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Wu Y, Lu Y, Bai Y, Zhu B, Chang F, Lu Y. Efficacy, Safety, and Immunogenicity of Subunit Respiratory Syncytial Virus Vaccines: Systematic Review and Meta-Analysis of Randomized Controlled Trials. Vaccines (Basel) 2024; 12:879. [PMID: 39204005 PMCID: PMC11360664 DOI: 10.3390/vaccines12080879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2024] [Revised: 07/23/2024] [Accepted: 07/24/2024] [Indexed: 09/03/2024] Open
Abstract
BACKGROUND Respiratory syncytial virus (RSV) is garnering increasing attention, with a growing number of subunit RSV vaccines under active clinical investigation. However, comprehensive evidence is limited. METHODS We conducted a comprehensive search across PubMed, Embase, the Cochrane Library, Web of Science, and ClinicalTrials.gov from database inception to 12 January 2024, focusing on published randomized controlled trials (RCTs). RESULTS A total of 17 studies were included, encompassing assessments of efficacy (5 studies), safety (17 studies), and immunogenicity (12 studies) of RSV subunit vaccines. The pooled risk ratio (RR) for RSV-associated acute respiratory infection (RSV-ARI) with subunit vaccines was 0.31 (95% CI: 0.23-0.43), for RSV-associated lower respiratory tract infection (RSV-LRTI), it was 0.32 (95% CI: 0.22-0.44), and for severe RSV-LRTI (RSV-SLRTI), it was 0.13 (95% CI: 0.06-0.29). There was no significant difference in serious adverse events (SAEs) between the vaccine and placebo groups, with a pooled RR of 1.05 (95% CI: 0.98-1.14). The pooled standardized mean difference (SMD) for the geometric mean titer (GMT) of neutralizing antibodies was 2.89 (95% CI: 2.43-3.35). CONCLUSION Subunit RSV vaccines exhibit strong efficacy, favorable safety profiles, and robust immunogenicity. Future research should focus on the cost-effectiveness of various vaccines to enhance regional and national immunization strategies.
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Affiliation(s)
| | | | | | | | | | - Yun Lu
- Correspondence: (F.C.); (Y.L.)
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Pang Y, Lu H, Cao D, Zhu X, Long Q, Tian F, Long X, Li Y. Efficacy, immunogenicity and safety of respiratory syncytial virus prefusion F vaccine: systematic review and meta-analysis. BMC Public Health 2024; 24:1244. [PMID: 38711074 PMCID: PMC11075318 DOI: 10.1186/s12889-024-18748-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2023] [Accepted: 04/30/2024] [Indexed: 05/08/2024] Open
Abstract
OBJECTIVE A notable research gap exists in the systematic review and meta-analysis concerning the efficacy, immunogenicity, and safety of the respiratory syncytial virus (RSV) prefusion F vaccine. METHODS We conducted a comprehensive search across PubMed, Embase, the Cochrane Central Register of Controlled Trials, and ClinicalTrials.gov to retrieve articles related to the efficacy, immunogenicity, and safety of RSV prefusion F vaccines, published through September 8, 2023. We adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. RESULTS A total of 22 randomized controlled trials involving 78,990 participants were included in this systematic review and meta-analysis. The RSV prefusion F vaccine exhibited a vaccine effectiveness of 68% (95% CI: 59-75%) against RSV-associated acute respiratory illness, 70% (95% CI: 60-77%) against medically attended RSV-associated lower respiratory tract illness, and 87% (95% CI: 71-94%) against medically attended severe RSV-associated lower respiratory tract illness. Common reported local adverse reactions following RSV prefusion F vaccination include pain, redness, and swelling at the injection site, and systemic reactions such as fatigue, headache, myalgia, arthralgia, nausea, and chills. CONCLUSIONS Our meta-analysis suggests that vaccines using the RSV prefusion F protein as antigen exhibit appears broadly acceptable efficacy, immunogenicity, and safety in the population. In particular, it provides high protective efficiency against severe RSV-associated lower respiratory tract disease.
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Affiliation(s)
- Yi Pang
- Youjiang Medical University for Nationalities, Baise, China
| | - Haishan Lu
- Clinicopathological Diagnosis & Research Center, The Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, China
- Key Laboratory of Tumor Molecular Pathology of Guangxi Higher Education Institutes, Baise, China
| | - Demin Cao
- Clinicopathological Diagnosis & Research Center, The Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, China
- Key Laboratory of Tumor Molecular Pathology of Guangxi Higher Education Institutes, Baise, China
| | - Xiaoying Zhu
- Clinicopathological Diagnosis & Research Center, The Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, China
- Key Laboratory of Tumor Molecular Pathology of Guangxi Higher Education Institutes, Baise, China
| | - Qinqin Long
- Clinicopathological Diagnosis & Research Center, The Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, China
- Key Laboratory of Tumor Molecular Pathology of Guangxi Higher Education Institutes, Baise, China
| | - Fengqin Tian
- Clinicopathological Diagnosis & Research Center, The Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, China
- Key Laboratory of Tumor Molecular Pathology of Guangxi Higher Education Institutes, Baise, China
| | - Xidai Long
- Clinicopathological Diagnosis & Research Center, The Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, China.
- Key Laboratory of Tumor Molecular Pathology of Guangxi Higher Education Institutes, Baise, China.
| | - Yulei Li
- Clinicopathological Diagnosis & Research Center, The Affiliated Hospital of Youjiang Medical University for Nationalities, Baise, China.
- Key Laboratory of Tumor Molecular Pathology of Guangxi Higher Education Institutes, Baise, China.
