Characterization of serum amyloid A protein mRNA expression and secondary amyloidosis in the domestic duck

Hemorrhagic Hepatopathy in Broiler Breeder Pullets: Gross and Microscopic Pathology and Factors Associated with Incidence

Hemorrhagic hepatopathy is a syndrome reported in layer pullets resulting in mortality and lesions including hepatic, splenic, and intestinal necrosis; hepatic and splenic enlargement; hemorrhages; amyloidosis of the muscle, spleen, and liver; accumulation of noncoagulated hemorrhagic fluid in the coelom; and frequently, granulomatous myositis at bacterin injection sites. The syndrome is characterized in the literature in table egg layer pullets and is thought to be associated with the administration of bacterin vaccines, namely, frequently Salmonella enterica subsp. enterica bacterins. Hemorrhagic hepatopathy is recognized by industry veterinarians as also occurring infrequently in broiler breeder pullets in the United States. As the condition is likely due to an inflammatory process in response to bacterial lipopolysaccharide inoculation, it is important to characterize both the pathologic changes and predisposing factors for the condition in broiler breeds, which are immunologically different from table egg layer breeds. In this study, we characterize the gross and microscopic lesions observed in a series of diagnostic laboratory cases of hemorrhagic hepatopathy in broiler breeder pullets and suggest a possible pathophysiology for the condition. Additionally, we report results from a case survey of the United States broiler industry that suggest that the condition is due to a reaction to bacterin vaccination and that certain bacterin products may predispose pullet flocks to develop the condition. Although further research is indicated, these findings establish hemorrhagic hepatopathy as a pathologic condition of broiler breeder pullets and may aid in the diagnosis and prevention of the syndrome.

Multi-omic analyses in Abyssinian cats with primary renal amyloid deposits

The amyloidoses constitute a group of diseases occurring in humans and animals that are characterized by abnormal deposits of aggregated proteins in organs, affecting their structure and function. In the Abyssinian cat breed, a familial form of renal amyloidosis has been described. In this study, multi-omics analyses were applied and integrated to explore some aspects of the unknown pathogenetic processes in cats. Whole-genome sequences of two affected Abyssinians and 195 controls of other breeds (part of the 99 Lives initiative) were screened to prioritize potential disease-associated variants. Proteome and miRNAome from formalin-fixed paraffin-embedded kidney specimens of fully necropsied Abyssinian cats, three affected and three non-amyloidosis-affected were characterized. While the trigger of the disorder remains unclear, overall, (i) 35,960 genomic variants were detected; (ii) 215 and 56 proteins were identified as exclusive or overexpressed in the affected and control kidneys, respectively; (iii) 60 miRNAs were differentially expressed, 20 of which are newly described. With omics data integration, the general conclusions are: (i) the familial amyloid renal form in Abyssinians is not a simple monogenic trait; (ii) amyloid deposition is not triggered by mutated amyloidogenic proteins but is a mix of proteins codified by wild-type genes; (iii) the form is biochemically classifiable as AA amyloidosis.

Hepatitis B Virus DNA Integration and Clonal Expansion of Hepatocytes in the Chronically Infected Liver

Human hepatitis B virus (HBV) can cause chronic, lifelong infection of the liver that may lead to persistent or episodic immune-mediated inflammation against virus-infected hepatocytes. This immune response results in elevated rates of killing of virus-infected hepatocytes, which may extend over many years or decades, lead to fibrosis and cirrhosis, and play a role in the high incidence of hepatocellular carcinoma (HCC) in HBV carriers. Immune-mediated inflammation appears to cause oxidative DNA damage to hepatocytes, which may also play a major role in hepatocarcinogenesis. An additional DNA damaging feature of chronic infections is random integration of HBV DNA into the chromosomal DNA of hepatocytes. While HBV DNA integration does not have a role in virus replication it may alter gene expression of the host cell. Indeed, most HCCs that arise in HBV carriers contain integrated HBV DNA and, in many, the integrant appears to have played a role in hepatocarcinogenesis. Clonal expansion of hepatocytes, which is a natural feature of liver biology, occurs because the hepatocyte population is self-renewing and therefore loses complexity due to random hepatocyte death and replacement by proliferation of surviving hepatocytes. This process may also represent a risk factor for the development of HCC. Interestingly, during chronic HBV infection, hepatocyte clones detected using integrated HBV DNA as lineage-specific markers, emerge that are larger than those expected to occur by random death and proliferation of hepatocytes. The emergence of these larger hepatocyte clones may reflect a survival advantage that could be explained by an ability to avoid the host immune response. While most of these larger hepatocyte clones are probably not preneoplastic, some may have already acquired preneoplastic changes. Thus, chronic inflammation in the HBV-infected liver may be responsible, at least in part, for both initiation of HCC via oxidative DNA damage and promotion of HCC via stimulation of hepatocyte proliferation through immune-mediated killing and compensatory division.

