Pre-vaccination Levels Research Articles

Rubella virus neutralizing antibody response after a third dose of measles-mumps-rubella vaccine in young adults

BackgroundThird doses of measles-mumps-rubella (MMR) vaccine have been administered during mumps outbreaks and in various non-outbreak settings. The immunogenicity of the rubella component has not been evaluated following receipt of a third dose of MMR vaccine. MethodsYoung adults aged 18–31 years with documented two doses of MMR vaccine received a third dose of MMR vaccine between July 2009 and October 2010. Rubella neutralizing antibody titers were assessed before, 1 month, and 1 year after receipt of a third dose of MMR vaccine. ResultsAmong 679 participants, 1.8% had rubella antibody titers less than 10 U/ml, immediately before vaccination, approximately 15 years after receipt of a second dose of MMR vaccine. One month after receipt of a third dose of MMR vaccine, average titers were 4.5 times higher and >50% of participants had a 4-fold boost. Response was highest among those with titers less than 10 U/ml prior to vaccination (geometric mean titer ratio = 18.8; 92% seroconversion) and decreased with increasing pre-vaccination titers. Average titers declined 1 year postvaccination but remained significantly higher than pre-vaccination levels. The proportion classified as low-positive antibody levels increased from 3% 1 month postvaccination to 24% 1 year postvaccination. ConclusionsVaccination with a third dose of MMR vaccine resulted in a robust boosting of rubella neutralizing antibody response that remained elevated 1 year later. Young adults with low rubella titers are more likely to benefit from a third dose of MMR vaccine.

Epidemiology of Measles in the Philippines

Background. Measles cases have decreased ever since vaccination has been introduced through the DOH Expanded Program on Immunization (DOH EPI) in the Philippines. Elimination is the current goal. However, despite high vaccine coverage, a nationwide outbreak occurred in 2013.
 Objectives. This study aimed to present measles incidence rates before and after the introduction of the measles vaccine, describe the changing epidemiology of measles, and assess the effectiveness of measles vaccination and baseline measles reporting.
 Methods. National data from 1960 to 2014 were used to determine incidence of measles and describe its epidemiology. Vaccine coverage and data on measles surveillance were used to estimate vaccine effectiveness by birth cohort and age group.
 Results. Reported measles incidence decreased after the introduction of measles vaccine compared to prevaccination levels (pre-vaccination: 36 per 100,000 to 73 per 100,000; 2008-2014 confirmed measles incidence: 1.47 to 23.76 per 100,000, suspected measles-5.7 to 58.08 per 100,000). A shift in the age distribution of cases was noted during the outbreak. Vaccine effectiveness by birth cohort ranged from 85-96% while the lowest VE estimate by age group was seen among those aged 26-30 years.
 Conclusion. Measles vaccine coverage should target wider age groups. Measles surveillance should be improved to help in evidence-based decisions for a more effective plan towards measles elimination.

Antibody Persistence at the Population Level 5 Years After Mass Vaccination With Meningococcal Serogroup A Conjugate Vaccine (PsA-TT) in Burkina Faso: Need for a Booster Campaign?

In Burkina Faso, serogroup A meningococcal (NmA) conjugate vaccine (PsA-TT, MenAfriVac) was introduced through a mass campaign in children and adults in December 2010. Similar to a serological survey in 2011, we followed population-level antibody persistence for 5 years after the campaign and estimated time of return to previously-published pre-vaccination levels. We conducted 2 cross-sectional surveys in 2013 and early 2016, including representative samples (N = 600) of the general population of Bobo-Dioulasso, Burkina Faso. Serum bactericidal antibody titers (rabbit complement) were measured against NmA reference strain F8236 (SBA-ref), NmA strain 3125 (SBA-3125), and NmA-specific immunoglobulin G (IgG) concentrations. During the 2016 survey, in different age groups between 6 and 29 years, the relative changes in geometric means compared to 2011 values were greater among younger age groups. They were between -87% and -43% for SBA-ref; -99% and -78% for SBA-3125; and -89% and -63% for IgG. In linear extrapolation of age-specific geometric means from 2013 to 2016, among children aged 1-4 years at the time of the PsA-TT campaign, a return to pre-vaccination levels should be expected after 12, 8, and 6 years, respectively, according to SBA-ref, SBA-3125, and IgG. Among older individuals, complete return to baseline is expected at the earliest after 11 years (SBA-ref and SBA-3125) or 9 years (IgG). Based on SBA-3125, a booster campaign after 8 years would be required to sustain direct immune protection for children aged 1-4 years during the PsA-TT campaign. Antibodies persisted longer in older age groups.

