Mutation analysis of feline Niemann-Pick C1 disease

Niemann-Pick C (NPC) disease is an autosomal recessive neurovisceral lysosomal storage disorder that results in defective intracellular transport of cholesterol. The major form of human NPC (NPC1) has been mapped to chromosome 18, the NPC1 gene (NPC1) has been sequenced and several mutations have been identified in NPC1 patients. A feline model of NPC has been characterized and is phenotypically, morphologically, and biochemically similar to human NPC1. Complementation studies using cultured fibroblasts from NPC affected cats and NPC1 affected humans support that the gene responsible for the NPC phenotype in this colony of cats is orthologous to human NPC1. Using human-based PCR primers, initial fragments of the feline NPC cDNA were amplified and sequenced. From these sequences, feline-specific PCR primers were generated and designed to amplify six overlapping bands that span the entire feline NPC1 open reading frame. A single base substitution (2864G-C) was identified in NPC1 affected cats. Obligate carriers are heterozygous at the same allele and a PCR-based assay was developed to identify the geneotype of all cats in the colony. The mutation results in an amino acid change from cysteine to serine (C955S). Several of the mutations identified in people occur in the same region. Marked similarity exists between the human and feline NPC1 cDNA sequences, and is greater than that between the human and murine NPC1 sequences. The human cDNA sequence predicts a 1278aa protein with a lysosomal targeting sequence, several trans-membrane domains and extensive homology with other known mediators of cholesterol homeostasis.

Molecular cloning of the feline thymus and activation-regulated chemokine cDNA and its expression in lesional skin of cats with eosinophilic plaque

Thymus and activation-regulated chemokine (TARC) is a member of CC chemokine and plays an essential role in recruitment of CC chemokine receptor 4 positive Th2 cells to allergic lesion. To investigate the association of TARC in allergic inflammation of cats, a TARC cDNA was cloned from feline thymus by RT-PCR with 3' rapid amplification of cDNA ends (RACE) method. The feline TARC clone contained a full length open reading frame encoding 99 amino acids which shared 80.8%, 72.5%, 65.6% and 67.8% homology with dog, human, mouse and rat homologues, respectively. Expression of TARC mRNA was detected not only in thymus but also in spleen, lung, lymph node, kidney, small intestine, colon and skin of the normal cat tissues examined. Furthermore, it was found that TARC mRNA was strongly expressed in lesional skin of cats with eosinophilic plaque. The present results demonstrated that TARC might be involved in the pathogenesis of eosinophilic plaque in cats.

Autosomal dominant retinal dystrophy (Rdy) in Abyssinian cats: exclusion of PDE6G and ROM1 and likely exclusion of Rhodopsin as candidate genes

Retinal dystrophy (Rdy) is an autosomal dominant photoreceptor dysplasia of Abyssinian cats and a model for autosomal dominant retinitis pigmentosa (ADRP) in man. We have pursued a candidate gene approach in the search for the causal mutation in Rdy. The genes RHO (encoding rhodopsin), ROM1 (encoding the structural retinal outer-membrane protein-1) and PDE6G (encoding the gamma subunit of the visual transduction protein cyclic guanosine monophosphate-phosphodiesterase) were polymerase chain reaction-amplified from normal feline genomic DNA. Leader, coding and 3' untranslated regions of each gene, and parts of introns were sequenced. Single-stranded conformation polymorphism (SSCP) analysis of Rdy-affected and normal cats was used to identify intragenic polymorphisms within ROM1 and PDE6G. DNA sequencing of all three genes in Rdy-affected cats was used to confirm results from SSCP. For both ROM1 and PDE6G polymorphisms identified by SSCP and sequencing showed disconcordance between the polymorphism and the disease phenotype within an Rdy disease pedigree. SSCP analysis of RHO performed across the 5' untranslated region, the entire coding sequence and the intron/exon boundaries in Rdy-affected and control cats failed to identify any intragenic polymorphisms that could be used for linkage analysis. DNA sequencing of these regions showed no differences between Rdy-affected and control cats. Mutations in ROM1 or in PDE6G are not causative of feline Rdy. The absence of potentially pathogenic polymorphisms in sequenced portions of the RHO gene makes it unlikely that a mutation in this gene is the cause of Rdy.

