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S J O'Brien

Publications and source records attributed to S J O'Brien.

At least 145 records · Page 8Linked to original sources
PubMed1997

Growth of lion and puma lentiviruses in domestic cat cells and comparisons with FIV.

Feline immunodeficiency virus (FIV-Fca) is a lentivirus that causes gradual immunological deterioration in domestic cats. Lentiviruses related to FIV have been detected in several nondomestic feline species; the biologic significance of these viruses remains to be defined. To examine the in vitro cell tropism of these nondomestic cat lentiviruses, prototypical puma and lion lentiviruses (FIV-Pco and FIV-Ple) were cultured in a variety of feline cell cultures. A domestic cat T lymphoma cell line, 3201, best supported the replication of both FIV-Pco and FIV-Ple. Moreover, FIV-Ple was lytic for these cells. RT-PCR amplification of a conserved pol gene region demonstrated species-specific primer homology. Sequence and phylogenetic analyses of this amplification product confirmed the identity of the replicating viruses and classified two previously uncharacterized viruses within predictable lion and puma clades. Sequence analysis of a conserved pol region demonstrated homology with previously characterized FIV-Ple and FIV-Pco. Western blot analysis using domestic cat anti-FIV-Fca sera showed that both FIV-Pco and FIV-Ple were antigenically related, to differing degrees, to three serotypes of FIV-Fca. These studies demonstrate that though nondomestic cat lentiviruses differ significantly from FIV-Fca and that a viral-specific protocol may be necessary for sensitive viral detection, these viruses can replicate in cells of domestic cats. suggesting the potential for cross-species transmission.

Animals↗
PubMed1997

The tax gene sequences form two divergent monophyletic lineages corresponding to types I and II of simian and human T-cell leukemia/lymphotropic viruses.

Evolutionary associations of human and simian T-cell leukemia/lymphotropic viruses I and II (HTLV-I/II and STLV-I/II) are inferred from phylogenetic analysis of tax gene sequences. Samples studied consisted of a geographically diverse assemblage of viral strains obtained from 10 human subjects and 20 individuals representing 12 species of nonhuman primates. Sequence analyses identified distinct substitutions, which distinguished between viral types I and II, irrespective of host species. Phylogenetic reconstruction of nucleotide sequences strongly supported two major evolutionary groups corresponding to viral types I and II. With the type I lineage, clusters were composed of strains from multiple host species. A genetically diverse, monophyletic lineage consisting of eight new viral strains from several species of Asian macaques was identified. The second lineage consisted of a monophyletic assemblage of HTLV-II/STLV-II strains from Africa and the New World, including an isolate from a pygmy chimp (Pan paniscus) as an early divergence within the lineage. High levels of genetic variation among strains from Asian STLV-I macaque suggest the virus arose in Asia. Evidence of the origin of the type II virus is less clear, but diversity among HTLV-II variants from a single isolated population of Mbati villagers is suggestive but not proof of an African origin.

Amino Acid Sequence↗
PubMed1997

Nature and origin of polymorphism in feline MHC class II DRA and DRB genes.

Transcripts of the MHC class II DRA and DRB gene homologues of the domestic cat (Felis catus) were cloned and sequenced to compare the pattern and process of DR gene divergence. Homologous DRB exon 2 sequences from 36 feral domestic cats throughout the world plus from three species of Felidae (tiger cat, Iriomote cat, and Geoffroy's cat) were also determined. Limited variation in the domestic cat Feca-DRA gene was observed, but abundant variation in the Feca-DRB gene was seen comprising 61 distinct DRB alleles. Phylogenetic analyses resolved at least five monophyletic feline DRB allelic lineages (DRB*1 to *5), which are clearly distinct from those of human (HLA-DRB1 to 9 lineages), mouse (H-2Ebeta b, u, f), and dog DRB alleles. Approximately 80% of individual cats contained three to six distinct DRB sequences, indicating that feline MHC maintains two to three DRB loci. Five cats had three DRB sequences in a single allelic lineage, indicating the occurrence of recent gene duplication of feline DRB genes. DRB sequences isolated from three exotic cats demonstrated close association with a particular domestic cat DRB lineage, suggesting that these allelic lineages are derived from common ancestral alleles that existed prior to the divergence of these feline species about 10 to 15 million years ago. Patterns of synonymous and nonsynonymous nucleotide substitution rates that occurred in Ag recognition sites (ARS) and nonrecognition (NAR) sites demonstrated a strong role of natural selection--positive selection for Ag recognition sites and negative selection for nonrecognition sites of feline DRB sequences--in the process of evolution of DR molecules.

