The disease yellow fever is controlled by the use of a live attenuated vaccine, strain 17D, derived by 176 passages of wild-type strain Asibi in chicken tissue. Next Generation Sequencing (NGS) technology has great applications to vaccine development and quality control and safety of live vaccines. We have compared low passage Asibi virus and 17D vaccine from a commercial dose of YF VaxTM by NGS and found that Asibi is a typical RNA virus with a quasispecies population while, surprisingly, commercial 17D vaccine has very little evidence of quasispecies, and this may contribute to the excellent safety record of the vaccine. This is the first comparison of a wild-type parent-live attenuated vaccine derivative for a human vaccine by NGS. We believe that investigation of the mechanism of limited quasi-species in 17D vaccine virus may have important applications to other live attenuated vaccines and development of future live attenuated vaccines. In this application we propose to obtain critical preliminary data to support a hypothesis for the mechanism of limited quasispecies in 17D vaccine by investigating what happens to the two viruses when passaged in different cell types or in vivo. We have preliminary data for unpassaged viruses and passage in three different cell types so Specific Aim 1 will investigate wild-type and vaccine strain virus genomic stability/diversity during infection of immunocompetent and immunocompromised mice to determine if the quasispecies populations of the two viruses identified above are retained or vary in different types of mice. In particular, lack of a functional innate immune response may enable 17D virus to generate a diverse population that results in a virulent phenotype.
Specific Aim 2 will use reverse genetics to investigate whether the structural genes, nonstructural genes, or both are responsible for the limited quasispecies of 17D virus by utilizing infectious clones of Asibi and 17D viruses, and chimeric Asibi/17D viruses. It is hypothesized that the restricted quasispecies in 17D vaccine virus is due to mutation(s) in the nonstructural (NS) proteins of the replication complex as a whole, rather than the RNA dependent RNA polymerase alone, that results in high fidelity of the 17D RNA polymerase.

Public Health Relevance

Next generation sequencing (NGS) (also known as Deep Sequencing and Massive Parallel Sequencing) has important applications to vaccine development plus quality and control of live vaccines. NGS of the wild-type yellow fever virus strain Asibi (wild-type parent to 17D vaccine) shows that it consists of a typical RNA virus quasi-species population whereas the live attenuated 17D vaccine virus derivative has very little evidence of quasi-species, which may contribute to the excellent safety record of the 17D vaccine. Understanding of the mechanism of lack of quasi species in the 17D live attenuated vaccine RNA virus may have important applications to the rational design of future live attenuated vaccines.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Exploratory/Developmental Grants (R21)
Project #
1R21AI113407-01A1
Application #
8893213
Study Section
Vaccines Against Microbial Diseases (VMD)
Program Officer
Repik, Patricia M
Project Start
2015-02-01
Project End
2017-01-31
Budget Start
2015-02-01
Budget End
2016-01-31
Support Year
1
Fiscal Year
2015
Total Cost
$193,750
Indirect Cost
$68,750
Name
University of Texas Medical Br Galveston
Department
Pathology
Type
Schools of Medicine
DUNS #
800771149
City
Galveston
State
TX
Country
United States
Zip Code
77555
Beck, Andrew S; Barrett, Alan D T (2015) Current status and future prospects of yellow fever vaccines. Expert Rev Vaccines 14:1479-92