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Leroux-Roels I, Van Ranst M, Vandermeulen C, Abeele CV, De Schrevel N, Salaun B, Verheust C, David MP, Kotb S, Hulstrøm V. Safety and Immunogenicity of a Revaccination With a Respiratory Syncytial Virus Prefusion F Vaccine in Older Adults: A Phase 2b Study. J Infect Dis 2024; 229:355-366. [PMID: 37699064 PMCID: PMC10873183 DOI: 10.1093/infdis/jiad321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2023] [Indexed: 09/14/2023] Open
Abstract
BACKGROUND In the previous (parent) study, 2 doses of different formulations of an investigational vaccine against respiratory syncytial virus (RSVPreF3 OA) were well tolerated and immunogenic in older adults. This multicenter phase 2b extension study assessed safety and immunogenicity of a revaccination (third) dose of the 120 μg RSVPreF3-AS01E formulation. METHODS In total, 122 older adults (60-80 years), previously vaccinated with 2 doses of RSVPreF3-AS01E formulations (containing 30, 60, or 120 μg RSVPreF3 antigen), received an additional 120 μg RSVPreF3-AS01E dose 18 months after dose 2. Vaccine safety was evaluated in all participants up to 6 months and immunogenicity in participants who received 120 μg RSVPreF3-AS01E doses until 1 month after dose 3. RESULTS Similar to the parent study, mostly mild-to-moderate solicited adverse events and no vaccine-related serious adverse events or potential immune-mediated disorders were reported. Neutralizing titers and cell-mediated immune responses persisted for 18 months after 2-dose vaccination. Dose 3 increased RSV-specific neutralizing titers against RSV-A and RSV-B and median CD4+ T-cell frequencies. After dose 3, RSV-specific neutralizing titers but not CD4+ T-cell frequencies were below levels detected 1 month after dose 1. CONCLUSIONS Revaccination with 120 μg RSVPreF3-AS01E 18 months after dose 2 is well tolerated and immunogenic in older adults. CLINICAL TRIALS REGISTRATION NCT04657198; EudraCT, 2020-000692-21.
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Affiliation(s)
- Isabel Leroux-Roels
- Centre for Vaccinology, Ghent University and Ghent University HospitalGhent, Belgium
| | - Marc Van Ranst
- Rega Institute for Medical Research, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Corinne Vandermeulen
- Leuven University Vaccinology Centre, Katholieke Universiteit Leuven, Leuven, Belgium
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Ma J, Chen L, Tang S, Shi Y. Efficacy and safety of respiratory syncytial virus vaccination during pregnancy to prevent lower respiratory tract illness in newborns and infants: a systematic review and meta-analysis of randomized controlled trials. Front Pediatr 2024; 11:1260740. [PMID: 38357264 PMCID: PMC10864603 DOI: 10.3389/fped.2023.1260740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Accepted: 12/28/2023] [Indexed: 02/16/2024] Open
Abstract
To evaluate the effectiveness and safety of respiratory syncytial virus (RSV) vaccination during pregnancy in preventing lower respiratory tract infection (LRTI) in infants and neonates, we conducted a systematic search of randomized controlled trials (RCTs) in five databases (PubMed, Embase and Cochrane Library, Web of Science, Cochrane Center Register of Controlled trial) until 1 May 2023. We performed a meta-analysis of the eligible trials using RevMan5.4.1 software. Our analysis included six articles and five RCTs. The meta-analysis revealed significant differences in the incidences of LRTI [risk ratio (RR): 0.64; 95% confidence interval (CI): 0.43, 0.96; p = 0.03)] and severe LRTI (RR: 0.37; 95% CI: 0.18, 0.79; p = 0.01) between the vaccine group and the placebo group for newborns and infants. These differences were observed at 90, 120, and 150 days after birth (p = 0.003, p = 0.05, p = 0.02, p = 0.03, p = 0.009, p = 0.05). At 180 days after birth, there was a significant difference observed in the incidence of LRTI between the two groups (RR: 0.43; 95% CI: 0.21, 0.90; p = 0.02). The safety results showed a significant difference in the incidence of common adverse events between the two groups (RR: 1.08; 95% CI: 1.04, 1.12; p < 0.0001). However, there was no significant difference observed in the incidence of serious adverse events (RR: 1.05; 95% CI: 0.97, 1.15; p = 0.23), common and serious adverse events (RR: 1.02; 95% CI: 0.96, 1.10; p = 0.23), or common and serious adverse events among pregnant women and newborns and infants (RR: 0.98; 95% CI: 0.93, 1.04; p = 0.52). In conclusion, maternal RSV vaccination is an effective and safe immunization strategy for preventing LRTI in postpartum infants, with greater efficacy observed within the first 150 days after birth.
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Affiliation(s)
- Juan Ma
- Department of Neonatology, Children’s Hospital of Chongqing Medical University, Chongqing, China
- China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Chongqing, China
- Chongqing Key Laboratory of Child Rare Diseases in Infection and Immunity, Chongqing, China
- Department of Neonatology, SongShan General Hospital, Chongqing, China
| | - Long Chen
- Department of Neonatology, Women and Children’s Hospital of Chongqing Medical University (Chongqing Health Center for Women and Children), Chongqing, China
| | - ShiFang Tang
- Department of Neonatology, SongShan General Hospital, Chongqing, China
| | - Yuan Shi
- Department of Neonatology, Children’s Hospital of Chongqing Medical University, Chongqing, China
- China International Science and Technology Cooperation Base of Child Development and Critical Disorders, Chongqing, China
- Chongqing Key Laboratory of Child Rare Diseases in Infection and Immunity, Chongqing, China
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Gong X, Luo E, Fan L, Zhang W, Yang Y, Du Y, Yang X, Xing S. Clinical research on RSV prevention in children and pregnant women: progress and perspectives. Front Immunol 2024; 14:1329426. [PMID: 38327765 PMCID: PMC10847284 DOI: 10.3389/fimmu.2023.1329426] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2023] [Accepted: 12/28/2023] [Indexed: 02/09/2024] Open
Abstract
Respiratory syncytial virus (RSV) is a significant causative agent of bronchitis and pneumonia in infants and children. The identification and structural analysis of the surface fusion glycoprotein of RSV represents a pivotal advancement in the development of RSV prevention. This review provides a comprehensive summary of RSV monoclonal antibody (mAb) and vaccine clinical trials registered on ClinicalTrials.gov, emphasizing on the classification, name, target, phase, clinical outcomes, and safety data of RSV vaccination in newborns, infants and children. We also discuss the characteristics of the types of RSV vaccines for maternal immunity and summarize the current clinical research progress of RSV vaccination in pregnant women and their protective efficacy in infants. This review will provide new ideas for the development of RSV prevention for children in the future.
