Search

Introduction Intentional aerosolization of Yersinia pestis may result in pneumonic plague which is highly fatal if not treated early. Methods We conducted a phase 1 randomized, double blind (within each group), placebo controlled, dose escalation trial to evaluate a plague vaccine, Flagellin/F1/V, in healthy adults aged 8 through 45 years. Vaccine was administered intramuscularly on Days 0 and 28 at a dose of 1, 3, 6 or 10 mcg. Subjects were observed for 4 h after vaccination for cytokine release syndrome. Reactogenicity and adverse events (AE) were collected for 14 and 28 days, respectively, after each vaccination. Serious AE were collected for the entire study. ELISA antibody and cytokines were measured at multiple time points. Subject’s participation lasted 13 months. Results Sixty healthy subjects were enrolled; 52% males, 100% non-Hispanic, 91.7% white and mean age 30.8 years. No severe reactogenicity events occurred; most AE were mild. No serious AE related to vaccine occurred. A dose response effect was observed to F1, V and flagellin. The peak ELISA IgG antibody titers (95% CI) after two 10 mcg doses of vaccine were 260.0 (102.6–659.0) and 983.6 (317.3–3048.8), respectively, against F1 and V antigens. The 6 mcg dose group provided similar titers. Titers were low for the placebo, 1 mcg and 3 mcg recipients. A positive antibody dose response was observed to F1, V and flagellin. Vaccine antigen specific serum IgE was not detected. There were no significant rises in serum or cellular cytokine responses and no significant IgG increase to flagellin after the second dose. Conclusion The Flagellin/F1/V vaccine exhibited a dose dependent increase in immunogenicity and was well tolerated at all doses. Antibody specific responses to F1, V and flagellin increased as dose increased. Given the results from this trial, testing higher doses of the vaccine may be merited.

Both live attenuated influenza vaccines (LAIV) and inactivated influenza vaccines (IIV) induce protective immunity against influenza. There is evidence that LAIV induces superior protection in children, whereas IIV may induce superior protection in adults. The immune mechanisms responsible for these differences have not been identified. We previously compared LAIV and IIV in young children of 6 to 36 months of age, and we demonstrated that while both induced similar hemagglutination inhibition (HAI) antibody responses, only LAIV induced significant increases in T cell responses. In the present study, 37 healthy adult subjects of 18 to 49 years of age were randomized to receive seasonal influenza vaccination with LAIV or IIV. Influenza virus-specific HAI, T cell, and secretory IgA (sIgA) responses were studied pre- and postvaccination. In contrast to the responses seen in young children, LAIV induced only minimal increases in serum HAI responses in adults, which were significantly lower than the responses induced by IIV. Both LAIV and IIV similarly induced only transient T cell responses to replication-competent whole virus in adults. In contrast, influenza virus-specific sIgA responses were induced more strongly by LAIV than by IIV. Our previous studies suggest that LAIV may be more protective than IIV in young children not previously exposed to influenza virus or influenza vaccines due to increased vaccine-induced T cell and/or sIgA responses. Our current work suggests that in adults with extensive and partially cross-reactive preexisting influenza immunity, LAIV boosting of sIgA responses to hemagglutinin (HA) and non-HA antigenic targets expressed by circulating influenza virus strains may be an important additional mechanism of vaccine-induced immunity.

Replication of Sabin strains used in oral poliovirus vaccine (OPV) in the intestines of vaccine recipients leads to reversions that increase virus neurovirulence. Previously, a small study reported that prior immunization with inactivated poliovirus vaccine (IPV) resulted in faster accumulation of revertant virus, thus potentially increasing the risk of vaccine-associated paralytic poliomyelitis. We studied the impact that prior immunization with IPV and OPV has on shedding of revertant virus by healthy infants. By polymerase chain reaction (PCR), we amplified full-length poliovirus genomes directly from stool specimens from unimmunized infants and from infants previously immunized with IPV or OPV. The amplicons were used to quantify reversions in the 5'-untranslated region, using oligonucleotide microarray hybridization. Nearly all 140 samples that were PCR positive contained varying amounts of revertants of all 3 poliovirus serotypes. Polioviruses of Sabin types 2 and 3 reverted more easily than those of type 1. Prior vaccination with IPV did not increase the proportion of revertants after OPV administration.

