathogenicity remains poorly understood. In vitro studies have shown that SAA is a marginally stable protein that folds into various oligomeric species at 4 °C. However, SAA is largely disordered at 37 °C, reminiscent of intrinsically disordered proteins. Non-pathogenic murine (m)SAA2.2 spontaneously forms amyloid fibrils in vitro at 37 °C whereas pathogenic mSAA1.1 has a long lag (nucleation) phase, and eventually forms fibrils of different morphology than mSAA2.2. Remarkably, human SAA1.1 does not form mature fibrils in vitro. Thus, it appears that the intrinsic amyloidogenicity of SAA is not a key determinant of pathogenicity, and that other factors, including fibrillation kinetics, ligand binding effects, fibril stability, nucleation efficiency, and SAA degradation may play key roles. This chapter will focus on the known structural and biophysical properties of SAA and discuss how these properties may help better understand the molecular mechanism of AA amyloidosis.

Comparative biophysical characterization of chicken β2-microglobulin

β(2)-microglobulin (β(2)m) is the smallest building block of molecules belonging to the immunoglobulin superfamily. By comparing thermodynamic and structural characteristics of chicken β(2)m with those of other species, we seek to elucidate whether it is possible to pinpoint features that set the avian protein apart from other β(2)m. The thermodynamic assays revealed that chicken β(2)m exhibits a lower melting temperature than human β(2)m, and the H/D exchange behavior observed by infrared spectroscopy indicates a more flexible structure of the former protein. To understand these differences at a molecular level, we determined the structure of free chicken β(2)m by X-ray crystallography to a resolution of 2.0 Å. Our comparisons indicate that certain biophysical characteristics of the chicken protein, particularly its conformational flexibility, diverge considerably from those of the other β(2)m analyzed, although basic structural features have been retained through evolution.

Investigation of serum amino acid and serum amyloid A concentrations in chickens with amyloid arthropathy

BACKGROUND

Increased proteolytic cleavage of serum amyloid A (SAA) may potentially contribute to the development of AA amyloid deposition.

OBJECTIVE

To study the possible relationship between amyloid artropathy and expression of SAA and some serum amino acids.

ANIMALS AND METHODS

Values of 15 serum amino acids and SAA were investigated in chickens with experimentally induced amyloid arthropathy. Thirty-four, 5-week-old chicks were allocated into two groups: one group was injected intra-articularly with 0.25 mL complete Freund's adjuvant at the left tibio-metatarsal joint to induce amyloid arthropathy, whereas the other group served as control. All pullets were necropsied 13 weeks after injection. Collected tissue samples were examined histopathologically. Blood samples were collected and SAA concentrations were measured with enzyme-linked immunosorbent assay. High-performance liquid chromatography was used to assess the amino acid concentrations in serum.

RESULTS

Amyloid accumulation in joints occurred only in the experimental group (89%). SAA concentrations of 166 ± 17 and 423 ± 39 (SD) ng/mL were found in the control and experimental groups, respectively (p < 0.001). In the experimental group, an increase was observed in all examined amino acid concentrations except for citrulline. The most significant (p < 0.001) increases were noticed in serine (from 159 ± 15 to 360 ± 29 µmol/L), glycine (from 151 ± 20 to 279 ± 16 µmol/L), isoleucine (from 48 ± 2 to 80 ± 6 µmol/L), and phenylalanine (from 49 ± 2 to 90 ± 3 µmol/L).

CONCLUSION

The results of this study suggest that there is a positive correlation between some serum amino acid values, especially serine, glycine, isoleucine, and phenylalanine, and the high concentrations of SAA in chickens with amyloid arthropathy.

A concise review of amyloidosis in animals

Amyloidosis refers to a group of protein misfolding diseases characterized by deposition of a particular amyloid protein in various organs and tissues of animals and humans. Various types and clinical forms of amyloidosis, in which the pathology and pathogenesis is diverse depending upon the underlying causes and species affected, are reported in domestic and wild animals. The clinical findings are also quite variable consequent to the variation of the tissues and organs involved and the extent of functional disruption of the affected organs in various animal species. The affected organs may be enlarged and exhibit variable pallor grossly, or the amyloid deposit may be discernible only after microscopic examination of the affected tissues. Amyloid appears as a pale eosinophilic homogenous extracellular deposit in tissues. However, microscopic examination and Congo red staining with green birefringence under polarized light are needed to confirm amyloid and differentiate it from other apparently similar extracellular deposits such as collagen and fibrin. Identifying the type of amyloid deposit needs immunohistochemical staining, ultrastructural characterization of the amyloid fibril, and if feasible also genetic studies of the involved species for clinical and prognostic purposes. This paper provides a concise review of the occurrence of amyloidosis in domestic and wild animals.