Amino Acid Sequence↗
PubMed1997

Phylogenetic reconstruction of the Felidae using 16S rRNA and NADH-5 mitochondrial genes.

The Felidae family represents a challenge for molecular phylogenetic reconstruction because it consists of 38 living species that evolved from a relatively recent common ancestor (10-15 million years ago). We have determined mitochondrial DNA sequences from two genes that evolve at relatively rapid evolutionary rates, 16S rRNA (379 bp) and NADH dehydrogenase subunit 5 (NADH-5, 318 bp), from multiple individuals of 35 species. Based on separate and combined gene analyses using minimum evolution, maximum parsimony, and maximum likelihood phylogenetic methods, we recognized eight significant clusters or species clades that likely reflect separate monophyletic evolutionary radiations in the history of this family. The clusters include (1) ocelot lineage, (2) domestic cat lineage, (3) Panthera genus, (4) puma group, (5) Lynx genus, (6) Asian leopard cat group, (7) caracal group, and (8) bay cat group. The results confirm and extend previously hypothesized associations in most cases, but in others, e.g., the bay cat group, suggest novel phylogenetic relationships. The results are compared and evaluated with molecular, cytogenetic, and morphological data to derive a phylogenetic synthesis of field evolutionary history.

Animals↗
PubMed1997

Do CuSums have a role in routine communicable disease surveillance?

The swift identification of outbreaks of infection is essential for effective control in the population. One of the functions of surveillance is to detect outbreaks but it could be argued that this is one of the weaker aspects of routine surveillance at present. This paper describes a technique which might meet this surveillance need. The CuSum technique allows rapid measurement of change from expected values based on historical data. It is very simple and seems to be a highly sensitive technique which can signal the need for further scrutiny of the data and/or for public health action, long before a change in incidence is apparent from raw data. This is particularly true for low-incidence infections where large functions can make interpretation difficult. CuSums represent a potentially useful adjunct to other surveillance methods in infection control.

Communicable Disease Control↗
PubMed1997

Comparative genomics: lessons from cats.

The genomics era, spear headed by dazzling technological developments in human and mouse gene mapping, has additionally provoked extensive comparative gene mapping projects for domestic species of several vertebrate orders. As the human genome project promises a one dimensional string of 100,000 genes and sequences, comparative mapping will extend that inference to a second dimension representing index species of the 20 living mammalian orders and to a third dimension by phylogenetic description of the genomes of mammal ancestors. We review here the remarkable extent of genome homology conservation among mammals illustrated by technology applications in the feline genome project.

Animals↗
PubMed1997

The adduction distraction maneuver.

The adduction distraction maneuver is presented as an adjunct to the surgeon's technical skills to assist with the initial introduction of the shoulder arthroscope. Both novice and experienced arthroscopists can experience difficulty establishing access to the glenohumeral joint. Often this results in articular cartilage or soft tissue damage. The adduction distraction maneuver when used in the "beach chair" seated position for shoulder arthroscopy can facilitate posterior portal placement and minimize iatrogenic trauma.

Arthroscopy↗
PubMed1997

Conservation genetics of the koala (Phascolarctos cinereus): low mitochondrial DNA variation amongst southern Australian populations.

