Investigating animal reservoirs for hepatitis E virus in Bangui, Central African Republic.

BACKGROUND: Hepatitis E virus (HEV) is a major cause of enterotropic viral hepatitis, a major public health problem in many developing countries. In Central African Republic (CAR), HEV genotypes 1, 2, and 3 have been found to have an impact on human health. However, data on HEV in animal reservoirs are still lacking for CAR. Here, we investigated the presence of HEV in farmed pigs and goats in Bangui, the capital city of CAR, using molecular methods. METHODOLOGY: In a prospective study, fecal samples from 61 pigs and 39 goats from farms in five districts (2nd, 4th, 6th, 7th, 8th) of Bangui were collected and tested for HEV RNA by real-time RT-PCR. The samples were further analyzed by nested-PCR and sequenced to determine the genotype and subtype to which the virus belong. RESULTS: In total, 22/100 (22.0%) feces samples were successfully amplified for HEV RNA by real time RT-PCR. All positive samples were from pigs (22/61; 36.1%), while all goat samples were negative (0/39). Twelve HEV RNA samples (12/22 or 54.5%) were successfully amplified by nested RT-PCR, and subsequently sequenced. Phylogenetic analysis revealed that the obtained sequences clustered with subtype 3h and were genetically related to the human HEV sequences from CAR. CONCLUSION: This study confirms that pigs constitute an HEV reservoir, with genotype 3 being the major circulating strain. Further studies are needed to investigate other local reservoirs and to improve knowledge of the molecular epidemiology of HEV in CAR.

Long-term efficacy and safety of a tetravalent dengue vaccine (TAK-003): 4·5-year results from a phase 3, randomised, double-blind, placebo-controlled trial.

BACKGROUND: About half of the world's population lives in dengue-endemic areas. We aimed to evaluate the long-term efficacy and safety of two doses of the tetravalent dengue vaccine TAK-003 in preventing symptomatic dengue disease of any severity and due to any dengue virus (DENV) serotypes in children and adolescents. METHODS: In this ongoing double-blind, randomised, placebo-controlled trial, we enrolled healthy participants aged 4-16 years at 26 medical and research centres across eight dengue-endemic countries (Brazil, Colombia, Dominican Republic, Nicaragua, Panama, Philippines, Sri Lanka, and Thailand). The main exclusion criteria were febrile illness (body temperature ≥38°C) at the time of randomisation, hypersensitivity or allergy to any of the vaccine components, pregnancy or breastfeeding, serious chronic or progressive disease, impaired or altered immune function, and previous receipt of a dengue vaccine. Participants were randomly assigned 2:1 (stratified by age and region) using an interactive web response system and dynamic block assignment to receive two subcutaneous doses of TAK-003 or placebo 3 months apart. Investigators, participants, and their parents or legal guardians were blinded to group assignments. Active febrile illness surveillance and RT-PCR testing of febrile illness episodes were performed for identification of virologically confirmed dengue. Efficacy outcomes were assessed in the safety analysis set (all randomly assigned participants who received ≥1 dose) and the per protocol set (all participants who had no major protocol violations), and included cumulative vaccine efficacy from first vaccination to approximately 4·5 years after the second vaccination. Serious adverse events were monitored throughout. This study is registered with ClinicalTrials.gov, NCT02747927. FINDINGS: Between Sept 7, 2016, and March 31, 2017, 20 099 participants were randomly assigned (TAK-003, n=13 401; placebo, n=6698). 20 071 participants (10 142 [50·5%] males; 9929 [49·5%] females; safety set) received TAK-003 or placebo, with 18 257 (91·0%) completing approximately 4·5 years of follow-up after the second vaccination (TAK-003, 12 177/13 380; placebo, 6080/6687). Overall, 1007 (placebo: 560; TAK-003: 447) of 27 684 febrile illnesses reported were virologically confirmed dengue, with 188 cases (placebo: 142; TAK-003: 46) requiring hospitalisation. Cumulative vaccine efficacy was 61·2% (95% CI 56·0-65·8) against virologically confirmed dengue and 84·1% (77·8-88·6) against hospitalised virologically confirmed dengue; corresponding efficacies were 53·5% (41·6-62·9) and 79·3% (63·5-88·2) in baseline seronegative participants (safety set). In an exploratory analysis, vaccine efficacy was shown against all four serotypes in baseline seropositive participants. In baseline seronegative participants, vaccine efficacy was shown against DENV-1 and DENV-2 but was not observed against DENV-3 and low incidence precluded evaluation against DENV-4. During part 3 of the trial (approximately 22-57 months after the first vaccination), serious adverse events were reported for 664 (5·0%) of 13 380 TAK-003 recipients and 396 (5·9%) of 6687 placebo recipients; 17 deaths (6 in the placebo group and 11 in the TAK-003 group) were reported, none were considered study-vaccine related. INTERPRETATION: TAK-003 demonstrated long-term efficacy and safety against all four DENV serotypes in previously exposed individuals and against DENV-1 and DENV-2 in dengue-naive individuals. FUNDING: Takeda Vaccines. TRANSLATIONS: For the Portuguese, Spanish translations and plain language summary of the abstract see Supplementary Materials section.