Vaccination of koalas (Phascolarctos cinereus) against Chlamydia pecorum using synthetic peptides derived from the major outer membrane protein.

Chlamydia pecorum is a mucosal infection, which causes debilitating disease of the urinary tract, reproductive tract and ocular sites of koalas (Phascolarctos cinereus). While antibiotics are available for treatment, they are detrimental to the koalas’ gastrointestinal tract microflora leaving the implementation of a vaccine as an ideal option for the long-term management of koala populations. We have previously reported on the successes of an anti-chlamydial recombinant major outer membrane protein (rMOMP) vaccine however, recombinant protein based vaccines are not ideal candidates for scale up from the research level to small-medium production level for wider usage. Peptide based vaccines are a promising area for vaccine development, because peptides are stable, cost effective and easily produced. In this current study, we assessed, for the first time, the immune responses to a synthetic peptide based anti-chlamydial vaccine in koalas. Five healthy male koalas were vaccinated with two synthetic peptides derived from C. pecorum MOMP and another five healthy male koalas were vaccinated with full length recombinant C. pecorum MOMP (genotype G). Systemic (IgG) and mucosal (IgA) antibodies were quantified and pre-vaccination levels compared to post-vaccination levels (12 and 26 weeks). MOMP-peptide vaccinated koalas produced Chlamydia-specific IgG and IgA antibodies, which were able to recognise not only the genotype used in the vaccination, but also MOMPs from several other koala C. pecorum genotypes. In addition, IgA antibodies induced at the ocular site not only recognised recombinant MOMP protein but also, whole native chlamydial elementary bodies. Interestingly, some MOMP-peptide vaccinated koalas showed a stronger and more sustained vaccine-induced mucosal IgA antibody response than observed in MOMP-protein vaccinated koalas. These results demonstrate that a synthetic MOMP peptide based vaccine is capable of inducing a Chlamydia-specific antibody response in koalas and is a promising candidate for future vaccine development.

Myeloid derived suppressor cells (MDSC) and anti-MUC1 immunosurveillance in pre-malignancy and cancer

Abstract Recent work from our lab showed that in a colon cancer prevention trial of a tumor antigen MUC1 vaccine in patients with premalignant colon adenomas, those who did not make anti-MUC1 IgG, had higher pre-vaccination levels of circulating MDSC compared to vaccine responders. This was the first observation of increased MDSC in premalignancy. MDSC in premalignancy have not been compared to MDSC in cancer and our hypothesis is that there might be differences in the composition of various MDSC subpopulation and their immunosuppressive functions due to the shorter time of exposure to disease and differences in the disease microenvironment. We are testing this hypothesis on two cohorts of patient samples, premalignant and malignant colon and pancreas. In both cohorts we saw an increase in MDSC in premalignant and malignant disease over healthy controls. The colon premalignant group could be divided into MDSChighAnti-MUC1 IgGlow and MDSClowAnti-MUC1 IgGhigh confirming our previous observations that MDSC are impeding anti-MUC1 immune response in premalignancy as well therefore potentially facilitating progression to cancer. The pancreas cohort also showed increase in MDSC in patients with pancreatic cysts (IPMN), precursors to pancreatic cancer, as well as their suppression of anti-tumor immunity. Furthermore, we found increased levels of PGE2 and its metabolite in patients’ serum from both cohorts, which is closely related to MDSC proliferation and mechanism of suppression. While we do not see much difference in the MDSC phenotype and subpopulation composition, the immunosuppressive capacity of tumor MDSC appears to be greater. We are currently testing this observation in vitro in T cell suppression assays.

Immunogenicity and persistence of a prime-boost re-vaccination strategy for pneumococcal vaccines in patients with rheumatoid arthritis