bcl-2 and MIB-1 labeling indexes in cats with lymphoma

Immunohistochemistry was used to examine feline lymphoid tumors for bcl-2 and MIB-1 expression. Tumor tissues from 29 cats were selected to represent 2 groups--cats that did not respond to chemotherapy and cats that responded to therapy. Median bcl-2 immunoreactivity was 60%, and median MIB-1 reactivity was 47%. There was no significant difference in median survival time between cats with tumors with high levels of bcl-2 expression and those with low levels of expression. There was no significant difference in median survival time between cats with tumors with high levels of MIB-1 expression and those with low levels of expression. Mean bcl-2 immunoreactivity was significantly (P = .0004) higher in low-grade (73.2%) than in high-grade (16.9%) lymphomas, whereas the mean MIB-1 immunoreactivity was significantly (P = .0201) higher in high-grade (61.2%) lymphomas than in low-grade (35.0%) lymphomas. The mean bcl-2 immunoreactivity was significantly (P = .0042) greater in T-cell lymphomas (66.8%) than in B-cell lymphomas (22.8%), whereas the mean MIB-1 immunoreactivity was significantly (P = .0052) lower in T-cell lymphomas (36.4%) than in B-cell lymphomas (65.2%). Although expression of bcl-2 and MIB-1 did not appear to be linked to responses to chemotherapy in cats with lymphoma, the data suggest a possible role for these regulatory proteins in the biology of feline lymphomas.

Hereditary cerebellar degeneration in three full sibling kittens

Two domestic shorthair littermate kittens had signs of cerebellar dysfunction, first observed between seven and eight weeks of age; a third littermate was unaffected. The signs were progressive and the more severely affected kitten was euthanased after six days. A postmortem examination revealed no gross lesions but the kitten had cerebellar cortical degeneration with extensive loss of Purkinje cells. The second kitten was euthanased at 10 months of age with similar, though more pronounced, changes. One of the two kittens in the next litter of the same parents had similar clinical signs and histopathological findings. The lesions in the cerebellum are interpreted as probably due to genetically determined abiotrophy. In addition, the two older kittens had medullary neuronal changes interpreted as probable neuraxonal dystrophy, and focal vacuolation of the neuropil in the medulla and cervical spinal cord.

[Progressive retinal atrophy in Abyssinian and Somali cats in the Netherlands (1981-2001)]

From 1981 to 2001, 248 Abyssinian and 127 Somali cats in the Netherlands were examined for hereditary eye disease. Distinct ophthalmoscopic signs consistent with hereditary progressive retinal atrophy (PRA) were observed in 11 Abyssinian cats, and subtle signs in 3 Abyssinian cats. A familial relationship was detected in 13 out of 14 of these cats, which supports a hereditary basis to the condition. Distinct funduscopic signs of retinal degeneration were observed at a median age of 4 years. One cat with advanced retinal degeneration was only 7 months old, whereas the remaining 10 cats were between 2 and 12 years old at the time of diagnosis. These differences in the age of onset are suggestive of at least two types of PRA occurring in Abyssinian cats in the Netherlands: a dysplastic, early-onset and a late-onset retinal degeneration. A large-scale and systematic examination programme for hereditary eye disease will be necessary to assess the incidence of PRA in the Dutch population of Abyssinian and Somali cats as a whole, and to provide a basis for a preventive breeding programme.

Prevalence of Bartonella species causing bacteraemia in domesticated and companion animals in the United Kingdom

Between October 1999 and February 2000, 691 blood samples examined routinely for either haematological or virological assessment were screened by culture for the presence of Bartonella species. They came from 615 animals: 360 cats, 211 dogs, 27 horses, 16 cattle and a gorilla. The samples were incubated for long periods on 10 per cent horse blood agar at 37 degrees C in an atmosphere containing 5 per cent carbon dioxide. Isolates were obtained from 35 samples from 34 (9.4 per cent) of the cats, but not from any of the other animals. Comparison of citrate synthase gene sequences from the isolates indicated that they were all Bartonella henselae. Analysis of 16S rRNA gene fragments indicated that 30 of the cats were infected solely with B henselae genotype II, two were infected solely with B henselae genotype I and two were infected with both genotypes.

