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Biomedical subjects

L A Ashworth

Publications and source records attributed to L A Ashworth.

At least 19 recordsLinked to original sources
PubMed1995

Constitutive expression of major histocompatibility complex class II antigens on monocytes and B cells correlates with disease in simian immunodeficiency virus-infected rhesus macaques.

Constitutive host factors that influence progression to AIDS are understood poorly. In the macaque model for AIDS, 35 animals infected with simian immunodeficiency virus (SIV) were analyzed for major histocompatibility complex class II antigen expression on blood monocytes and B cells by immunostaining and flow cytometry. Expression varied widely between animals but was constant with time. Level of expression and the proportion of monocytes and B cells that expressed class II were not affected by SIV infection. Significantly more animals developed AIDS in the group with low class II expression than in the group with high expression (P < .001). Progression to disease was faster in animals that expressed poorly (P < .01), and opportunistic pathogens were more common (P < .05). Thus, the constitutive level of class II antigen expression may be a useful prognostic indicator for human immunodeficiency virus disease in humans and may be an important factor in the design of vaccine trials.

AIDS Vaccines↗
PubMed1995

Adverse events and antibody response to accelerated immunisation in term and preterm infants.

A study was performed to compare adverse events and antibody response in term and preterm children vaccinated with diphtheria, tetanus, and pertussis vaccine at 2, 3, and 4 months of age. A total of 124 children were recruited and grouped according to gestational age: 37 weeks or more (n = 52), 34 to 36 weeks (n = 40), and less than 34 weeks (n = 32). Study nurses followed up children 24 hours after each vaccination to record temperature, redness, and swelling at the injection site and any systemic symptoms. Proportions of children experiencing adverse events did not differ between groups. Blood samples were obtained six weeks after the vaccination course at which time all children had protective levels of diphtheria and tetanus antitoxins. Geometric mean antibody titres (95% confidence interval) to pertussis toxin were 2754 (2042 to 3715), 5495 (4074 to 7413), and 3690 (2951 to 4677), to filamentous haemagglutinin were 541 (282 to 1023), 951 (537 to 1698), and 614 (426 to 1023), and to agglutinogens 2 and 3 were 12,106 (6918 to 21,380), 21,330 (13,183 to 34,674), and 22,387 (15,136 to 33,113) in children born at a gestational age of less than 34 weeks, 34 to 36 weeks, and 37 weeks or more respectively. These findings support the current recommendations that preterm children are vaccinated at chronological age according to the national schedule.

Age Factors↗
PubMed1995

Hormonal and metabolic profiles in subjects with obstructive sleep apnea syndrome and the acute effects of nasal continuous positive airway pressure (CPAP) treatment.

Nocturnal secretion of growth hormone is impaired in patients with obstructive sleep apnea (OSA), but the metabolic consequences have not been reported. We measured blood levels of the hormones insulin, C-peptide, growth hormone, cortisol and glucagon together with the intermediary metabolites of carbohydrate (glucose, pyruvate, lactate, alanine) and lipid metabolism [glycerol, nonesterified fatty acids (NEFA), 3-hydroxybutyrate] in six obese nondiabetic men with OSA on two nights. In the first study, the untreated subjects showed frequent apneas and consequent hypoxemia. The hormone and metabolite concentrations were compared with those obtained on the following night when the subjects were treated effectively with nasal continuous positive airway pressure (CPAP). There were no significant differences in the concentrations of insulin, C-peptide, cortisol or glucagon. We confirmed a marked reduction in growth hormone concentrations in OSA, with a significant increase on the CPAP night. The nocturnal profiles of glucose, pyruvate, lactate, alanine and glycerol showed no differences between the two nights, but concentrations of NEFA and 3-hydroxybutyrate, both products of lipolysis, were significantly greater on the treatment night. Because growth hormone has a lipolytic action, the results suggest that suppression of secretion of growth hormone in untreated OSA results in impaired lipolysis, which is rapidly reversed by nasal CPAP.

Adult↗
PubMed1994

Localization of antigenic domains on the major subunits of Bordetella pertussis serotype 2 and 3 fimbriae.