Diseases of the Avian Urinary System

Diseases of the renal system can be caused by infectious and noninfectious processes. Creating a relevant differential diagnosis for kidney disease in the live or dead bird requires a structured approach where the list of differentials is narrowed based on the signalment of the bird; its history, including its diet and management; physical findings; and other diagnostic findings. This article aims to provide the reader not only a list of the diseases that occur in birds but also the guidelines on when a disease should be considered in a differential.

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.

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.

Amyloidosis in a Captive Zebra Finch (Taeniopygia guttata) Research Colony

Five birds in a captive zebra finch research colony were diagnosed with systemic amyloidosis within a 7-mo period by means of postmortem Congo red staining and green birefringence under polarized light. The liver was the most frequently and usually the most seriously affected organ, followed by the spleen and then the kidney. All 5 birds had been clinically affected with various inflammatory, infectious, and neoplastic conditions associated with amyloid A (AA) amyloidosis in humans and animals. Immunohistochemistry using antisera against duck AA protein revealed that tissues from 2 of the 5 birds were positive for the presence of AA protein and systemic inflammation-associated amyloidosis. Although the development of AA amyloidosis has been associated with chronic inflammation, trauma, and various infectious and neoplastic diseases as well as possible genetic predispositions and stresses linked to overcrowding, the root causes for individual cases of AA amyloidosis are incompletely understood. As far as we know, this report is the first description of AA amyloidosis in captive, research zebra finches.

Animal models and the molecular biology of hepadnavirus infection

Australian antigen, the envelope protein of hepatitis B virus (HBV), was discovered in 1967 as a prevalent serum antigen in hepatitis B patients. Early electron microscopy (EM) studies showed that this antigen was present in 22-nm particles in patient sera, which were believed to be incomplete virus. Complete virus, much less abundant than the 22-nm particles, was finally visualized in 1970. HBV was soon found to infect chimpanzees, gorillas, orangutans, gibbon apes, and, more recently, tree shrews (Tupaia belangeri) and cynomolgus macaques (Macaca fascicularis). This restricted host range placed limits on the kinds of studies that might be performed to better understand the biology and molecular biology of HBV and to develop antiviral therapies to treat chronic infections. About 10 years after the discovery of HBV, this problem was bypassed with the discovery of viruses related to HBV in woodchucks, ground squirrels, and ducks. Although unlikely animal models, their use revealed the key steps in hepadnavirus replication and in the host response to infection, including the fact that the viral nuclear episome is the ultimate target for immune clearance of transient infections and antiviral therapy of chronic infections. Studies with these and other animal models have also suggested interesting clues into the link between chronic HBV infection and hepatocellular carcinoma.

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.

Detection of up-regulated serum amyloid A transcript and of amyloid AA aggregates in skeletal muscle lesions of rainbow trout infected with Flavobacterium psychrophilum

Serum amyloid A (SAA) is a family of acute-phase proteins, recognized as important effectors of innate immunity in higher vertebrates. Under pro-inflammatory conditions, up-regulation of saa transcripts occurs not only in the liver, but also in several extrahepatic tissues of a wide variety of vertebrates. SAA is also known as the precursor to amyloid A (AA), a major component of amyloid fibrils deposited in liver, kidney and spleen of humans suffering chronic inflammatory diseases. Here we show the up-regulation of saa transcription in lesions affecting skin, adipose tissue and skeletal muscle of rainbow trout naturally and experimentally infected with Flavobacterium psychrophilum, the causative agent of cold water disease (CWD). Using an antiserum against a trout acute SAA peptide that was previously shown to specifically recognize intact recombinant trout SAA and peptides derived from it, we showed by confocal microscopy analysis extensive colocalization of SAA and thioflavin T (ThT) staining in the skeletal muscle fibers of infected fish, suggesting for the first time the presence of AA-derived aggregates in the skeletal muscle of a lower vertebrate. These findings support the idea that SAA and/or its derivatives could constitute relevant markers for fish health and also for fish meat quality control.

