Variola, the causative agent of smallpox, is a highly infectious double-stranded DNA virus of the orthopox genus that replicates within the cytoplasm of infected cells. For unknown reasons prominent ...skin manifestations, including “pox,” mark the course of this systemic human disease. Here we characterized smallpox growth factor (SPGF), a protein containing an epidermal growth factor (EGF)-like domain that is conserved among orthopox viral genomes, and investigated its possible mechanistic link. We show that after recombinant expression, refolding, and purification, the EGF domain of SPGF binds exclusively to the broadly expressed cellular receptor, erb-B1 (EGF receptor), with subnanomolar affinity, stimulating the growth of primary human keratinocytes and fibroblasts. High affinity monoclonal antibodies specific for SPGF reveal in vivo immunoprotection in a murine vaccinia pneumonia model by a mechanism distinct from viral neutralization. These findings suggest that blockade of pathogenic factor actions, in general, may be advantageous to the infected host.
ADP-ribosylation is an enzyme-catalyzed posttranslational protein modification in which mono(ADP-ribosyl)transferases (mARTs) and poly(ADP-ribosyl)transferases (pARTs) transfer the ADP-ribose moiety ...from NAD onto specific amino acid side chains and/or ADP-ribose units on target proteins.
Using a combination of database search tools we identified the genes encoding recognizable pART domains in the public genome databases. In humans, the pART family encompasses 17 members. For 16 of these genes, an orthologue exists also in the mouse, rat, and pufferfish. Based on the degree of amino acid sequence similarity in the catalytic domain, conserved intron positions, and fused protein domains, pARTs can be divided into five major subgroups. All six members of groups 1 and 2 contain the H-Y-E trias of amino acid residues found also in the active sites of Diphtheria toxin and Pseudomonas exotoxin A, while the eleven members of groups 3 - 5 carry variations of this motif. The pART catalytic domain is found associated in Lego-like fashion with a variety of domains, including nucleic acid-binding, protein-protein interaction, and ubiquitylation domains. Some of these domain associations appear to be very ancient since they are observed also in insects, fungi, amoebae, and plants. The recently completed genome of the pufferfish T. nigroviridis contains recognizable orthologues for all pARTs except for pART7. The nearly completed albeit still fragmentary chicken genome contains recognizable orthologues for twelve pARTs. Simpler eucaryotes generally contain fewer pARTs: two in the fly D. melanogaster, three each in the mosquito A. gambiae, the nematode C. elegans, and the ascomycete microfungus G. zeae, six in the amoeba E. histolytica, nine in the slime mold D. discoideum, and ten in the cress plant A. thaliana. GenBank contains two pART homologues from the large double stranded DNA viruses Chilo iridescent virus and Bacteriophage Aeh1 and only a single entry (from V. cholerae) showing recognizable homology to the pART-like catalytic domains of Diphtheria toxin and Pseudomonas exotoxin A.
The pART family, which encompasses 17 members in the human and 16 members in the mouse, can be divided into five subgroups on the basis of sequence similarity, phylogeny, conserved intron positions, and patterns of genetically fused protein domains.
We introduced previously an on-line resource, RANKPEP that uses position specific scoring matrices (PSSMs) or profiles for the prediction of peptide-MHC class I (MHCI) binding as a basis for CD8 ...T-cell epitope identification. Here, using PSSMs that are structurally consistent with the binding mode of MHC class II (MHCII) ligands, we have extended RANKPEP to prediction of peptide-MHCII binding and anticipation of CD4 T-cell epitopes. Currently, 88 and 50 different MHCI and MHCII molecules, respectively, can be targeted for peptide binding predictions in RANKPEP. Because appropriate processing of antigenic peptides must occur prior to major histocompatibility complex (MHC) binding, cleavage site prediction methods are important adjuncts for T-cell epitope discovery. Given that the C-terminus of most MHCI-restricted epitopes results from proteasomal cleavage, we have modeled the cleavage site from known MHCI-restricted epitopes using statistical language models. The RANKPEP server now determines whether the C-terminus of any predicted MHCI ligand may result from such proteasomal cleavage. Also implemented is a variability masking function. This feature focuses prediction on conserved rather than highly variable protein segments encoded by infectious genomes, thereby offering identification of invariant T-cell epitopes to thwart mutation as an immune evasion mechanism.
Aims: To establish a typing method for tracing the epidemic relationship of 16 strains of Salmonella serotype Havana isolated from captive raptors showing no symptomatology and residing in a wildlife ...hospital in Spain.
Methods and Results: Antimicrobial susceptibility testing, ribotyping, pulsed field gel electrophoresis (PFGE) and amplified fragment length polymorphism (AFLP) methodology were applied. Ten unrelated strains of serotype Havana were included as a control group to provide a basis of for the efficiency of the different markers used. All outbreak‐related strains were resistant to nalidixic acid and streptomycin and showed the same ripotype, pulsotype and AFLP pattern.
Conclusions: This is the first time that AFLP analysis has been tested with serotype Havana isolates and it has demonstrated to be the most useful epidemiological tool for discriminating between unrelated and outbreak‐related strains of this serotype. The results obtained suggest that all the Salmonella serotype Havana isolates represented a common outbreak strain whose origin of contamination could not be established although it is thought that it was the poultry meat used for raptors'diet.
Significance and Impact of the Study: Our study suggests the importance of microbiological analysis of these products in order to prevent contamination and dissemination of Salmonellae in this kind of Hospital.
Birds are considered dinosaurs that passed the 65 million years ago bottleneck. Songbirds (Passeriformes) include about half extant bird species (about 5000) and are generally the most air-thriving ...bird species, concordantly with their small size. Mayor Histocompatibility complex (MHC) molecules stimulate immune responses against microbes and its class I molecules have seven conserved residues in all vertebrates from jawed-fishes, 300 million years ago, to humans, including chickens. All wild songbird species tested by us (n=18) and others (n= 2) differ in alpha 1 domain residue 10 and alpha 2 residue 96 from all other vertebrates. Amplification, cloning and sequencing were performed by standard methods. Sequences alignment were done by using PAUP and MEGA programs software. Crystallographic studies were performed by using mammal and bird MHC molecules from MPID database and other sources and showed that these changes did not significantly vary the MHC class I molecule stability in songbirds. Further alpha 1 and alpha 2 domain comparisons by simple Composition Distances and Bayesian Inference showed that songbirds overall MHC class I molecules are phylogenetically more separated from mammal than other birds molecules. In addition MHC class I introns from Passeriformes (songbirds) were found to be longer than humans, chicken introns being the shortest ones. These small mainly air-borne dinosaurs (Passeriformes) have undergone a different evolutive pathway, regarding to MHC, than all other tested vertebrates and more terrestrial birds. This may have been originated by an altogether different dinosaurs linage origin or to adaptation to more aerial than terrestrial environment or other unknown cause. In any case, the specific changes observed in this work for class I molecules in songbirds have reached a entropic, stable solution similar to that reached by other vertebrates.
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