ABSTRACTObjectives: Patients with rheumatoid arthritis (RA) are at an increased risk of Pneumococcal infections. Immunogenicity and persistence of a prime-boost revaccination strategy using 13-valent/23-valent anti-pneumococcal vaccines was evaluated in patients with RA treated by Methotrexate (MTX) and anti-TNF.Method: Twenty-four patients with RA received one dose of PCV13 (Prevenar13®; Pfizer) followed two months later by one dose of PPV23 (Pneumovax®, Merck). Concentrations of IgG specific for 7 serotypes common to both vaccines and 3 uncommon serotypes, included only in the PPV23 were measured by ELISA and Opsonophagocytic Assay (OPA) at baseline and after 4, 12 and 24 months post-vaccine.Results: Similar percentages of protection were found at 4 months (63% vs. 55%), 12 months (54% vs. 50%) and 24 months (52% vs. 55%) for the 7 common and 3 uncommon serotypes when antibody titers were assayed by ELISA. Based on functional antibody measurements by OPA, a decrease of protected patients was observed 24 months after vaccine with only 19% of patients protected compared to 29% at baseline.Conclusion: Although the combined pneumococcal revaccination strategy induces good protection in the short term in RA patients, this protection does not persist beyond two years with levels of functional antibody decreasing below pre-vaccine levels. We did not observe a higher efficacy of the conjugate vaccine compared to the polysaccharide vaccine. Our results clearly question the advantage of the prime-boost strategy as it highlight the possible hyporesponse induced by PPV23 against the immune response elicited by the primo-injection of the PCV13 vaccine.

Immunogenicity and safety of the quadrivalent meningococcal ACWY-tetanus toxoid conjugate vaccine (MenACWY-TT) in splenectomized or hyposplenic children and adolescents: Results of a phase III, open, non-randomized study

BackgroundIndividuals with functional or anatomic asplenia are at high risk for meningococcal disease. We evaluated the immunogenicity and safety of 1 and 2 doses of the quadrivalent meningococcal serogroups A, C, W, Y tetanus toxoid-conjugate vaccine (MenACWY-TT) in this high-risk population. MethodsThis phase III, open-label, controlled, non-randomized study (NCT01641042) enrolled 1–17-year-olds with impaired splenic activity (high-risk group) and age-matched healthy controls (control group). We measured immune responses to MenACWY-TT by serum bactericidal activity assays using rabbit (rSBA) and human (hSBA) complement and in terms of antibodies against polysaccharides of the 4 vaccine serogroups. We evaluated vaccine response rates (VRRs) as 4-fold increases from pre-vaccination levels or titers ≥1:32 (rSBA)/≥1:8 (hSBA). We recorded solicited and unsolicited adverse events (AEs) during 4 and 31 days post-vaccination, and serious AEs (SAEs) and new onset of chronic illnesses (NOCIs) throughout the study. ResultsThe according-to-protocol cohort for immunogenicity included 40 participants per group. In both groups, the first MenACWY-TT dose induced rSBA VRRs of 92.5–100% and hSBA VRRs of 55.6–77.1% across vaccine serogroups. Following the second MenACWY-TT dose, all participants had high responses, with rSBA and hSBA VRRs of 73.0–100% across vaccine serogroups. rSBA and hSBA geometric mean titers for each serogroup increased in both groups (with different magnitudes, but ≥13.1-fold) compared with baseline levels. Polysaccharide antibody concentrations ≥2.0 μg/ml were detected in ≥84.4% of participants and were similar between groups. Incidences of solicited and unsolicited AEs were comparable between groups. We recorded SAEs in 4/43 participants in the high-risk group and 1/43 participants in the control group (none vaccine-related). No NOCIs were reported. ConclusionIn this descriptive study, MenACWY-TT induced similar functional and humoral immune responses and had a clinically acceptable safety profile in children and adolescents with impaired splenic activity and in healthy controls.

Persistence of immune response to an adjuvanted varicella-zoster virus subunit vaccine for up to year nine in older adults

ABSTRACTBackground: In adults aged ≥60 years, two doses of the herpes zoster subunit vaccine (HZ/su; 50 µg varicella-zoster virus glycoprotein E [gE] and AS01B Adjuvant System) elicited humoral and cell-mediated immune responses persisting for at least six years. We assessed immunogenicity nine years post-initial vaccination.Methods: This open extension study (NCT02735915) followed 70 participants who received two HZ/su doses in the initial trial (NCT00434577). Blood samples to assess the cellular (intracellular cytokine staining) and humoral (ELISA) immunity were taken at year nine post-initial vaccination.Results: Participants' mean age at dose 1 was 72.3 years. The fold increases over pre-vaccination in the mean frequency of gE-specific CD4+ T-cells expressing ≥2 activation markers plateaued from year four post-dose 1 until year nine. Anti-gE antibody geometric mean concentrations plateaued and remained above pre-vaccination levels from year four onwards. Immunogenicity at year nine was similar across age strata (60–69, ≥70 years) and confirmed statistical prediction model results using data for up to year six. Further modeling using all data up to year nine predicted immune responses would remain above the pre-vaccination level up to year 15.Conclusion: In adults aged ≥60 years, HZ/su-induced immunogenicity remained above pre-vaccination levels for at least nine years post-initial vaccination.Summary: After vaccination with HZ/su, both cell mediated and humoral immunity remained above pre-vaccination levels up to year 9 regardless of age group. Immune responses are predicted to remain above baseline up to 15 years post initial vaccination.