Increasing fatal AA amyloidosis in hunting falcons and how to identify the risk: a report from the United Arab Emirates

In hunting falcons, a fatal syndrome of wasting, weight loss, green mutes and, finally, sudden death of emaciated birds has been observed in the United Arab Emirates (UAE). Histological examination using Congo red has revealed amyloid in most organs, in particular in the liver, spleen, kidney, and adrenal glands. Moreover, a retrospective study revealed amyloidosis in 100 cases among a total of 623 necropsied falcons between August 1995 and March 2004 in Dubai/UAE (16%; varying from 8 to 30% in different raptor bird species). The amyloid was immunohistochemically classified as amyloid A (AA), which was confirmed by Western blot analysis and N-terminal amino acid sequence analysis, suggesting it to be secondary to a chronic inflammatory process. Retrospective analysis has indicated a significantly increased prevalence of bumble foot and visceral gout among falcons with amyloidosis. In addition, a significant increase of amyloidosis from 5.6% of necropsied falcons with amyloidosis in 1995 to 40.0% in 2004 has been noticed. Finally, a semi-quantitative serum test for falcon serum amyloid A (f-SAA) has been developed. Among 38 falcons with fatal AA amyloidosis, f-SAA was increased pathologically in 36, whereas f-SAA was elevated in only one of 15 apparently disease-free falcons (p < 0.001). This significant result indicates that a normal f-SAA will indicate a minimal or even absent risk of succumbing to AA amyloidosis.

Acceleration of murine AA amyloid deposition by bovine amyloid fibrils and tissue homogenates

Acceleration of amyloid deposition by administration of amyloid fibrils and transmissibility of disease have been reported for several types of amyloidosis. Reactive amyloidosis (AA) occurs in a wide variety of domestic animal species and is characterized by amyloid deposition mainly in spleen, liver, and kidneys. Because the visceral organs of domestic animals have traditionally been used in Asian cuisines, it is important to examine whether dietary ingestion of the organs themselves (rather than purified amyloid fibrils) accelerates AA amyloid deposition. Herein, we show that murine AA amyloidosis develops rapidly after intraperitoneal or oral administration of purified amyloid fibrils or homogenates of amyloid-laden bovine liver. The amyloidosis development in mice was dependent on the concentration of amyloid fibrils or amyloidotic liver homogenates. We found that experimental murine AA amyloidosis was accelerated by dietary ingestion of both purified amyloid fibrils and tissue homogenates that contain amyloid fibrils. We also investigated livers of beef cattle and food chickens to examine whether they contain amyloid-enhancing factor activity. By microscopic examination of hematoxylin and eosin- and Congo red-stained sections, no amyloid deposition was detected in these livers, and no effective activity for experimental induction of AA amyloidosis in mice was detected in homogenates of these livers.

Evaluation of goose serum amyloid a acute phase response by enzyme-linked immunosorbent assay

Serum amyloid A (SAA) is of interest as the circulating precursor of amyloid A protein, the fibrillar component of AA (secondary) amyloid deposits, and also as an extremely sensitive and rapid major acute phase protein. Serum concentrations of acute phase proteins (APPs) provide valuable information about the diagnosis and prognosis of various diseases, and thus the relevance of APPs for monitoring the health status of domestic animals is widely accepted. More importantly, the measurement of SAA concentration assists in assessing the prognosis in secondary amyloidosis, which is a common disease of geese, affecting an increasing number of animals. In the present study we introduce a highly sensitive goose-specific ELISA method for measuring SAA concentration in goose serum or plasma samples. Samples were taken from geese of the Landes Grey and Hungarian White breeds, which were stimulated for an acute phase reaction by administration of a commercially available fowl cholera vaccine containing inactivated Pasteurella multocida. Strong and characteristically rapid acute phase responses were measured in both breeds, peaking at approximately 24 h after inoculation. The maximum SAA concentration was 1200 microg/ml. At 72 h postinoculation, the concentrations returned to pre-inoculation values. There was significantly (p = 0.004) less intense response in the control groups; however, a very mild increase of SAA levels was detected due to the stress inevitably caused by the sampling procedure.