Consistency of immunogenicity in three consecutive lots of a tetravalent dengue vaccine candidate (TAK-003): A randomized placebo-controlled trial in US adults.

BACKGROUND: We conducted a trial to demonstrate immunogenic equivalence of three consecutive manufacturing lots of Takeda's tetravalent dengue vaccine candidate, TAK-003, and further assessed its safety and reactogenicity. METHODS: Healthy US adults (n = 923) randomized 2:2:2:1 to four groups received two doses of one of three TAK-003 lots or placebo on Days 0 and 90, with follow-up to Day 270. Primary endpoint evaluated lot-to-lot equivalence of geometric mean neutralizing titers at Day 120 against each of 4 dengue serotypes in baseline seronegative participants. Solicited local and systemic, and unsolicited adverse events (AEs) were assessed for 7, 14 and 28 days after each dose, respectively. Serious AEs (SAE) were monitored throughout the study. RESULTS: Eight of 12 prespecified equivalence comparisons were met in the per-protocol set but failed marginally in the other 4 mainly due to loss of statistical power following higher than anticipated baseline seropositivity and drop-out rates. All three TAK-003 lots elicited high rates of tetravalent dengue seropositivity (96.7 %, 93.0 % and 97.5 % at Day 120; 91.0 %, 80.5 % and 85.7 % at Day 270) and had similar reactogenicity profiles with no vaccine-related SAEs. CONCLUSIONS: The three lots of TAK-003 were immunogenic for all four dengue serotypes and well tolerated in healthy adults. Despite not meeting all equivalence comparisons, no major differences were observed between lots and the data support acceptable consistency of the manufacturing process. Trial registrationClinicalTrials.gov identifier: NCT03423173.

Molecular characterization of measles viruses in Central African Republic, 2012-2016.

Despite being preventable through vaccination, measles is still one of the most important causes of morbidity and mortality in young children in Africa. In 2015, several African countries, including the Central African Republic (CAR), began implementing national measles elimination programs. However, measles remains a public health problem in Africa, particularly in the CAR. A retrospective study was conducted at the Institut Pasteur de Bangui, using blood samples (n = 255) and oral swabs (n = 7) collected between January 2012 and December 2016 from measles IgM-positive cases, to attempt genotyping of circulating measles virus strains. Overall, 50 samples were positive by real-time polymerase chain reaction, and 40 sequences of acceptable quality were obtained. The phylogenetic analysis showed that 38 strains belonged to genotype B3 suggesting that this genotype was endemic in the CAR during the study period. No genotype B2 sequences were detected, suggesting that this genotype is no longer present in the CAR.

Bridging the immunogenicity of a tetravalent dengue vaccine (TAK-003) from children and adolescents to adults.

Immunobridging is an important methodology that can be used to extrapolate vaccine efficacy estimates to populations not evaluated in clinical studies, and that has been successfully used in developing many vaccines. Dengue, caused by a mosquito-transmitted flavivirus endemic to many tropical and subtropical regions, is traditionally thought of as a pediatric disease but is now a global threat to both children and adults. We bridged immunogenicity data from a phase 3 efficacy study of a tetravalent dengue vaccine (TAK-003), performed in children and adolescents living in endemic areas, with an immunogenicity study in adults in non-endemic areas. Neutralizing antibody responses were comparable in both studies following receipt of a two-dose TAK-003 schedule (months 0 and 3). Similar immune responses were observed across exploratory assessments of additional humoral responses. These data support the potential for clinical efficacy of TAK-003 in adults.