Activating mutations in the catalytic or juxtamembrane domain of c-kit in splenic mast cell tumors of cats

OBJECTIVE

To evaluate splenic mast cell tumors (MCT) of cats for activating mutations in the proto-oncogene c-kit.

SAMPLE POPULATION

10 formalin-fixed, paraffin-embedded splenic MCT from cats in the pathology database of the Veterinary Medical Teaching Hospital at the University of California, Davis.

PROCEDURE

Genomic DNA was isolated from tumor specimens, and the polymerase chain reaction (PCR) procedure was performed for exons 11, 12, and 17. The PCR products were analyzed by use of agarose gel electrophoresis and then directly sequenced.

RESULTS

We did not identify mutations in the juxtamembrane domain (encoded by exons 11 and 12) or catalytic domain (encoded by exon 17) of c-kit in any of the splenic MCT specimens.

CONCLUSIONS AND CLINICAL RELEVANCE

Although mutations in the proto-oncogene c-kit occur frequently in naturally developing MCT in dogs and aggressive mastocytosis in humans, the data reported here documented that dysregulation of Kit function through activating mutations is unlikely in splenic MCT of cats. Therapeutic strategies aimed at inhibiting Kit signaling (ie, kinase inhibitors such as imatinib [STl571]) may not be of benefit for the treatment of this disease in cats.

Hypertrophic cardiomyopathy in a mixed breed cat family

A spayed female mixed cat (case 1) and its female offspring, the result of a pairing between case 1 and its male sibling, were diagnosed with hypertrophic cardiomyopathy (HCM). A pedigree survey revealed that the prevalence of HCM was at least 12.5% in the family, which was considered to be significantly higher than that in a hospital-based population (approximately 1.6%). Thus, this finding seems to support the suspected occurrence of familial HCM in this group of related cats.

Comparative oncological studies of feline bronchioloalveolar lung carcinoma, its derived cell line and xenograft

Although certain neoplasms are unique to man, others occur across species. One such neoplasm is bronchioloalveolar lung carcinoma (BAC), a neoplasm of the Type II pneumocyte that affects humans, sheep, and small animals (dogs and cats). Human BAC occurs largely in nonsmokers. Sheep BAC is caused by the jaagsiekte retrovirus and is endemic and contagious. Feline BAC is neither endemic nor contagious and occurs sporadically and spontaneously in older purebred cats. In these respects, feline BAC is more closely similar to human BAC than sheep BAC (jaagsiekte) is. To study feline BAC further, we established the first immortal cell line (SPARKY) and transplantable scid mouse xenograft (Sparky-X) from a malignant pleural effusion of a 12-year-old Persian male with autopsy-confirmed BAC. SPARKY exhibited a Type II pneumocyte phenotype characterized by surfactant and thyroid-transcription factor-1 immunoreactivities and lamellar bodies. SPARKY's karyotype was aneuploid (66 chromosomes: 38, normal cat) and showed evidence of genomic instability analogous to human lung cancers. p53 showed a homozygous G to T transversion at codon 167, the feline equivalent of human codon 175, one of the many hot spots mutated in the lung cancers of smokers. H-ras and K-ras were not altered. By reverse transcription-PCR, SPARKY lacked expression of retroviral JSRVgag transcripts that were present in the lungs of sheep BAC (jaagsiekte). Unlike human BAC xenografts, SPARKY-X retained its unique lepidic BAC growth pattern even though it was grown in murine s.c. tissues. This property may be related to the ability of SPARKY-X to up-regulate its surfactant genes (SP-A, SP-B, and SP-D). These studies of feline BAC may allow insights into the human disease that are not possible by studying human BAC directly.

Lack of correlation between Bartonella DNA detection within fleas, serological results, and results of blood culture in a Bartonella-infected stray cat population

OBJECTIVE

To correlate the presence of different Bartonella species in the blood of a stray cat population trapped on a French military base with specific antibodies and species detected in cat fleas.