Amyloidogenic potential of foie gras

The human cerebral and systemic amyloidoses and prion-associated spongiform encephalopathies are acquired or inherited protein folding disorders in which normally soluble proteins or peptides are converted into fibrillar aggregates. This is a nucleation-dependent process that can be initiated or accelerated by fibril seeds formed from homologous or heterologous amyloidogenic precursors that serve as an amyloid enhancing factor (AEF) and has pathogenic significance in that disease may be transmitted by oral ingestion or parenteral administration of these conformationally altered components. Except for infected brain tissue, specific dietary sources of AEF have not been identified. Here we report that commercially available duck- or goose-derived foie gras contains birefringent congophilic fibrillar material composed of serum amyloid A-related protein that acted as a potent AEF in a transgenic murine model of secondary (amyloid A protein) amyloidosis. When such mice were injected with or fed amyloid extracted from foie gras, the animals developed extensive systemic pathological deposits. These experimental data provide evidence that an amyloid-containing food product hastened the development of amyloid protein A amyloidosis in a susceptible population. On this basis, we posit that this and perhaps other forms of amyloidosis may be transmissible, akin to the infectious nature of prion-related illnesses.

Serum amyloid A in geese; cloning and expression of recombinant protein

We defined the nucleotide-sequence of the full-length goose serum amyloid A and compared it to SAA sequences of the duck. The aim of this work was to clone and express recombinant goose SAA and to produce antibody against this protein: Total RNA was isolated from goose liver and used to synthesise first strand cDNA. The coding region of the goose SAA cDNA was amplified by PCR using primers corresponding to the appropriate conservative regions of duck SAA mRNA. The product was subcloned into pET-15b expression vector to result in a His*Tag fusion protein expression. The protein was purified by affinity chromatography. Rabbits were then immunized against the recombinant purified goose SAA protein. The anti-SAA serum was tested by Western blotting. Full-length goose SAA mRNA sequence has been obtained and sequenced.

Serum amyloid A production by chicken fibroblast-like synoviocytes

In brown chicken with chronic inflammatory processes of the joints amyloid arthropathy easily develops. The amyloid has been shown to be of the AA type which is derived from serum amyloid A (SAA). The aim of the present study was to investigate whether fibroblast-like synoviocytes (FLS) originating from brown chicken and other chicken breeds express SAA mRNA and produce SAA protein. FLS were isolated from the knee joint synovium of healthy brown chickens, white chickens, and broilers. The absence of macrophages in FLS cultures was confirmed by assessment of the phagocytic capability and by immunohistochemistry. Additionally, cultured cells were identified by electron microscopy and immunohistochemical staining. Expression of SAA mRNA in normal and lipopolysaccharide (LPS)-stimulated cells was assessed by in situ hybridization, Northern blot analysis, reverse transcriptase-polymerase chain reaction (RT-PCR), Southern blot analysis and real-time quantitative PCR. SAA protein production was analyzed by Western blotting and ELISA. SAA mRNA was detected in unstimulated FLS isolated from the three different chicken breeds and more abundantly in those stimulated with LPS. However, SAA protein production was only detected in culture medium and cell lysate of LPS-stimulated FLS. Furthermore, FLS produced SAA in a concentration-dependent manner after stimulation with different amounts of LPS. The data suggest that during infection and inflammation chicken FLS may act as a source of articular SAA. This process may enhance development of amyloid from SAA in the joint.

Expression of serum amyloid A in chondrocytes and myoblasts differentiation and inflammation: possible role in cholesterol homeostasis

Serum amyloid A (SAA) is synthesized by the liver during the acute phase. Local expression of SAA mRNA has been reported also in non-liver cells, a potential local source of SAA protein not related to the systemic acute phase response. SAA function has not been established yet. In the present study, we identified SAA as a protein expressed by chondrocytes and myoblasts in response to inflammatory stimula. In both cell systems, SAA mRNA and protein expression is strongly stimulated by bacterial lipopolysaccharide treatment. SAA mRNA expression is also enhanced during terminal differentiation of cells of the chondrogenic and myogenic lineage; mRNA is barely detectable in prechondrogenic cells and is highly expressed in differentiated hyperthrophic chondrocytes. An increased level of SAA mRNA was also observed in vivo when we compared mRNA extracted from tibiae of 10 day embryos, still fully cartilaginous, with tibiae from 18 day embryos, a stage when the endochondral ossification process has already started. p38 activation, a well-known event of the chondrogenesis signaling cascade, controls expression of SAA in cartilage following inflammatory stimuli. SAA secreted by stimulated chondrocytes is associated with cholesterol. Cholesterol is synthesized by the same chondrocytes and is also increased in inflammatory conditions. A role of SAA in cholesterol homeostasis in chondrocytes is proposed.