Humoral immunity 10 years after booster immunization with an adolescent and adult formulation combined tetanus, diphtheria, and 5-component acellular pertussis vaccine in the USA

BackgroundIn a prospective, randomized pivotal phase III clinical trial, the immunogenicity and reactogenicity of a tetanus-diphtheria-acellular pertussis vaccine (Tdap) and a tetanus-diphtheria vaccine (Td) vaccine were studied in participants aged 11–64 years. Here we report antibody persistence through 10 years after vaccination. MethodsParticipants who received Tdap or Td in the original phase III trial and provided pre- and post-vaccination serum samples were recruited to donate sera at 1, 3, 5 and 10 years post-vaccination. Antibody concentrations were measured using standard assay techniques. ResultsInitially, 1457 Tdap and 1152 Td recipients were included; of these, 175 persons from Tdap group were available at the final study bleed point. Nearly all adolescents in both groups had diphtheria antibody levels ≥0.1 IU/mL 1 month after vaccination, which were maintained in ≥95% of vaccinees at 5 and 10 years. Among adults, ≥94% had diphtheria antibody levels ≥0.1 IU/mL 1 month after vaccination, which were maintained in ≥80% at 5 and 10 years. Nearly all participants had tetanus antibodies ≥0.1 IU/mL throughout the study. PT antibodies declined to pre-vaccination levels approximately 5 years post-vaccination; FHA, PRN and FIM antibodies waned at 5 and 10 years but remained several-fold higher than pre-vaccination levels. ConclusionsTdap and Td provide long-lasting protective immune responses against diphtheria and tetanus. Pertussis antibodies following Tdap generally exceeded pre-vaccination levels throughout the study, but showed substantial waning. These data may inform discussion of the need for repeat Tdap booster vaccinations among adults. Trial registrationThe original phase III clinical trial, as well as the 1-, 3-, and 5-year serology follow-up studies were conducted prior to mandatory registration. The 10-year serology follow-up data collection was performed as part of a repeat Tdap administration clinical trial that was registered under clinicaltrials.gov number NCT01439165.

Effect of influenza vaccine on tumor necrosis factor-like weak inducer of apoptosis (TWEAK) in older adults

Influenza immunization is recommended for older adults annually, and has been reported to have cardiovascular protective effects. TNF-related weak inducer of apoptosis (TWEAK), an inflammatory mediator implicated in the development of cardiovascular diseases, could be a mechanism for such effect. The objective of this study was to evaluate the effect of influenza vaccine on TWEAK levels. Older persons over 70 years of age were recruited during 2007–2008 influenza season and immunized with the standard dose trivalent inactivated influenza vaccine. Frailty was evaluated using a validated set of criteria. Sera were collected immediately before and during the 4th week after vaccination. Pre- and post-vaccination levels of TWEAK, soluble CD163 (sCD163) and strain-specific influenza antibody titers were measured in 69 participants. Multiple regression analyses were employed to examine the effect of influenza vaccine on TWEAK and sCD163, adjusting for age, sex, and hypertension. Post-vaccination TWEAK [mean ± standard deviation (SD) = 591.7 ± 290.1 pg/ml] was significantly lower than pre-vaccination level (690.6 ± 330.0 pg/ml) (p = .003). No significant difference was observed between pre and post-vaccination sCD163 levels (p = .71). Post-vaccination TWEAK levels were significantly higher in men (p = .01) and in participants with college or higher level of education (p = .044). There was no significant difference in post-vaccination TWEAK according to other demographics or pre-existing medical conditions. A 2-fold or greater antibody titer against H1N1 vaccine strain was associated with a more pronounced reduction in TWEAK at the p < .10 level (p = .091). A time by frailty interaction term (p = .091) indicated that the vaccination-induced reduction of TWEAK was greatest among frail individuals. These results of this observational study indicate that the impact of Influenza vaccine on TWEAK, including the role of specific antibody responses of specific vaccine strains and frailty status, warrants further investigation. Such investigation may elucidate whether this effect plays a role in mediating cardiovascular protection of influenza vaccination.