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Affiliation(s)
- Xuejia Gong
- Good Clinical Practice Department, Chengdu Women’s and Children’s Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Erdan Luo
- Good Clinical Practice Department, Chengdu Women’s and Children’s Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Li Fan
- Good Clinical Practice Department, Chengdu Women’s and Children’s Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Wanggang Zhang
- Good Clinical Practice Department, Chengdu Women’s and Children’s Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Yan Yang
- Medical Department, Chengdu Women’s and Children’s Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Yuhua Du
- Obstetrical Department, Chengdu Women’s and Children’s Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Xiao Yang
- Good Clinical Practice Department, Chengdu Women’s and Children’s Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
| | - Shasha Xing
- Good Clinical Practice Department, Chengdu Women’s and Children’s Central Hospital, School of Medicine, University of Electronic Science and Technology of China, Chengdu, China
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Saeland E, van der Fits L, Bolder R, Heemskerk-van der Meer M, Drijver J, van Polanen Y, Vaneman C, Tettero L, Cox F, Serroyen J, Jorgensen MJ, Langedijk JPM, Schuitemaker H, Callendret B, Zahn RC. Combination Ad26.RSV.preF/preF protein vaccine induces superior protective immunity compared with individual vaccine components in preclinical models. NPJ Vaccines 2023; 8:45. [PMID: 36949051 PMCID: PMC10033289 DOI: 10.1038/s41541-023-00637-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 02/27/2023] [Indexed: 03/24/2023] Open
Abstract
Respiratory syncytial virus (RSV) is a leading cause of severe respiratory disease for which no licensed vaccine is available. We have previously shown that a prefusion (preF) conformation-stabilized RSV F protein antigen and an adenoviral vector encoding RSV preF protein (Ad26.RSV.preF) are immunogenic and protective in animals when administered as single components. Here, we evaluated a combination of the 2 components, administered as a single injection. Strong induction of both humoral and cellular responses was shown in RSV-naïve and pre-exposed mice and pre-exposed African green monkeys (AGMs). Both components of the combination vaccine contributed to humoral immune responses, while the Ad26.RSV.preF component was the main contributor to cellular immune responses in both mice and AGMs. Immunization with the combination elicited superior protection against RSV A2 challenge in cotton rats. These results demonstrate the advantage of a combination vaccine and support further clinical development.
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Affiliation(s)
- Eirikur Saeland
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands.
| | | | - Renske Bolder
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
| | | | - Joke Drijver
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
| | | | | | | | - Freek Cox
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
| | - Jan Serroyen
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
| | - Matthew J Jorgensen
- Department of Pathology, Section on Comparative Medicine, Wake Forest School of Medicine, Winston-Salem, NC, USA
| | | | | | | | - Roland C Zahn
- Janssen Vaccines & Prevention B.V., Leiden, The Netherlands
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7
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Mineva GM, Purtill H, Dunne CP, Philip RK. Impact of breastfeeding on the incidence and severity of respiratory syncytial virus (RSV)-associated acute lower respiratory infections in infants: a systematic review highlighting the global relevance of primary prevention. BMJ Glob Health 2023; 8:bmjgh-2022-009693. [PMID: 36746518 PMCID: PMC9906265 DOI: 10.1136/bmjgh-2022-009693] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2022] [Accepted: 11/07/2022] [Indexed: 02/08/2023] Open
Abstract
BACKGROUND Respiratory syncytial virus (RSV) is the principal cause of acute lower respiratory infections (ALRI) among infants worldwide, and an important cause of morbidity, hospitalisation and mortality. While infants are universally exposed to RSV, most mortality occurs among normal term infants from low-income and middle-income countries. Breastfeeding has been suggested to have a protective effect against RSV infection. This study aims to determine the association of breastfeeding on the frequency and severity of RSV-associated ALRI among infants. METHODS A systematic review was conducted using keywords and Medical Subject Headings on MEDLINE, PubMed, Google Scholar, EMBASE, MedRxiv and Cochrane Central Register of Controlled Trials. Full-text articles published in English from 2000 to 2021 that studied exclusively or partially breastfed infants who developed RSV-associated ALRI <12 months of age were included. Covidence software-based evidence extraction and Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocol guidelines were followed. Quality of evidence was analysed using UK National Service Framework grading and the risk-of-bias assessment using Robvis. RESULTS Among 1368 studies screened, 217 qualified full-text review and 198 were excluded based on pre-agreed criteria. Nineteen articles published from 12 countries that included 16 787 infants from 31 countries (of which 8 middle-income) were retained for analysis. Results indicate that non-breastfeeding practices pose a significant risk for severe RSV-associated ALRI and hospitalisation. Exclusive breastfeeding for >4-6 months significantly lowered hospitalisation, length of stay, supplemental oxygen demand and admission to intensive care units. CONCLUSION In the context of no effective or standardised treatment for established RSV-associated ALRI, available evidence suggest that breastfeeding is associated with lower frequency and severity of RSV-associated ALRI, based on observational studies of variable grades of evidence and risk-of-bias. With both exclusive and partial breastfeeding benefiting infants who develop RSV-associated ALRI, breastfeeding should be promoted globally as an adjunct primary prevention; in addition to emerging immunoprophylaxis and maternal immunisation strategies.
