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Biomedical subjects

S Chatfield

Publications and source records attributed to S Chatfield.

At least 19 recordsLinked to original sources
PubMed2004

Perinatal transport: problems in neonatal intensive care capacity.

OBJECTIVE: To assess the quantity and nature of transfers within the Yorkshire perinatal service, with the aim of identifying suitable outcome measures for the assessment of future service improvements. DESIGN/SETTING: Collection of data on perinatal transfers from all neonatal and maternity units located in the Yorkshire region of the United Kingdom from May to November 2000. PATIENTS: Expectant mothers (in utero transfers) and neonates (ex utero transfers). INTERVENTIONS: None MAIN OUTCOME MEASURES: Quantification of in utero and ex utero transfers; the reasons for and resources required to support transfers; the nature of each transfer (acute, specialist, non-acute, into or out of region). RESULTS: In the period studied, there were 800 transfers (337 in utero; 463 ex utero); 306 transfers were "acute" (80% of transfers in utero), 214 because of specialist need, and 280 "non-acute". Some 37% of capacity transfers occurred from the two level 3 units in the region. Of 254 transfers out of the 14 neonatal units for intensive care, 44 (17.3%) were transferred to hospitals outside the normal neonatal commissioning boundaries. CONCLUSIONS: The study highlights a continuing apparent lack of capacity within the neonatal service in the Yorkshire region, resulting in considerable numbers of neonatal and maternal transfers.

England↗
PubMed2000

Safety and immune responses to attenuated Salmonella enterica serovar typhi oral live vector vaccines expressing tetanus toxin fragment C.

Attenuated Salmonella enterica serovar Typhi vaccine strain CVD 908-htrA was used as a vector to deliver fragment C of tetanus toxin as a single-dose oral tetanus vaccine candidate to elicit protective levels of serum tetanus antitoxin. Twenty-one healthy adult volunteers received doses of 1.6 x 10(7) to 8.2 x 10(9) CFU of one of two strains, CVD 908-htrA(pTETnir15) or CVD 908-htrA(pTETlpp), which contained plasmid-encoded fragment C, with sodium bicarbonate, and the safety and immune responses to serovar Typhi antigens and tetanus toxin were assessed. No volunteer had fever or positive blood cultures after vaccination, although diarrhea occurred in 3 volunteers and vomiting in 2 volunteers within 3 weeks after vaccination. Most volunteers excreted the vaccine strain in the first 72 h after vaccination. Three of nine volunteers who received 10(8) CFU or higher doses of the CVD 908-htrA(pTETlpp) construct developed rises in serum antitoxin antibodies. The serum and cellular immune responses to serovar Typhi antigens were less frequent than those previously observed in volunteers who ingested the parent strain CVD 908-htrA. This study demonstrates that fragment C of tetanus toxin delivered orally to volunteers in an S. Typhi vector can elicit protective levels of serum antitoxin.

Adolescent↗
PubMed2000

Carbohydrate biopolymers enhance antibody responses to mucosally delivered vaccine antigens.

We have evaluated the ability of two carbohydrate biopolymers, chitosan and gellan, to enhance antibody responses to subunit influenza virus vaccines delivered to the respiratory tracts of mice. Groups of mice were vaccinated three times intranasally (i.n.) with 10 microg of purified influenza B/Panama virus surface antigens (PSAs), which consist of hemagglutinin (HA) and neuraminidase (NA), either alone or admixed with chitosan or gellan solutions. Separate groups were vaccinated subcutaneously (s.c.) with PSAs adsorbed to Alhydrogel or chitosan or gellan alone i.n. Serum antibody responses were determined by enzyme-linked immunosorbent assay (ELISA) for influenza virus-specific immunoglobulin G (IgG) and by HA inhibition (HAI) and NA inhibition (NAI) assays. The local respiratory immune response was measured by assaying for influenza virus-specific IgA antibody in nasal secretions and by enumerating nasal and pulmonary lymphocytes secreting IgA, IgG, and IgM anti-influenza virus-specific antibodies by enzyme-linked immunospotting (ELISPOT). When administered alone i.n., B/Panama PSA was poorly immunogenic. Parenteral immunization with B/Panama PSA with Alhydrogel elicited high titers of anti-B/Panama antibodies in serum but a very poor respiratory anti-B/Panama IgA response. In contrast, i.n. immunization with PSA plus chitosan stimulated very strong local and systemic anti-B/Panama responses. Gellan also enhanced the local and serum antibody responses to i.n. PSA but not to the same extent as chitosan. The ability of chitosan to augment the immunogenicity of influenza vaccines given i.n. was confirmed using PSA prepared from an influenza A virus (A/Texas H1N1).

