ABSTRACT
The Cyathostominae are a complex group of nematodes and are the primary parasitic pathogens of horses. Little is known of their basic biology. As part of an investigation into mechanisms involved in reactivation of mucosal larval stages, we identified a gene encoding a predicted LIM domain-containing protein (Cy-LIM-1). LIM domains are cysteine- and histidine-rich motifs that are thought to direct protein-protein interactions. Proteins that contain these domains have a wide range of functions including gene regulation, cell fate determination and cytoskeleton organization. The Cy-lim-1 mRNA was identified as an abundant transcript following differential display-arbitrary primed reverse transcriptase-polymerase chain reaction amplification of RNA from faecal fourth stage larvae (FL4), which had been obtained from the diarrhoea of clinical cases of larval cyathostominosis. Detailed analysis showed that Cy-lim-1 was transcribed in FL4 and in other developmental stages; however there were differences in transcription of alternatively spliced variants amongst the stages. The predicted peptide sequence of Cy-lim-1 showed high identity to two LIM domain-containing proteins from Caenorhabditis elegans. RT-PCR analysis of these Cy-lim-1 homologues in C. elegans indicated that the two genes, which are described as separate entities in GenBank, are likely to compose a single gene of which alternative splice variants are transcribed. The LIM proteins from the cyathostomins and C. elegans were classified as LIM-only (LMO) proteins and, along with LMO proteins identified in sequence databases of other nematodes, comprise a group of LIM proteins distinct to those defined in other organisms.
Subject(s)
DNA-Binding Proteins/genetics , Genes, Helminth , Helminth Proteins/genetics , Homeodomain Proteins/genetics , Nematoda/genetics , Amino Acid Sequence , Animals , DNA, Complementary/genetics , DNA, Helminth/genetics , DNA-Binding Proteins/chemistry , DNA-Binding Proteins/metabolism , Helminth Proteins/metabolism , Homeodomain Proteins/chemistry , Homeodomain Proteins/metabolism , Models, Molecular , Molecular Sequence Data , Protein Conformation , Transcription, GeneticABSTRACT
Feline calicivirus (FCV) is an important pathogen of domestic cats. In this study, we have determined the genetic diversity of FCV within four geographically separate colonies of endemically infected cats by sequencing the immunodominant and variable region E of the capsid gene. Comparison of isolates between colonies and between unrelated published sequences gave nucleotide distance values of 26-35% and 22-40%, respectively and suggested each colony was infected with a distinct virus strain. Comparison of isolates within individual endemically infected colonies showed nucleotide distance variability of 0-16%. This was greater than distances previously reported for epidemiologically related isolates from cases of acute disease (0-5%) and was consistent with the evolution of FCV from a single distinct ancestor sequence in each colony. The pattern of nucleotide substitutions generating the observed intra-colony diversity was associated with strong evidence for positive selection acting on immunodominant regions of the FCV capsid protein. We suggest that endemically infected colonies of cats may be important generators of genetic diversity for FCV and that this may ultimately lead to the generation of new strains.
Subject(s)
Caliciviridae Infections/veterinary , Calicivirus, Feline/genetics , Calicivirus, Feline/immunology , Capsid Proteins/genetics , Cat Diseases/virology , Genetic Variation , Amino Acid Sequence , Animals , Antigenic Variation/genetics , Base Sequence , Caliciviridae Infections/epidemiology , Caliciviridae Infections/virology , Calicivirus, Feline/isolation & purification , Capsid Proteins/immunology , Cat Diseases/epidemiology , Cats , Cell Line , Endemic Diseases/veterinary , Immunodominant Epitopes , Molecular Sequence Data , Mutation, Missense , Phylogeny , Prevalence , RNA, Viral/genetics , RNA, Viral/isolation & purification , Reverse Transcriptase Polymerase Chain Reaction , Selection, Genetic , Sequence AnalysisABSTRACT
Pulmonary aspiration of gastric contents is common in enterally fed patients. Tinting enteral feedings with blue dye is thought to aid the early detection of aspiration in hospitalized patients. The blue-dye method is popular despite evidence that it is not sensitive. Reports of absorption of blue dye from enteral feedings in patients with sepsis and other critical illnesses are increasing. The presence of blue and green skin and urine, and serum discoloration has been linked with death. FD&C Blue No.1 and related dyes have toxic effects on mitochondria, suggesting that dye absorption is harmful. This study reviews the literature on the dye method and dye pharmacology, reports the results of a survey of current dye use, and describes 2 recent deaths associated with blue-dye absorption. We concluded that the use of blue dye in enteral feedings should be abandoned and replaced by evidence-based methods for the prevention of aspiration.