Koala (Phascolarctos cinereus) populations in southern Australia have a history of bottlenecks-earlier this century the species became extinct in South Australia, and almost so in Victoria. Subsequently large numbers of animals from island populations (founded from very few animals) have been translocated back to mainland sites and to other islands in the region. As part of a larger study of the genetic structure of koala populations in southern Australia, we have undertaken a survey of mitochondrial DNA restriction fragment length polymorphism (mtDNA-RFLP) variability. Genomic DNA from 91 koalas from five populations was examined using 23 restriction enzymes, and mtDNA fragments were detected using a domestic cat full-length mtDNA clone. Only one of the enzymes, TaqI, revealed polymorphism-a relatively low amount of variation compared with other mammals, although low mtDNA-RFLP variation has also been reported in Queensland koalas. French Island and populations established predominantly from French Island immigrant koalas, either directly or via other island populations, were indistinguishable by haplotype frequencies. The mtDNA data are thus consistent with the interpretation that the koala translocation programme has homogenized gene frequencies amongst those populations involved. South Gippsland is not recorded as having received translocated koalas directly, and has significantly different mtDNA-RFLP haplotype frequencies from all other populations examined. The fact that this distinction was not previously observed in nuclear gene frequencies may reflect predominantly male-mediated dispersal in koalas.

Animals↗
PubMed1997

Methicillin-resistant Staphylococcus aureus (MRSA) in nursing homes in a major UK city: an anonymized point prevalence survey.

An anonymized point-prevalence survey of methicillin-resistant Staphylococcus aureus (MRSA) carriage was conducted amongst a stratified random sample of nursing home residents in Birmingham, UK, during 1994. Microbiological sampling from noses, fingers and the environment was undertaken. Information about potential risk factors for the acquisition of MRSA was gathered. MRSA was isolated from cultures of the nose or fingers of 33 of the 191 residents who took part in the study (17%) but only 1 of the 33 positive residents had a clinical infection. Although just 10 of the 87 environmental samples were MRSA positive, there was some environmental contamination in most homes. Risk factors for MRSA carriage were hospital admission within the last year (relative prevalence 2.09, 95% CI 1.13-3.88; P < 0.05) and surgical procedures within the last year (relative prevalence 4.02, 95% CI 2.18-7.43; P = 0.002). Phage-typing of the strains revealed similarities with those circulating in Birmingham hospitals. These findings suggest that the prevalence of MRSA in nursing homes in Birmingham was high, and that the strains may have originated in hospitals.

Bacteriophage Typing↗
PubMed1997

Comparative anchor tagged sequences (CATS) for integrative mapping of mammalian genomes.

Precise comparisons of mammalian gene maps require common anchor loci as landmarks for conserved chromosomal segments. Using a computer script that automates DNA sequence database alignments, we designed 410 evolutionarily conserved primer pair sequences which are specific for anchor locus gene amplification from any mammalian species' DNA. Primer pairs were designed to span introns for polymorphism ascertainment, and to include sufficient exonic sequence (25-400 bp) to allow for gene identification. A total of 318 primer pairs were optimized for domestic cats, and 86% of the sequenced feline PCR products showed homology to the gene of primer origin. A screen of 20 mammals from 11 orders revealed that 35-52% of the 318 primers yielded a single PCR product without further optimization suggesting that nearly 75% can be optimized for any eutherian mammal.

Animals↗
PubMed1997

Novel alleles of the chemokine-receptor gene CCR5.

The CCR5 gene encodes a cell-surface chemokine-receptor molecule that serves as a coreceptor for macrophage-tropic strains of HIV-1. Mutations in this gene may alter expression or function of the protein product, thereby altering chemokine binding/signaling or HIV-1 infection of cells that normally express CCR5 protein. Indeed, homozygotes for a 32-bp deletion allele of CCR5 (CCR5-delta 32), which causes a frameshift at amino acid 185, are relatively resistant to HIV-1 infection. Here we report the identification of 16 additional mutations in the coding region of the CCR5 gene, all but 3 of which are codon altering or "nonsynonymous." Most mutations were rare (found only once or twice in the sample); five were detected exclusively among African Americans, whereas eight were observed only in Caucasians. The mutations included 11 codon-altering nonsynonymous variants, one trinucleotide deletion, one chain-termination mutant, and three synonymous mutations. The high predominance of codon-altering alleles among CCR5 mutants (14/17 [81%], including CCR5-delta 32) is consistent with an adaptive accumulation of function-altering alleles for this gene, perhaps as a consequence of historic selective pressures.