METHODS

The prevalence of Bartonella bacteremia was investigated in 61 cats by plating frozen whole blood on blood agar plates. Identification of isolates and detection of Bartonella DNA from cat flea batches from ten cats was achieved by PCR amplification and sequencing. Antibody detection was performed by microimmunofluorescence.

RESULTS

We obtained 38 isolates of Bartonella from blood. Sixteen were identified as B. clarridgeiae, 15 as B. henselae genotype/serotype Houston 1 (type I), and seven as B. henselae genotype/serotype Marseille (type II). B. henselae was detected in five fleas, and B. clarridgeiae in one flea. Sixty-one per cent of the cats had detectable antibodies against at least one species or serotype. Sixteen cats had antibodies against only one antigen. For each species, the distribution of bacteremia among the cats could not be correlated with either the distribution of infected fleas or the distribution of specific antibodies.

CONCLUSIONS

The lack of correlation between Bartonella DNA detection within fleas, serological results, and results of blood culture is probably due to a lack of natural heterologous protection between species or serotypes. Cats suffer bacteremia with three Bartonella species and should therefore be considered the reservoirs of at least three human pathogens.

[DNA-diagnosis of congenital diseases in companion animals and the role of the practicing veterinarian]

The knowledge on the impact of gene defects on the development of disease in companion animals is increasing rapidly. The gene defects may be differentiated in an initiating defect, which is the cause of illness, and a promoting defect, which enhances the chance on illness. Up till now only initiating defects are known in dogs and cats. All this is of great importance for breeding purposes, because within a breed there is narrow relationship which means the genetic diversity is small, and with all the disadvantages thereof. The identification in good time of gene defects in breeding animals, so that these animals being excluded from breeding, is of utmost importance in preventing congenital diseases. For that reason more and more the owners will appeal to veterinary surgeons to cooperate in procedures to screen potential breeding animals, or to declare the animals free from gene defects. The problems with regard to the diagnostic tests, including the DNA-tests, and their predictive values are discussed.

Feline STK gene expression in mammary carcinomas

The human RON and its mouse homologue stk are members of the MET family of tyrosine kinase receptors. We have previously shown that the RON gene is over-expressed in human breast carcinomas. As cat mammary tumours have been proposed as a suitable model for aggressive human breast cancer, we identified the feline stk gene and studied its expression in cat mammary cancer. Feline stk sequences were found highly homologous to the stk and RON gene exons that encode the juxtamembrane and transmembrane domains of the stk and RON receptors. Feline stk-specific transcript was detected by RT-PCR in cat lung and in 7/8 feline mammary carcinomas and a synchronous skin metastasis examined. Western blot and immunohistochemical analyses were carried out with an antibody that recognized both the human RON and mouse stk receptors. This antibody specifically detected a 135 Kd feline protein and stained 10/34 mammary carcinoma archival samples. These data show that the pattern of expression and distribution of the stk protein in feline mammary cancer could be superimposed on that of the RON receptor in human breast cancer and suggest that these feline tumours are a suitable model to test innovative approaches to therapy of aggressive human breast carcinomas.

Recognition and diagnosis of lysosomal storage diseases in the cat and dog

Lysosomal storage diseases are rare, inherited disorders caused by the deficiency of 1 or more enzymes within the lysosomes of cells or by the deficiency of an activating protein or cofactor necessary for enzyme activity. The enzyme deficiency leads to a catabolic blockade and subsequent accumulation of storage material, and this in turn leads, albeit indirectly, to a wide array of clinical signs. Many features of storage diseases make them difficult to recognize and diagnose. In this review, we summarize the clinical features of these diseases and outline the steps required to confirm a diagnosis.