Antibody-binding domains on the major subunits of Bordetella pertussis serotype 2 (Fim2) and 3 fimbriae (Fim3) have been identified using synthetic peptides which were screened for recognition by anti-protein monoclonal antibodies (mAbs). The presence of non-contiguous fimbrial epitopes was demonstrated by both anti-Fim2 and anti-Fim3 mAbs, several of which recognized at least two peptides that were discontinuous in the amino acid sequence of the corresponding subunits. The specificity of one mAb, 51/24, directed against Fim2, was investigated by replacement-set analysis of a 10-residue peptide, and revealed that antibody binding to the peptide was dependent on the sequence N94PQ96 which is non-conserved in Fim3. Furthermore, proline at residue 95 was found to be essential for mAb 51/24 binding. The specific anti-Fim3 mAb, AG3A, was found to recognize the 10-residue carboxy-terminal peptide from both Fim3 and, unexpectedly, from Fim2. This result suggests that mAb AG3A serospecificity at the protein level is determined by a conformational constraint which prevents mAb AG3A binding to the Fim2 C-terminal domain. Several free peptides containing amino acid residues which comprise part of the Fim2 and Fim3 epitopic domains were prepared as immunogens. One of these peptides was immunogenic in the mouse, indicating the location of a T-helper cell epitope within the peptide sequence, and induced a strong anti-peptide antibody response. The other peptides each required immunization as a conjugate with a carrier protein for anti-peptide antibody stimulation. All four anti-peptide antibody preparations only weakly recognized fimbriae-coated ELISA plates.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

Immunogenicity of combined diphtheria, tetanus, and pertussis vaccine given at 2, 3, and 4 months versus 3, 5, and 9 months of age.

In the UK an accelerated schedule for immunisation against diphtheria, tetanus, and pertussis (injections at 2, 3, and 4 months of age) was introduced in 1990 to replace the more widely spaced schedule of 3, 5, and 9 months. There is concern, however, that the new schedule may be less immunogenic and therefore less protective than the old schedule. We have measured serum concentrations of antibodies against diphtheria, pertussis, and tetanus in infants immunised according to the two regimens. Both schedules resulted in protective concentrations of antibody against tetanus and diphtheria and in satisfactory antibody responses to three pertussis antigens (filamentous haemagglutinin, pertussis toxin, fimbriae). However, immunisation by the old schedule led to significantly higher antibody concentrations against both diphtheria and tetanus than did immunisation by the new schedule (p less than 0.01). In infants immunised with the new schedule, postimmunisation antibody concentrations against tetanus toxoid and against two pertussis antigens (pertussis toxin and fimbriae) were significantly lower in infants in whom preimmunisation (maternally derived) antibody concentrations were high (p less than 0.02). The findings suggest that with an accelerated immunisation schedule maternal antibodies can have an inhibitory effect on the responses to immunisation against tetanus and pertussis.

Antibodies, Bacterial↗
PubMed1992

Intrarectal challenge of macaques vaccinated with formalin-inactivated simian immunodeficiency virus.

Macaques can be protected from intravenous infection with simian immunodeficiency virus (SIV) by vaccination with chemically inactivated virus. However, protection against infection via a mucosal surface has not been demonstrated. We vaccinated four rhesus macaques with formalin-inactivated SIV given intramuscularly. These monkeys, which had remained virus free for 10 months after intravenous challenge with SIV, were given a further dose of vaccine and together with four unvaccinated controls were challenged intrarectally with SIV. Subsequently, virus was isolated from all control animals on five successive occasions, but the vaccinated animals remained free of virus. Proviral DNA could not be detected in peripheral blood mononuclear cells from the vaccinated animals. Preliminary data indicate that vaccinated animals make a local antibody response.

AIDS Vaccines↗
PubMed1991

Persistence of antibody after accelerated immunisation with diphtheria/tetanus/pertussis vaccine.

OBJECTIVE: To determine the persistence of antibody to diphtheria, tetanus, and pertussis in children receiving an accelerated schedule of primary immunisation. DESIGN: Controlled study of antibody testing of blood samples from children immunised according to various schedules: three doses of triple vaccine completed at 8-13 calendar months, 6-7 calendar months, before 6 calendar months, or three doses followed by diphtheria/tetanus before age 2. SETTING: Plymouth Health Authority. SUBJECTS: 129 children aged 4 years who had received three doses of diphtheria/tetanus/pertussis vaccine with or without a diphtheria/tetanus booster. MAIN OUTCOME MEASURES: Diphtheria and tetanus antitoxin concentrations and antibody titres to pertussis toxin, filamentous haemagglutinin, and agglutinogens 2 and 3. RESULTS: All children had protective concentrations of antitoxin to diphtheria and tetanus (greater than or equal to 0.01 IU/ml). There was no evidence of a significant difference in diphtheria or tetanus antitoxin concentrations and pertussis antibody titres in children immunised with an accelerated course (third dose of triple vaccine before 6 months) compared with those who received a longer course (third dose at 8-13 months) with no booster (geometric mean antitoxin concentration 0.411 (95% confidence interval 0.273 to 0.618) v 0.426 (0.294 to 0.616) for diphtheria and 0.358 (0.231 to 0.556) v 0.299 (0.197 to 0.453) for tetanus; geometric mean antibody titres 903 (500 to 1631) v 1386 (848 to 2266) for pertussis filamentous haemagglutinin, 179 (130 to 248) v 232 (167 to 322) for pertussis toxin, and 2002 (1276 to 3142) v 3591 (2220 to 5809) for agglutinogens 2 and 3). CONCLUSION: Immunisation with three doses of triple vaccine at monthly intervals completed before 6 months of age probably provides adequate protection against diphtheria, tetanus, and whooping cough which will persist until the age of the preschool booster.

