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Biomedical subjects

C W Ward

Publications and source records attributed to C W Ward.

At least 91 records · Page 5Linked to original sources
PubMed1990

Pilins from the B serogroup of Bacteroides nodosus: characterization, expression, and cross-protection.

Sequences of pilin genes from four strains of serogroup B of the ovine pathogen Bacteroides nodosus have been determined. These sequences permit comparisons of amino acid sequence between pilins from different subtypes (B1, B2, B3, B4) of the B serogroup and assessment of intraserogroup variation. Pili of B. nodosus strains 234 (B1) and 183 (B2) were produced by Pseudomonas aeruginosa harboring a plasmid-borne B. nodosus pilin gene, and these pili were used in sheep vaccination trials. Pili from strain 183 (B2) were found to be a senior antigen to pili from strains of other B subtypes, providing protection against footrot infection caused by strains of the other B subtypes. Pili of this strain are therefore the most suitable candidate for inclusion in a pilus-based vaccine. Pili of strain 234 from subtype B1, the reference strain of the B serogroup, provided poor protection against infection with other subtypes.

Amino Acid Sequence↗
PubMed1990

Gut hypersensitivity reactions in guinea pigs following vaccination or infection with Trichostrongylus colubriformis.

A quantitative approach to measuring gut hypersensitivity responses to parasite antigens is described. Guinea pigs exposed to infection with Trichostrongylus colubriformis, were sensitised to excretory-secretory products and homogenates of third-stage larvae (L3), fourth-stage larvae (L4) and adult worms. The nature of these responses and their modification by pharmacological agents were typical of immediate-type hypersensitivity reactions. Gut sensitivity was greatest in the anterior half of the small intestine, persisted for at least 12 months and was more pronounced against L3 antigens than against L4 or adult preparations. Guinea pigs injected with homogenates of L3, L4 or adult worms were sensitised to these homogenates, but not to T. colubriformis excretory-secretory products.

Animals↗
PubMed1990

Enhancement of skeletal muscle fatigue by the calcium channel antagonist diltiazem.

This study sought to determine the effects of diltiazem on normal muscle twitches and on twitches evoked during repetitive stimulation. Initial experiments showed that diltiazem (5 and 30 microM) had slight, but insignificant, effects on peak twitch tension and the time course of the twitch. When muscles were stimulated at 1 or 5 Hz, 30 microM diltiazem significantly depressed the height and time course of the staircase period and increased the rate and magnitude of fatigue. Contrary to control, diltiazem caused a complete loss of developed tension during both stimulation protocols. Results suggest that although diltiazem has little effect on single twitches, it has marked inhibitory effects on twitches evoked during repetitive activity; the result being enhancement of the fatigue process.

Animals↗
PubMed1989

Coat protein of potyviruses. 6. Amino acid sequences suggest watermelon mosaic virus 2 and soybean mosaic virus-N are strains of the same potyvirus.

The amino acid sequence of the coat protein of watermelon mosaic virus 2 (WMV 2) was determined by a combination of peptide and nucleic acid sequencing. The coat protein of WMV 2 contained 281 amino acid residues including a single cysteine at position 132 and a blocked amino terminus. Comparison with the coat protein sequences of 20 strains of ten distinct potyviruses showed sequence homologies ranging from 43% to 69% except for the N strain of soybean mosaic virus (SMV-N), where the sequence homology with WMV 2 was 83%. This degree of homology and the location of sequence differences between WMV 2 and SMV-N is much closer to that observed between strains of the same virus than that found between distinct potyviruses. These data suggest that WMV 2 and SMV-N may be strains of the same virus.

Amino Acid Sequence↗
PubMed1989

Possible members of the potyvirus group transmitted by mites or whiteflies share epitopes with aphid-transmitted definitive members of the group.

There are at least ten viruses identified in the literature that resemble definitive potyviruses in having flexuous filamentous particles and inducing the formation of "pinwheel" cytoplasmic inclusions in infected cells but that are transmitted by eriophyid mites, whiteflies or soil fungi and not by aphids, the vectors of the definitive potyviruses. The taxonomic status of these viruses is uncertain at present. Using a broadly cross-reactive antiserum raised against the dissociated coat protein core (residues 68-285) of a definitive potyvirus (Johnsongrass mosaic virus), we have shown that wheat streak mosaic virus which is transmitted by mite and sweet potato mild mottle virus which is transmitted by whitefly have coat proteins that share epitopes with definitive potyviruses. This finding further supports their classification as definitive members of the potyvirus group. The cross-reactive antiserum used here had been shown previously to react with coat proteins of fifteen different definitive potyviruses. The antiserum did not react with coat proteins of potexviruses and tobamoviruses.

