1
|
Sena J, Karwal L, Bell C, Devitt N, Schilkey F, Huang C, Livengood J, Das S, Dean HJ. Identification and quantitation of multiple variants in RNA virus genomes. Biol Methods Protoc 2024; 9:bpae004. [PMID: 38414646 PMCID: PMC10898329 DOI: 10.1093/biomethods/bpae004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 01/17/2024] [Accepted: 01/30/2024] [Indexed: 02/29/2024] Open
Abstract
The goal of the study was to identify and characterize RNA virus variants containing mutations spread over genomic distances >5 kb. As proof of concept, high-quality viral RNA of the Dengue 2 component of Takeda's tetravalent dengue vaccine candidate (TDV-2) was used to develop a reverse transcription-polymerase chain reaction protocol to amplify a ∼5.3 kb cDNA segment that contains the three genetic determinants of TDV-2 attenuation. Unique molecular identifiers were incorporated into each viral cDNA molecule for PacBio library preparation to improve the quantitative precision of the observed variants at the attenuation loci. Following assay optimization, PacBio long-read sequencing was validated with multiple clone-derived TDV-2 revertant variants and four complex revertant mixtures containing various compositions of TDV-2 and revertant viruses. PacBio sequencing analysis correctly identified and quantified variant composition in all tested samples, demonstrating that TDV-2 revertants could be identified and characterized and supporting the use of this method in the differentiation and quantification of complex variants of other RNA viruses. Long-read sequencing can identify complex RNA virus variants containing multiple mutations on a single-genome molecule, which is useful for in-depth genetic stability and revertant detection of live-attenuated viral vaccines, as well as research in virus evolution to reveal mechanisms of immune evasion and host cell adaption.
Collapse
Affiliation(s)
- Johnny Sena
- National Center for Genome Resources, Santa Fe, NM, United States
| | - Lovkesh Karwal
- Vaccine Business Unit, Takeda Pharmaceuticals, Cambridge, MA, United States
| | - Callum Bell
- National Center for Genome Resources, Santa Fe, NM, United States
| | - Nicholas Devitt
- National Center for Genome Resources, Santa Fe, NM, United States
| | - Faye Schilkey
- National Center for Genome Resources, Santa Fe, NM, United States
| | - Claire Huang
- Arboviral Diseases Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, United States
| | - Jill Livengood
- Vaccine Business Unit, Takeda Pharmaceuticals, Cambridge, MA, United States
| | - Subash Das
- Vaccine Business Unit, Takeda Pharmaceuticals, Cambridge, MA, United States
| | - Hansi J Dean
- Vaccine Business Unit, Takeda Pharmaceuticals, Cambridge, MA, United States
| |
Collapse
|
2
|
Single dose of chimeric dengue-2/Zika vaccine candidate protects mice and non-human primates against Zika virus. Nat Commun 2021; 12:7320. [PMID: 34916486 PMCID: PMC8677809 DOI: 10.1038/s41467-021-27578-w] [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] [Received: 06/25/2021] [Accepted: 11/30/2021] [Indexed: 12/30/2022] Open
Abstract
The development of a safe and effective Zika virus (ZIKV) vaccine has become a global health priority since the widespread epidemic in 2015-2016. Based on previous experience in using the well-characterized and clinically proven dengue virus serotype-2 (DENV-2) PDK-53 vaccine backbone for live-attenuated chimeric flavivirus vaccine development, we developed chimeric DENV-2/ZIKV vaccine candidates optimized for growth and genetic stability in Vero cells. These vaccine candidates retain all previously characterized attenuation phenotypes of the PDK-53 vaccine virus, including attenuation of neurovirulence for 1-day-old CD-1 mice, absence of virulence in interferon receptor-deficient mice, and lack of transmissibility in the main mosquito vectors. A single DENV-2/ZIKV dose provides protection against ZIKV challenge in mice and rhesus macaques. Overall, these data indicate that the ZIKV live-attenuated vaccine candidates are safe, immunogenic and effective at preventing ZIKV infection in multiple animal models, warranting continued development.
Collapse
|
3
|
Choy MM, Ng DHL, Siriphanitchakorn T, Ng WC, Sundstrom KB, Tan HC, Zhang SL, Chan KWK, Manuel M, Kini RM, Chan KR, Vasudevan SG, Ooi EE. A Non-structural 1 Protein G53D Substitution Attenuates a Clinically Tested Live Dengue Vaccine. Cell Rep 2021; 31:107617. [PMID: 32402284 DOI: 10.1016/j.celrep.2020.107617] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2019] [Revised: 03/03/2020] [Accepted: 04/15/2020] [Indexed: 12/26/2022] Open
Abstract
The molecular basis of dengue virus (DENV) attenuation remains ambiguous and hampers a targeted approach to derive safe but nonetheless immunogenic live vaccine candidates. Here, we take advantage of DENV serotype 2 PDK53 vaccine strain, which recently and successfully completed a phase-3 clinical trial, to identify how this virus is attenuated compared to its wild-type parent, DENV2 16681. Site-directed mutagenesis on a 16681 infectious clone identifies a single G53D substitution in the non-structural 1 (NS1) protein that reduces 16681 infection and dissemination in both Aedes aegypti, as well as in mammalian cells to produce the characteristic phenotypes of PDK53. Mechanistically, NS1 G53D impairs the function of a known host factor, the endoplasmic reticulum (ER)-resident ribophorin 1 protein, to properly glycosylate NS1 and thus induce a host antiviral gene through ER stress responses. Our findings provide molecular insights on DENV attenuation on a clinically tested strain.