Cloning of the cat TSH receptor and evidence against an autoimmune etiology of feline hyperthyroidism

Cats are the only nonhuman mammalian species with a high incidence of hyperthyroidism, and a better understanding of the pathogenesis of feline hyperthyroidism is of clinical relevance for veterinary medicine. The etiology of this disease in cats remains controversial. Both an intrinsic autonomy of growth and function of follicular cells as well as an autoimmune-related mechanism have been proposed. To explore the role of the autologous TSH receptor (TSHR) in the pathogenesis of hyperthyroidism in cats, we cloned the coding sequence of the feline TSHR by RT-PCR. The open reading frame consists of 2292 nucleotides and encodes a 763-amino acid protein, one amino acid less than the human TSHR. Species comparison reveals that the cat TSHR is most closely related to the canine TSHR, with 96% identity and 97% similarity in amino acid sequence. cAMP accumulation, inositol phosphate production, and TSH binding were similar in the feline TSHR, compared with the human receptor. Analogous to the human TSHR, the cat TSHR also displays basal constitutive activity. To test the possibility that hyperthyroid cats develop antibodies that stimulate the autologous receptor, transfected cells expressing the feline TSHR were treated with sera or purified IgG obtained from 16 hyperthyroid cats. There was no increase in cAMP-dependent luciferase activity in the hyperthyroid cats, suggesting the absence of stimulatory autoantibodies. These sera were also negative for TSH-binding inhibitory Igs in an RRA. At least in the animals included in this study, there is no evidence for the presence of circulating thyroid stimulating factors as a mechanism underlying the pathogenesis of feline hyperthyroidism, and the findings support a model involving intrinsic autonomy of thyroid follicular cell growth and function.

Molecular cloning and expression analysis of feline melanoma antigen (MAGE) obtained from a lymphoma cell line

Melanoma antigens (MAGE) are regarded as inducing tumor-specific immune response and thought to be potential therapeutical agents for cancer immunotherapy. We hereby report the cloning of feline MAGE cDNA obtained from a lymphoma cell line derived from cat malignant lymphoma, and its expression pattern in tumor and normal tissues. The cDNA encoding the MAGE is 1668 base pairs (bp) in length, and contains an open reading frame (ORF) of 936 bp encoding a protein of 311 amino acids. The predicted amino acid sequence has 29-46% of homology with other MAGE proteins from human and mouse. mRNA transcripts for the feline MAGE were detected in certain tumors, but not in adult cat normal tissues except in testis, by reverse transcription polymerase chain reaction (RT-PCR) analysis. This indicates that the expression pattern of feline MAGE mRNA is similar to those of other MAGE family genes in tumors and normal tissues.

Point mutation of neu oncogene in animal peripheral nerve sheath tumors

Thirty-four peripheral nerve sheath tumors of four domesticated animal species were characterized and assayed for point mutation of the neu oncogene. Based on their morphoimmunophenotype, 32 tumors were classified as schwannomas. Schwannoma morphology was characterized by the presence of Antoni type A and B pattern and immunoreactivity for S-100 protein and vimentin. Two anaplastic and metastatic tumors originating from spinal cord root, immunonegative for S-100 protein and positive for vimentin, were classified as malignant peripheral nerve sheath tumors (MPNSTs). Four malignant schwannomas and two MPNSTs expressed a point mutation of the neu oncogene by the polymerase chain reaction-restriction fragment length polymorphism method. The finding of neu oncogene mutation could be a useful diagnostic genetic marker in the malignant form of peripheral nerve sheath tumors in animals.

Prevalence of polycystic kidney disease in Persian cats in the United Kingdom

The prevalence of polycystic kidney disease was assessed in 132 Persian cats, 46 of them referred for the investigation and treatment of medical or surgical conditions, and 86 apparently healthy cats referred specifically to be screened for the disease. Cats referred for the investigation of renomegaly or renal failure were excluded, and cats under 10 months old were only included if they had been examined postmortem. One hundred and twenty-six of the cats were examined ultrasonographically with a 7.5 MHz sector scanner, and the other six cats were examined postmortem. Forty-nine of the 86 cats referred specifically for screening (57.0 per cent) and 16 of the 46 cats referred for other clinical reasons (34.8 per cent) were affected by the disease, giving an overall prevalence of 49.2 per cent.