Immunogenicity and safety of concomitant and sequential administration of yellow fever YF-17D vaccine and tetravalent dengue vaccine candidate TAK-003: A phase 3 randomized, controlled study.

BACKGROUND: Yellow fever (YF) vaccination is often mandatory for travelers to YF-endemic areas. The areas with risk of YF partially overlap with those of dengue, for which there is currently no recommended vaccine available for dengue-naïve individuals. This phase 3 study assessed the immunogenicity and safety of concomitant and sequential administration of YF (YF-17D) and tetravalent dengue (TAK-003) vaccines in healthy adults aged 18-60 years living in areas of the US non-endemic for either virus. METHODS: Participants were randomized 1:1:1 to receive the following vaccinations at Months 0, 3, and 6, respectively: YF-17D+placebo, TAK-003, and TAK-003 (Group 1); TAK-003+placebo, TAK-003, and YF-17D (Group 2); or YF-17D+TAK-003, TAK-003, and placebo (Group 3). The primary objective was to demonstrate non-inferiority (upper bound of 95% confidence interval [UB95%CI] of difference <5%) of YF seroprotection rate one month following concomitant administration of YF-17D and TAK-003 (Group 3) compared with YF-17D plus placebo (Group 1). The secondary objectives included demonstration of non-inferiority of YF and dengue geometric mean titers (GMTs) (UB95%CI for GMT ratio <2.0), and safety. RESULTS: 900 adults were randomized. YF seroprotection rates one month post-YF-17D (Month 1) were 99.5% and 99.1% in Group 1 and 3, respectively, and non-inferiority was demonstrated (UB95%CI = 2.69% i.e. <5%). Non-inferiority was also demonstrated for GMTs against YF one month post-YF-17D, and against DENV-2, -3, and -4 (UB95%CI <2), but not DENV-1 (UB95%CI: 2.22), one month post-second TAK-003 vaccination. Adverse event rates following TAK-003 were consistent with previous results, and no important safety risks were identified. CONCLUSIONS: In this study, YF-17D vaccine and TAK-003 were immunogenic and well tolerated when sequentially or concomitantly administered. The non-inferiority of immune responses to YF-17D and TAK-003 was demonstrated for concomitant administration of the 2 vaccines compared to separate vaccination, except against DENV-1 but with GMTs similar to those observed in other TAK-003 trials. TRIAL REGISTRATION: ClinicalTrials.gov identified: NCT03342898.

A randomized phase 3 trial of the immunogenicity and safety of coadministration of a live-attenuated tetravalent dengue vaccine (TAK-003) and an inactivated hepatitis a (HAV) virus vaccine in a dengue non-endemic country.

BACKGROUND: Vaccination against hepatitis A virus (HAV) is largely recommended for travelers worldwide. Concurrent dengue and HAV vaccination may be desired in parallel for travelers to countries where both diseases are endemic. This randomized, observer-blind, phase 3 trial evaluated coadministration of HAV vaccine with tetravalent dengue vaccine (TAK-003) in healthy adults aged 18-60 years living in the UK. METHODS: Participants were randomized (1:1:1) to receive HAV vaccine and placebo on Day 1, and placebo on Day 90 (Group 1), TAK-003 and placebo on Day 1, and TAK-003 on Day 90 (Group 2), or TAK-003 and HAV vaccine on Day 1, and TAK-003 on Day 90 (Group 3). The primary objective was non-inferiority of HAV seroprotection rate (anti-HAV ≥ 12.5 mIU/mL) in Group 3 versus Group 1, one month post-first vaccination (Day 30) in HAV-naïve and dengue-naïve participants. Sensitivity analyses were performed on combinations of baseline HAV and dengue serostatus. Secondary objectives included dengue seropositivity one month post-second vaccination (Day 120), HAV geometric mean concentrations (GMCs), and safety. RESULTS: 900 participants were randomized. On Day 30, HAV seroprotection rates were non-inferior following coadministration of HAV and TAK-003 (Group 3: 98.7 %) to HAV administration alone (Group 1: 97.1 %; difference: -1.68, 95 % CI: -8.91 to 4.28). Sensitivity analyses including participants who were neither HAV-naïve nor DENV-naïve at baseline supported this finding. Anti-HAV GMCs on Day 30 were 82.1 (95 % CI: 62.9-107.1) mIU/mL in Group 1 and 93.0 (76.1-113.6) mIU/mL in Group 3. By Day 120, 90.9-96.8 % of TAK-003 recipients were seropositive (neutralizing antibody titer > 10) to all four dengue serotypes. Coadministration of HAV vaccine and TAK-003 was well tolerated, with no important safety risks identified. CONCLUSION: Immune responses following coadministration of HAV vaccine and TAK-003 were non-inferior to administration of HAV vaccine alone. The results support the coadministration of HAV vaccine and TAK-003 with no adverse impact on immunogenicity, safety, and reactogenicity of either vaccine. CLINICALTRIALS: gov registration: NCT03525119.