Animals↗
PubMed2000

Comparison of abilities of Salmonella enterica serovar typhimurium aroA aroD and aroA htrA mutants to act as live vectors.

We compared the ability of Salmonella enterica serovar Typhimurium SL1344 aroA aroD (BRD509) and aroA htrA (BRD807) mutants to act as live vectors for delivery of fragment C of tetanus toxin (FrgC). FrgC was expressed in these strains from either pTETnir15 or pTEThtrA1. BRD509FrgC(+) strains elicited approximately 2-log-higher serum anti-FrgC antibody titers than BRD807FrgC(+) strains. All mice immunized with BRD807pTEThtrA1, BRD509pTEThtrA1, and BRD509pTETnir15 (but not BRD807pTETnir15) were protected against tetanus.

3-Phosphoshikimate 1-Carboxyvinyltransferase↗
PubMed2000

Salmonella enterica serovar typhimurium surA mutants are attenuated and effective live oral vaccines.

A previously described attenuated TnphoA mutant (BRD441) of Salmonella enterica serovar Typhimurium C5 (I. Miller, D. Maskell, C. Hormaeche, K. Johnson, D. Pickard, and G. Dougan, Infect. Immun. 57:2758-2763, 1989) was characterized, and the transposon was shown to be inserted in surA, a gene which encodes a peptidylprolyl-cis, trans-isomerase. A defined surA deletion mutation was introduced into S. enterica serovar Typhimurium C5 and the mutant strain, named S. enterica serovar Typhimurium BRD1115, was extensively characterized both in vitro and in vivo. S. enterica serovar Typhimurium BRD1115 was found to be defective in the ability to adhere to and invade eukaryotic cells. Furthermore, S. enterica serovar Typhimurium BRD1115 was attenuated by at least 3 log units when administered orally or intravenously to BALB/c mice. Complementation of the mutation with a plasmid carrying the intact surA gene almost completely restored the virulence of BRD1115. In addition, S. enterica serovar Typhimurium BRD1115 demonstrated potential as a vaccine candidate, since mice immunized with BRD1115 were protected against subsequent challenge with S. enterica serovar Typhimurium C5. S. enterica serovar Typhimurium BRD1115 also showed potential as a vehicle for the effective delivery of heterologous antigens, such as the nontoxic, protective fragment C domain of tetanus toxin, to the murine immune system.

Administration, Oral↗
PubMed2000

Phase 2 clinical trial of attenuated Salmonella enterica serovar typhi oral live vector vaccine CVD 908-htrA in U.S. volunteers.

Salmonella enterica serovar Typhi strain CVD 908-htrA is a live attenuated strain which may be useful as an improved oral typhoid vaccine and as a vector for cloned genes of other pathogens. We conducted a phase 2 trial in which 80 healthy adults received one of two dosage levels of CVD 908-htrA in a double-blind, placebo-controlled, crossover study. There were no differences in the rates of side effects among volunteers who received high-dose vaccine (4.5 x 10(8) CFU), lower-dose vaccine (5 x 10(7) CFU), or placebo in the 21 days after vaccination, although recipients of high-dose vaccine (8%) had more frequent diarrhea than placebo recipients (0%) in the first 7 days. Seventy-seven percent and 46% of recipients of high- and lower-dose vaccines, respectively, briefly excreted vaccine organisms in their stools. All blood cultures were negative. Antibody-secreting cells producing antilipopolysaccharide (LPS) immunoglobulin A (IgA) were detected in 100 and 92% of recipients of high- and lower-dose vaccines, respectively. Almost half the volunteers developed serum anti-LPS IgG. Lymphocyte proliferation and gamma interferon production against serovar Typhi antigens occurred in a significant proportion of vaccinees. This phase 2 study supports the further development of CVD 908-htrA as a single-dose vaccine against typhoid fever and as a possible live vector for oral delivery of other vaccine antigens.

Administration, Oral↗
PubMed1999

Prior immunity to homologous and heterologous Salmonella serotypes suppresses local and systemic anti-fragment C antibody responses and protection from tetanus toxin in mice immunized with Salmonella strains expressing fragment C.