Phase I Randomized Study of a Tetravalent Dengue Purified Inactivated Vaccine in Healthy Adults from Puerto Rico.

.The safety and immunogenicity of four adjuvanted formulations of an investigational tetravalent dengue purified inactivated vaccine (DPIV) were evaluated in a predominantly dengue-primed population in Puerto Rico. In this placebo-controlled, randomized, observer-blind, phase I trial, 100 healthy adults were randomized 1:1:1:1:1 to receive DPIV at Day (D)0 and D28 (1 μg per dengue virus [DENV] type 1–4 adjuvanted with either alum, AS01E or AS03B, or 4 μg per DENV type adjuvanted with alum) or saline placebo. Functional antibody responses were assessed using a microneutralization assay at D56, Month (M)7, and M13. All DPIV formulations were well tolerated and no safety signals were identified through M13. The M13 according-to-protocol (ATP) immunogenicity cohort included 83 participants. The ATP analysis of immunogenicity was performed only on the 78 subjects seropositive for ≥ 1 DENV type at baseline: 69 tetravalent, three trivalent, two bivalent, and four monovalent. In all DPIV groups, geometric mean antibody titers (GMTs) increased from D0 to D56 and waned modestly through M13, while remaining well above prevaccination levels. The 4 μg + alum and the AS01E- and AS03B-adjuvanted formulations were highly immunogenic, with M13-neutralizing antibody GMTs against all four DENV types above 1,000. M13/D0 GMT ratios were highest in the 1 μg + AS03B group (ranging 3.2–3.7 depending on the DENV type). These results encourage continued clinical development of DPIV (ClinicalTrials.gov: NCT01702857).

Sustained Decline in Acute Gastroenteritis-Associated Hospitalizations and Outpatient Visits Among American Indian/Alaska Native Children After Rotavirus Vaccine Introduction, 2001-2014.

We examined the uptake of rotavirus vaccine and compared trends in acute gastroenteritis (AGE)-associated hospitalizations and outpatient visits among American Indian and Alaska Native (AI/AN) children aged <5 years before and after introduction of the rotavirus vaccine. The rates of AGE-associated hospitalization and outpatient visits among AI/AN children remained below prevaccine levels.

Pre-vaccine plasma levels of soluble inflammatory indices negatively predict responses to HAV, HBV, and tetanus vaccines in HCV and HIV infection

BackgroundChronic hepatitis C virus (HCV) and HIV infections are associated with impaired responses to neo-antigens contained in hepatitis A virus (HAV)/hepatitis B virus (HBV) vaccines, yet responsible mechanisms are unclear. MethodsACTG 5232 and CFAR0910 were clinical trials where pre-vaccine levels of plasma IP10, IL-6, sCD163 and sCD14 were measured in viremic HCV- (n = 15) or HIV-infected participants (n = 24) and uninfected controls (n = 10). Accelerated dosing HAV/HBV vaccine and tetanus booster were administered and antibody response was measured at 0, 1, 3, 8, and 24 weeks. ResultsPre-vaccine plasma IP10, IL-6, and sCD14 levels were elevated in both HCV and HIV-infected participants, while sCD163 was also elevated in HCV-infected participants. Pre-immunization tetanus antibody levels were lower in HIV-infected than in uninfected participants, while vaccine induced antibody responses were intact in HCV and HIV-infected participants. After HAV/HBV vaccination, HCV and HIV-infected participants had lower and less durable HAV and HBV antibody responses than uninfected controls.Among HCV-infected participants, pre-vaccine plasma IP10, IL-6, sCD14, and sCD163 levels inversely correlated with HAV, HBV and tetanus antibody responses after vaccine. Low HAV/HBV vaccine responses in HIV-infected participants prohibited assessment of immune correlates. ConclusionsDuring HCV and HIV infection markers of systemic inflammation reflect immune dysfunction as demonstrated by poor response to HAV/HBV neo-antigen vaccine.

Adenovirus 4/7 Vaccine's Effect on Disease Rates Is Associated With Disappearance of Adenovirus on Building Surfaces at a Military Recruit Base.