Antibodies Produced in Response to a Live-Attenuated Dengue Vaccine Are Functional in Activating the Complement System.

BACKGROUND: Antibody-driven complement system (CS) activation has been associated with protection against symptomatic dengue virus (DENV) infection. Aggregation, opsonization, lysis, and phagocytosis are mechanisms triggered by antibody-antigen immunocomplexes following fixation of the component 1q (C1q) and activation of the classical pathway. As a result, DENV neutralization and clearance are facilitated, whereas antibody-dependent enhancement of infection is inhibited. We investigated the ability of antibodies produced in response to Takeda's dengue vaccine candidate, TAK-003, to fix C1q and activate CS. METHODS: Serum samples were collected from seronegative and seropositive participants in a phase 2 clinical trial (DEN-203), pre- and postvaccination. Samples were evaluated for the presence of complement-fixing antibodies (CFAs) against DENV using a Luminex multiplex-based immunoassay. RESULTS: TAK-003 elicited production of CFAs against all 4 DENV serotypes, which persisted for 1 year postvaccination, irrespective of baseline serostatus. CFA levels were correlated with neutralizing antibody titers and virus-binding total IgG and IgG1 concentrations. Furthermore, efficiency of CFA fixation was greater in samples with higher polyclonal IgG avidity. CONCLUSIONS: These results indicate that antibodies produced after TAK-003 vaccination are functional in both activating CS and neutralizing virus infection by all DENV serotypes, which may contribute to efficacy of TAK-003. CLINICAL TRIALS REGISTRATION: NCT01511250.

Characterization of the cell-mediated immune response to Takeda's live-attenuated tetravalent dengue vaccine in adolescents participating in a phase 2 randomized controlled trial conducted in a dengue-endemic setting.

BACKGROUND: As robust dengue-specific CD4+ and CD8+ T cell responses are essential for protective immunity, we assessed cell-mediated immune (CMI) responses to a DENV-2-based dengue tetravalent vaccine candidate (TAK-003) in adolescents living in Panama, a dengue-endemic country. METHODS: Peripheral blood mononuclear cells were collected from a subset of 67 participants ≥ 10 years old included in a phase 2 clinical trial of TAK-003 (Clinicaltrials.gov: NCT02302066). Following stimulation with dengue peptides, the frequency, magnitude, and cross-reactivity of the CD8+ and CD4+ T cell IFN-γ, TNF-α and IL-2 responses were assessed by flow cytometry. RESULTS: Intracellular cytokine staining identified NS1, NS3, and NS5 as the most common non-structural (NS) targets of the CD4+ T-cell response (IFN-γ+); NS3 and NS5 were the main NS targets of the CD8+ T cell response (IFN-γ+). Both CD4+ and CD8+ T-cell responses were multi-functional (IFN-γ + TNF-α + IL-2+) and cross-reactive against DENV-1, -3, and -4 serotypes. Similar responses were seen in all CMI assessments irrespective of participant baseline status for dengue neutralizing antibodies and T cells. CONCLUSIONS: TAK-003 elicited cross-reactive, multi-functional CD4+ and CD8+ T-cell responses, irrespective of dengue pre-exposure.

Three-year Efficacy and Safety of Takeda's Dengue Vaccine Candidate (TAK-003).