We have investigated the effect of preexisting immunity to homologous (Salmonella typhimurium) or heterologous (S. dublin) serotypes of Salmonella on the ability of an attenuated S. typhimurium aroA aroD vector (BRD509) to immunize mice against the heterologous antigen fragment C (FrgC). We studied two strains, BRD847 and BRD937, expressing FrgC carried on plasmids that differ only with respect to the promoter controlling FrgC expression, the nirB promoter in the case of BRD847 and the htrA promoter in the case of BRD937. Mice were preimmunized orally with S. typhimurium BRD509, S. dublin aroA aroD (BRD620), or saline. Forty-four days later, they were immunized orally with BRD847 or BRD937. Prior immunity to S. typhimurium severely depressed the serum immunoglobulin G (IgG) and IgA anti-FrgC response in both BRD847- and BRD937-immunized mice. Mice with existing immunity to S. dublin also had lower IgG anti-FrgC geometric mean titers (GMTs) than did mice preimmunized with saline, but this difference was significant only in the case of mice immunized with BRD937. However, in nonimmune mice or in mice preimmunized with S. typhimurium or S. dublin, the anti-FrgC IgG GMTs were always higher in mice in the BRD937 groups than in the equivalent BRD847 groups. This is reflected in the effect of prior immunity on the ability of oral immunization with BRD847 or BRD937 to protect mice from challenge with a lethal dose of tetanus toxin. All of the mice preimmunized with saline and then immunized with BRD847 or BRD937 survived challenge. Only 20% of the animals immunized with BRD847 and 60% of the mice in the BRD937 group survived tetanus toxin challenge if they were preimmunized with BRD509. Preexisting immunity to S. dublin did not affect the ability of BRD937 to immunize mice against tetanus, but it did reduce the efficiency of BRD847: only 60% percent of the mice survived challenge. The intestinal secretory IgA responses to FrgC were very similar in the BRD847 and BRD937 groups. Prior immunity did depress the IgA anti-FrgC titers but only significantly so in the mice preimmunized with BRD509. These results show that preexisting Salmonella immunity, particularly to homologous serotypes, can severely compromise the ability of live Salmonella vectors to deliver heterologous antigens to the mammalian immune system. However, the results also indicate that this may be overcome by the design of more powerful in vivo expression systems.

Animals↗
PubMed1999

A comparison of the efficacy of the alginate preparation, Gaviscon Advance, with placebo in the treatment of gastro-oesophageal reflux disease.

The aim of this study was to compare the efficacy of the sodium alginate preparation, Gaviscon Advance, with placebo in the relief of symptoms of reflux oesophagitis. This was a randomised, double-blind, parallel-group, multicentre study conducted at 13 GP centres in the UK. Patients aged between 18 and 70 years, who had experienced symptoms of reflux oesophagitis within the previous 24 h, and on two other occasions within the previous week, were recruited into the study. Patients were evaluated at baseline, and then reassessed after two and four weeks of treatment with sodium alginate or placebo, for symptoms of reflux oesophagitis in the previous 24 h. Patients were required to fill out a diary card twice daily, from which frequency and severity of symptoms were assessed, and the percentage of symptom-free days and nights calculated. Of the 100 patients recruited into the study, 98 received medication (safety population; placebo, n = 50; sodium alginate, n = 48) and 94 were eligible for inclusion in the intention-to-treat (ITT) population (placebo, n = 48; sodium alginate, n = 46). For this population, sodium alginate was assessed as significantly superior by both investigators and patients at week two (p < 0.001 and p = 0.004, respectively) and at week four (p = 0.001 and p < 0.001, respectively). Significantly more patients in the safety population on placebo withdrew from the study (40%) compared with sodium alginate (21%; p = 0.04), due primarily to lack of effect and adverse events. The sodium alginate preparation demonstrated a superior efficacy compared with placebo, which was achieved in a more acceptable volume of medication than a previous standard preparation, Liquid Gaviscon. The reduced dosage volume of the 'new' preparation (Gaviscon Advance) may be expected to improve patient compliance, and thereby increase treatment efficacy.

Adult↗
PubMed1998

Protective effect on Leishmania major infection of migration inhibitory factor, TNF-alpha, and IFN-gamma administered orally via attenuated Salmonella typhimurium.