Collapse
Affiliation(s)
- Milly M Choy
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Dorothy H L Ng
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore 169857, Singapore; Department of Infectious Diseases, Singapore General Hospital, Singapore 169108, Singapore
| | - Tanamas Siriphanitchakorn
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore 169857, Singapore; Department of Biological Sciences, National University of Singapore, Singapore 117558, Singapore
| | - Wy Ching Ng
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Karin B Sundstrom
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Hwee Cheng Tan
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Summer L Zhang
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Kitti W K Chan
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Menchie Manuel
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore 169857, Singapore
| | - R Manjunatha Kini
- Department of Biological Sciences, National University of Singapore, Singapore 117558, Singapore
| | - Kuan Rong Chan
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore 169857, Singapore
| | - Subhash G Vasudevan
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore 169857, Singapore; Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore
| | - Eng Eong Ooi
- Programme in Emerging Infectious Diseases, Duke-NUS Medical School, Singapore 169857, Singapore; Saw Swee Hock School of Public Health, National University of Singapore, Singapore 117549, Singapore; Department of Microbiology and Immunology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore 119228, Singapore.
| |
Collapse
|
4
|
Pinheiro-Michelsen JR, Souza RDSO, Santana IVR, da Silva PDS, Mendez EC, Luiz WB, Amorim JH. Anti-dengue Vaccines: From Development to Clinical Trials. Front Immunol 2020; 11:1252. [PMID: 32655561 PMCID: PMC7325986 DOI: 10.3389/fimmu.2020.01252] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Accepted: 05/18/2020] [Indexed: 12/19/2022] Open
Abstract
Dengue Virus (DENV) is an arbovirus (arthropod-borne virus). Four serotypes of DENV are responsible for the infectious disease called dengue that annually affects nearly 400 million people worldwide. Although there is only one vaccine formulation licensed for use in humans, there are other vaccine formulations under development that apply different strategies. In this review, we present information about anti-dengue vaccine formulations regarding development, pre-clinical tests, and clinical trials. The improvement in vaccine development against dengue is much needed, but it should be considered that the correlate of protection is still uncertain. Neutralizing antibodies have been proposed as a correlate of protection, but this ignores the key role of T-cell mediated immunity in controlling DENV infection. It is important to confirm the accurate correlate of protection against DENV infection, and also to have other anti-dengue vaccine formulations licensed for use.
Collapse
Affiliation(s)
- Josilene Ramos Pinheiro-Michelsen
- Laboratório de Agentes Infecciosos e Vetores, Centro das Ciências Biológicas e da Saúde, Universidade Federal do Oeste da Bahia, Barreiras, Brazil
- Programa de Pós-graduação em Biologia e Biotecnologia de Microrganismos, Universidade Estadual de Santa Cruz, Barreiras, Brazil
| | - Rayane da Silva Oliveira Souza
- Laboratório de Agentes Infecciosos e Vetores, Centro das Ciências Biológicas e da Saúde, Universidade Federal do Oeste da Bahia, Barreiras, Brazil
| | - Itana Vivian Rocha Santana
- Laboratório de Agentes Infecciosos e Vetores, Centro das Ciências Biológicas e da Saúde, Universidade Federal do Oeste da Bahia, Barreiras, Brazil
| | - Patrícia de Souza da Silva
- Laboratório de Agentes Infecciosos e Vetores, Centro das Ciências Biológicas e da Saúde, Universidade Federal do Oeste da Bahia, Barreiras, Brazil
- Programa de Pós-graduação em Biologia e Biotecnologia de Microrganismos, Universidade Estadual de Santa Cruz, Barreiras, Brazil
| | - Erick Carvalho Mendez
- Programa de Pós-graduação em Biologia e Biotecnologia de Microrganismos, Universidade Estadual de Santa Cruz, Barreiras, Brazil
| | - Wilson Barros Luiz
- Programa de Pós-graduação em Biologia e Biotecnologia de Microrganismos, Universidade Estadual de Santa Cruz, Barreiras, Brazil
| | - Jaime Henrique Amorim
- Laboratório de Agentes Infecciosos e Vetores, Centro das Ciências Biológicas e da Saúde, Universidade Federal do Oeste da Bahia, Barreiras, Brazil
- Programa de Pós-graduação em Biologia e Biotecnologia de Microrganismos, Universidade Estadual de Santa Cruz, Barreiras, Brazil
| |
Collapse
|
5
|
Moi ML, Ami Y, Muhammad Azami NA, Shirai K, Yoksan S, Suzaki Y, Kitaura K, Lim CK, Saijo M, Suzuki R, Takasaki T, Kurane I. Marmosets (Callithrix jacchus) as a non-human primate model for evaluation of candidate dengue vaccines: induction and maintenance of specific protective immunity against challenges with clinical isolates. J Gen Virol 2017; 98:2955-2967. [PMID: 29160199 DOI: 10.1099/jgv.0.000913] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Dengue virus (DENV) is one of the major infectious diseases in tropical regions and approximately half of the world population is at risk of infection. Vaccines would offer an effective control measure against this disease. We previously reported on the utility of marmosets as an animal model for studying primary and secondary dengue infections. Infected marmosets consistently develop viraemia and antibody kinetics that reflect those of patients with dengue. Thus, it is important to determine the utility of marmosets as an animal model for demonstrating vaccine efficacy. In this study, marmosets were inoculated with candidate vaccine and parent strains and challenged with a clinical DENV strain. The viraemia and antibody kinetics in these marmosets were determined. Marmosets consistently develop lower viraemia with an attenuated vaccine strain. During secondary challenge, the IgM response was delayed, whereas the IgG levels rose rapidly, indicating a secondary antibody response. The neutralizing activities against the homotypic serotype were high; all marmosets were protected against viraemia following secondary inoculation. The viraemia markers and antibody responses were consistent with those of human DENV infection and vaccinees. These results demonstrate the utility of marmosets as an animal model for the study of vaccine efficacy.