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Affiliation(s)
- Gabriela M Mineva
- Division of Neonatology, Department of Paediatrics, University Maternity Hospital Limerick, Limerick, Ireland
| | - Helen Purtill
- Mathematics and Statistics, University of Limerick, Limerick, Ireland
| | - Colum P Dunne
- Centre for Interventions in Infection, Inflammation and Immunity (4i), University of Limerick School of Medicine, Limerick, Ireland
| | - Roy K Philip
- Division of Neonatology, Department of Paediatrics, University Maternity Hospital Limerick, Limerick, Ireland .,Division of Neonatology, Department of Paediatrics, University of Limerick School of Medicine, Limerick, Ireland
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8
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Montesinos-Guevara C, Buitrago-Garcia D, Felix ML, Guerra CV, Hidalgo R, Martinez-Zapata MJ, Simancas-Racines D. Vaccines for the common cold. Cochrane Database Syst Rev 2022; 12:CD002190. [PMID: 36515550 PMCID: PMC9749450 DOI: 10.1002/14651858.cd002190.pub6] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
BACKGROUND The common cold is a spontaneously remitting infection of the upper respiratory tract, characterised by a runny nose, nasal congestion, sneezing, cough, malaise, sore throat, and fever (usually < 37.8 ºC). Whilst the common cold is generally not harmful, it is a cause of economic burden due to school and work absenteeism. In the United States, economic loss due to the common cold is estimated at more than USD 40 billion per year, including an estimate of 70 million workdays missed by employees, 189 million school days missed by children, and 126 million workdays missed by parents caring for children with a cold. Additionally, data from Europe show that the total cost per episode may be up to EUR 1102. There is also a large expenditure due to inappropriate antimicrobial prescription. Vaccine development for the common cold has been difficult due to antigenic variability of the common cold viruses; even bacteria can act as infective agents. Uncertainty remains regarding the efficacy and safety of interventions for preventing the common cold in healthy people, thus we performed an update of this Cochrane Review, which was first published in 2011 and updated in 2013 and 2017. OBJECTIVES To assess the clinical effectiveness and safety of vaccines for preventing the common cold in healthy people. SEARCH METHODS We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (April 2022), MEDLINE (1948 to April 2022), Embase (1974 to April 2022), CINAHL (1981 to April 2022), and LILACS (1982 to April 2022). We also searched three trials registers for ongoing studies, and four websites for additional trials (April 2022). We did not impose any language or date restrictions. SELECTION CRITERIA Randomised controlled trials (RCTs) of any virus vaccine compared with placebo to prevent the common cold in healthy people. DATA COLLECTION AND ANALYSIS We used Cochrane's Screen4Me workflow to assess the initial search results. Four review authors independently performed title and abstract screening to identify potentially relevant studies. We retrieved the full-text articles for those studies deemed potentially relevant, and the review authors independently screened the full-text reports for inclusion in the review, recording reasons for exclusion of the excluded studies. Any disagreements were resolved by discussion or by consulting a third review author when needed. Two review authors independently collected data on a data extraction form, resolving any disagreements by consensus or by involving a third review author. We double-checked data transferred into Review Manager 5 software. Three review authors independently assessed risk of bias using RoB 1 tool as outlined in the Cochrane Handbook for Systematic Reviews of Interventions. We carried out statistical analysis using Review Manager 5. We did not conduct a meta-analysis, and we did not assess publication bias. We used GRADEpro GDT software to assess the certainty of the evidence and to create a summary of findings table. MAIN RESULTS: We did not identify any new RCTs for inclusion in this update. This review includes one RCT conducted in 1965 with an overall high risk of bias. The RCT included 2307 healthy young men in a military facility, all of whom were included in the analyses, and compared the effect of three adenovirus vaccines (live, inactivated type 4, and inactivated type 4 and 7) against a placebo (injection of physiological saline or gelatin capsule). There were 13 (1.14%) events in 1139 participants in the vaccine group, and 14 (1.19%) events in 1168 participants in the placebo group. Overall, we do not know if there is a difference between the adenovirus vaccine and placebo in reducing the incidence of the common cold (risk ratio 0.95, 95% confidence interval 0.45 to 2.02; very low-certainty evidence). Furthermore, no difference in adverse events when comparing live vaccine preparation with placebo was reported. We downgraded the certainty of the evidence to very low due to unclear risk of bias, indirectness because the population of this study was only young men, and imprecision because confidence intervals were wide and the number of events was low. The included study did not assess vaccine-related or all-cause mortality. AUTHORS' CONCLUSIONS: This Cochrane Review was based on one study with very low-certainty evidence, which showed that there may be no difference between the adenovirus vaccine and placebo in reducing the incidence of the common cold. We identified a need for well-designed, adequately powered RCTs to investigate vaccines for the common cold in healthy people. Future trials on interventions for preventing the common cold should assess a variety of virus vaccines for this condition, and should measure such outcomes as common cold incidence, vaccine safety, and mortality (all-cause and related to the vaccine).