BACKGROUND: Takeda's live attenuated tetravalent dengue vaccine candidate (TAK-003) is under evaluation in a long-term clinical trial across 8 dengue-endemic countries. Previously, we have reported its efficacy and safety in both seronegative and seropositive participants and that its performance varies by serotype, with some decline in efficacy from first to second year postvaccination. This exploratory analysis provides an update with cumulative and third-year data. METHODS: Healthy 4-16 year olds (n = 20099) were randomized 2:1 to receive TAK-003 or placebo (0, 3 month schedule). The protocol included baseline serostatus testing of all participants and detection of all symptomatic dengue throughout the trial with a serotype specific reverse transcriptase-polymerase chain reaction. RESULTS: Cumulative efficacy after 3 years was 62.0% (95% confidence interval, 56.6-66.7) against virologically confirmed dengue (VCD) and 83.6% (76.8-88.4) against hospitalized VCD. Efficacy was 54.3% (41.9-64.1) against VCD and 77.1% (58.6-87.3) against hospitalized VCD in baseline seronegatives, and 65.0% (58.9-70.1) against VCD and 86.0% (78.4-91.0) against hospitalized VCD in baseline seropositives. Efficacy against VCD during the third year declined to 44.7% (32.5-54.7), whereas efficacy against hospitalized VCD was sustained at 70.8% (49.6-83.0). Rates of serious adverse events were 2.9% in TAK-003 group and 3.5% in placebo group during the ongoing long-term follow-up (ie, second half of the 3 years following vaccination), but none were related. No important safety risks were identified. CONCLUSIONS: TAK-003 was efficacious against symptomatic dengue over 3 years. Efficacy declined over time but remained robust against hospitalized dengue. A booster dose evaluation is planned.

Efficacy of a Dengue Vaccine Candidate (TAK-003) in Healthy Children and Adolescents 2 Years after Vaccination.

BACKGROUND: Takeda's dengue vaccine is under evaluation in an ongoing phase 3 efficacy study; we present a 2-year update. METHODS: Children (20 099, 4-16 years old) were randomized to receive 2 doses of TAK-003 or placebo 3 months apart and are under surveillance to detect dengue by serotype-specific RT-PCR. RESULTS: Cumulative efficacy against dengue approximately 27 months since first dose was 72.7% (95% confidence interval [CI], 67.1%-77.3%), including 67.0% (95% CI, 53.6%-76.5%) in dengue-naive and 89.2% (95% CI, 82.4%-93.3%) against hospitalized dengue. In the second year, decline in efficacy was observed (56.2%; 95% CI, 42.3%-66.8%) with the largest decline in 4-5 year olds (24.5%; 95% CI, -34.2% to 57.5%); efficacy was 60.6% (95% CI, 43.8%-72.4%) in 6-11 year and 71.2% (95% CI, 41.0%-85.9%) in 12-16 year age groups. As TAK-003 efficacy varies by serotype, changes in serotype dominance partially contributed to efficacy differences in year-by-year analysis. No related serious adverse events occurred during the second year. CONCLUSIONS: TAK-003 demonstrated continued benefit independent of baseline serostatus in reducing dengue with some decline in efficacy during the second year. Three-year data will be important to see if efficacy stabilizes or declines further.Clinical Trials Registration. NCT02747927.Takeda's tetravalent dengue vaccine (TAK-003) continued to demonstrate benefit in reducing dengue independent of baseline serostatus up to 2 years after completing vaccination with some decline in efficacy during the second year in 4-16 year olds in dengue-endemic countries.

Fatal Outcome in a Hepatitis E Virus/Human Immunodeficiency Virus Co-Infected Malnourished Child in the Central African Republic.

Hepatitis E virus (HEV) infection is responsible for major endemic outbreaks in developing countries. Human immunodeficiency virus (HIV) and HEV are widespread in the Central African Republic. We report the first documented case of an HEV infection in a 36-month-old child already suffering from HIV and severe acute malnutrition (SAM). The HIV patient was hospitalized for SAM with persistent diarrhea and prolonged fever. The presence of IgG anti-HEV antibodies was noted. Sequencing of the amplified HEV RNA revealed the presence of genotype 3c. The alanine aminotransferase level was slightly above average. The patient died despite being treated by antiretroviral therapy accompanied by probabilistic antibiotic therapy and nutritional rehabilitation. HEV/HIV co-infection in a malnourished patient can accelerate a fatal outcome. In the presence of biological abnormalities in a severe acutely malnourished HIV-infected patient, HEV RNA detection should be added to the standard medical assessment in sub-Saharan African countries.