Febrile respiratory illness resulting from adenovirus types 4 and 7 (Ad4/7) was endemic at military training camps, but controlled by an Ad4/7 vaccine from the 1970s to 1999, the year it was discontinued. Thereafter, rates returned to prevaccine levels. Rates dropped after reintroduction of an Ad4/7 vaccine in 2011. Surfaces of the barracks and medical clinic of a training camp were swabbed in 3 studies in 2004 and 1 study in 2007, and tested with culture and polymerase chain reaction (PCR). Similar swabbing was done in 2013 and 2015 and tested with PCR. In the studies before 2011 (prevaccine), 12% of samples were Ad4/7 positive by culture and 27% positive by PCR. In the 2 studies after 2011 (postvaccine), no samples were Ad4/7 positive. The Ad 4/7 vaccine has resulted in the near elimination of Ad4/7-related disease and the disappearance of Ad4/7 from surfaces in a military basic training camp. Renewed transmission of Ad4/7 in this setting would likely require new importation from military recruits and an immunologically naive cohort, which the current vaccination program prevents.

Persistence of Immune Response to an Adjuvanted Varicella-Zoster Virus Subunit Candidate Vaccine for up to Year 9 in Older Adults

BackgroundIn the ZOE-50 and ZOE-70 clinical trials, the candidate herpes-zoster subunit vaccine (HZ/su; 50µg varicella-zoster virus glycoprotein E [gE] and AS01B Adjuvant System) demonstrated high efficacy against HZ, with limited waning over 4 years and consistent efficacy across age cohorts. In adults ≥60 years of age, the immune responses elicited by 2 HZ/su doses administered 2 months apart persisted for at least 6 years.1 Here we report immunogenicity and safety 9 years post-initial vaccination.MethodsThis Phase IIIB, open, long-term extension study (NCT02735915) followed 70 participants who received 2 HZ/su doses in the initial trial (NCT00434577). Blood samples to evaluate the persistence of cellular (intracellular cytokine staining) and humoral (ELISA) immune responses were taken at 9 years post-initial vaccination. Limited safety follow-up was performed (1 visit).ResultsAll 70 participants (mean age at dose 1: 72.3 years; 61.4% female) were included in the according-to-protocol analysis. The fold increases over pre-vaccination in the frequency of gE-specific CD4+ T-cells expressing ≥2 activation markers plateaued after 4 years post-dose 1 (year 4: 3.4, year 5: 3.0, year 6: 3.4, year 9: 3.4). Anti-gE antibody geometric mean concentrations were also stable from year 4 onwards (Table 1) and remained above the pre-vaccination value of 1213.1mIU/mL. Cellular and humoral responses at year 9 were similar across age strata (60–69, ≥70 years). No vaccine-related serious adverse events nor suspected HZ episodes were reported.ConclusionIn adults ≥60 years of age, HZ/su-induced cellular and humoral immune responses remained above pre-vaccination levels for at least 9 years post-initial vaccination, confirming immune persistence predictions2 based on 6-year data.Table 1Pre-vaccination (95% CI)Year 4 (95% CI)Year 5 (95% CI)Year 6 (95% CI)Year 9 (95% CI) Anti-gE antibody GMC (mlU/mL) 1213.1 (983.8–1495.9)9643.5 (8309.7–11191.3)9124.1 (7805.1–10666.0)8490.5 (7292.1–9885.7)8931.2 (7625.7–10460.3)Disclosures S. Volpe, GSK: Employee, Salary; T. F. Schwarz, GSK: Investigator and Scientific Advisor, Consulting fee; J. Smetana, GSK: Investigator, personal fees; S. Ravault, GSK: Employee, GSK shares and Salary; M. P. David, GSK: Employee, Salary and stock; A. Bastidas, GSK: Employee, Salary; L. Oostvogels, GSK: Employee and Shareholder, Salary and shares

Langerhans-type dendritic cells electroporated with TRP-2 mRNA stimulate cellular immunity against melanoma: Results of a phase I vaccine trial