Collapse
Affiliation(s)
- Meng Ling Moi
- Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Yasushi Ami
- Division of Experimental Animal Research, National Institute of Infectious Diseases, Musashimurayama, Tokyo, Japan
| | | | - Kenji Shirai
- Department of Rheumatology and Clinical Immunology, Clinical Research Center for Allergy and Rheumatology, Sagamihara National Hospital, National Hospital Organization, Kanagawa, Japan
| | - Sutee Yoksan
- Institute of Molecular Biosciences, Mahidol University, Salaya, Nakhon Pathom, Thailand
| | - Yuriko Suzaki
- Division of Experimental Animal Research, National Institute of Infectious Diseases, Musashimurayama, Tokyo, Japan
| | - Kazutaka Kitaura
- Department of Rheumatology and Clinical Immunology, Clinical Research Center for Allergy and Rheumatology, Sagamihara National Hospital, National Hospital Organization, Kanagawa, Japan
| | - Chang-Kweng Lim
- Department of Virology I, National Institute of Infectious Diseases, Tokyo, Japan
| | - Masayuki Saijo
- Department of Virology I, National Institute of Infectious Diseases, Tokyo, Japan
| | - Ryuji Suzuki
- Department of Rheumatology and Clinical Immunology, Clinical Research Center for Allergy and Rheumatology, Sagamihara National Hospital, National Hospital Organization, Kanagawa, Japan
| | | | - Ichiro Kurane
- National Institute of Infectious Diseases, Tokyo, Japan
| |
Collapse
|
6
|
Fall G, Di Paola N, Faye M, Dia M, Freire CCDM, Loucoubar C, Zanotto PMDA, Faye O, Sall AA. Biological and phylogenetic characteristics of West African lineages of West Nile virus. PLoS Negl Trop Dis 2017; 11:e0006078. [PMID: 29117195 PMCID: PMC5695850 DOI: 10.1371/journal.pntd.0006078] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 11/20/2017] [Accepted: 10/27/2017] [Indexed: 11/19/2022] Open
Abstract
The West Nile virus (WNV), isolated in 1937, is an arbovirus (arthropod-borne virus) that infects thousands of people each year. Despite its burden on global health, little is known about the virus’ biological and evolutionary dynamics. As several lineages are endemic in West Africa, we obtained the complete polyprotein sequence from three isolates from the early 1990s, each representing a different lineage. We then investigated differences in growth behavior and pathogenicity for four distinct West African lineages in arthropod (Ap61) and primate (Vero) cell lines, and in mice. We found that genetic differences, as well as viral-host interactions, could play a role in the biological properties in different WNV isolates in vitro, such as: (i) genome replication, (ii) protein translation, (iii) particle release, and (iv) virulence. Our findings demonstrate the endemic diversity of West African WNV strains and support future investigations into (i) the nature of WNV emergence, (ii) neurological tropism, and (iii) host adaptation. The West Nile virus (WNV) can cause severe neurological diseases including meningitis, encephalitis, and acute flaccid paralysis. Differences in WNV genetics could play a role in the frequency of neurological symptoms from an infection. For the first time, we observed how geographically similar but genetically distinct lineages grow in cellular environments that agree with the transmission chain of West Nile virus—vertebrate-arthropod-vertebrate. We were able to connect our in vitro and in vivo results with relevant epidemiological and molecular data. Our findings highlight the existence of West African lineages with higher virulence and replicative efficiency in vitro and in vivo compared to lineages similar to circulating strains in the United States and Europe. Our investigation of four West African lineages of West Nile virus will help us better understand the biology of the virus and assess future epidemiological threats.