The genes encoding murine macrophage migration inhibitory factor (MIF), IL-2, IFN-gamma or TNF-alpha were cloned individually into an expression plasmid under the control of the inducible promoter nirB and transfected into the aroA- aroD- deletion mutant strain of Salmonella typhimurium (BRD509). These S. typhimurium derivatives (henceforward called constructs and termed GIDMIF, GIDIL2, GIDIFN and GIDTNF) expressed their respective cytokines in vitro under anaerobic conditions and stably colonized BALB/c mice up to 14 days after oral administration. The highly susceptible BALB/c mice that had received the constructs orally and that had been subsequently infected via the footpad with Leishmania major, developed significantly reduced disease compared with control mice administered the untransfected Salmonella strain (BRD509). Importantly, a combination of GIDMIF, GIDIFN, and GIDTNF administered orally after L. major infection was able to significantly limit lesion development and reduced parasite loads by up to three orders of magnitude. Spleen and lymph node cells of mice administered this combination expressed markedly higher levels of inducible nitric oxide synthase (iNOS) compared with those from mice receiving an equivalent dose of the control strain of Salmonella (BRD509). These data therefore demonstrate the feasibility of therapeutic treatment in an infectious disease model using cytokines delivered by attenuated Salmonella. The protective effect observed correlates with the induction of inducible nitric oxide synthase in vivo.

Administration, Oral↗
PubMed1998

Oral vaccination against tetanus: comparison of the immunogenicities of Salmonella strains expressing fragment C from the nirB and htrA promoters.

We have found the in vivo-regulated nirB promoter (PnirB) to be effective for directing expression of a number of antigens in salmonella in vivo. We wished to determine if other in vivo-regulated promoters have utility for antigen expression in salmonella and to compare the effectiveness of these promoters with that of PnirB. To this end, we have devised a scheme that allows the promoter element of the PnirB-fragment C plasmid pTETnir15 to be swapped with other promoters of interest. We demonstrate the usefulness of this system by replacing PnirB with PhtrA to create plasmid pTEThtrA1. htrA is a stress response gene that is required for virulence of salmonella in mice and survival within macrophages. Expression of fragment C in Salmonella typhimurium BRD509 (aroA aroD) harboring pTEThtrA1 (strain BRD937) correlated with growth temperature in vitro. A comparison was made of the immune responses to fragment C elicited in mice immunized orally with BRD937 or BRD847 (BRD509/pTETnir15) or subcutaneously with purified fragment C plus alhydrogel. High levels of anti-fragment C antibodies that persisted for at least 12 weeks were present in all groups of mice. Vaccination with BRD937 was the most effective means of immunization: the serum immunoglobulin G (IgG), IgA, and IgM anti-fragment C titers were higher in the BRD937-immunized mice throughout the duration of the study than in mice in the other groups. The kinetics of the serum anti-fragment C responses were different in different groups. The response was most rapid in the BRD937 group, with the titers almost at peak levels at 2 weeks postimmunization. Only the mice immunized with BRD937 or BRD847 developed an intestinal IgA response to fragment C. Again, the response was superior in the BRD937 group. The peak of the intestinal response was delayed with respect to the serum response. Analysis of the IgG subtype response to fragment C revealed a dominant IgG2a response in the salmonella-immunized mice, indicating a type 1 helper T-cell response to fragment C, whereas the major subtype in the group parenterally immunized with fragment C plus alhydrogel was IgG1. The IgG1/IgG2a ratio was much higher in sera of BRD937-immunized mice than in sera of BRD847-immunized mice. At 15 to 20 weeks after immunization, the mice immunized with BRD937 or BRD847 were solidly immune to tetanus toxin and salmonella. The immune responses to fragment C seen in mice immunized with BRD937 are the strongest we have observed and indicate that the htrA promoter may be very useful for expressing foreign antigens in salmonella vaccine strains.

Administration, Oral↗
PubMed1998

Reinfusion of discard blood from venous access devices.