Antibodies, Bacterial↗
PubMed1991

Phase II trial of whole-cell pertussis vaccine vs an acellular vaccine containing agglutinogens.

An acellular pertussis vaccine containing agglutinogens 2 and 3, pertussis toxin, and filamentous haemagglutinin was developed by the Centre for Applied Microbiology and Research in the UK. 188 infants were entered into a randomised blind trial and received either the acellular or a whole-cell vaccine, combined with diphtheria and tetanus toxoids, in a 3, 5, and 8-10 month schedule. Local reactions were similar in the two groups but significantly fewer infants had systemic symptoms after the acellular vaccine. Mean log-antibody titres to the agglutinogen and toxin components were higher with the acellular than with the whole-cell vaccine. Persistence of antibodies one year after the third dose was also better in the acellular group.

Antibodies, Bacterial↗
PubMed1990

Recognition of pertussis toxin by antibodies to synthetic peptides.

Eight synthetic peptides, selected from the amino acid sequence of pertussis toxin (PT) subunits S1, S2, S3 and S4, were assessed for their ability to induce protein-recognizing and neutralizing antibodies. Seven of these peptides, prepared as conjugates of either keyhole limpet haemocyanin or tetanus toxoid, induced significant levels of antibody, all of which reacted with SDS-denatured PT on Western blots. Six of the antibodies bound to PT-coated ELISA plates; this binding was inhibited by homologous peptide antigen. However, none of the antibodies, including those directed against the N-terminus of subunit S1, were able to attenuate in vivo or in vitro toxin-dependent activity. Further investigation revealed that only one antibody, specific for the C-terminus of S1 (peptide Slc, 237-255), could recognize the conformation of native PT in solution. The other five antipeptide antibodies which reacted with PT-coated ELISA plates did not recognize PT when captured onto ELISA plates via either a monoclonal antibody or fetuin, unless the conformation of the toxin had been relaxed by reduction with dithiothreitol. Conversely, the native PT-recognizing response of peptide Slc did not bind the conformationally relaxed PT molecule. From this study, it appears likely that a peptide capable of inducing PT-neutralizing antibody must closely resemble the conformation of the cognate sequence in the native protein.

Amino Acid Sequence↗
PubMed1989

Serotyping Bordetella pertussis strains.

The serotyping scheme for Bordetella pertussis, developed in the 1950s, depends on the presence or absence of various strains of three major agglutinogens, two of which have been shown to be fimbrial proteins, and several minor agglutinogens, the biochemical nature of which is unknown. This article reviews the reasons for the confusion which has recently arisen over the nomenclature of the serotype antigens and proposes a simplified serotyping scheme based on the fimbrial components.

Agglutination↗
PubMed1989

Serum IgG, IgA, and IgM responses to pertussis toxin, filamentous hemagglutinin, and agglutinogens 2 and 3 after infection with Bordetella pertussis and immunization with whole-cell pertussis vaccine.

Class antibody responses to pertussis toxin (PT), filamentous hemagglutinin (FHA), and agglutinogens 2 and 3 (Agg 2/3) were studied in 114 patients with pertussis, 49 family contacts of patients with pertussis, and 139 infants attending vaccination clinics. IgG responses to FHA and PT were similar in patients with pertussis and in infants immunized three times with whole-cell pertussis vaccine. IgA responses to FHA and PT were greater in patients with pertussis than in vaccines, and a serum log10 titer of IgA to PT greater than 1.9 was a useful discriminant of Bordetella pertussis infection. When compared with patients with pertussis, vaccinees had a greater IgG response to Agg 2/3 and an equivalent IgA response to Agg 2/3. Serologic responses to FHA, PT, and Agg 2/3 were common in family contacts but were smaller than the responses in patients with pertussis. Initial titers of IgG to FHA and IgA to FHA were significantly higher (P less than .005 and P less than .05, respectively) in family contacts aged 3-10 y than in patients with pertussis in an identical age group.