Collapse
Affiliation(s)
- Gamou Fall
- Pôle de Virologie, Unité des Arbovirus et virus des fièvres hémorragiques, Institut Pasteur de Dakar, Dakar, Sénégal
| | - Nicholas Di Paola
- Laboratory of Molecular Evolution and Bioinformatics, Department of Microbiology, Biomedical Sciences Institute, University of Sao Paulo, Sao Paulo, Brazil
| | - Martin Faye
- Pôle de Virologie, Unité des Arbovirus et virus des fièvres hémorragiques, Institut Pasteur de Dakar, Dakar, Sénégal
| | - Moussa Dia
- Pôle de Virologie, Unité des Arbovirus et virus des fièvres hémorragiques, Institut Pasteur de Dakar, Dakar, Sénégal
| | | | - Cheikh Loucoubar
- Groupe à 4 ans de Biostatistiques, Bioinformatique et modélisation, Institut Pasteur de Dakar, Dakar, Sénégal
| | - Paolo Marinho de Andrade Zanotto
- Laboratory of Molecular Evolution and Bioinformatics, Department of Microbiology, Biomedical Sciences Institute, University of Sao Paulo, Sao Paulo, Brazil
- * E-mail:
| | - Ousmane Faye
- Pôle de Virologie, Unité des Arbovirus et virus des fièvres hémorragiques, Institut Pasteur de Dakar, Dakar, Sénégal
| | - Amadou Alpha Sall
- Pôle de Virologie, Unité des Arbovirus et virus des fièvres hémorragiques, Institut Pasteur de Dakar, Dakar, Sénégal
| |
Collapse
|
7
|
Dietrich EA, Ong YT, Stovall JL, Dean H, Huang CYH. Limited Transmission Potential of Takeda's Tetravalent Dengue Vaccine Candidate by Aedes albopictus. Am J Trop Med Hyg 2017; 97:1423-1427. [PMID: 28820715 DOI: 10.4269/ajtmh.17-0185] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Recombinant live-attenuated chimeric tetravalent dengue vaccine viruses, TDV-1, -2, -3, and -4, contain the premembrane and envelope genes of dengue virus serotypes 1-4 in the replicative background of the attenuated dengue virus type-2 (DENV-2) PDK-53 vaccine strain. Previous results have shown that these recombinant vaccine viruses demonstrate limited infection and dissemination in Aedes aegypti and are unlikely to be transmitted by the primary mosquito vector of DENVs. In this report, we expand this analysis by assessing vector competence of all four serotypes of the TDV virus in Aedes albopictus, the secondary mosquito vector of DENVs. Our results indicate that these vaccine viruses demonstrate incompetence or defective infection and dissemination in these mosquitoes and will likely not be transmissible.
Collapse
Affiliation(s)
- Elizabeth A Dietrich
- Arbovirus Diseases Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado
| | - Yee Tsuey Ong
- Arbovirus Diseases Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado
| | - Janae L Stovall
- Arbovirus Diseases Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado
| | - Hansi Dean
- Takeda Vaccines, Inc., Cambridge, Massachusetts
| | - Claire Y-H Huang
- Arbovirus Diseases Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado
| |
Collapse
|
8
|
Osorio JE, Wallace D, Stinchcomb DT. A recombinant, chimeric tetravalent dengue vaccine candidate based on a dengue virus serotype 2 backbone. Expert Rev Vaccines 2016; 15:497-508. [DOI: 10.1586/14760584.2016.1128328] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
|
9
|
Osorio JE, Partidos CD, Wallace D, Stinchcomb DT. Development of a recombinant, chimeric tetravalent dengue vaccine candidate. Vaccine 2015; 33:7112-20. [PMID: 26585500 DOI: 10.1016/j.vaccine.2015.11.022] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Dengue is a significant threat to public health worldwide. Currently, there are no licensed vaccines available for dengue. Takeda Vaccines Inc. is developing a live, attenuated tetravalent dengue vaccine candidate (TDV) that consists of an attenuated DENV-2 strain (TDV-2) and three chimeric viruses containing the prM and E protein genes of DENV-1, -3 and -4 expressed in the context of the attenuated TDV-2 genome backbone (TDV-1, TDV-3, and TDV-4, respectively). TDV has been shown to be immunogenic and efficacious in nonclinical animal models. In interferon-receptor deficient mice, the vaccine induces humoral neutralizing antibody responses and cellular immune responses that are sufficient to protect from lethal challenge with DENV-1, DENV-2 or DENV-4. In non-human primates, administration of TDV induces innate immune responses as well as long lasting antibody and cellular immunity. In Phase 1 clinical trials, the safety and immunogenicity of two different formulations were assessed after intradermal or subcutaneous administration to healthy, flavivirus-naïve adults. TDV administration was generally well-tolerated independent of dose and route. The vaccine induced neutralizing antibody responses to all four DENV serotypes: after a single administration of the higher formulation, 24-67%% of the subjects seroconverted to all four DENV and >80% seroconverted to three or more viruses. In addition, TDV induced CD8(+) T cell responses to the non-structural NS1, NS3 and NS5 proteins of DENV. TDV has been also shown to be generally well tolerated and immunogenic in a Phase 2 clinical trial in dengue endemic countries in adults and children as young as 18 months. Additional clinical studies are ongoing in preparation for a Phase 3 safety and efficacy study.
Collapse
|
10
|
George SL, Wong MA, Dube TJT, Boroughs KL, Stovall JL, Luy BE, Haller AA, Osorio JE, Eggemeyer LM, Irby-Moore S, Frey SE, Huang CYH, Stinchcomb DT. Safety and Immunogenicity of a Live Attenuated Tetravalent Dengue Vaccine Candidate in Flavivirus-Naive Adults: A Randomized, Double-Blinded Phase 1 Clinical Trial. J Infect Dis 2015; 212:1032-41. [PMID: 25791116 PMCID: PMC4559193 DOI: 10.1093/infdis/jiv179] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2014] [Accepted: 03/16/2015] [Indexed: 11/14/2022] Open
Abstract
BACKGROUND Dengue viruses (DENVs) infect >300 million people annually, causing 96 million cases of dengue disease and 22 000 deaths [1]. A safe vaccine that protects against DENV disease is a global health priority [2]. METHODS We enrolled 72 flavivirus-naive healthy adults in a phase 1 double-blinded, randomized, placebo-controlled dose-escalation trial (low and high dose) of a live attenuated recombinant tetravalent dengue vaccine candidate (TDV) given in 2 doses 90 days apart. Volunteers were followed for safety, vaccine component viremia, and development of neutralizing antibodies to the 4 DENV serotypes. RESULTS The majority of adverse events were mild, with no vaccine-related serious adverse events. Vaccinees reported injection site pain (52% vs 17%) and erythema (73% vs 25%) more frequently than placebo recipients. Low levels of TDV-serotype 2 (TDV-2), TDV-3, and TDV-4 viremia were observed after the first but not second administration of vaccine. Overall seroconversion rates and geometric mean neutralization titers after 2 doses were 84.2% and 54.1, respectively, for DENV serotype 1 (DENV-1); 92.1% and 292.8, respectively, for DENV-2; 86.8% and 32.3, respectively, for DENV-3; and 71.1% and 15.0, respectively, for DENV-4. More than 90.0% of high-dose recipients had trivalent or broader responses. CONCLUSIONS TDV was generally well tolerated, induced trivalent or broader neutralizing antibodies to DENV in most flavivirus-naive vaccinees, and is undergoing further development. CLINICAL TRIALS REGISTRATION NCT01110551.