Enterococcus faecalis of human and poultry origin share virulence genes supporting the zoonotic potential of E. faecalis

Enterococcus faecalis is a major cause of nosocomial infections in humans and has been linked to severe extra-intestinal infections in poultry. A zoonotic potential has been suggested and the aim of the present study was to investigate similarities in virulence gene profiles of E. faecalis originating from infections in humans and poultry respectively. A total of 106 isolates of E. faecalis [26 human clinical isolates, 60 poultry clinical isolates (including two small-colony variants (SCVs) and 20 poultry cloacal isolates] were investigated for presence of seven virulence-associated genes: ace, asa1, cylA, efaA, EF0591, esp and gelE. For each gene, the PCR-amplification product was sequenced from one isolate in each group to explore intragenic variations between genes of human and poultry origin. Haemolytic and protease activities were assessed and isolates were assigned a sequence type (ST). Three of the seven genes investigated (ace, efaA and gelE) were present in all isolates. The asa1 was detected in 63/80 and 13/26 isolates of poultry and human origin respectively. For cylA, the numbers were 46/80 and 14/26 respectively. Among poultry isolates, esp and EF0591 were the least frequently observed genes (1/80 and 20/80 respectively); the prevalences among human isolates were 1/26 and 18/26 respectively. A high degree of similarity between genes in human and poultry isolates were confirmed by sequencing of amplification products. None of the cylA-positive isolates demonstrated haemolytic activity, while the phenotypic expression of gelatinase varied. The ST16 was the only ST shared by human and poultry isolates. The SCV isolates did not show a unique virulence profile or phylogeny. In conclusion, regardless of the distinct phylogenetic background of most E. faecalis isolates of human and poultry origin, we found major similarities in virulence gene profile and gene sequences in isolates from the two sources, supporting the zoonotic risk associated with this organism.

Transmission and genetic diversity of Enterococcus faecalis among layer chickens during hatch

BACKGROUND

Studies on transmission of Enterococcus faecalis among chickens during hatch have not been carried out so far. Information about vertical transmission and subsequent spreading and colonization of the cloacal mucosa through cloacal 'drinking' during hatch are important to understand the epidemiology of E. faecalis infections. In the present investigation vertical transmission and subsequent spreading and colonization of the cloacal mucosa of chickens by E. faecalis through cloacal 'drinking' were examined.

METHODS

Two different batches of layer chickens originating from 45 weeks old Brown and White Lohmann parents, respectively from the same farm were sampled in the hatcher. Isolates were confirmed to be E. faecalis by polymerase chain reaction (PCR) and further by multilocus sequence typing (MLST) to state their population structure and comparison made to sequence types previously obtained from chicken.

RESULTS

A total of 480 chickens were swabbed from the cloacae just after hatch and after 24 hours. A total of 101 isolates were confirmed as E. faecalis by a species specific PCR. The prevalence of E. faecalis increased from 14% at 0 h to 97% after 24 h for the Brown Lohmann chickens and from 0.5% to 23% for the White Lohmann flock. The 84 isolates analysed by MLST were distributed on 14 sequence types (ST). Three ST (401, 82 and 249) accounted for 64% of all isolates analysed by MLST after 24 h. ST 82 has previously been reported from amyloid arthropathy and other lesions in poultry.

CONCLUSIONS

The present findings demonstrated a high potential of a few contaminated eggs or embryos to rapidly facilitate the spread of E. faecalis to almost all chickens during hatch.

Association of Enterococcus cecorum with vertebral osteomyelitis and spondylolisthesis in broiler parent chicks

Enterococcus cecorum is the most frequently occurring enterococcal species in the intestine of chickens of over 12 weeks of age, and there are few reports on its isolation from the skeleton of broiler parent chicks. In the present study, observations on vertebral osteomyelitis and spondylolisthesis ('kinky back syndrome') showing high incidence in 8 broiler parent flocks in different parts of Hungary are summarised. Clinical signs were seen only in roosters between 5 and 13 weeks of age. Diseased birds were alert and remained sitting on their hocks with their feet slightly raised off the ground. Incidence of the disease among male birds ranged from 8% to 30% depending on flocks. Enlargement and distortion of the body of the 6th vertebra were seen as the main pathological lesions. The cavity of the spinal canal was constricted by the distorted vertebral bodies. Resorption of bone tissue and sequestrum formation, signs of increased osteoclast activity, proliferation of fibrotic tissues, infiltration with heterophils and formation of sclerotic layers were detected in the vertebral bodies. From all 24 samples collected from the vertebral lesions, Enterococcus cecorum was isolated and identified using metabolic fingerprinting as well as 16S rRNA gene sequencing. Demonstration of E. cecorum from the vertebral lesions in all examined broiler breeder roosters showing the same clinical and pathological findings in different flocks suggested the pathogenic role of this microorganism for the first time in Hungary.