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Affiliation(s)
- Camila Montesinos-Guevara
- Cochrane Ecuador, Centro de Investigación en Salud Pública y Epidemiología Clínica (CISPEC), Facultad de Ciencias de la Salud Eugenio Espejo, Universidad UTE, Quito, Ecuador
| | - Diana Buitrago-Garcia
- Institute of Social and Preventive Medicine (ISPM), Graduate School of Health Sciences, University of Bern, Bern, Switzerland
| | - Maria L Felix
- Departamento de Neonatología, Facultad de Ciencias de la Salud Eugenio Espejo, Universidad UTE, Quito, Ecuador
| | - Claudia V Guerra
- Cochrane Ecuador, Centro de Investigación en Salud Pública y Epidemiología Clínica (CISPEC), Facultad de Ciencias de la Salud Eugenio Espejo, Universidad UTE, Quito, Ecuador
| | - Ricardo Hidalgo
- Cochrane Ecuador, Centro de Investigación en Salud Pública y Epidemiología Clínica (CISPEC), Facultad de Ciencias de la Salud Eugenio Espejo, Universidad UTE, Quito, Ecuador
| | - Maria José Martinez-Zapata
- Cochrane Ecuador, Centro de Investigación en Salud Pública y Epidemiología Clínica (CISPEC), Facultad de Ciencias de la Salud Eugenio Espejo, Universidad UTE, Quito, Ecuador
- Iberoamerican Cochrane Centre, Biomedical Research Institute Sant Pau (IIB Sant Pau), CIBER Epidemiología y Salud Pública (CIBERESP), Barcelona, Spain
| | - Daniel Simancas-Racines
- Cochrane Ecuador, Centro de Investigación en Salud Pública y Epidemiología Clínica (CISPEC), Facultad de Ciencias de la Salud Eugenio Espejo, Universidad UTE, Quito, Ecuador
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Qiu X, Xu S, Lu Y, Luo Z, Yan Y, Wang C, Ji J. Development of mRNA vaccines against respiratory syncytial virus (RSV). Cytokine Growth Factor Rev 2022; 68:37-53. [PMID: 36280532 DOI: 10.1016/j.cytogfr.2022.10.001] [Citation(s) in RCA: 25] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2022] [Revised: 10/04/2022] [Accepted: 10/05/2022] [Indexed: 02/06/2023]
Abstract
Respiratory syncytial virus (RSV) is a single-stranded negative-sense RNA virus that is the primary etiologic pathogen of bronchitis and pneumonia in infants and the elderly. Currently, no preventative vaccine has been approved for RSV infection. However, advances in the characterization, and structural resolution, of the RSV surface fusion glycoprotein have revolutionized RSV vaccine development by providing a new target for preventive interventions. In general, six different approaches have been adopted in the development of preventative RSV therapeutics, namely, particle-based vaccines, vector-based vaccines, live-attenuated or chimeric vaccines, subunit vaccines, mRNA vaccines, and monoclonal antibodies. Among these preventive interventions, MVA-BN-RSV, RSVpreF3, RSVpreF, Ad26. RSV.preF, nirsevimab, clesrovimab and mRNA-1345 is being tested in phase 3 clinical trials, and displays the most promising in infant or elderly populations. Accompanied by the huge success of mRNA vaccines in COVID-19, mRNA vaccines have been rapidly developed, with many having entered clinical studies, in which they have demonstrated encouraging results and acceptable safety profiles. In fact, Moderna has received FDA approval, granting fast-track designation for an investigational single-dose mRNA-1345 vaccine against RSV in adults over 60 years of age. Hence, mRNA vaccines may represent a new, more successful, chapter in the continued battle to develop effective preventative measures against RSV. This review discusses the structure, life cycle, and brief history of RSV, while also presenting the current advancements in RSV preventatives, with a focus on the latest progress in RSV mRNA vaccine development. Finally, future prospects for this field are presented.
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Affiliation(s)
- Xirui Qiu
- Jiangsu Key Laboratory of Pediatric Respiratory Disease, Institute of Pediatrics, Nanjing University of Chinese Medicine, Nanjing, China
| | - Siyan Xu
- Jiangsu Key Laboratory of Pediatric Respiratory Disease, Institute of Pediatrics, Nanjing University of Chinese Medicine, Nanjing, China
| | - Yang Lu
- Jiangsu Key Laboratory of Pediatric Respiratory Disease, Institute of Pediatrics, Nanjing University of Chinese Medicine, Nanjing, China
| | - Zichen Luo
- Jiangsu Key Laboratory of Pediatric Respiratory Disease, Institute of Pediatrics, Nanjing University of Chinese Medicine, Nanjing, China
| | - Yangtian Yan
- Jiangsu Key Laboratory of Pediatric Respiratory Disease, Institute of Pediatrics, Nanjing University of Chinese Medicine, Nanjing, China
| | - Chuyue Wang
- Jiangsu Key Laboratory of Pediatric Respiratory Disease, Institute of Pediatrics, Nanjing University of Chinese Medicine, Nanjing, China
| | - Jianjian Ji
- Jiangsu Key Laboratory of Pediatric Respiratory Disease, Institute of Pediatrics, Nanjing University of Chinese Medicine, Nanjing, China.