Agglutinins↗
PubMed1988

Trial of a new acellular pertussis vaccine in healthy adult volunteers.

Immunogenicity and reactogenicity of a new acellular pertussis vaccine were tested in healthy adults. The vaccine contained three constituents of Bordetella pertussis; filamentous haemagglutinin, pertussis toxin (PT) and fimbriae bearing agglutinogens 2 and 3. The constituents were separately purified, treated with formaldehyde and combined with one of two aluminium adjuvants. Subjects received one dose of vaccine or an appropriate adjuvant-only preparation and were monitored for clinical responses for 7 days. Results with the two forms of vaccine were similar. Of 35 vaccinees, none had a temperature higher than 37 degrees C or a severe reaction, one had a moderate reaction (possibly due in part to intercurrent infection) and nine had mild reactions confined to localized discomfort and/or erythema or induration at the injection site. All vaccinees had good serum antibody responses to vaccine antigens measured by ELISA and for PT, by neutralization of its effects on Chinese hamster ovary cells.

Adjuvants, Immunologic↗
PubMed1988

In vivo production of a tissue-destructive protease by Legionella pneumophila in the lungs of experimentally infected guinea-pigs.

A tissue-destructive protease of Legionella pneumophila was assayed for in the lungs of experimentally infected guinea-pigs by ELISA. It was found in amounts equivalent to the known lethal dose of purified protease administered by the intranasal route. The identity of the protease was confirmed by immunoblot analysis. This is further evidence that Legionella pneumophila protease may play a major role in the pathogenesis of Legionnaires' disease.

Animals↗
PubMed1988

Inactivation of human alpha-1-antitrypsin by a tissue-destructive protease of Legionella pneumophila.

Three extracellular proteases produced by Legionella pneumophila during growth in liquid medium were examined for their effects on human alpha-1-antitrypsin (alpha-1-AT). One of these proteases, tissue-destructive protease (TDP) destroyed completely the trypsin-inhibitory capacity of alpha-1-AT at protease: inhibitor molar ratios down to 0.002:1. After inactivation by TDP, the Mr of alpha-1-AT was reduced by 5000 in SDS-PAGE. This suggested that inactivation entailed only limited cleavage.

Electrophoresis, Polyacrylamide Gel↗
PubMed1988

Rapid diagnosis of whooping cough using monoclonal antibody.

A counterimmunoelectrophoresis (CIE) method for antigen detection using monoclonal antibody was assessed for its ability to aid in the rapid diagnosis of Bordetella pertussis in 59 patients. A positive diagnosis from a combination of results from tests of serum and urine was obtained in 51 (87%) of cases. For sera, CIE had a sensitivity of 85% and a specificity of 94%; for urine samples the sensitivity was 81% and a specificity of 100%. Antigen detection by CIE is simple to perform and yields results on the same day, thus allowing treatment to begin at an early stage.

Antibodies, Monoclonal↗
PubMed1988

Agglutinogens and fimbriae of Bordetella pertussis.

Agglutinogen 2 (AGG2) of Bordetella pertussis is a fimbrial antigen and therefore a potential adhesin and acellular vaccine component. AGG2 was found to dissociate only under harsh conditions into the subunits of mol. wt. 22500 seen in SDS-PAGE. Results from studies of agglutinogen 3 (AGG3) are presented which confirm previous findings from this Laboratory that AGG3 is also a fimbrial protein but with a subunit mol. wt. of 22000. The amino acid sequence of AGG2, deduced from the nucleotide sequence of the gene encoding it, was used as a basis for synthesis of three peptides. Coupled to Keyhole Limpet Haemocyanin (KLH), the peptides were immunogenic in mice, inducing antibodies which bound well to homologous peptide in ELISA but poorly to intact fimbriae. Monoclonal and polyclonal serotype-specific antibodies failed to react significantly with the peptides or their KLH-conjugates. These results indicate that the synthetic peptides do not represent the serotype 2 epitope. Mice immunized with purified AGG2 or AGG3 were found to be protected against respiratory infection with B. pertussis. Results presented here indicate that this protection is, to a large extent, serotype-specific and that immunization of mice with AGG2 or AGG3 can lead to a change in serotype of the infecting strain. These results are analogous to findings from epidemiological studies of the protection induced in children by whole cell vaccines. They reaffirm the importance of both AGG2 and AGG3 as components of whole cell and acellular vaccines.

Amino Acid Sequence↗