ReviewFlavivirus vaccines: Virus-like particles and single-round infectious particles as promising alternatives
Introduction
Flaviviruses infect mammals and arthropods and cause human disease. They are distributed worldwide and are a significant public health problem, with up to 400 million people infected annually [1]. Flavivirus are transmitted to humans by arthropod vectors, such as mosquitoes and ticks. Flavivirus vectors are distributed mainly in highly populated tropical zones, resulting in a high fraction of the global population at risk of infection with these viruses. The impact of the disease caused by flavivirus can be expected to increase as infected vectors are transported unintentionally to non-endemic areas, as climate change increases vector distribution, and as vectors adapt to more extreme climates [2]. The more relevant are dengue (DENV), Zika (ZIKV), West Nile (WNV), yellow fever (YFV) and Japanese encephalitis virus (JEV), which are transmitted by mosquitoes, and the tick-borne encephalitis virus (TBEV), which is transmitted by ticks. Most infections by these viruses are asymptomatic or cause mild symptoms, like fever, rash, vomiting, headache, and malaise. However, a fraction of infected people develops more severe forms of the disease, resulting in bleeding, organ failure, shock, and central nervous system illness, as encephalitis and meningitis. In addition, ZIKV was the first flavivirus described as capable of crossing the placental barrier and being transmitted from mother to child, affecting the development of the fetal brain and causing congenital Zika syndrome [3], [4].
As for other virus infections, the best way to counteract this health problem is prevention. Vector control is a highly relevant control measure but can be challenging or nearly impossible in wilderness areas. Therefore, vaccination has been determined as necessary for flavivirus disease control. Vaccine development has been challenging, as vaccination can cause severe disease and vaccine design should protect against various relevant serotypes. Although vaccines have been developed for some of these viruses, most of them are live-attenuated vaccines with concerns for their safety or are only suitable for adults. For example, the safety and efficacy of the licensed dengue vaccine has not been demonstrated for its application to children, who are highly susceptible to severe forms of the disease. Another challenge for flavivirus vaccine development is that they are required in the poorest regions of the world, so very low costs are required to make them accessible to the target population [5]. Here we discuss the potential of single-round infectious particles (SRIP) and virus-like particles (VLP) as vaccines against flavivirus fever, including the challenges of vaccine development based on such technologies.
Section snippets
The genus flavivirus
Flaviviruses are enveloped, icosahedral viruses with capsids with diameter around 50 nm and a positive-sense, single-stranded RNA genome of ca. 11 kb that codifies for 7 non-structural proteins (NS1, NS2A, NS2B, NS3, NS4A, NS4B and NS5) and 3 structural proteins (C, prM and E) (Fig. 1a). These viruses replicate in the cytoplasm and assemble and mature as they transit from the cytoplasm through the endoplasmic reticulum (ER) and the Golgi. The flavivirus viral RNA is translated as a single
Flavivirus vaccines
Vaccines are available for four arthropod-borne flaviviruses: YFV, JEV, TBEV and DENV. The 17D vaccine against YFV is a live attenuated vaccine derived from wild-type strain Asibi and has been used since the 1930 s to prevent yellow fever [12]. In the case of JEV, there are three kinds of available vaccines: live attenuated cell culture-derived vaccines, inactivated cell culture or mouse brain-derived vaccines and live chimeric vaccines [13]. Vaccines against TBEV are all inactivated vaccines
Virus-like particles and single-round infectious particles as alternative vaccines against flavivirus fever
Virus-like particles (VLP) do not contain the viral genome and therefore, do not replicate in cells. They are a more stable and safer alternative to live, attenuated, or inactivated vaccines, as they are not infectious and cannot revert to an infectious form. Also, the particulate form of VLP makes them more immunogenic than sub-unit vaccines. VLP are obtained by transfecting cells with a plasmid or viral vector containing structural genes of a virus. When the structural proteins are produced,
Molecular biology strategies to obtain flavivirus VLPs