Collapse
Affiliation(s)
- Sarah L. George
- Department of Internal Medicine, Division of Infectious Diseases, Allergy and Immunology, Saint Louis University School of Medicine
- St. Louis Veterans Administration Medical Center, Missouri
| | | | | | - Karen L. Boroughs
- Arboviral Diseases Branch, Division of Vector-Borne Disease, Centers for Disease Control and Prevention, Fort Collins, Colorado
| | - Janae L. Stovall
- Arboviral Diseases Branch, Division of Vector-Borne Disease, Centers for Disease Control and Prevention, Fort Collins, Colorado
| | - Betty E. Luy
- Arboviral Diseases Branch, Division of Vector-Borne Disease, Centers for Disease Control and Prevention, Fort Collins, Colorado
| | - Aurelia A. Haller
- Arboviral Diseases Branch, Division of Vector-Borne Disease, Centers for Disease Control and Prevention, Fort Collins, Colorado
| | | | - Linda M. Eggemeyer
- Department of Internal Medicine, Division of Infectious Diseases, Allergy and Immunology, Saint Louis University School of Medicine
| | - Sharon Irby-Moore
- Department of Internal Medicine, Division of Infectious Diseases, Allergy and Immunology, Saint Louis University School of Medicine
| | - Sharon E. Frey
- Department of Internal Medicine, Division of Infectious Diseases, Allergy and Immunology, Saint Louis University School of Medicine
| | - Claire Y.-H. Huang
- Arboviral Diseases Branch, Division of Vector-Borne Disease, Centers for Disease Control and Prevention, Fort Collins, Colorado
| | | |
Collapse
|
11
|
Kenney JL, Brault AC. The role of environmental, virological and vector interactions in dictating biological transmission of arthropod-borne viruses by mosquitoes. Adv Virus Res 2014; 89:39-83. [PMID: 24751194 DOI: 10.1016/b978-0-12-800172-1.00002-1] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Arthropod-borne viruses (arboviruses) are transmitted between vertebrate hosts and arthropod vectors. An inherently complex interaction among virus, vector, and the environment determines successful transmission of the virus. Once believed to be "flying syringes," recent advances in the field have demonstrated that mosquito genetics, microbiota, salivary components, and mosquito innate immune responses all play important roles in modulating arbovirus transmissibility. The literature on the interaction among virus, mosquito, and environment has expanded dramatically in the preceding decade and the utilization of next-generation sequencing and transgenic vector methodologies assuredly will increase the pace of knowledge acquisition in this field. This chapter outlines the interplay among the three factors in both direct physical and biochemical manners as well as indirectly through superinfection barriers and altered induction of innate immune responses in mosquito vectors. The culmination of the aforementioned interactions and the arms race between the mosquito innate immune response and the capacity of arboviruses to antagonize such a response ultimately results in the subjugation of mosquito cells for viral replication and subsequent transmission.
Collapse
Affiliation(s)
- Joan L Kenney
- Arbovirus Research Branch, Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, U.S. Centers for Disease Control and Prevention, Fort Collins, Colorado, USA
| | - Aaron C Brault
- Arbovirus Research Branch, Division of Vector-Borne Diseases, National Center for Emerging and Zoonotic Infectious Diseases, U.S. Centers for Disease Control and Prevention, Fort Collins, Colorado, USA.
