Using recombinant DNA technology for the development of live-attenuated dengue vaccines

Approaches of dengue control: vaccine strategies and future aspects

Dengue, caused by the dengue virus (DENV), affects millions of people worldwide every year. This virus has two distinct life cycles, one in the human and another in the mosquito, and both cycles are crucial to be controlled. To control the vector of DENV, the mosquito Aedes aegypti, scientists employed many techniques, which were later proved ineffective and harmful in many ways. Consequently, the attention shifted to the development of a vaccine; researchers have targeted the E protein, a surface protein of the virus and the NS1 protein, an extracellular protein. There are several types of vaccines developed so far, such as live attenuated vaccines, recombinant subunit vaccines, inactivated virus vaccines, viral vectored vaccines, DNA vaccines, and mRNA vaccines. Along with these, scientists are exploring new strategies of developing improved version of the vaccine by employing recombinant DNA plasmid against NS1 and also aiming to prevent the infection by blocking the DENV life cycle inside the mosquitoes. Here, we discussed the aspects of research in the field of vaccines until now and identified some prospects for future vaccine developments.

Administration of Defective Virus Inhibits Dengue Transmission into Mosquitoes

The host-vector shuttle and the bottleneck in dengue transmission is a significant aspect with regard to the study of dengue outbreaks. As mosquitoes require 100–1000 times more virus to become infected than human, the transmission of dengue virus from human to mosquito is a vulnerability that can be targeted to improve disease control. In order to capture the heterogeneity in the infectiousness of an infected patient population towards the mosquito population, we calibrate a population of host-to-vector virus transmission models based on an experimentally quantified infected fraction of a mosquito population. Once the population of models is well-calibrated, we deploy a population of controls that helps to inhibit the human-to-mosquito transmission of the dengue virus indirectly by reducing the viral load in the patient body fluid. We use an optimal bang-bang control on the administration of the defective virus (transmissible interfering particles (TIPs)) to symptomatic patients in the course of their febrile period and observe the dynamics in successful reduction of dengue spread into mosquitoes.

A Review on Dengue Vaccine Development

Dengue virus (DENV) has become a global health threat with about half of the world's population at risk of infection. Although the disease caused by DENV is self-limiting in the first infection, the antibody-dependent enhancement (ADE) effect increases the mortality in the second infection with a heterotypic virus. Since there is no specific efficient medicine in treatment, it is urgent to develop vaccines to prevent infection and disease progression. Currently, only a live attenuated vaccine, chimeric yellow fever 17D-tetravalent dengue vaccine (CYD-TDV), has been licensed for clinical use in some countries, and many candidate vaccines are still under research and development. This review discusses the progress, strengths, and weaknesses of the five types of vaccines including live attenuated vaccine, inactivated virus vaccine, recombinant subunit vaccine, viral vectored vaccine, and DNA vaccine.

Vaccines We Need But Don't Have

Vaccinations have had tremendous success in the 20th century. However, in the 21st century, we are facing complex immunological issues in relation to controlling underlying infectious diseases. Therefore, new technologies are needed to develop vaccines against infectious diseases like respiratory syncytial virus, human immunodeficiency virus, and cytomegalovirus. In addition, recent emerging infections have taught us that we must prepare preventative measures in advance using our scientific abilities.

Production of a neutralizing antibody against envelope protein of dengue virus type 2 using the linear array epitope technique

Dengue virus (DENV; genus Flavivirus) contains a positive-stranded RNA genome. Binding of DENV to host cells is mediated through domain III of the viral envelope protein. Many therapeutic mAbs against domain III have been generated and characterized because of its high antigenicity. We have previously established a novel PCR method named the linear array epitope (LAE) technique for producing monoclone-like polyclonal antibodies. To prove this method could be utilized to produce antibody against epitopes with low antigenicity, a region of 10 aa (V365NIEAEPPFG374) from domain III of the envelope protein in DENV serotype 2 (DENV2) was selected to design the primers for the LAE technique. A DNA fragment encoding 10 directed repeats of these 10 aa for producing the tandem-repeated peptides was obtained and fused with glutathione S-transferase (GST)-containing vector. This fusion protein (GST-Den EIII10-His6) was purified from Escherichia coli and used as antigen for immunizing rabbits to obtain the polyclonal antibody. Furthermore, the EIII antibody could recognize envelope proteins either ectopically overexpressed or synthesized by DENV2 infection using Western blot and immunofluorescence assays. Most importantly, this antibody was also able to detect DENV2 virions by ELISA, and could block viral entry into BHK-21 cells as shown by immunofluorescence and quantitative real-time PCR assays. Taken together, the LAE technique could be applied successfully for the production of antibodies against antigens with low antigenicity, and shows high potential to produce antibodies with good quality for academic research, diagnosis and even therapeutic applications in the future.