DENVax live attenuated chimeric dengue vaccine

Mulhern, Kaitlyn, author
Nyborg, Jennifer, advisor
Livengood, Jill, advisor
Stinchcomb, Dan, committee member
Blair, Carol, committee member
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Dengue viruses are endemic in regions inhabited by roughly one half of the world’s population and can cause symptoms ranging from a headache and fever to even death. There is no vaccine to prevent infection by dengue viruses and the only current protection and prevention is mosquito control. The dengue viruses and the Aedes aegypti mosquito that carries them are spreading to more areas of the world and are therefore posing an even greater threat to public health. There is an urgent need for an effective vaccine that confers protection against infection by all four dengue serotypes. Several companies are currently developing dengue vaccines using different technologies including a live attenuated virus vaccine, DNA vaccine, and a chimeric vaccine in the yellow fever virus vaccine backbone. Inviragen, Inc., a biotech company, in collaboration with the Center for Disease Control and Prevention (CDC), is developing a chimeric live attenuated virus vaccine that is currently in clinical testing. The Inviragen/CDC dengue vaccine is based on an attenuated dengue-2 virus, called PDK-53, which was developed by passaging the virus 53 times in primary dog kidney cells (PDK). The attenuating mutations in the dengue-2 PDK-53, which are in the nonstructural genes of the virus, are well defined and characterized. This is essential in a live attenuated vaccine in order to monitor the stability of the mutations throughout vaccine manufacture and development. The four separate serotype-specific vaccine viruses are constructed by inserting the appropriate structural E and prM gene sequences into the nonstructural genes of the attenuated dengue-2 PDK-53 backbone. The phenotypic properties including plaque size, temperature sensitivity, peak titers, efficiency of replication, and neurovirulence, showed that the ehimeric viruses for each serotype were attenuated in comparison to the wild type parental viruses. Tetravalent formulations with the chimeric D2/1, D2/3 and D2/4 viruses as well as the D2-PDK53 virus were tested for antibody responses in AG 129 mice. Two separate projects involving Inviragen’s dengue vaccine, DENVax, are discussed in this thesis. In the first project, assays were developed to purify and quantify the residual host cell DNA in the vaccine using real time qPCR. Initially, the purification of host cell DNA present in research grade vaccine lots was optimized and internal controls were generated to monitor the efficiency of DNA extraction from the samples. The purified DNA was then amplified by PCR and quantified using two fluorescence-based methodologies, SYBR Green and TaqMan. The SYBR Green method was used to test the virus samples and reproducible results were obtained. The TaqMan assay allows for multiplexing, which allows simultaneous detection of two PCR products; Vero cell DNA present in virus samples and an internal control. The multiplexing TaqMan reactions need to be further optimized. In the second project, three separate “second generation” DENVax4 viruses were designed and generated. Of the three, two viable infectious viruses were generated and tested for phenotypic growth in vitro, and sequenced. These viruses grew to similar titers and phenotypes to the existing DENYax4, and immunogenicity testing in AG 129 mice is planned.
2010 Summer.
Includes bibliographic references.
Covers not scanned.
Print version deaccessioned 2022.
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Dengue viruses
Dengue viruses -- Prevention
Associated Publications