Animals↗
PubMed1989

Identification and classification of potyviruses on the basis of coat protein sequence data and serology. Brief review.

The identification and classification of potyviruses has been in a very unsatisfactory state due to the large size of the group, the apparent vast variation among the members and the lack satisfactory taxonomic parameters that will distinguish distinct viruses from strains. In the past, use of classical methods, such as host range and symptomatology, cross-protection, morphology of cytoplasmic inclusions and conventional serology, revealed a "continuum" implying that the "species" and "strain" concepts cannot be applied to potyviruses. In contrast nucleic acid and amino acid sequence data of coat proteins has clearly demonstrated that potyviruses can be divided into distinct members and strains. This sequence data in combination with information of the structure of the potyvirus particle has been used to develop simple techniques such as HPLC peptide profiling, serology (using polyclonal antibody probes obtained by cross-adsorption with core protein from trypsin treated particles) and cDNA hybridization. These findings, along with immunochemical analyses of overlapping synthetic peptides have established the molecular basis for potyvirus serology; explained many of the problems associated with the application of conventional serology; and provided a sound basis for the identification and classification of potyviruses. As a result, the virus/strain status of some potyviruses has been redefined, requiring a change in the potyvirus nomenclature. These new developments necessitate a re-evaluation of the earlier literature on symptomatology, cross-protection, cytoplasmic inclusion body morphology and serology.

Amino Acid Sequence↗
PubMed1989

Characterization of the major immunogen in the excretory-secretory products of exsheathed third-stage larvae of Trichostrongylus colubriformis.

The excretory-secretory products of exsheathed third-stage larvae of Trichostrongylus colubriformis conferred some protection to guinea pigs against homologous challenge. A glycoprotein with an apparent molecular mass of approximately 94 kDa was the dominant immunogen in post-exsheathment products. Immunoblots revealed IgG antibodies to this glycoprotein in sera from multiply-infected guinea pigs and some sheep, and in sera of guinea pigs after three truncated infections which had been restricted by anthelmintic treatments to development of the third parasitic stage. IgA antibodies to this protein were also found in intestinal lymph of a naturally infected sheep. Fluorescent antibody studies indicated that this 94 kDa component was associated with cells in the central body cavity of third-stage larvae, but was absent from fourth-stage larvae or adult worms. Fractionation and protection assays in guinea pigs revealed that while the native and aggregated 94 kDa protein conferred some host protection, it was not the only protective component of the excretory-secretory products of exsheathed third-stage larvae of T. colubriformis.

Animals↗
PubMed1989

A novel host-protective antigen from Trichostrongylus colubriformis.

The detergent-soluble fraction from Trichostrongylus colubriformis third-stage larvae contained a simple set of antigens, one of which (molecular weight 41,000) induced 43-51% protection in guinea pigs following immunization. Isolation and partial amino acid sequence analysis of this protective antigen showed it was parasite tropomyosin.

Amino Acid Sequence↗
PubMed1989

Molecular cloning and analysis of the N5 neuraminidase subtype from an avian influenza virus.

The neuraminidase (NA) gene from the prototype N5 influenza virus, A/Shearwater/Australia/72, has been cloned and completely sequenced. An open reading frame of 1404 bp (468 amino acids) is flanked by 20-bp 5'- and 31-bp 3'-untranslated regions. The deduced amino acid sequence of the N5 gene was compared with sequences from N2, N1, N7, N8, and N9 subtypes. One hundred thirteen amino acid residues (24%) are completely conserved across subtypes and include active site residues, cysteines, potential glycosylation sites, and certain glycines which suggests that these subtypes share a common ancestor and adopt the same 3-D conformation. Three groups can be assigned from amino acid homologies: (i) N5, N8, N1; (ii) N7, N9; and (iii) N2 where the percentage identity within groups is 55-68% and between groups is 40-46%, the N5-N8 pair bearing the closest identity (68%). Phylogenetic analysis suggests that these groups diverged concurrently.