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10
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Choy RKM, Bourgeois AL, Ockenhouse CF, Walker RI, Sheets RL, Flores J. Controlled Human Infection Models To Accelerate Vaccine Development. Clin Microbiol Rev 2022; 35:e0000821. [PMID: 35862754 PMCID: PMC9491212 DOI: 10.1128/cmr.00008-21] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The timelines for developing vaccines against infectious diseases are lengthy, and often vaccines that reach the stage of large phase 3 field trials fail to provide the desired level of protective efficacy. The application of controlled human challenge models of infection and disease at the appropriate stages of development could accelerate development of candidate vaccines and, in fact, has done so successfully in some limited cases. Human challenge models could potentially be used to gather critical information on pathogenesis, inform strain selection for vaccines, explore cross-protective immunity, identify immune correlates of protection and mechanisms of protection induced by infection or evoked by candidate vaccines, guide decisions on appropriate trial endpoints, and evaluate vaccine efficacy. We prepared this report to motivate fellow scientists to exploit the potential capacity of controlled human challenge experiments to advance vaccine development. In this review, we considered available challenge models for 17 infectious diseases in the context of the public health importance of each disease, the diversity and pathogenesis of the causative organisms, the vaccine candidates under development, and each model's capacity to evaluate them and identify correlates of protective immunity. Our broad assessment indicated that human challenge models have not yet reached their full potential to support the development of vaccines against infectious diseases. On the basis of our review, however, we believe that describing an ideal challenge model is possible, as is further developing existing and future challenge models.
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Affiliation(s)
- Robert K. M. Choy
- PATH, Center for Vaccine Innovation and Access, Seattle, Washington, USA
| | - A. Louis Bourgeois
- PATH, Center for Vaccine Innovation and Access, Seattle, Washington, USA
| | | | - Richard I. Walker
- PATH, Center for Vaccine Innovation and Access, Seattle, Washington, USA
| | | | - Jorge Flores
- PATH, Center for Vaccine Innovation and Access, Seattle, Washington, USA
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11
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Leroux-Roels I, Davis MG, Steenackers K, Essink B, Vandermeulen C, Fogarty C, Andrews CP, Kerwin E, David MP, Fissette L, Abeele CV, Collete D, de Heusch M, Salaun B, De Schrevel N, Koch J, Verheust C, Dezutter N, Struyf F, Mesaros N, Tica J, Hulstrøm V. Safety and immunogenicity of a respiratory syncytial virus prefusion F (RSVPreF3) candidate vaccine in older adults: phase I/II randomized clinical trial. J Infect Dis 2022; 227:761-772. [PMID: 35904987 PMCID: PMC10044090 DOI: 10.1093/infdis/jiac327] [Citation(s) in RCA: 43] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2022] [Revised: 07/21/2022] [Accepted: 07/28/2022] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND The aim was to investigate safety and immunogenicity of vaccine formulations against respiratory syncytial virus (RSV) containing the stabilized prefusion conformation of RSV fusion protein (RSVPreF3). METHODS This phase I/II, randomized, controlled, observer-blind study enrolled 48 young adults (YA; 18-40 years) and 1005 older adults (OA; 60-80 years) between January and August 2019. Participants were randomized into equally sized groups to receive two doses of unadjuvanted (YA and OA) or AS01-adjuvanted (OA) vaccine or placebo two months apart. Vaccine safety and immunogenicity were assessed until one (YA) or 12 months (OA) after second vaccination. RESULTS The RSVPreF3 vaccines boosted humoral (RSVPreF3-specific IgG and RSV-A neutralizing antibody) responses, which increased in an antigen-concentration-dependent manner and were highest post-dose one. Compared to pre-vaccination, the geometric mean frequencies of polyfunctional CD4+ T-cells increased after each dose and were significantly higher in adjuvanted than unadjuvanted vaccinees. Post-vaccination immune responses persisted until end of follow-up. Solicited adverse events (AEs) were mostly mild-to-moderate and transient. Despite a higher observed reactogenicity of AS01-containing vaccines, no safety concerns were identified for any assessed formulation. CONCLUSIONS Based on safety and immunogenicity profiles, the AS01E-adjuvanted vaccine containing 120 μg of RSVPreF3 was selected for further clinical development. TRIAL REGISTRATION ClinicalTrials.gov NCT03814590; URL: https://clinicaltrials.gov/ct2/show/NCT03814590.
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Affiliation(s)
- Isabel Leroux-Roels
- Center for Vaccinology (CEVAC), Ghent University Hospital, 9000 Ghent, Belgium
| | - Matthew G Davis
- Rochester Clinical Research, Rochester, NY 14609, United States
| | - Katie Steenackers
- Vaccine and Infectious Disease Institute, University of Antwerp, 2610 Wilrijk, Belgium
| | - Brandon Essink
- Meridian Clinical Research Omaha, Omaha, NE 68134, United States
| | - Corinne Vandermeulen
- Leuven University Vaccinology Center, Department of Public Health & Primary Care, KU Leuven, 3000 Leuven, Belgium
| | - Charles Fogarty
- Lung and Chest Medical Associates, Spartanburg Medical Research, Spartanburg, SC 29303, United States
| | | | - Edward Kerwin
- Crisor, LLC c/o Clinical Research Institute of Southern Oregon, Medford, OR 97504, United States
| | | | | | | | | | | | | | | | - Juliane Koch
- UCB Pharma GmbH, Alfred-Nobel-Strasse 10, 40789 Monheim am Rhein, Germany
| | | | | | - Frank Struyf
- Janssen Research & Development, Turnhoutseweg 30, B-2340 Beerse, Belgium
| | - Narcisa Mesaros
- Janssen Research & Development, Turnhoutseweg 30, B-2340 Beerse, Belgium
| | - Jelena Tica
- Janssen-Cilag GmbH, Johnson & Johnson Platz 1, 41470 Neuss, Germany
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12
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Saeland E, van der Fits L, Bolder R, Heemskerk-van der Meer M, Drijver J, van Polanen Y, Vaneman C, Tettero L, Serroyen J, Schuitemaker H, Callendret B, Langedijk JPM, Zahn RC. Immunogenicity and protective efficacy of adenoviral and subunit RSV vaccines based on stabilized prefusion F protein in pre-clinical models. Vaccine 2021; 40:934-944. [PMID: 34973849 DOI: 10.1016/j.vaccine.2021.12.043] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Revised: 10/29/2021] [Accepted: 12/16/2021] [Indexed: 11/29/2022]
Abstract
Respiratory Syncytial Virus (RSV) remains a leading cause of severe respiratory disease for which no licensed vaccine is available. We have previously described the derivation of an RSV Fusion protein (F) stabilized in its prefusion conformation (preF) as vaccine immunogen and demonstrated superior immunogenicity in naive mice of preF versus wild type RSV F protein, both as protein and when expressed from an Ad26 vaccine vector. Here we address the question if there are qualitative differences between the two vaccine platforms for induction of protective immunity. In naïve mice, both Ad26.RSV.preF and preF protein induced humoral responses, whereas cellular responses were only elicited by Ad26.RSV.preF. In RSV pre-exposed mice, a single dose of either vaccine induced cellular responses and strong humoral responses. Ad26-induced RSV-specific cellular immune responses were detected systemically and locally in the lungs. Both vaccines showed protective efficacy in the cotton rat model, but Ad26.RSV.preF conferred protection at lower virus neutralizing titers in comparison to RSV preF protein. Factors that may contribute to the protective capacity of Ad26.RSV.preF elicited immunity are the induced IgG2a antibodies that are able to engage Fcγ receptors mediating Antibody Dependent Cellular Cytotoxicity (ADCC), and the induction of systemic and lung resident RSV specific CD8 + T cells. These data demonstrate qualitative improvement of immune responses elicited by an adenoviral vector based vaccine encoding the RSV preF antigen compared to the subunit vaccine in small animal models which may inform RSV vaccine development.