Hepatitis E virus outbreak associated with rainfall in the Central African Republic in 2008-2009.

BACKGROUND: Infection by hepatitis E virus (HEV) can cause a high burden of morbidity and mortality in countries with poor access to clean water and sanitation. Our study aimed to investigate the situation of HEV infections in the Central African Republic (CAR). METHODS: A retrospective analysis of the blood samples and notification forms collected through the national yellow fever (YF) surveillance program, but for which a diagnosis of YF was discarded, was carried out using an anti-HEV IgM ELISA and a HEV-specific RT-PCR. RESULTS: Of 2883 YF-negative samples collected between January 2008 and December 2012, 745 (~ 26%) tested positive by at least either of the 2 tests used to confirm HEV cases. The results revealed that the CAR was hit by a large HEV outbreak in 2008 and 2009. The results also showed a clear seasonal pattern with correlation between HEV incidence and rainfall in Bangui. A phylogenetic analysis showed that the circulating strains belonged to genotypes 1e and 2b. CONCLUSIONS: Overall, this study provides further evidences that HEV can be a significant cause of acute febrile jaundice, particularly among adults during rainy season or flood, in a country from Sub-Saharan Africa.

Safety and immunogenicity of a tetravalent dengue vaccine in children aged 2-17 years: a randomised, placebo-controlled, phase 2 trial.

BACKGROUND: An unmet clinical need remains for an effective tetravalent dengue vaccine suitable for all age groups, regardless of serostatus. We assessed the immunogenicity and safety of three different dose schedules of a tetravalent dengue vaccine (TAK-003) over a 48-month period in children living in dengue-endemic countries. METHODS: We did a large, phase 2, double-blind, placebo-controlled trial at three sites in the Dominican Republic, Panama, and the Philippines. Healthy participants aged 2-17 years were randomly assigned 1:2:5:1 using an interactive web response system with stratification by age to receive either a two-dose primary series (days 1 and 91), one primary dose (day 1), one primary dose plus booster (days 1 and 365), or placebo. Participants and relevant study personnel were masked to the random assignment until completion of the study at month 48. To maintain masking, TAK-003 recipients were administered placebo doses when appropriate. The primary objective was assessment of neutralising geometric mean titres for each serotype to month 48 assessed in the per-protocol immunogenicity subset. Secondary safety endpoints included proportions of participants with serious adverse events and symptomatic virologically confirmed dengue. This study is registered with ClinicalTrials.gov, NCT02302066. FINDINGS: Between Dec 5, 2014, and Feb 13, 2015, 1800 children were randomly assigned to the following groups: two-dose primary series (n=201), one primary dose (n=398), one primary dose plus 1-year booster (n=1002), and placebo (n=199). Of them, 1479 (82%) participants completed the 48-month study. Immunogenicity endpoints were assessed in 562 participants enrolled in the immunogenicity subset, of whom 509 were included in the per-protocol subset. At month 48, antibody titres remained elevated in all TAK-003 groups compared with placebo, irrespective of baseline serostatus. At month 48, geometric mean titres were 378 (95% CI 226-632) in two-dose, 421 (285-622) in one-dose, 719 (538-960) in one-dose plus 1-year booster, and 100 (50-201) in placebo recipients against DENV 1; 1052 (732-1511), 1319 (970-1794), 1200 (927-1553), and 208 (99-437) against DENV 2; 183 (113-298), 201 (135-298), 288 (211-392), and 71 (37-139) against DENV 3; and 152 (97-239), 164 (114-236), 219 (165-290), and 46 (26-82) against DENV 4; and tetravalent seropositivity rate was 89% (79-96), 86% (80-92), 97% (93-99), and 60% (47-72), respectively. Virologically confirmed dengue was recorded in 37 (2%) TAK-003 and 13 (7%) placebo participants, with a relative risk of 0·35 (0·19-0·65). No vaccine-related serious adverse events or severe dengue virus disease were reported. INTERPRETATION: TAK-003 elicited antibody responses against all four serotypes, which persisted to 48 months post-vaccination, regardless of baseline serostatus. No important safety risks were identified. We observed a long-term reduction in risk of symptomatic dengue virus disease in vaccinees. Results from this study provide a long-term safety database and support assessment of the vaccine in the ongoing phase 3 efficacy study. FUNDING: Takeda Vaccines.