Systemic AA-amyloidosis in a European Wild Boar (Sus scrofa) Suffering from Generalized Tuberculosis

Summary An adult female wild boar (Sus scrofa) was found moribund in Cabaneros National Park (central Spain). The animal had a markedly emaciated carcass, with body weight of 25.9 kg. At necropsy, most of the parenchymatous organs had widespread variably sized granulomas. Generalized tuberculosis was confirmed by PCR detection of Mycobacterium bovis in the mandibular lymph node. Large amounts of a hyaline, pale eosinophilic material were observed in liver, kidney and intestine. Congo red staining and green birefringence identified amyloid, which was further classified as AA type based on immunohistochemical results. It is speculated that the abundant serum amyloid A derivatives deposited in the tissues as AA-amyloid may be associated with the generalized tuberculosis. This is the first report of amyloidosis in the European wild boar.

The effects of vitamin A, pentoxyfylline and methylprednisolone on experimentally induced amyloid arthropathy in brown layer chicks

The effects of vitamin A, pentoxyfylline and methylprednisolone on experimentally induced amyloid arthropathy were investigated. In this study, 175 1-day-old brown layer chicks were used. Throughout the study Group II (vitamin A) received high doses of vitamin A (75,000 IU/kg), whereas Group I (negative control), Group III (positive control), Group IV (pentoxyfylline) and Group V (methylprednisolone) received normal levels of vitamin A in the diet. At the fifth week, the experimental Groups II, III, IV and V were injected with Freund's adjuvant intra-articularly to induce amyloid arthropathy. Group IV received pentoxyfylline and Group V received methylprednisolone (10 mg/kg, intramuscularly) once. Joint and blood samples were examined 13 weeks after the injections. The values in Groups I, II, III, IV and V, respectively, were as follows: amyloid arthropathy formation (%), 0, 100, 87, 76, 66; serum amyloid A (ng/ml), 166+/-17, 607+/-40, 423+/-39, 342+/-27, 293+/-22; serum retinol (microg/dl): 59.75+/-3.8, 42.72+/-3, 59.24+/-3.6, 102+/-9.1, 101.3+/-12.3; heterophil/lymphocyte ratio: 0.504, 0.75, 0.75, 0.087, 0.44. In conclusion, it was observed that vitamin A enhanced the development of amyloid arthropathy and there were positive associations between amyloidosis, increased levels of serum amyloid A and increased numbers of tissue infiltrating macrophages. Methylprednisolone had a more successful inhibitory effect on amyloid arthropathy than pentoxyfylline.

Pathology of AA amyloidosis in domestic sheep and goats

We describe the main pathologic changes in small ruminants affected by AA amyloidosis, together with the partial sequence of the protein involved. Twenty-one sheep and one goat were selected for presenting macroscopic kidney lesions compatible with systemic amyloidosis. Available tissue samples were studied by histologic, immunopathologic, and ultrastructural means. Renal lesions were characterized grossly by pale cortical surfaces with scattered, miliary, whitish-yellow foci and on cut cortical surfaces by straight, whitish-yellow striations. Gangrenous pneumonia was observed in 16 out of 21 affected sheep (76.2%), although other chronic inflammations were also observed. Amyloid was detected in all grossly affected kidneys using Congo red staining, lesions being most remarkable in glomeruli, affecting 95.5% of animals studied. Congophilic deposits were also observed in intertubular interstitium (68.2%) and medulla (57.1%). All amyloid-affected animals presented proximal convoluted tubule lesions, mostly characterized by an increase in diameter and by hyaline granular degeneration that were responsible for the macroscopic appearance of the kidney. Histologically, amyloid was also seen in blood vessels, spleen, liver, lymph nodes, gastrointestinal tract, and adrenal glands. All amyloid deposits demonstrated greenish-yellow birefringence with polarized light, and the antisera prepared against goat amyloid extracts specifically reacted with birefringent congophilic deposits of both sheep and goats. Ultrastructurally, these deposits were formed by masses of straight, nonbranching fibrils located predominantly in the basement membranes of glomerular capillaries and in the mesangium. Partial sequence of the protein in sheep and goats indicated a high degree of homology with the previously reported sequence of sheep Serum Amyloid A.