PURPOSE/OBJECTIVES: To determine if clots are present in the initial 10 ml of blood routinely discarded from venous access devices (VADs) prior to blood sampling, and to determine if clots form in the discard blood specimen during the five minutes required to complete blood specimen sampling. DESIGN: A pretest/post-test design. SETTING: A large, mid-Atlantic research institution. SAMPLE: A convenience sample of 50 adult patients with cancer (27 males and 23 females) with a median age of 60. A large sampling size variation existed among the different VADs. METHOD: Two 5 ml discard specimens were drawn into separate syringes. Syringe #1 was filtered immediately, and syringe #2 was filtered after a five-minute dwell time. Both samples were filtered through a 40 micron filter. MAIN RESEARCH VARIABLE: The presence or absence of clots. FINDINGS: Fifty percent (n = 25) of the VADs had clots present on the filter from syringe #1. The clots varied in length, width, depth, and diameter, which precluded a consistent measurement. The investigators were able to measure either the diameter or length, depending on the shape of the clots. The majority of the clots (n = 17) appeared to be shaped like the lumen of a catheter and varied from 0.1 cm to 1.2 cm in length. Six clots were round and varied in diameter from 1.6 mm to 2.8 mm. Only 4% (n = 2) of the VADs had clots in syringe #2, but those clots were much larger, measuring 8.3 mm and 18.4 mm. CONCLUSIONS: The study addresses concerns of the investigators regarding the clinical practice of reinfusing discard blood obtained from VADs. Whether the clots present in the catheter and their reinfusion represent a significant risk to patient outcome is unclear. IMPLICATIONS FOR NURSING PRACTICE: Until further research is conducted and the degree of risk can be better defined, methods of drawing blood that require reinfusion of discard blood from VADs are not recommended.

Adult↗
PubMed1997

DBT: a partial D phenotype associated with the low-incidence antigen Rh32.

Eight probands are described with a D phenotype in which a partial D antigen is associated with Rh32 antigen; three of these probands were investigated because of the anti-D in their serum. The partial D lacks epD1-epD5 and epD9 and some epD6/7 and only expresses epD8 and other parts of epD6/7. The strength of the partial D antigen varies between unrelated DBT individuals. The Rh32 antigen of the DBT cells is weaker than that of D(C)(e) cells. Tests on DBT, DFR and R0Har cells with anti-epD6/7 split these monoclonal anti-D into eight patterns of reaction. A new pattern of reactions was observed, presaging a new epitope, but this was not numbered.

Antibodies, Monoclonal↗
PubMed1997

Randomised controlled double blind study of role of recombinant erythropoietin in the prevention of chronic lung disease.

AIM: To evaluate the role of recombinant human erythropoietin (R-HuEpo) in reducing iron infusion, which may exacerbate free radical damage, leading to chronic lung disease. METHODS: A multicentre, randomised, placebo controlled, double blind study was carried out in four neonatal intensive care units in Yorkshire. Infants were randomly allocated and received either R-HuEpo (480 U/kg/wk) or placebo by twice weekly subcutaneous injection. The primary outcome measure was the number of days on respiratory support and a secondary outcome the number of blood transfusions required. RESULTS: Forty two very low birthweight (VLBW) infants were randomly allocated. There was little difference in the need for respiratory support one month after randomisation, but subsequently there was a trend towards a reduction in the proportion requiring respiratory support in the R-HuEpo group (difference at three months -0.50, 95% confidence interval -1.00, 0.17). During stay in hospital, the median number of blood transfusions was lower for infants in the R-HuEpo group (difference in medians -2, 95% CI -4, 0). The study was stopped early because of failure to recruit babies at the expected rate. CONCLUSIONS: R-HuEpo seems to reduce the number of days in oxygen for ill VLBW infants. These data could be used to construct a larger multicentre study to evaluate this effect further.

Blood Transfusion↗
PubMed1996

Attenuated Salmonella as live oral vaccines against typhoid fever and as live vectors.

Attenuated Salmonella typhi vaccine strain CVD 908, which harbors deletion mutations in aroC and aroD, has been shown to be well-tolerated and highly immunogenic, eliciting impressive serum antibody, mucosal IgA and cell-mediated immune responses. A further derivative prepared by introducing a deletion in htrA (which encodes a heat-shock protein that also has activity as a serine protease in CVD 908 (Chatfield et al., unpublished data) resulted in CVD 908-htrA. In phase 1 clinical trials, CVD 908-htrA appears very attractive as a live oral vaccine candidate. Both CVD 908 and CVD 908-htrA are useful as live vector vaccines to deliver foreign antigens to the immune system. Conditions that enhance the expression and immunogenicity of foreign antigens carried by CVD 908 and CVD 908-htrA are being investigated.

Administration, Oral↗
PubMed1996

Immunisation of mice using Salmonella typhimurium expressing human papillomavirus type 16 E7 epitopes inserted into hepatitis B virus core antigen.