Objectives: To evaluate the safety and immunogenicity of unconjugated Haemophilus influenzae type b (Hib) polysaccharide (PRP) vaccine and two PRP-protein-conjugated vaccines as a model for the comparison of protein-conjugated versus plain polysaccharide vaccines in the elderly. Design: Randomized, double-blind, prospective study. Setting: University-based center for vaccine research and development. Participants: A total of 125 adults, aged 64 to 92, who were judged to be in general good health and lacking any significant underlying medical conditions. Intervention: Subjects were randomized to receive one of three vaccines: Group 1 (n=39), PRP; Group 2 (n=44), PRP conjugated to an outer-membrane protein complex of Neisseria meningitidis (PRP-OMP); and Group 3 (n=42), PRP conjugated to diphtheria toxoid (PRP-D). Sera were obtained before immunization and 1 and 12 months later. Measurements: Subjects maintained a diary of injection site and systemic reactions for 3 days after immunization. A radioantigen-binding assay was used to measure total concentrations of serum anticapsular antibody, and an enzyme-linked immunosorbent assay was used to measure immunoglobulin (Ig) G1 and IgG2 anticapsular antibody responses. Antibody functional activity was assessed using a complement-mediated bactericidal assay. Results: Before vaccination, the geometric mean serum anticapsular antibody concentration was 0.8 μg/mL, but fewer than 10% of subjects had detectable bactericidal activity (titer>1:4). The magnitude, subclass distribution, and bactericidal activity of antibody responses to unconjugated PRP vaccine were similar to those observed in previous studies of younger adults immunized with PRP. The OMP conjugate, which is highly immunogenic after one dose in 2-month old infants, did not elicit anticapsular antibody responses in the elderly greater than those elicited by PRP vaccine (P=.43). In contrast, the D conjugate, which is poorly immunogenic in 2-month old infants, elicited higher anticapsular antibody responses than PRP vaccine in the elderly (P=.01) and higher levels than the OMP-conjugate 1 year after vaccination (P

Combinatorial cloning and expression library analysis were used to determine the expressed human antibody repertoire specific for the capsular polysaccharide (PS) of Streptococcus pneumoniae serotype 6B. Sequence analysis of 55 6B-specific antibody Fab fragments isolated from six vaccinated donors reveal that different individuals used a variety of heavy and light chain germ line variable (V) region genes to form pneumococcal capsular PS (PPS) 6B-specific paratopes. Within each donor, however, the response was more restricted, with five of the six donors using at most one or two gene pairs to form combining sites. Analysis also indicated that although the response in each donor was oligoclonal in terms of variable gene usage, the combination of extensive somatic hypermutation, deletion of germ line-encoded residues, insertion of non-germ line-encoded residues, and intraclonal isotype switching generated a surprising degree of paratope diversity within the individuals analyzed. In contrast to previously studied PS-specific responses, we find that the PPS 6B repertoire makes use of a diverse collection of heavy-chain and light-chain V region gene products to form specific paratopes, with no apparent tendency for conservation of immunoglobulin gene usage between individuals.

Combinatorial cloning and expression library analysis were used to isolate human antibody Fab fragments specific for the capsular polysaccharide ofStreptococcus pneumoniaeserotype 23F. Thirty 23F-specific Fabs were isolated from seven vaccinated donors, and the sequences of the heavy (H)- and light (L)-chain variable regions were determined. All individuals utilized either the Vκ A23 L chain, the Vκ L6 L chain, or both chains in forming the 23F-specific combining site. Vκ A23 L chains paired primarily with VH3-23 H chains. Vκ L6 L chains were more promiscuous in heavy-chain usage between individuals. Both H and L chains were mutated, primarily in the complementarity-determining regions, compared to their closest germ line counterpart, suggesting a recall response that has undergone affinity maturation. H-chain isotypes were reflective of those found in the serum. Shared somatic modifications demonstrated that immunoglobulin G2 (IgG2) and IgA antibodies arose from the same somatically matured B cell. Our results indicate that the response to the serotype 23F pneumococcal capsular polysaccharide is oligoclonal within the individual, with one or two paratope families accounting for the majority of expressed antibody. We also determined that, in spite of the combinatorial diversity available to the immune system, the 23F-specific response is highly restricted at the population level, with the same two L-chain-determined paratope families recurring in all individuals. Lastly, analysis of the isolated Fabs indicate all have undergone extensive somatic mutation, as well as class switch, maturational events that presumably require the participation of T cells.