Amino Acid Sequence↗
PubMed1989

Characterization of cDNA clones coding for muscle tropomyosin of the nematode Trichostrongylus colubriformis.

The host-protective antigen from detergent-solubilised extracts of the sheep intestinal helminth Trichostrongylus colubriformis has been identified as tropomyosin. Complementary DNA clones coding for T. colubriformis muscle tropomyosin have been isolated and characterised as the first step in obtaining recombinant protein to carry out more extensive vaccination trials. The clones represent an mRNA of 1544 bases, including a relatively long 5' untranslated sequence of 307 bases and a 3' non-coding region of 344 bases. The mRNA codes for a highly alpha-helical protein of 284 residues with a molecular weight of 33,000; characteristics typically observed for the muscle tropomyosins of higher organisms. The T. colubriformis protein has 58% sequence identity with rabbit and Drosophila melanogaster muscle tropomyosins, and the differences in the protein sequence are randomly distributed throughout the molecule. There is complete identity between the three sequences for the N-terminal 9 residues, the region believed to be essential for the polymerisation of tropomyosin molecules and for binding to actin and troponin.

Amino Acid Sequence↗
PubMed1989

Localization of virus-specific and group-specific epitopes of plant potyviruses by systematic immunochemical analysis of overlapping peptide fragments.

Virus-specific or group-specific antibody probes to potyviruses can be produced by targeting the immune response to the virus-specific, N-terminal region of the capsid protein (29-95 amino acids depending on the virus) or to the conserved core region (216 amino acids) of the capsid protein, respectively. Immunochemical analysis of overlapping, synthetic octapeptides covering the capsid protein of the Johnsongrass strain of Johnsongrass mosaic virus (JGMV-JG) has delineated the peptide sequences recognized by five polyclonal rabbit antisera and two mouse monoclonal antibodies (mAbs). The antibodies characterized were (i) three virus-specific rabbit polyclonal antisera and one virus-specific mouse mAb (1/25) raised against native virus particles, (ii) one polyclonal antiserum raised against trypsin-derived core particles of JGMV-JG, (iii) one group-specific polyclonal antiserum raised against the denatured, truncated coat protein from trypsin-derived core particles of JGMV-JG, and (iv) one group-specific mouse mAb (1/16) raised against native virus particles. The two epitopes seen by mAb 1/25 occurred at residues 18-27 and 43-52 and overlapped with the two major epitopes seen by the virus-specific polyclonal antiserum. The group-specific epitope seen in JGMV-JG by mAb 1/16 was also recognized strongly in potato virus Y, the type member of the potyvirus group. The multiple epitopes seen by the cross-reactive polyclonal antisera were distributed across the entire core region of the coat protein and their relative antibody binding responses varied between JGMV-JG, potato virus Y, and six other distinct potyviruses.

Amino Acid Sequence↗
PubMed1989

The use of 3' non-coding nucleotide sequences in the taxonomy of potyviruses: application to watermelon mosaic virus 2 and soybean mosaic virus-N.

The sequence of the 3' 1106 nucleotides of the watermelon mosaic virus 2 (WMV 2) genome has been determined. The sequence contains the complete coding region of the viral coat protein followed by a 3' untranslated sequence of 251 nucleotides. When these sequences were compared with the equivalent regions of the N strain of soybean mosaic virus (SMV-N), the coat protein coding regions were 82% homologous, whereas the 3' untranslated sequences were 78% homologous. Optimal alignment of the 3' untranslated regions of RNA from 13 strains of seven other distinct potyviruses revealed that the degree of homology between strains was in the range 83 to 99%. In contrast, the sequences from distinct viruses had identities in the range 39 to 53%, comparable to the level of identity found between the 3' non-coding regions of viruses from unrelated plant virus groups. On the basis of these results, WMV 2 and SMV-N could be regarded as strains of one virus. These results also suggest that the sequence of the 3' untranslated region of the potyvirus genome may be an accurate marker of genetic relatedness and could serve as an aid to identification and classification of potyviruses.

Amino Acid Sequence↗
PubMed1988

Coat protein of potyviruses. 4. Comparison of biological properties, serological relationships, and coat protein amino acid sequences of four strains of potato virus Y.