| |
Collapse
|
12
|
Osorio JE, Velez ID, Thomson C, Lopez L, Jimenez A, Haller AA, Silengo S, Scott J, Boroughs KL, Stovall JL, Luy BE, Arguello J, Beatty ME, Santangelo J, Gordon GS, Huang CYH, Stinchcomb DT. Safety and immunogenicity of a recombinant live attenuated tetravalent dengue vaccine (DENVax) in flavivirus-naive healthy adults in Colombia: a randomised, placebo-controlled, phase 1 study. THE LANCET. INFECTIOUS DISEASES 2014; 14:830-8. [PMID: 25087476 PMCID: PMC4648257 DOI: 10.1016/s1473-3099(14)70811-4] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
BACKGROUND Dengue virus is the most serious mosquito-borne viral threat to public health and no vaccines or antiviral therapies are approved for dengue fever. The tetravalent DENVax vaccine contains a molecularly characterised live attenuated dengue serotype-2 virus (DENVax-2) and three recombinant vaccine viruses expressing the prM and E structural genes for serotypes 1, 3, and 4 in the DENVax-2 genetic backbone. We aimed to assess the safety and immunogenicity of tetravalent DENVax formulations. METHODS We undertook a randomised, double-blind, phase 1, dose-escalation trial between Oct 11, 2011, and Nov 9, 2011, in the Rionegro, Antioquia, Colombia. The first cohort of participants (aged 18-45 years) were randomly assigned centrally, via block randomisation, to receive a low-dose formulation of DENvax, or placebo, by either subcutaneous or intradermal administration. After a safety assessment, participants were randomly assigned to receive a high-dose DENVax formulation, or placebo, by subcutaneous or intradermal administration. Group assignment was not masked from study pharmacists, but allocation was concealed from participants, nurses, and investigators. Primary endpoints were frequency and severity of injection-site and systemic reactions within 28 days of each vaccination. Secondary endpoints were the immunogenicity of DENVax against all four dengue virus serotypes, and the viraemia due to each of the four vaccine components after immunisation. Analysis was by intention to treat for safety and per protocol for immunogenicity. Because of the small sample size, no detailed comparison of adverse event rates were warranted. The trial is registered with ClinicalTrials.gov, number NCT01224639. FINDINGS We randomly assigned 96 patients to one of the four study groups: 40 participants (42%) received low-dose vaccine and eight participants (8%) received placebo in the low-dose groups; 39 participants (41%) received high-dose vaccine, with nine (9%) participants assigned to receive placebo. Both formulations were well tolerated with mostly mild and transient local or systemic reactions. No clinically meaningful differences were recorded in the overall incidence of local and systemic adverse events between patients in the vaccine and placebo groups; 68 (86%) of 79 participants in the vaccine groups had solicited systemic adverse events compared with 13 (76%) of 17 of those in the placebo groups. By contrast, 67 participants (85%) in the vaccine group had local solicited reactions compared with five (29%) participants in the placebo group. Immunisation with either high-dose or low-dose DENVax formulations induced neutralising antibody responses to all four dengue virus serotypes; 30 days after the second dose, 47 (62%) of 76 participants given vaccine seroconverted to all four serotypes and 73 (96%) participants seroconverted to three or more dengue viruses. Infectious DENVax viruses were detected in only ten (25%) of 40 participants in the low-dose group and 13 (33%) of 39 participants in the high-dose group. INTERPRETATION Our findings emphasise the acceptable tolerability and immunogenicity of the tetravalent DENVax formulations in healthy, flavivirus-naive adults. Further clinical testing of DENVax in different age groups and in dengue-endemic areas is warranted. FUNDING Takeda Vaccines.
Collapse
Affiliation(s)
| | - Ivan D Velez
- Programa de Estudio y Control de Enfermedades Tropicales (PECET), Universidad de Antioquia, Medellín, Colombia
| | | | - Liliana Lopez
- Programa de Estudio y Control de Enfermedades Tropicales (PECET), Universidad de Antioquia, Medellín, Colombia
| | - Alejandra Jimenez
- Programa de Estudio y Control de Enfermedades Tropicales (PECET), Universidad de Antioquia, Medellín, Colombia
| | | | | | | | - Karen L Boroughs
- Division of Vector Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, USA
| | - Janae L Stovall
- Division of Vector Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, USA
| | - Betty E Luy
- Division of Vector Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, USA
| | | | | | | | | | - Claire Y-H Huang
- Division of Vector Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, CO, USA
| | | |
Collapse
|
13
|
Huang CYH, Kinney RM, Livengood JA, Bolling B, Arguello JJ, Luy BE, Silengo SJ, Boroughs KL, Stovall JL, Kalanidhi AP, Brault AC, Osorio JE, Stinchcomb DT. Genetic and phenotypic characterization of manufacturing seeds for a tetravalent dengue vaccine (DENVax). PLoS Negl Trop Dis 2013; 7:e2243. [PMID: 23738026 PMCID: PMC3667780 DOI: 10.1371/journal.pntd.0002243] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 04/16/2013] [Indexed: 12/15/2022] Open
Abstract
Background We have developed a manufacturing strategy that can improve the safety and genetic stability of recombinant live-attenuated chimeric dengue vaccine (DENVax) viruses. These viruses, containing the pre-membrane (prM) and envelope (E) genes of dengue serotypes 1–4 in the replicative background of the attenuated dengue-2 PDK-53 vaccine virus candidate, were manufactured under cGMP. Methodology/Principal Findings After deriving vaccine viruses from RNA-transfected Vero cells, six plaque-purified viruses for each serotype were produced. The plaque-purified strains were then analyzed to select one stock for generation of the master seed. Full genetic and phenotypic characterizations of the master virus seeds were conducted to ensure these viruses retained the previously identified attenuating determinants and phenotypes of the vaccine viruses. We also assessed vector competence of the vaccine viruses in sympatric (Thai) Aedes aegypti mosquito vectors. Conclusion/Significance All four serotypes of master vaccine seeds retained the previously defined safety features, including all three major genetic loci of attenuation, small plaques, temperature sensitivity in mammalian cells, reduced replication in mosquito cell cultures, and reduced neurovirulence in new-born mice. In addition, the candidate vaccine viruses demonstrated greatly reduced infection and dissemination in Aedes aegypti mosquitoes, and are not likely to be transmissible by these mosquitoes. This manufacturing strategy has successfully been used to produce the candidate tetravalent vaccine, which is currently being tested in human clinical trials in the United States, Central and South America, and Asia. Transmitted by Aedes spp. mosquitoes found worldwide, dengue is the most important mosquito-borne viral disease in the world. The incidence of dengue has increased 30-fold over the past 50 years, and is now endemic in over 100 countries. Vaccination is believed to be one of the most effective strategies in dengue prevention. However, no vaccine is currently available, and prevention strategies to control mosquitoes in endemic areas have been insufficient in controlling dengue. We have developed a recombinant live-attenuated tetravalent vaccine against all four serotypes of dengue virus. This candidate vaccine is currently under human clinical evaluation. In this report, we provide information regarding our manufacturing strategy, and present details of the genetic and biological characterization of the master seed virus for each vaccine serotype. The study described here, our previously reported and ongoing pre-clinical studies, and current clinical trials will provide critical information to evaluate the safety and efficacy of the vaccine to protect humans against dengue.