Immunoglobulin G (IgG) subclass antibody responses to pneumococcal vaccines were determined for human subjects in four age groups. The ratios of IgG1/IgG2 antibody concentrations declined with advancing age for all five of the serotypes tested. Protein-conjugate vaccines elicited enhanced IgG antibody responses over plain polysaccharide vaccines in infants but not in adult groups.

Prior to initiating a phase 1 dose escalation trial of the safety and immunogenicity of live, oral, recombinant, attenuated Salmonella enterica serovar Typhi vaccine strains in human subjects, the suitability of conventional blood culture procedures to rapidly and reliably detect the organisms in human blood was investigated. Blood culture specimens, with and without added growth supplements, were inoculated with study organism concentrations ranging from approximately 300 to as few as 1 to 2 CFU/10 ml culture and processed in a Bactec 9240 fluorescent series aerobic blood culture system. All cultures seeded with >6 CFU and 93% of cultures seeded with ∼1 to 2 CFU were identified as positive for microbial growth within 44 h of incubation. The results were within the performance standard of ≤5 days to detection that is expected for Gram-negative cultures seeded at 10 to 50 CFU/vial. Recovery of test organisms from blood culture was not improved by the addition of supplements, but cultures with added supplements were identified positive an average of 5 h sooner than those without added supplements. Reliable detection of the investigational vaccine strains at

Healthy adults > or = 50 years old were immunized with either pentavalent Corynebacterium diphtheriae C7 (beta197) cross-reactive material (CRM197) protein-conjugated pneumococcal vaccine (CV) containing 10 microgram each of capsular oligosaccharides from serotypes 6B, 14, 18C, 19F, and 23F or with licensed (23-valent, 25 microgram/serotype) pneumococcal polysaccharide vaccine (PV). Adverse reactions, predominantly local in nature, occurred in 20 of 23 CV recipients versus 13 of 23 PV recipients (P

Background. Two doses of either trivalent live attenuated or inactivated influenza vaccines (LAIV and TIV, respectively) are approved for young children ($24 months old for LAIV and $6 months old for TIV) and induce protective antibody responses. However, whether combinations of LAIV and TIV are safe and equally immunogenic is unknown. Furthermore, LAIV is more protective than TIV in children for unclear reasons. Methods. Children 6‐35 months old were administered, 1 month apart, 2 doses of either TIV or LAIV, or combinations of LAIV and TIV in both prime/boost sequences. Influenza-specific antibodies were measured by hemagglutination inhibition (HAI), and T cells were studied in flow cytometric and functional assays. Highly conserved M1, M2, and NP peptides predicted to be presented by common HLA class I and II were used to stimulate interferon-c enzyme-linked immunospot responses. Results. All LAIV and/or TIV combinations were well tolerated and induced similar HAI responses. In contrast, only regimens containing LAIV induced influenza-specific CD4 1 , CD8 1 , and cdT cells, including T cells specific for highly conserved influenza peptides. Conclusions. Prime/boost combinations of LAIV and TIV in young children were safe and induced similar protective antibodies. Only LAIV induced CD4 1 ,C D8 1 ,a ndcd T cells relevant for broadly protective heterosubtypic immunity.

Background. Vaccinia virus (VV) membrane proteins are candidates for orthopoxvirus subunit vaccines and potential targets for therapeutic antibodies. Human antibody responses to these proteins after VV vaccination have not been well characterized. Methods. Pre- and postvaccination (day 26-30) serum specimens from 80 VV vaccine recipients were examined for immunoglobulin G antibodies specific for B5, A33, A27, and L1 by enzyme-linked immunosorbent assay (ELISA). Responses were compared between vaccinia-naive and previously vaccinated (nonnaive) recipients and between nonnaive recipients of undiluted or 1:10 diluted vaccine. Results. VV vaccination elicited anti-A33 and anti-A27 antibodies in nearly all vaccinia-naive subjects (100% and 93%, respectively). Preexisting antibodies were commonly detected in nonnaive subjects (for anti-B5, 68%; for anti-A33, 59%; for anti-A27, 38%; and for anti-L1, 10%). Anti-B5 antibodies were strongly boosted by undiluted vaccine (geometric mean titer [GMT], 151 vs. 1010 for pre- vs. postvaccination; P