ABSTRACTPurpose: We conducted a phase I vaccine trial to determine safety, toxicity, and immunogenicity of autologous Langerhans-type dendritic cells (LCs), electroporated with murine tyrosinase-related peptide-2 (mTRP2) mRNA in patients with resected AJCC stage IIB, IIC, III, or IV (MIa) melanoma. Experimental Design: Nine patients received a priming immunization plus four boosters at three week intervals. Vaccines comprised 10 × 106 mRNA-electroporated LCs, based on absolute number of CD83+CD86brightHLA-DRbrightCD14neg LCs by flow cytometry. Initial vaccines used freshly generated LCs, whereas booster vaccines used viably thawed cells from the cryopreserved initial product. Post-vaccination assessments included evaluation of delayed-type hypersensitivity (DTH) reactions after booster vaccines and immune response assays at one and three months after the final vaccine. Results: All patients developed mild DTH reactions at injection sites after booster vaccines, but there were no toxicities exceeding grade 1 (CTCAE, v4.0). At one and three months post-vaccination, antigen-specific CD4 and CD8 T cells increased secretion of proinflammatory cytokines (IFN-γ, IL-2, and TNF-α), above pre-vaccine levels, and also upregulated the cytotoxicity marker CD107a. Next-generation deep sequencing of the TCR-V-β CDR3 documented fold-increases in clonality of 2.11 (range 0.85–3.22) for CD4 and 2.94 (range 0.98–9.57) for CD8 T cells at one month post-vaccines. Subset analyses showed overall lower fold-increases in clonality in three patients who relapsed (CD4: 1.83, CD8: 1.54) versus non-relapsed patients (CD4: 2.31, CD8: 3.99). Conclusions: TRP2 mRNA-electroporated LC vaccines are safe and immunogenic. Responses are antigen-specific in terms of cytokine secretion, cytolytic degranulation, and increased TCR clonality, which correlates with clinical outcomes.

Antibody-Based Correlates of Protection Against Cholera Analysis of a Challenge Study in a Cholera-Naïve Population.

ABSTRACTImmunologic correlates of protection can be used to infer vaccine efficacy for populations in which challenge trials or field studies are infeasible. In a recent cholera challenge trial (W. H. Chen et al., Clin Infect Dis 62:1329–1335, 2016, https://doi.org/10.1093/cid/ciw145), 134 North American cholera-naive volunteers were randomized to receive either the live, attenuated single-dose cholera vaccine CVD (Center for Vaccine Development) 103-HgR or placebo, and the titers of vibriocidal antibodies against the classical Inaba strain were assessed at 10 days after treatment. Subsequent to the immunologic evaluation, each subject ingested a fixed quantity of virulent Vibrio cholerae O1 El Tor Inaba. Data from this trial suggest that the vaccine-induced increase in the vibriocidal antibody titer prior to challenge is tightly linked with protection: 51/51 vaccinees with postvaccination vibriocidal antibody titers of ≥2,560 were protected against moderate/severe diarrhea, and 60/62 vaccinees who seroconverted or experienced a 4-fold or greater increase in vibriocidal antibody titer relative to prevaccination levels were similarly protected. Atypically high vibriocidal antibody titers were observed in some placebo subjects; protection was limited in these individuals and differed substantially from the level of protection experienced by vaccinees with the same postvaccination titers. Since only 1 of 66 placebo recipients experienced seroconversion, seroconversion was found to be uniquely associated with vaccination and insensitive to the effects of factors that can cause titers to be elevated but are weakly associated with protection. Thus, vibriocidal antibody seroconversion was found to be better than the vibriocidal antibody titer for inferring vaccine efficacy in cholera-naive populations for which studies based upon exposure to V. cholerae are impractical. (This study has been registered at ClinicalTrials.gov under registration no. NCT01895855.)

The effect of pneumococcal conjugate vaccines on incidence and microbiology associated with complicated acute otitis media

ObjectivesThe objectives of this study were to investigate the incidence of complicated acute otitis media (cAOM) as well as the associated microbiology before and after introduction of the 7- and 13-valent pneumococcal conjugate vaccines (PCV-7 and -13), respectively. CAOM comprises “heavy” AOM (AOM demanding hospitalization), mastodismus (M) and acute mastoiditis (AM). MethodsA retrospective cohort study of the incidence and microbiology associated with cAOM during the non-PCV era, the PCV-7 and 13 eras, respectively. Clinical and microbiological data were prospectively registered in a local database. The incidences of cAOM as well as the distribution of various bacterial strains in the three eras were compared. ResultsA total of 246 cases of cAOM (125 in the pre-vaccine period (2001–2006), 50 in the PCV-7 period (2007–2010) and 71 in the PCV-13 period (2011–2015)) were identified.The incidence of hAOM decreased by 62% in the PCV7-era but increased to almost pre-vaccine levels in the PCV-13 era. In the M + AM group, a decrease by almost 21% in the PCV7-era was found compared to the pre vaccine era, whereas the decrease was only 12% in the PCV13-era.The three most common findings in both hAOM and M + AM were Streptococcus pneumonia (SP), group A streptococcus (GAS) and “no growth”. In the hAOM group, SP decreased from 38% in the pre-vaccine era to 31% in the PCV7-era and further to 16% in the PCV13-era. GAS decreased from 17% in the pre-vaccine era to 0% in the PCV7-era and 16% in the PCV13-era. The percentage of “no growth” increased from 12% to 38% and 44%, respectively.In the M + AM group, SP decreased to 10% in the PCV13-era compared with 44% in the pre-vaccine era and 41% in the PCV7-era. An increase in GAS from 15% in the pre-vaccine era and PCV7-era to 30% in the PCV13-era was observed. The “no growth” percentage increased from 13% in the pre-vaccine era to 26% in the PCV7-era and 33% in the PCV13-era. ConclusionIntroduction of PCV7 and PCV13 has been associated with an overall reduction of cAOM in Central Region Denmark. Pneumococci were still one of the two most common bacteria species related to cAOM though a decrease in pneumococci positive cases was observed. We found an increase in M + AM induced by GAS and a relatively large increase in “no growth”, which might be caused by a more aggressive pre-hospital approach to treatment with antibiotics. Consequently, it is not evident whether the reduction of incidences is caused by the vaccines or a more aggressive antimicrobial attitude to manage AOM. The shift to GAS from SP is worrisome, and therefore continuous surveillance of the microbiology associated with AOM is warranted.