Entecavir therapy combined with DNA vaccination for persistent duck hepatitis B virus infection

This study was designed to test the efficacy of antiviral treatment with entecavir (ETV) in combination with DNA vaccines expressing duck hepatitis B virus (DHBV) antigens as a therapy for persistent DHBV infection in ducks. Ducks were inoculated with 10(9) DHBV genomes at 7 days of age, leading to widespread infection of the liver and viremia within 7 days, and were then treated orally with either ETV (0.1 mg/kg of body weight/day) or distilled water from 21 days posthatch for 244 days. Treatment with ETV caused a 4-log drop in serum DHBV DNA levels within 80 days and a slower 2- to 3-log drop in serum DHBV surface antigen (DHBsAg) levels within 120 days. Following withdrawal of ETV, levels of serum DHBV DNA and DHBsAg rebounded to match those in the water-treated animals within 40 days. Sequential liver biopsy samples collected throughout the study showed that ETV treatment reduced DHBV DNA replicative intermediates 70-fold in the liver, while the level of the stable, template form, covalently closed circular DNA decreased only 4-fold. ETV treatment reduced both the intensity of antigen staining and the percentage of antigen-positive hepatocytes in the liver, but the intensity of antigen staining in bile duct cells appeared not to be effected. Intramuscular administration of five doses of a DNA vaccine expressing the DHBV presurface, surface, precore, and core antigens, both alone and concurrently with ETV treatment, on days 50, 64, 78, 127, and 141 did not result in any significant effect on viral markers.

Evaluation of feline serum amyloid A (SAA) as an inflammatory marker

The concentration of feline serum amyloid A (fSAA) was determined by a direct enzyme-linked immunosorbent assay (ELISA) by using fSAA specific monoclonal antibodies, to evaluate the fSAA as an inflammatory marker in cats. The mean concentration +/- standard deviation of fSAA was found to be 0.60 +/- 1.06 microg/m l and 33.65 +/- 67.59 microg/ml in serum samples from normal cats (n=45) and cats (n=312) with various diseases and disorders, respectively. A significant difference (p<0.001) was found between the two groups. It was also found that the concentration of fSAA begins to increase rapidly at approximately 3-6 hr after spay, and increases up to significantly high levels in some disorders, like injury, renal failure, infectious diseases, etc.

Evolution of effectors and receptors of innate immunity

The bony fishes are derived from one of the earliest divergent vertebrate lineages to have both innate and acquired immune systems. They are considered by some to be an ideal model to study the underpinnings of immune systems precisely because of their phylogenetic position and the fact that their adaptive immune systems have not been elaborated to the extent seen in mammals. By the same token, examination of innate immune systems in invertebrates and early chordates can provide insight into how homologous systems operate in fish and higher vertebrates. Herein, we provide an overview of the molecular evidence that we hope helps clarify the evolutionary relationships of innate immune molecules identified in bony fishes. The innate immune systems being considered include select chemokines (CC and CXC chemokines and their receptors), cytokines (IL-1, IL-8, interferons, TGF-beta, TNF-alpha), acute phase proteins (SAA, SAP, CRP, alpha2M, and the complement components--C3-C9, MASP, MBL, Bf), NK cell receptors, and molecules upstream and downstream of the Toll signaling pathways.

Characterization of monoclonal antibodies specific for feline serum amyloid (SAA) protein

Serum amyloid A (SAA) has been characterized as an inflammatory marker in many species. In this study, we have developed and characterized monoclonal antibodies (MAbs) against feline SAA (fSAA) derived from culture hybridomas. These hybridomas were produced from the fusion of Balb/c-derived myeloma s/p20-Ag14 and splenocytes from mice immunized with purified recombinant feline SAA (rfSAA). Six hybridomas secreting MAbs, M2, M5, M7, M8, M13, and M15, were selected and subcloned on the basis of their specificity to rfSAA by enzyme-linked immunoabsorbent assay (ELISA), and confirmed based on their specificity to rf-SAA by immunoblot analysis. Out of six clones, two clones (M5 and M7) showed higher reactivity with rf-SAA, and were selected for further analysis of ELISA additivity and Western blot cross-reactivity tests. As a result, M5 and M7 clones recognized the same or excessively near epitopes on rfSAA and reacted with rfSAA, fSAA and equine recombinant SAA, but showed no reaction with human recombinant SAA. Because of their specificity, these MAbs may be usefully applied in studying the measurement of SAA concentration in cat serum.