Table 1 summarizes some examples of the production of flavivirus VLP, along with the strategies used and the results obtained. The flavivirus E protein is the target of neutralizing antibodies, thus, most studies have focused on producing flavivirus VLP that contain the E protein. It has been shown that expression of prM is necessary for the secretion of the E protein [36], and the most common strategy to produce flavivirus VLP is based on producing a prM-E fusion protein that is processed to
Molecular biology strategies to produce flavivirus SRIP
Table 2 summarizes examples of the approaches used to produce SRIP, as well as the main results obtained to date. There are mainly two strategies to obtain SRIP. In the first one, cells are co-transfected with two plasmids that complement each other: one provides the defective genome to be packaged into SRIP and the other provides one or all of the structural proteins necessary for packaging (Fig. 2, b). The second strategy consists in using a packaging cell line that expresses the structural
Expression host systems
The selection of the expression host depends greatly on the characteristics of the proteins to be expressed, as the functional characteristics of the expressed proteins will be determined by the host. The prM and E proteins are N-glycosylated at the N15 and N154 sites, respectively, and only eukaryotic cells possess the necessary machinery for glycosylation and correct glycoprotein folding. It has been reported that removal of the N15 and N154 N-glycosylation sites results in protein misfolding
Characterization
Characterization of VLP and SRIP include electron microscopy, safety, immunogenicity, and recognition by antibodies. Flavivirus VLP can have a wide size distribution. DENV-2 and TBEV VLP were spherical ≈30 nm diameter particles [96], [97]. As they do not contain a nucleocapsid, size is smaller than the ≈ 50 nm diameter of the viruses. WNV VLP have two size distributions, one larger (40–50 nm), containing fully mature M protein, and another smaller (20–30 nm), with immature prM protein [43].
Conclusions and challenges
VLP and SRIP have been developed for the most studied arthropod-borne flaviviruses, such as dengue, Zika, West-Nile, yellow fever, Japanese encephalitis, and tick-borne encephalitis virus. VLP and SRIP were demonstrated to be safe and immunogenic, and to induce a protective humoral and cellular immune responses in animal models. Also, molecular biology strategies have allowed to overcome some of the problems related to the expression of flaviviral proteins, helping in the development of stable
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgements
This work was supported by UNAM-PAPIIT IT-200521 and IV-200820. ECJ is a graduate student in the Programa de Doctorado en Ciencias Bioquímicas and received a CONACyT scholarship.
References (110)
- et al.
Association between microcephaly, Zika virus infection, and other risk factors in Brazil: final report of a case-control study
Lancet Infect Dis.
(2018) - et al.
Structure of Dengue Virus: Implications for Flavivirus Organization, Maturation, and Fusion
Cell
(2002) - et al.
Structural Changes and Functional Control of the Tick-Borne Encephalitis Virus Glycoprotein E by the Heterodimeric Association with Protein prM
Virology
(1994) - et al.
From research to phase III: Preclinical, industrial and clinical development of the Sanofi Pasteur tetravalent dengue vaccine
Vaccine.
(2011) - et al.
Adverse events following yellow fever immunization: Report and analysis of 67 neurological cases in Brazil
Vaccine.
(2014) - et al.
Adverse events following yellow fever preventive vaccination campaigns in eight African countries from 2007 to 2010
Vaccine.
(2013) - et al.
Neurologic disease associated with 17D–204 yellow fever vaccination: A report of 15 cases
Vaccine.
(2007) - et al.
Maternally Acquired Zika Antibodies Enhance Dengue Disease Severity in Mice
Cell Host Microbe.
(2018) - et al.
Human Cytotoxic T Lymphocyte Responses to Live Attenuated 17D Yellow Fever Vaccine: Identification of HLA-B35-Restricted CTL Epitopes on Nonstructural Proteins NS1, NS2b, NS3, and the Structural Protein E
Virology
(2002) - et al.
A vaccine inducing solely cytotoxic T lymphocytes fully prevents Zika virus infection and fetal damage
Cell Rep.
(2021)
Effects of the number of amino acid residues in the signal segment upstream or downstream of the NS2B-3 cleavage site on production and secretion of prM / M-E virus-like particles of West Nile virus
Microbes Infect.
An optimized expression vector for improving the yield of dengue virus-like particles from transfected insect cells
J Virol Methods.
Generation and preclinical immunogenicity study of dengue type 2 virus-like particles derived from stably transfected mosquito cells
Vaccine.
Immunogenicity and efficacy of two types of West Nile virus-like particles different in size and maturation as a second-generation vaccine candidate
Vaccine.