Alleles↗
PubMed1997

Rates of nuclear and cytoplasmic mitochondrial DNA sequence divergence in mammals.

Differential rates of nucleotide substitution among different gene segments and between distinct evolutionary lineages is well documented among mitochondrial genes and is likely a consequence of locus-specific selective constraints that delimit mutational divergence over evolutionary time. We compared sequence variation of 18 homologous loci (15 coding genes and 3 parts of the control region) among 10 mammalian mitochondrial DNA genomes which allowed us to describe different mitochondrial evolutionary patterns and to produce an estimation of the relative order of gene divergence. The relative rates of divergence of mitochondrial DNA genes in the family Felidae were estimated by comparing their divergence from homologous counterpart genes included in nuclear mitochondrial DNA (Numt, pronounced "new might"), a genomic fossil that represents an ancient transfer of 7.9 kb of mitochondrial DNA to the nuclear genome of an ancestral species of the domestic cat (Felis catus). Phylogenetic analyses of mitochondrial (mtDNA) sequences with multiple outgroup species were conducted to date the ancestral node common to the Numt and the cytoplasmic (Cymt) mtDNA genes and to calibrate the rate of sequence divergence of mitochondrial genes relative to nuclear homologous counterparts. By setting the fastest substitution rate as strictly mutational, an empirical "selective retardation index" is computed to quantify the sum of all constraints, selective and otherwise, that limit sequence divergence of mitochondrial gene sequences over time.

Animals↗
PubMed1997

Evolutionary analysis of the 5'-terminal region of hepatitis G virus isolated from different regions in China.

We have determined the nucleotide sequence of the 5'-terminal region of the hepatitis G virus (HGV) genome in 11 hepatitis patients from three cities in China. Phylogenetic analyses revealed that the Chinese isolates were genetically distinct from previously described West African isolates (type 1) and American, European and East African isolates (type 2), with a mean sequence divergence of approximately 10%. The mean divergence between isolates from Lanzhou, in the northwest of China, and those from Shanghai and Nanjing, on the east coast of China, was 5% (range 3-7%). The isolates from Shanghai and Nanjing were closely related to a common strain in Japan, while some of those from Lanzhou were closely related to a southeast Asian type 3 isolate. Thus, the Chinese isolates belong to the type 3 variant of HGV.

Base Sequence↗
PubMed1997

Infectivity of lion and puma lentiviruses for domestic cats.

Infection of domestic cats with feline immunodeficiency virus (FIV) causes progressive immunological deterioration similar to that caused by human immunodeficiency virus (HIV). Lentiviruses related to but phylogenetically distinct from FIV have been detected in several non-domestic feline species. Serological cross-reactivity of these viruses raises the question as to whether inter-species transmission may occur. To address this issue, we asked whether lion lentivirus (FIV-Ple) or two strains of puma lentivirus (FIV-Pco) could replicate or cause disease in domestic cats. We found that domestic cats inoculated with FIV-Ple developed persistent cell-associated viraemia, transient cell-free viraemia and antiviral antibody. Clinical disease was not detected throughout a 6 month observation period. Two of four cats inoculated with FIV-Pco developed cell-associated viraemia, seroconverted and exhibited transient lymphadenopathy. No changes in white blood cell parameters or other haematological abnormalities were detected in any of the infected cats. Virus-specific RNA was detected in co-cultivated lymphocytes of all infected cats by RT-PCR. These findings reveal that non-domestic cat lentiviruses are infectious for domestic cats and can establish persistent infection in the absence of disease.

Animals↗