Immunogenicity and safety of lyophilized and liquid dengue tetravalent vaccine candidate formulations in healthy adults: a randomized, phase 2 clinical trial.

Takeda has developed a live-attenuated dengue tetravalent vaccine candidate (TAK-003) which has been shown to be immunogenic with acceptable reactogenicity in phase 1 trials. In agreement with World Health Organization prequalification requirements for dengue vaccines, Takeda has manufactured a lyophilized formulation of TAK-003 that allows stable storage at +2°C to +8°C. This randomized, double-blind, phase 2 study (NCT02193087) was performed in 1002 healthy dengue-naïve adults, 18-49 years of age, across seven centers in the USA to compare the safety and immunogenicity of one or two doses of a lyophilized TAK-003 formulation with the liquid TAK-003 formulation used in previous phase 1 studies. The primary objective was to show immunologic equivalence in terms of geometric mean titers (GMT) of neutralizing antibodies to the four dengue serotypes one month after one dose of the lyophilized and liquid formulations. Secondary assessments were of safety and seropositivity rates, including after a second dose. The primary endpoint was not met, because immunologic equivalence after one dose was only shown for the DENV-2 serotype. Nonetheless, GMTs and seropositivity rates to all four serotypes were achieved with all formulations after two doses and are in line with what was observed in previous studies. Additionally, in view of the acceptable reactogenicity, with no vaccine-related serious adverse events reported, these data support continuing further clinical development of the lyophilized TAK-003 formulation.

Safety and immunogenicity of a single dose of a tetravalent dengue vaccine with two different serotype-2 potencies in adults in Singapore: A phase 2, double-blind, randomised, controlled trial.

BACKGROUND: Early formulations of Takeda's tetravalent dengue vaccine candidate (TAK-003) have demonstrated notably higher neutralizing antibody responses against serotype 2 than other serotypes. Here, we assessed the immunogenicity and tolerability in adults living in Singapore of two TAK-003 formulations: an early formulation, referred to as HD-TDV, and a new formulation with 10-fold lower serotype 2 potency, referred to as TDV (NCT02425098). METHODS: Subjects aged 21-45 years were stratified by baseline dengue serostatus and randomised 1:1 to receive a single dose of either HD-TDV or TDV. Immunogenicity was evaluated at Days 15, 30, 90, 180, and 365 post-vaccination as geometric mean titres (GMTs) of neutralising antibodies and seropositivity rates. Viremia was assessed per vaccine strain. Solicited and unsolicited adverse events (AEs) were assessed by severity and causality. RESULTS: Of 351 subjects randomised, 176 received HD-TDV and 175 received TDV. Peak GMTs against all serotypes were observed at Day 30, with highest GMTs against DENV-2 in both groups. In subjects seronegative at baseline, the response to DENV-2 was less dominant with TDV (Day 30 GMTs: 813 for TDV, 10,966 for HD-TDV). In these subjects, DENV-4 seropositivity rates and GMTs were higher with TDV (Day 30 GMTs: 58 for TDV, 21 for HD-TDV; seropositivity rates: 76% for TDV, 60% for HD-TDV). Viremia mainly occurred for TDV-2 in both vaccine groups, with a lower incidence in TDV recipients, and mostly resolved by Day 30. Both vaccine formulations showed an acceptable safety profile with similar overall rates of solicited and unsolicited AEs across vaccine groups. CONCLUSIONS: These results suggest a more balanced immune response with the new formulation TDV compared with the early formulation HD-TDV, particularly in subjects who were seronegative prior to vaccination, and support the choice of the new formulation for the phase 3 efficacy assessment.

Complete Genome Sequences of Igbo-Ora and Babanki Alphavirus Strains Isolated in the Central African Republic in the 1960s and 1970s.

Vector-borne viruses are becoming increasingly important from a public health standpoint with the emergence or reemergence of viruses and extension of the areas at risk. Here, we report the whole-genome sequences of two alphaviruses, namely, one Igbo-Ora virus and one Babanki virus, that were isolated several decades ago in Africa from human serum.