Four strains of potato virus Y, PVY-D, PVY-10, PVY-18, and PVY-43, obtained from different Australian sources were compared on the basis of their biological, serological and coat protein structural properties. Each of the strains could be distinguished on the basis of their reactions on selected test plant species. Two of the PVY strains, PVY-D and PVY-10, induced symptoms similar to those produced by the PVYO strain group. The reactions of PVY-18 and PVY-43, although comparable to PVYN in some hosts, did not completely match the description of the PVYN strain group. In contrast to the other three strains, PVY-18 could not be transmitted by Myzus persicae in repeated tests. No difference was observed in the serological properties of the four PVY strains in different assay systems, using polyclonal antisera. The amino acid sequences of the coat proteins of PVY-10, PVY-18, and PVY-43 were obtained and compared with the coat protein sequences of pepper mottle virus (PeMV) [Dougherty WG, Allison RF, Parks TD, Johnston RE, Feild MJ, Armstrong FB (1985) Virology 146: 282-292] and PVY-D [Shukla DD, Inglis AS, McKern NM, Gough KH (1986) Virology 152: 118-125]. The homology between the PVY strains ranged from 96.3 to 99.3% and with the PeMV sequence, 91.4 to 92.9%. Based on this high sequence homology, and the previous observation that coat protein sequences of potyvirus strains are always greater than 90% identical, PeMV could be considered a strain of PVY. However, PVY and PeMV are reported to be only distantly serologically related and on this basis PeMV is currently considered to be an independent member of the Potyvirus group.

Amino Acid Sequence↗
PubMed1988

Coat protein of potyviruses. 5. Symptomatology, serology, and coat protein sequences of three strains of passionfruit woodiness virus.

Three strains of passionfruit woodiness virus, Tip Blight (PWV-TB), Severe (PWV-S) and Mild (PWV-M), were compared on the basis of their biological, serological and coat protein structural properties. Each of the strains could be distinguished on the basis of their reactions on selected test plant species but no differences were observed in the serological properties of the three PWV strains. Molecular weight estimates on SDS-PAGE suggest the PWV coat protein contains 275 amino acid residues and sequence data for 269 of these residues is presented. The amino terminal peptide is blocked and has not been sequenced. The coat proteins of PWV-TB and PWV-S, which cause severe symptoms in infected plants, showed only three sequence differences compared to the eleven or twelve sequence changes between their coat proteins and that of the mild strain. The high sequence homology (96-99%) between the three PWV strains is similar to that previously reported for two strains of tobacco etch virus and three strains of sugarcane mosaic virus. Sequence homology between the three strains of PWV and published sequences for the coat proteins of eight distinct potyviruses ranged from 43-71% (average 57%).

Amino Acid Sequence↗
PubMed1985

Structural homologies between RNA gene segments 10 and 11 from UK bovine, simian SA11, and human Wa rotaviruses.

The nucleotide sequences of gene segments 10 and 11 from UK bovine rotavirus have been determined. Gene 10 is 751 nucleotides long and contains a single long open reading frame capable of coding for a protein of 175 amino acids. When compared with the published data for gene 10 of the simian rotavirus SA11 and human Wa strains it was found to be more closely related to the SA11 structure (92% nucleotide sequence homology; 97% amino acid sequence homology) than to the human Wa structure (84% nucleotide, 86% amino acid sequence homology). All three strains have two potential N-glycosylation sites in the hydrophobic N terminus of the gene 10 protein. Gene 11 from UK bovine rotavirus is 667 nucleotides long with a single long open reading frame capable of coding for a protein of 198 amino acids. When compared with the published sequence of gene 11 from the human rotavirus Wa, the UK bovine rotavirus gene 11 was found to be one nucleotide longer in the 5'-noncoding region and three nucleotides longer in the coding region. The nucleotide sequence homology was 86%. The predicted proteins coded by segment 11 in UK and Wa rotaviruses are both rich in serine and threonine (23%) and very hydrophilic, but differ appreciably in amino acid sequence (83% homology).

Amino Acid Sequence↗
PubMed1984

Nucleotide sequence of gene segment 9 encoding a nonstructural protein of UK bovine rotavirus.

A full-length ds cDNA copy of UK bovine rotavirus gene segment 9, which codes for a nonstructural protein, has been cloned into the PstI site of pBR322, and its sequence has been determined by cloning into bacteriophage M13mp8. Gene 9 is 1076 nucleotides long and contains a single, long, open-reading frame capable of coding for a protein of 313 amino acid residues. The possible function of this nonstructural protein in virus replication is discussed.

Animals↗