Virulence genes and P fimbriae PapA subunit diversity in canine and feline uropathogenic Escherichia coli

In this study, a total of 118 Escherichia coli strains isolated from dogs (93) and cats (25) with urinary tract infection (UTI) were tested in a multiplex polymerase chain reaction for the presence of adhesin-encoding genes (pap, sfa, and afa), hemolysin encoding genes (hly), cytotoxic necrotizing factor 1 (cnf1) and aerobactin (aer) genes. Virulence gene frequencies detected in those isolates which had been randomly collected (68 canine strains) were: 43% pap, 57% sfa, 1% afa, 44% hly, 41% cnf1 and 34% aer. These frequencies were much higher in the remaining 50 hemolytic strains of either cat or dog origin. Virulence factor associations in the 80 hemolytic strains studied revealed that 50/80 simultaneously had two adhesin genes (pap and sfa) and two cytotoxin genes (hly and cnf1), and 15/80 in addition had the aer gene. The major structural subunit and antigenic determinant of P fimbriae of uropathogenic E. coli is PapA. Polymorphism in this subunit was studied by an F antigen-specific papA allele polymerase chain reaction in 51 canine and 22 feline pap positive E. coli strains. The most prevalent canine papA alleles were F10 (39%), F15 (37%) and F12 (35%). In feline strains F15 (50%) was more frequent, other allele frequencies were F12 (45%), F14 and F10 (27%) and F16 (23%). Only nine canine and two feline strains were negative for one of the 11 serologically defined F types of P fimbriae. Three copies of the pap operon were found in 16/51 canine and 9/22 feline UTI E. coli pap positive strains. In this study, we show that a particular combination of virulence genes appears with high frequency in dog and cat urinary tract E. coli strains (pap, sfa, hly, and cnf1). In spite of the more frequent presence of F10, F12 and F15 papA alleles in this virulence gene combination, the occurrence of different papA alleles in strains where up to three copies of the pap operon are present accounts for the observed P fimbriae diversity.

PCR detection of the Cryptococcus neoformans CAPS9 gene from a biopsy specimen from a case of feline cryptococcosis

A polymerase chain reaction assay was developed to detect Cryptococcus neoformans in biopsy samples. The assay detects the CAP59 gene of Cryptococcus neoformans and was used to substantiate cutaneous cryptococcosis in a 5-year-old cat submitted to the Veterinary Medicine Center at the University of Tokyo.

Laminin alpha 2 (merosin)-deficient muscular dystrophy and demyelinating neuropathy in two cats

We report laminin alpha 2 (merosin) deficiency associated with muscular dystrophy and demyelinating neuropathy in two cats. The cats developed progressive muscle weakness, and atrophy. Either hypotonia or contractures resulted in recumbency, necessitating euthanasia. Muscle biopsies showed dystrophic changes including marked endomysial fibrosis, myofiber necrosis, variability of fiber size, and perimysial lipid accumulation. Immunohistochemistry showed that laminin alpha 2 chain was absent or reduced, while dystrophin and all the components of the dystrophin-associated glycoprotein complex were present and normal. One cat was examined in detail. Motor nerve conduction velocity (MNCV) was decreased, and ultrastructurally the peripheral nerves showed Schwann cell degeneration and demyelination. Brain imaging was not performed, but white matter changes were not apparent in the brain at necropsy. The disease in these cats is similar to primary or secondary merosin (laminin alpha 2)-deficient congenital muscular dystrophy (CMD) in humans and to dystrophia muscularis in mice.

Feline atopy in three littermates

This case report describes the history, clinical signs and diagnosis of a pruritic skin disease in three sibling cats living the same household. Clinical signs consistent with pruritus (i.e. hair pulling, hair loss, excessive grooming and face rubbing) were first noted when the cats were 6 months of age. The cats were treated for a possible ear mite and/or flea infestation; there was no response to treatment and clinical signs progressed. Although the presence of pruritus in a multiple cat household suggested an infectious or contagious aetiology, none could be identified. There was no improvement in clinical signs after a 60-day flea control trial, three treatments of ivermectin, an 8-week restricted diet or removal from the home for 10 days. A diagnosis of feline atopy was made on the basis of elimination of other causes of pruritus, consistent history and clinical signs, a positive intradermal skin test and response to therapy.