Inactivated poliovirus vaccine (IPV) is believed to induce significantly lower mucosal immunity than oral poliovirus vaccine (OPV). Most of the data supporting this were generated before enhanced IPV (eIPV) was introduced. Excretion of poliovirus by OPV recipients can be used to assess intestinal immunity. We studied polymerase chain reaction amplification of viral complementary DNA from the stool of children vaccinated with either OPV alone or eIPV. Of first-time OPV recipients, 92% excreted virus after 1 week, and 81% excreted virus after 3 weeks. Prior vaccination with OPV reduced the number to 22% and shortened the duration of virus excretion (to 5% after 3 weeks). Two doses of IPV reduced the number of poliovirus-positive 1-week samples (to 76%), the duration of shedding (to 37% at 3 weeks), and the quantity of excreted virus. This suggests that IPV-vaccinated communities are partially protected from the spread of poliovirus. Further enhancement of IPV potency may lead to even higher levels of mucosal immunity.

Sabin strains of poliovirus used in the manufacture of oral poliovirus vaccine (OPV) are prone to genetic variations that occur during growth in cell cultures and the organisms of vaccine recipients. Such derivative viruses often have increased neurovirulence and transmissibility, and in some cases they can reestablish chains of transmission in human populations. Monitoring for vaccine-derived polioviruses is an important part of the worldwide campaign to eradicate poliomyelitis. Analysis of vaccine-derived polioviruses requires, as a first step, their isolation in cell cultures, which takes significant time and may yield viral stocks that are not fully representative of the strains present in the original sample. Here we demonstrate that full-length viral cDNA can be PCR amplified directly from stool samples and immediately subjected to genomic analysis by oligonucleotide microarray hybridization and nucleotide sequencing. Most fecal samples from healthy children who received OPV were found to contain variants of Sabin vaccine viruses. Sequence changes in the 5′ untranslated region were common, as were changes in the VP1-coding region, including changes in a major antigenic site. Analysis of stool samples taken from cases of acute flaccid paralysis revealed the presence of mixtures of recombinant polioviruses, in addition to the emergence of new sequence variants. Avoiding the need for cell culture isolation dramatically shortened the time needed for identification and analysis of vaccine-derived polioviruses and could be useful for preliminary screening of clinical samples. The amplified full-length viral cDNA can be archived and used to recover live virus for further virological studies.

To evaluate the safety and immunogenicity of unconjugated Haemophilus influenzae type b (Hib) polysaccharide (PRP) vaccine and two PRP-protein-conjugated vaccines as a model for the comparison of protein-conjugated versus plain polysaccharide vaccines in the elderly.Randomized, double-blind, prospective study.University-based center for vaccine research and development.A total of 125 adults, aged 64 to 92, who were judged to be in general good health and lacking any significant underlying medical conditions.Subjects were randomized to receive one of three vaccines: Group 1 (n=39), PRP; Group 2 (n=44), PRP conjugated to an outer-membrane protein complex of Neisseria meningitidis (PRP-OMP); and Group 3 (n=42), PRP conjugated to diphtheria toxoid (PRP-D). Sera were obtained before immunization and 1 and 12 months later.Subjects maintained a diary of injection site and systemic reactions for 3 days after immunization. A radioantigen-binding assay was used to measure total concentrations of serum anticapsular antibody, and an enzyme-linked immunosorbent assay was used to measure immunoglobulin (Ig) G1 and IgG2 anticapsular antibody responses. Antibody functional activity was assessed using a complement-mediated bactericidal assay.Before vaccination, the geometric mean serum anticapsular antibody concentration was 0.8 microg/mL, but fewer than 10% of subjects had detectable bactericidal activity (titer1:4). The magnitude, subclass distribution, and bactericidal activity of antibody responses to unconjugated PRP vaccine were similar to those observed in previous studies of younger adults immunized with PRP. The OMP conjugate, which is highly immunogenic after one dose in 2-month old infants, did not elicit anticapsular antibody responses in the elderly greater than those elicited by PRP vaccine (P=.43). In contrast, the D conjugate, which is poorly immunogenic in 2-month old infants, elicited higher anticapsular antibody responses than PRP vaccine in the elderly (P=.01) and higher levels than the OMP-conjugate 1 year after vaccination (P.006).Elderly adults develop protective anticapsular antibody responses to unconjugated and conjugated PRP vaccine. The higher anticapsular antibody responses to the D conjugate but not to the OMP conjugate in the elderly, which is the reverse of that observed in immunized infants, implies fundamental differences in the immunological mechanisms by which the two age groups respond to PRP and by which the OMP and D conjugates elicit anticapsular antibody responses.