Immunogenicity and safety of one versus two doses of tetravalent dengue vaccine in healthy children aged 2-17 years in Asia and Latin America: 18-month interim data from a phase 2, randomised, placebo-controlled study.

BACKGROUND: Development of vaccines that are effective against all four dengue virus serotypes (DENV-1-4) in all age groups is important. Here, we present 18-month interim data from an ongoing study undertaken to assess the immunogenicity and safety of Takeda's tetravalent dengue vaccine (TDV) candidate over 48 months in children living in dengue-endemic countries. METHODS: We undertook a phase 2, multicentre, randomised, double-blind, placebo-controlled study at three sites in the Dominican Republic, Panama, and the Philippines. We randomly assigned children aged 2-17 years to receive either two TDV doses 3 months apart (group 1), one TDV dose (group 2), one TDV dose and a booster dose 1 year later (group 3), or placebo (group 4). We did the randomisation (1:2:5:1) using an interactive web response system stratified by age. The primary endpoint of this 18-month interim analysis was DENV serotype-specific antibody geometric mean titres (GMTs) in the per-protocol immunogenicity subset on days 1, 28, 91, 180, 365, 393, and 540. Secondary safety endpoints were the proportions of participants with serious adverse events and with virologically confirmed dengue in the safety set, and solicited and unsolicited adverse events in the immunogenicity subset. This trial is registered with ClinicalTrials.gov, number NCT02302066. FINDINGS: Between Dec 5, 2014, and Feb 13, 2015, 1800 children were randomly assigned to group 1 (n=201), group 2 (n=398), group 3 (n=1002), and group 4 (n=199). 1794 participants received at least one dose of TDV or placebo (safety set), of whom 562 participated in the immunogenicity subset and 509 were included in the per-protocol set. Antibody titres remained elevated 18 months after vaccination in all TDV groups. At day 540, in groups 1, 2, 3, and 4, respectively, DENV-1 GMTs were 476 (95% CI 286-791), 461 (329-647), 1056 (804-1388), and 92 (49-173); DENV-2 GMTs were 1212 (842-1744), 1242 (947-1628), 1457 (1182-1796), and 177 (93-337); DENV-3 GMTs were 286 (171-478), 298 (205-433), 548 (411-730), and 78 (44-137); and DENV-4 GMTs were 98 (65-150), 102 (75-139), 172 (133-222), and 33 (21-52). Limited differences in GMTs were observed between groups 1 and 2 (in which participants received one and two doses of TDV, respectively). In baseline-seronegative participants, a 1-year booster clearly increased GMTs. Vaccine-related unsolicited adverse events occurred in 14 (2%) of 562 participants, but no vaccine-related serious adverse events arose. Symptomatic, virologically confirmed dengue was recorded in 21 (1·3%) of 1596 participants vaccinated with TDV compared with nine (4·5%) of 198 placebo recipients. INTERPRETATION: TDV was well tolerated and immunogenic against all four dengue serotypes, irrespective of baseline dengue serostatus. These data provide proof of concept for TDV and support the ongoing phase 3 efficacy assessment of two doses 3 months apart. FUNDING: Takeda Vaccines.

Free-living amoebae isolated in the Central African Republic: epidemiological and molecular aspects.

Among the many species of free-living amoebae infecting humans, only Naegleria fowleri, a few species of Acanthamoeba, Balamuthia mandrillaris recently Sappinia diploïdea and Paravahlkampfia Francina are responsible for human diseases especially deadly encephalitis outside of Acanthamoeba keratitis related. In the Central African Republic (CAR), no studies have previously been conducted about free amoebae and no suspicious cases of encephalitis or amoebic keratitis was reported even though the ecosystem supported the proliferation of these microorganisms. The objective of this study was to identify free-living amoebae present in CAR and to define the molecular characteristic. Bathing sites and cerebrospinal fluid from patients died of bacterial meningitis untagged were explored by culture and PCR and the amplicons were sequenced which allowed to characterize the species found. Only species of the genus Tetramitus, namely T. Entericus, T. waccamawensis and T.sp similar to those already described in the world and not pathogenic for humans were found in bathing sites, the cerebrospinal fluid meanwhile remained negative. Although no pathogen species such as Naegleria fowleri or species of Acanthamoeba have been isolated, this study worth pursuing because this investigation was very limited in space because of the insecurity in the country.