Collapse
MESH Headings
- Aedes
- Animals
- Animals, Newborn
- Cell Line
- Dengue/pathology
- Dengue/virology
- Dengue Vaccines/adverse effects
- Dengue Vaccines/genetics
- Dengue Vaccines/immunology
- Dengue Vaccines/standards
- Dengue Virus/genetics
- Dengue Virus/immunology
- Disease Models, Animal
- Female
- Genomic Instability
- Mice
- Mice, Inbred ICR
- Quality Control
- Technology, Pharmaceutical/methods
- Temperature
- Vaccines, Attenuated/adverse effects
- Vaccines, Attenuated/genetics
- Vaccines, Attenuated/immunology
- Vaccines, Attenuated/standards
- Vaccines, Synthetic/adverse effects
- Vaccines, Synthetic/genetics
- Vaccines, Synthetic/immunology
- Vaccines, Synthetic/standards
- Viral Plaque Assay
- Virulence
- Virus Replication/radiation effects
Collapse
Affiliation(s)
- Claire Y-H Huang
- Arboviral Diseases Branch, Division of Vector-Borne Diseases, Centers for Disease Control and Prevention, Fort Collins, Colorado, USA.
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Messer WB, Yount B, Hacker KE, Donaldson EF, Huynh JP, de Silva AM, Baric RS. Development and characterization of a reverse genetic system for studying dengue virus serotype 3 strain variation and neutralization. PLoS Negl Trop Dis 2012; 6:e1486. [PMID: 22389731 PMCID: PMC3289595 DOI: 10.1371/journal.pntd.0001486] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2011] [Accepted: 12/07/2011] [Indexed: 12/15/2022] Open
Abstract
Dengue viruses (DENV) are enveloped single-stranded positive-sense RNA viruses transmitted by Aedes spp. mosquitoes. There are four genetically distinct serotypes designated DENV-1 through DENV-4, each further subdivided into distinct genotypes. The dengue scientific community has long contended that infection with one serotype confers lifelong protection against subsequent infection with the same serotype, irrespective of virus genotype. However this hypothesis is under increased scrutiny and the role of DENV genotypic variation in protection from repeated infection is less certain. As dengue vaccine trials move increasingly into field-testing, there is an urgent need to develop tools to better define the role of genotypic variation in DENV infection and immunity. To better understand genotypic variation in DENV-3 neutralization and protection, we designed and constructed a panel of isogenic, recombinant DENV-3 infectious clones, each expressing an envelope glycoprotein from a different DENV-3 genotype; Philippines 1982 (genotype I), Thailand 1995 (genotype II), Sri Lanka 1989 and Cuba 2002 (genotype III) and Puerto Rico 1977 (genotype IV). We used the panel to explore how natural envelope variation influences DENV-polyclonal serum interactions. When the recombinant viruses were tested in neutralization assays using immune sera from primary DENV infections, neutralization titers varied by as much as ∼19-fold, depending on the expressed envelope glycoprotein. The observed variability in neutralization titers suggests that relatively few residue changes in the E glycoprotein may have significant effects on DENV specific humoral immunity and influence antibody mediated protection or disease enhancement in the setting of both natural infection and vaccination. These genotypic differences are also likely to be important in temporal and spatial microevolution of DENV-3 in the background of heterotypic neutralization. The recombinant and synthetic tools described here are valuable for testing hypotheses on genetic determinants of DENV-3 immunopathogenesis.
Collapse
Affiliation(s)
- William B. Messer
- Division of Infectious Diseases, Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Boyd Yount
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Kari E. Hacker
- Department of Microbiology and Immunology, and Southeast Regional Center of Excellence for Biodefense and Emerging Infectious Diseases Research, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Eric F. Donaldson
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Jeremy P. Huynh
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Aravinda M. de Silva
- Department of Microbiology and Immunology, and Southeast Regional Center of Excellence for Biodefense and Emerging Infectious Diseases Research, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States of America
| | - Ralph S. Baric
- Department of Epidemiology, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, United States of America
| |
Collapse
|
15
|
Rodriguez-Roche R, Villegas E, Cook S, Poh Kim PAW, Hinojosa Y, Rosario D, Villalobos I, Bendezu H, Hibberd ML, Guzman MG. Population structure of the dengue viruses, Aragua, Venezuela, 2006-2007. Insights into dengue evolution under hyperendemic transmission. INFECTION GENETICS AND EVOLUTION 2011; 12:332-44. [PMID: 22197765 PMCID: PMC3919160 DOI: 10.1016/j.meegid.2011.12.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Revised: 12/08/2011] [Accepted: 12/10/2011] [Indexed: 12/16/2022]
Abstract
During the past three decades there has been a notable increase in dengue disease severity in Venezuela. Nevertheless, the population structure of the viruses being transmitted in this country is not well understood. Here, we present a molecular epidemiological study on dengue viruses (DENV) circulating in Aragua State, Venezuela during 2006-2007. Twenty-one DENV full-length genomes representing all of the four serotypes were amplified and sequenced directly from the serum samples. Notably, only DENV-2 was associated with severe disease. Phylogenetic trees constructed using Bayesian methods indicated that only one genotype was circulating for each serotype. However, extensive viral genetic diversity was found in DENV isolated from the same area during the same period, indicating significant in situ evolution since the introduction of these genotypes. Collectively, the results suggest that the non-structural (NS) proteins may play an important role in DENV evolution, particularly NS1, NS2A and NS4B proteins. The phylogenetic data provide evidence to suggest that multiple introductions of DENV have occurred from the Latin American region into Venezuela and vice versa. The implications of the significant viral genetic diversity generated during hyperendemic transmission, particularly in NS protein are discussed and considered in the context of future development and use of human monoclonal antibodies as antivirals and tetravalent vaccines.