ContextThere is renewed interest in use of smallpox vaccine due to the potential for a bioterrorist attack. This would involve vaccinating health care workers who were previously vaccinated.ObjectiveTo evaluate the use of diluted vaccinia virus in vaccination of previously vaccinated (non-naive) participants.Design, Setting, and ParticipantsEighty non-naive participants, aged 32 to 60 years, were randomized in a single-blinded study to receive either undiluted or diluted (1:3.2, 1:10, or 1:32) doses of smallpox vaccine. A comparison group, aged 18 to 31 years, of 10 vaccinia-naive participants received undiluted vaccine. Participants were enrolled between April 1 and May 15, 2002, at the National Institute of Allergy and Infectious Diseases Vaccine and Treatment Evaluation Unit at Saint Louis University, St Louis, Mo.InterventionSmallpox vaccine was administered by scarification using 15 skin punctures in the deltoid region of the arm.Main Outcome MeasuresPresence of a major reaction, defined as a vesicular or pustular lesion or area of palpable induration surrounding a central lesion following vaccination, and measures of viral shedding and antibody titers.ResultsInitial vaccination resulted in a major reaction in 64 of 80 non-naive participants. Ninety-five percent of non-naive participants had major reactions in the undiluted group, 90% in the 1:3.2 dilution group, 81% in the 1:10 dilution group, and 52.6% in the 1:32 dilution group. All (n = 10) of the vaccinia-naive participants had major reactions. Compared with vaccinia-naive participants, non-naive participants had significantly smaller skin lesions (P = .04) and significantly less incidence of fever (P = .02). Preexisting antibody was present in 76 of 80 non-naive participants. Antibody responses were significantly higher and occurred more rapidly in the non-naive participants compared with the vaccinia-naive participants (P = .002 for day 28 and P = .003 for 6 months). Vaccinia-naive participants shed virus from the vaccination site 2 to 6 days longer and had significantly higher peak mean viral titers when compared with the non-naive participants (P = .002).ConclusionsPreviously vaccinated persons can be successfully revaccinated with diluted (≤1:10) smallpox vaccine. Fewer adverse reactions were observed in this study of non-naive participants when compared with events in vaccinia-naive participants, which may be due to immunologic memory.

To investigate the basis of the immune defect in children who acquire invasive Haemophilus disease despite previous vaccination with Haemophilus influenzae type b (Hib) polysaccharide vaccine, we determined the ability of vaccine failure patients with low levels of serum anticapsular antibody (less than 1 microgram/ml) to respond to reimmunization. Thirty-four patients, ranging in age from 27 to 61 months, were vaccinated with either Hib polysaccharide (n = 20) or Hib polysaccharide-outer membrane protein conjugate vaccine (n = 14). All but three of the children had normal serum concentrations of immunoglobulins, including IgG2. The geometric mean serum anticapsular antibody concentration of the group given polysaccharide vaccine increased from 0.27 microgram/ml before vaccination to 0.65 microgram/ml 1 month later (p less than 0.05), but the magnitude of the response was nearly 10-fold less than that of 31 age-matched control children given polysaccharide vaccine (6.3 micrograms/ml, p less than 0.001). In contrast, all 14 patients with vaccine failure who were given conjugate vaccine showed increases of fivefold or more in serum anticapsular antibody (geometric means 0.35 and 12.8 micrograms/ml, respectively; p less than 0.001). All patients with vaccine failure who did not respond to polysaccharide vaccine were subsequently given conjugate vaccine, and all had high antibody responses. Most patients tested showed increases in complement-mediated serum bactericidal activity. These data suggest that immunization with conjugate vaccine confers protection against Hib disease to children who, because of genetic or other reasons, cannot respond to the unconjugated form of the polysaccharide vaccine.