Identical amyloid precursor proteins in two breeds of chickens which differ in susceptibility to develop amyloid arthropathy

Chickens (Gallus gallus domesticus) can suffer from AA amyloidosis featuring the joints as major targets of amyloid accumulation. Analysis of post-mortem recordings from commercial chickens revealed that amyloid arthropathy frequently occurred in brown layer chickens, but never in white layers. The suspected higher susceptibility of brown layers was confirmed experimentally by inducing amyloidosis with an arthropathic and amyloidogenic strain of E. faecalis. Sequence analysis of cDNA coding for SAA, the amyloid precursor protein, revealed that the SAA proteins are identical in both breeds, although some nucleotide differences existed in the untranslated regions of the mRNAs. The chicken SAA gene was found to be a single copy gene which comprises 4 exons. The first of these exons apparently occupies a conserved position and is not translated. Investigation of the affected joints using in situ hybridization demonstrated local SAA gene expression. It is concluded that the likelihood of an E. faecalis induced arthritis to progress to amyloidosis is breed-dependent, but is not a consequence of a more amyloidogenic SAA.

Molecular cloning and sequencing of equine cDNA encoding serum amyloid A (SAA)

The serum amyloid A (SAA) protein is a characteristic and sensitive acute phase reactant in all vertebrates investigated. We molecularly cloned the equine cDNA encoding SAA from the liver of a healthy horse by polymerase chain reaction (PCR). The cloned cDNA is 480 bases in length, and contains an open reading frame (ORF) of 387 nucleotides encoding a precursor SAA protein of 128 amino acids. The precursor of horse SAA seems to have an 18-residue signal peptide and differs from the reported amino acid sequences of the horse SAA by substitution of valine at residue 81. It shows high homology with SAA amino acid sequence of other species such as dog (80.6%), mink (77.5%), human (76.9%) and duck (71.9%). An insertion of eight amino acids at residues between 85 and 92, as compared to human SAA, has also been found in horse SAA. The availability of the equine SAA cDNA will provide a useful reagent for studying its role in diseased horses.

Amyloid arthropathy in chickens

The present paper presents an overview of current knowledge of amyloid arthropathy in chickens, and covers the pathogenesis of amyloidosis in general and in birds, field cases reported, and the studies performed to assess the amyloidogenicity of various agents compared to that of Enterococcus faecalis. An animal model of amyloid arthropathy is presented, as are studies on the pathogenesis of arthropathic and amyloidogenic E. faecalis infections in brown layers. The review concludes with a description of the pathology of amyloid arthropathy, the biochemical characterization of the chicken joint amyloid protein as being of the AA type, investigation of the serum amyloid A (SAA) gene involved, and local SAA mRNA expression in joint and liver.

Diet, amyloid enhancing factor (AEF) and amyloidogenesis: an hypothesis

At least two forms of amyloidosis, amyloid A (AA) and prion protein (PrP), can be transmitted by dietary ingestion of an agent(s) present in crude mammalian tissues. Although the incubation time for PrP or scrapie-induced diseases to develop in experimental animals extends over months or years, AA or secondary amyloidosis in mice is inducible within a week. In response to inflammatory stimuli we hypothesize that dietary factor(s) modulate the rate at which beta-pleated sheet fibrils accumulate in most forms of amyloidosis. The critical importance of precursor protein polymorphism, cell surface proteoglycans (PG), lipids and apolipoprotein metabolism has also been addressed in this hypothesis.

Cloning and expression of a cDNA encoding the large subunit of duck replication factor C

A cDNA encoding an avian homologue of the large subunit of replication factor C (RFC-L) has been cloned from a duck liver cDNA expression library prepared in bacteriophage lambda. The full length cDNA encodes a protein with a predicted size of approximately 130 kDa, consistent with the size of the polypeptide detected in duck liver. The duck RFC-L amino acid sequence shares 66.4% and 68.4% identity with mouse and human RFC-L proteins, respectively. We identified a 4kb RFC-L mRNA expressed in most duck tissues.