Production of Japanese encephalitis virus-like particles using the baculovirus e insect cell system
J Biosci Bioeng.
A strong endoplasmic reticulum retention signal in the stem–anchor region of envelope glycoprotein of dengue virus type 2 affects the production of virus-like particles
Virology
Enhancing biosynthesis and secretion of premembrane and envelope proteins by the chimeric plasmid of dengue virus type 2 and Japanese encephalitis virus.
Investigating Tick-borne Flaviviral-like Particles as a Delivery System for Gene Therapy
Curr Ther Res.
Capsid containing virus like particle vaccine against Zika virus made from a stable cell line
Vaccine.
A Single-Dose Live-Attenuated Zika Virus Vaccine with Controlled Infection Rounds that Protects against Vertical Transmission
Cell Host Microbe.
Construction and characterization of a second-generation pseudoinfectious West Nile virus vaccine propagated using a new cultivation system
Vaccine.
Construction and evaluation of a chimeric pseudoinfectious virus vaccine to prevent Japanese encephalitis
Vaccine.
Replicon-based Japanese encephalitis virus vaccines elicit immune response in mice
J Virol Methods.
Efficient, trans-complementing packaging systems for chimeric, pseudoinfectious dengue 2/yellow fever viruses
Virology
Production and characterization of vaccines based on flaviviruses defective in replication
Virology
Utility of Japanese encephalitis virus subgenomic replicon-based single-round infectious particles as antigens in neutralization tests for Zika virus and three other flaviviruses
J Virol Methods.
Tetravalent recombinant dengue virus-like particles as potential vaccine candidates : immunological properties.
Cloning and Expression of Recombinant Tick-Borne Encephalitis Virus-like Particles in Pichia pastoris
Osong Public Heal Res Perspect.
Molecular Organization of a Recombinant Subviral Particle from Tick-Borne Encephalitis Virus
Mol Cell.
Diagnostic aptitude of West Nile virus-like particles expressed in insect cells
Diagnostic Microbiol Infect Dis.
The continued threat of emerging flaviviruses
Nat Microbiol.
Flaviviruses, an expanding threat in public health: focus on dengue, West Nile, and Japanese encephalitis virus
J Neurovirol.
The Brazilian Zika virus strain causes birth defects in experimental models
Nature
Current Flavivirus Research Important for Vaccine Development
Vaccines.
Maturation of flaviviruses starts from one or more icosahedrally independent nucleation centres
EMBO Rep.
Flavivirus cell entry and membrane fusion
Viruses.
Anti-flavivirus vaccines: Review of the present situation and perspectives of subunit vaccines produced in escherichia coli
Vaccines.
Live Attenuated Yellow Fever 17D Vaccine: A Legacy Vaccine Still Controlling Outbreaks In Modern Day
Curr Infect Dis Rep.
Japanese encephalitis: a review of clinical guidelines and vaccine availability in Asia
Trop Dis Travel Med vaccines.
Tick-borne encephalitis: A review of epidemiology, clinical characteristics, and management
World J Clin cases.
Yellow fever vaccine-associated viscerotropic disease: current perspectives
Drug Des Devel Ther.
Expert Opinion on Vaccination of Travelers Against Japanese Encephalitis
J Travel Med.
Efficacy and Long-Term Safety of a Dengue Vaccine in Regions of Endemic Disease
N Engl J Med.
Effect of Dengue Serostatus on Dengue Vaccine Safety and Efficacy
N Engl J Med.
Prior Exposure to Zika Virus Significantly Enhances Peak Dengue-2 Viremia in Rhesus Macaques
Sci Rep.
Dengue virus sero-cross-reactivity drives antibody-dependent enhancement of infection with zika virus
Nat Immunol.
Zika virus infection enhances future risk of severe dengue disease
Science
Cited by (7)
Low-temperature culture enhances production of flavivirus virus-like particles in mammalian cells
2024, Applied Microbiology and BiotechnologyMetagenomics analysis reveals presence of the Merida-like virus in Georgia
2023, Frontiers in MicrobiologyBiological determinants perpetuating the transmission dynamics of mosquito-borne flaviviruses
2023, Emerging Microbes and Infections