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Affiliation(s)
| | | | - Renske Bolder
- Janssen Vaccines & Prevention, Leiden, the Netherlands
| | | | - Joke Drijver
- Janssen Vaccines & Prevention, Leiden, the Netherlands
| | | | | | | | - Jan Serroyen
- Janssen Vaccines & Prevention, Leiden, the Netherlands
| | | | | | | | - Roland C Zahn
- Janssen Vaccines & Prevention, Leiden, the Netherlands
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13
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Aliprantis AO, Wolford D, Caro L, Maas BM, Ma H, Montgomery DL, Sterling LM, Hunt A, Cox KS, Vora KA, Roadcap BA, Railkar RA, Lee AW, Stoch SA, Lai E. A Phase 1 Randomized, Double-Blind, Placebo-Controlled Trial to Assess the Safety, Tolerability, and Pharmacokinetics of a Respiratory Syncytial Virus Neutralizing Monoclonal Antibody MK-1654 in Healthy Adults. Clin Pharmacol Drug Dev 2020; 10:556-566. [PMID: 33125189 DOI: 10.1002/cpdd.883] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 09/24/2020] [Indexed: 12/26/2022]
Abstract
Respiratory syncytial virus (RSV) is the leading cause of acute lower respiratory tract infection and related morbidity and mortality in infants. Passive immunization with an RSV-neutralizing antibody can provide rapid protection to this vulnerable population. Proof-of-concept for this approach has been demonstrated by palivizumab; however, the use of this antibody is generally restricted to the highest-risk infants due to monthly dosing requirements and its cost. To address the large unmet medical need for most infants, we are evaluating MK-1654, a fully human RSV-neutralizing antibody with half-life extending mutations targeting site IV of the fusion protein. In this 2-part, placebo-controlled, double-blind, first-in-human study, 152 healthy adults were randomized 3:1 to receive a single dose of MK-1654 or placebo in 5 cohorts (100 or 300 mg as an intramuscular dose or 300, 1000, or 3000 mg as an intravenous dose). Safety, pharmacokinetics, antidrug antibodies, and RSV serum-neutralizing antibody titers were evaluated through 1 year. MK-1654 serum concentrations increased proportionally with dose and resulted in corresponding elevations in RSV serum-neutralizing antibody titers. The antibody displayed a half-life of 73 to 88 days and an estimated bioavailability of 69% at the 300-mg dose. The overall safety profile of MK-1654 was similar to placebo, and treatment-emergent antidrug antibodies were low (2.6%) with no associated adverse events. These data support the continued development of MK-1654 for the prevention of RSV disease in infants.