Rationale for two influenza B lineages in seasonal vaccines: A meta-regression study on immunogenicity and controlled field trials

B lineage mismatch prompted introduction of quadri-valent influenza vaccines (QIV) with two influenza B viruses representing distinct antigenic lineages. To explore the impact on antibody induction and vaccine effectiveness predicted from antibody (VEab), we performed a systematic literature search on immunogenicity studies conducted to assess antibody superiority of QIV over trivalent influenza vaccine (TIV). Thirteen relevant articles described 31 trials from 2007 and 2013. Log-transformed GMT trial estimates and their variances were converted to clinical protection rates predicted from antibody (PRab). VEab estimates were calculated from pre- and post-vaccination PRab. Without specific pre-vaccination immunity, average VEab was 69% for match, and −4% for lineage mismatch. With increasing pre-vaccination seropositivity, mismatch impact declined to 2%. We also performed an umbrella literature search for randomised controlled trials and test-negative case-control trials with TIV, and estimated vaccine effectiveness against laboratory-confirmed influenza B (VEf). Sixty-eight eligible clinical articles described 110 season-trials from 1965 to 2012, covering seasons with B lineage match (n=52), lineage drift (n=15) and lineage mismatch (n=43). With no pre-vaccination antibody levels determined, we used chance of previous exposure to influenza B (Ppe) as pre-seasonal immunity measure. When Ppe was 0%, average VEf for matched seasons was 67%, and for mismatched seasons 35%, indicating a moderate, yet significant mismatch impact on VEf. With increasing Ppe, mismatch impact declined to 3%. Thus serological and field trials indicate that B lineage mismatch impact is negatively related to pre-seasonal immunity and that the gain of QIV over TIV most benefits infants and children not yet exposed to influenza B.

Correlates of protection for inactivated enterovirus 71 vaccine: the analysis of immunological surrogate endpoints

ABSTRACTBackground: Inactivated Enterovirus 71 (EV71) vaccines showed significant efficacy against the diseases associated with EV71 and a neutralizing antibody (NTAb) titer of 1:16–1:32 was suggested as the correlates of the vaccine protection. This paper aims to further estimate the immunological surrogate endpoints for the protection of inactivated EV71 vaccines and the effect factors.Methods: Pre-vaccination NTAb against EV71 at baseline (day 0), post-vaccination NTAb against EV71 at day 56, and the occurrence of laboratory-confirmed EV71-associated diseases during a 24-months follow-up period were collected from a phase 3 efficacy trial of an inactivated EV71 vaccine. We used the mixed-scaled logit model and the absolute sigmoid function by some extensions in continuous models to estimate the immunological surrogate endpoint for the EV71 vaccine protection, respectively.Results: For children with a negative baseline of EV71 NTAb titers, an antibody level of 26.6 U/ml (1:30) was estimated to provide at least a 50% protection for 12 months, and an antibody level of 36.2 U/ml (1:42) may be needed to achieve a 50% protective level of the population for 24 months.Conclusion: Both the pre-vaccination NTAb level and the vaccine protective period could affect the estimation of the immunological surrogate for EV71 vaccine. A post-vaccination NTAb titer of 1:42 or more may be needed for long-term protection.Clinical trial registration: NCT01508247.