Collapse
|
16
|
Maharaj PD, Anishchenko M, Langevin SA, Fang Y, Reisen WK, Brault AC. Structural gene (prME) chimeras of St Louis encephalitis virus and West Nile virus exhibit altered in vitro cytopathic and growth phenotypes. J Gen Virol 2011; 93:39-49. [PMID: 21940408 DOI: 10.1099/vir.0.033159-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Despite utilizing the same avian hosts and mosquito vectors, St Louis encephalitis virus (SLEV) and West Nile virus (WNV) display dissimilar vector-infectivity and vertebrate-pathogenic phenotypes. SLEV exhibits a low oral infection threshold for Culex mosquito vectors and is avirulent in avian hosts, producing low-magnitude viraemias. In contrast, WNV is less orally infective to mosquitoes and elicits high-magnitude viraemias in a wide range of avian species. In order to identify the genetic determinants of these different phenotypes and to assess the utility of mosquito and vertebrate cell lines for recapitulating in vivo differences observed between these viruses, reciprocal WNV and SLEV pre-membrane and envelope protein (prME) chimeric viruses were generated and growth of these mutant viruses was characterized in mammalian (Vero), avian (duck) and mosquito [Aedes (C6/36) and Culex (CT)] cells. In both vertebrate lines, WNV grew to 100-fold higher titres than SLEV, and growth and cytopathogenicity phenotypes, determined by chimeric phenotypes, were modulated by genetic elements outside the prME gene region. Both chimeras exhibited distinctive growth patterns from those of SLEV in C6/36 cells, indicating the role of both structural and non-structural gene regions for growth in this cell line. In contrast, growth of chimeric viruses was indistinguishable from that of virus containing homologous prME genes in CT cells, indicating that structural genetic elements could specifically dictate growth differences of these viruses in relevant vectors. These data provide genetic insight into divergent enzootic maintenance strategies that could also be useful for the assessment of emergence mechanisms of closely related flaviviruses.
Collapse
Affiliation(s)
- Payal D Maharaj
- Center for Vector-borne Disease Research and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.,Division of Vector-Borne Diseases, Centers for Disease Control and Prevention (CDC), Fort Collins, CO 80521, USA
| | - Michael Anishchenko
- Center for Vector-borne Disease Research and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.,Division of Vector-Borne Diseases, Centers for Disease Control and Prevention (CDC), Fort Collins, CO 80521, USA
| | - Stanley A Langevin
- Center for Vector-borne Disease Research and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
| | - Ying Fang
- Center for Vector-borne Disease Research and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
| | - William K Reisen
- Center for Vector-borne Disease Research and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
| | - Aaron C Brault
- Center for Vector-borne Disease Research and Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.,Division of Vector-Borne Diseases, Centers for Disease Control and Prevention (CDC), Fort Collins, CO 80521, USA
| |
Collapse
|
17
|
Osorio JE, Brewoo JN, Silengo SJ, Arguello J, Moldovan IR, Tary-Lehmann M, Powell TD, Livengood JA, Kinney RM, Huang CYH, Stinchcomb DT. Efficacy of a tetravalent chimeric dengue vaccine (DENVax) in Cynomolgus macaques. Am J Trop Med Hyg 2011; 84:978-87. [PMID: 21633037 DOI: 10.4269/ajtmh.2011.10-0592] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Three tetravalent formulations of chimeric dengue (DENVax) viruses containing the pre-membrane and envelope genes of serotypes 1-4 expressed by the attenuated DENV-2 PDK-53 genome were tested for safety, immunogenicity, and efficacy in cynomolgus macaques (Macaca fascicularis). Subcutaneous injection of the DENVax formulations was well-tolerated. Low levels of viremia of only one of the four vaccine viruses were detected yet virus neutralizing antibody titers were induced against all four dengue virus serotypes after one or two administrations of vaccine. All animals immunized with the high-dose formulation were protected from viremia, and all immunized animals were completely protected from DENV-3 and DENV-4 challenge. A lower dose of DENVax formulation partially protected animals from DENV-1 or DENV-2 challenge. In contrast, all control animals developed high levels of viremia for multiple days after challenge with DENV 1-4. This study highlights the immunogenicity and efficacy of the tetravalent DENVax formulations in nonhuman primates.
Collapse
|