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Affiliation(s)
| | | | | | | | - Hua Ma
- Merck & Co., Inc., Kenilworth, New Jersey, USA
| | | | | | | | - Kara S Cox
- Merck & Co., Inc., Kenilworth, New Jersey, USA
| | | | | | | | | | | | - Eseng Lai
- Merck & Co., Inc., Kenilworth, New Jersey, USA
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14
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Soto JA, Stephens LM, Waldstein KA, Canedo-Marroquín G, Varga SM, Kalergis AM. Current Insights in the Development of Efficacious Vaccines Against RSV. Front Immunol 2020; 11:1507. [PMID: 32765520 PMCID: PMC7379152 DOI: 10.3389/fimmu.2020.01507] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 06/09/2020] [Indexed: 01/24/2023] Open
Affiliation(s)
- Jorge A Soto
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Instituto Milenio de Inmunología e Inmunoterapia, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Laura M Stephens
- Interdisciplinary Graduate Program in Immunology, University of Iowa, Iowa City, IA, United States
| | - Kody A Waldstein
- Interdisciplinary Graduate Program in Immunology, University of Iowa, Iowa City, IA, United States
| | - Gisela Canedo-Marroquín
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Instituto Milenio de Inmunología e Inmunoterapia, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Steven M Varga
- Interdisciplinary Graduate Program in Immunology, University of Iowa, Iowa City, IA, United States.,Department of Microbiology and Immunology, University of Iowa, Iowa City, IA, United States.,Department of Pathology, University of Iowa, Iowa City, IA, United States
| | - Alexis M Kalergis
- Departamento de Genética Molecular y Microbiología, Facultad de Ciencias Biológicas, Instituto Milenio de Inmunología e Inmunoterapia, Pontificia Universidad Católica de Chile, Santiago, Chile.,Departamento de Endocrinología, Facultad de Medicina, Instituto Milenio de Inmunología e Inmunoterapia, Pontificia Universidad Católica de Chile, Santiago, Chile
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15
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Antibody Response to the Furin Cleavable Twenty-Seven Amino Acid Peptide (p27) of the Fusion Protein in Respiratory Syncytial Virus (RSV) Infected Adult Hematopoietic Cell Transplant (HCT) Recipients. Vaccines (Basel) 2020; 8:vaccines8020192. [PMID: 32326278 PMCID: PMC7349179 DOI: 10.3390/vaccines8020192] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2020] [Revised: 04/14/2020] [Accepted: 04/17/2020] [Indexed: 02/04/2023] Open
Abstract
Background: Cleavage of the inactive precursor fusion protein (F0) of respiratory syncytial virus (RSV) at two furin-recognition sites is required for membrane fusion activity, and the cleavage releases the twenty-seven amino acid peptide (p27). However, a recent study shows that p27 was an immunodominant epitope in RSV infected children, indicating that p27 was recognized as an immunogen. In the present study, we investigated the immunogenicity of p27 in an immunocompromised population of adults by measuring serum and mucosal antibody responses to p27 in samples from adult hematopoietic cell transplant (HCT) recipients. Methods: We prospectively enrolled a cohort of RSV infected HCT recipients. Serum and nasal-wash samples were obtained within the first week of RSV infection (acute) and 3 to 5 weeks post-infection (convalescent). We quantified the serum and mucosal IgG and IgA anti-p27 antibodies by a RSV/A p27 peptide enzyme-linked immunosorbent assay (ELISA) and serum and mucosal p27 like antibodies (P27LA) by a p27 competitive antibody (P27CA) assay. Results: The lower limit of detection for the ELISA and P27CA assays was 0.2 and 50 ng/mL, respectively with no cross-reaction detected with a panel of monoclonal antibodies targeting pre-fusion and post-fusion antigenic sites. P27 antibodies were detected at nanogram concentration in sera and nasal washes in the majority of RSV infected HCT recipients. However, there was no significant difference in the geometric mean antibody concentrations between the acute and convalescent sera (except for serum P27LA), between HCT recipients who shed RSV <14 days and ≥14 days, as well as between RSV/A and RSV/B infected HCT recipients. In addition, approximately 30% of HCT recipients had a 4-fold or greater decrease in mucosal IgG and IgA anti-p27 antibodies during viral clearance. Conclusion: In conclusion, in RSV naturally infected adult HCT recipients, the antibodies against p27 were detectable in both serum and nasal wash samples with higher concentration in serum than that in nasal washes. However, nearly 30% of RSV infected HCT recipients had a significant decrease in their mucosal anti-p27 antibody, suggesting that IgG and IgA anti-p27 antibodies were binding to either free viruses or RSV infected cells containing p27, and that anti-p27 antibodies in the respiratory tract were part of the mucosal antibody response in controlling RSV infection.
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16
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Steff AM, Cadieux-Dion C, de Lannoy G, Prato MK, Czeszak X, André B, Ingels DC, Louckx M, Dewé W, Picciolato M, Maleux K, Fissette L, Dieussaert I. Hamster neogenin, a host-cell protein contained in a respiratory syncytial virus candidate vaccine, induces antibody responses in rabbits but not in clinical trial participants. Hum Vaccin Immunother 2020; 16:1327-1337. [PMID: 31951765 PMCID: PMC7482880 DOI: 10.1080/21645515.2019.1693749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
A recombinant respiratory syncytial virus (RSV) fusion glycoprotein candidate vaccine (RSV-PreF) manufactured in Chinese hamster ovary cells was developed for immunization of pregnant women, to protect newborns against RSV disease through trans-placental antibody transfer. Traces of a host-cell protein, hamster neogenin (haNEO1), were identified in purified RSV-PreF antigen material. Given the high amino-acid sequence homology between haNEO1 and human neogenin (huNEO1), there was a risk that potential vaccine-induced anti-neogenin immunity could affect huNEO1 function in mother or fetus. Anti-huNEO1 IgGs were measured by enzyme-linked immunosorbent assay in sera from rabbits and trial participants (Phase 1 and 2 trials enrolling 128 men and 500 non-pregnant women, respectively; NCT01905215/NCT02360475) collected after immunization with RSV-PreF formulations containing different antigen doses with/without aluminum-hydroxide adjuvant. In rabbits, four injections administered at 14-day intervals induced huNEO1-specific IgG responses in an antigen-dose- and adjuvant-dependent manner, which plateaued in the highest-dose groups after three injections. In humans, no vaccination-induced anti-huNEO1 IgG responses were detected upon a single immunization, as the values in vaccine and control groups fluctuated around pre-vaccination levels up to 90/360 days post-vaccination. A minority of participants had anti-huNEO1 levels ≥ assay cutoff before vaccination, which did not increase post-vaccination. Thus, despite detecting vaccine-induced huNEO1-specific responses in rabbits, we found no evidence that the candidate vaccine had induced anti-huNEO1 immunity in human adults. The antigen purification process was nevertheless optimized, and haNEO1-reduced vaccines were used in a subsequent Phase 2 trial enrolling 400 non-pregnant women (NCT02956837), in which again no vaccine-induced anti-huNEO1 responses were detected.
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