Live vaccines based on BRD509, an attenuated S. typhimurium (aroA, aroD) strain, were constructed that directed the expression of hepatitis B core antigen particles (HBcAg) (BRD969) or HBcAg harbouring human papillomavirus type 16 E7 protein sequences (BRD974), under the control of the in vivo inducible nirB promoter. These strains were used to orally or intravenously immunise different inbred mouse strains and humoral, secretory and cellular anti-E7 and anti-HBcAg responses were monitored. Both BRD969 and BRD974 induced anti-HBcAg humoral IgG responses following oral or intravenous immunisation of B10 mice, although responses were higher in BRD969 immunised animals. IgG subclass analysis revealed a predominantly IgG2a response in these animals. BRD974, but not BRD969, induced anti-E7 humoral IgG responses. Anti-HBcAg (BRD969 and BRD974) and anti-E7 (BRD974) IgA responses were detected in the intestines of orally immunised mice. Anti-Salmonella but not anti-HBcAg or anti-E7 T helper cell responses were detected in mice immunised with BRD509, BRD969 and BRD974. Thus Salmonella vaccine strains can be used to efficiently deliver HBcAg and E7 epitopes to the mucosal and systemic immune systems.

Amino Acid Sequence↗
PubMed1996

Role of the Bordetella pertussis P.69/pertactin protein and the P.69/pertactin RGD motif in the adherence to and invasion of mammalian cells.

The role of the Bordetella pertussis P.69/pertactin protein in mammalian cell adhesion and invasion was investigated. Salmonella strains expressing surface-associated P.69/pertactin from a chromosomally located prn gene were significantly more invasive than isogenic parental strains. This effect was most pronounced in the poorly invasive, semi-rough S. typhimurium strain LB5010. Escherichia coli K-12 strain HB101 harbouring the plasmid p41869D, which encodes the full-length prn gene under the control of the tac promoter on the broad-host-range plasmid pMMB66EH, was significantly more adhesive to HEp-2 and Chinese Hamster Ovary (CHO) cells growing in culture than E. coli HB101(pMMB66EH). However, the ability of E. coli to invade mammalian cells was not affected by P.69/pertactin expression. P.69/pertactin-mediated adhesiveness of HB101 to HEp-2 and CHO cells was not influenced by the viability of the bacterial cells. However, adherence was markedly reduced when assays were performed for less than 3 h, at 4 degrees C or in the presence of cycloheximide, suggesting the active participation of the eukaryotic cell in bacterial adhesion. Site-directed mutagenesis was used to mutate Asp to Glu in an Arg-Gly-Asp (RGD-->RGE) sequence present in mature P.69/pertactin and the mutated gene was cloned in the same broad-host-range vector (plasmid p41869E). This mutation had no detectable influence on the ability of P.69/pertactin to mediate adhesion of HB101 to HEp-2 or CHO cells. Plasmids p41869D and p41869E were introduced into the bvg-negative B. pertussis strain BP347. Expression of P.69RGD or P.69RGE did not enhance the adhesiveness of BP347 for epithelial (HEp-2 and CHO) cells.

Animals↗
PubMed1996

Expression and immunogenicity of pertussis toxin S1 subunit-tetanus toxin fragment C fusions in Salmonella typhi vaccine strain CVD 908.

Salmonella typhi vaccine strain CVD 908 can deliver heterologous antigens to the host immune system following mucosal immunization. Stable expression of foreign proteins in Salmonella cells often requires antigen-specific engineering strategies. Fusion of antigens to stabilizing proteins has proven to be a successful strategy for rescuing otherwise unstable proteins. We designed plasmids to allow the fusion of antigens to the amino terminus or carboxyl terminus of fragment C of tetanus toxin, separated by a 4-amino-acid hinge region. Towards the ultimate goal of developing a live oral diphtheria-pertussis-tetanus vaccine, we used these plasmids to stably express the S1 subunit of pertussis toxin in CVD 908. Driven by the anaerobically inducible nirB promoter, the S1 subunit alone was expressed poorly in Salmonella cytoplasm. In contrast, hybrid proteins with S1 fused to either the amino or carboxyl terminus of fragment C were expressed at a high level in CVD 908 and were recognized in Western blot (immunoblot) analysis by monoclonal antibodies directed to S1 and to fragment C. Mice were immunized by the oral or intranasal routes with CVD 908 derivatives harboring these recombinant plasmids. All fusion proteins elicited serum antibody responses to fragment C following intranasal immunization, whereas oral inoculation did not. The configuration of antigens constituting the fusion was critical; S1 fused to the amino terminus of fragment C was less effective than S1 fused to the carboxyl terminus in generating anti-fragment C antibodies. CVD 908 expressing truncated S1 fused to the carboxyl terminus of fragment C elicited neutralizing serum pertussis antitoxin following intranasal immunization of mice.

Animals↗