Comparison Between Virus Infectivity for Influenza Virus A Wild Type Strains and Their High Yielding Virus Reassortants and Other Determinants of Yield During Vaccine Strain Development
Date of Award
Master's Thesis - Restricted (NYMC/Touro only) Access
Master of Science
Microbiology and Immunology
Dr. Doris Bucher
Dr. Andrew A. Fulvini
Dr. Jianhua Le
Influenza viruses cause a wide variety of respiratory illnesses from minor upper respiratory infections to severe lower respiratory infections and death. Influenza viruses cause 3 to 5 million severe illnesses and 250,000 to 500,000 deaths globally each year, according to the World Health Organization (WHO).
High Yield reassortants (HYR) have been used to make influenza type A vaccines since 1971. An HYR influenza vaccine virus must have the wild-type (WT) target virus's HA and NA genes and the ability to develop to high titers in ovo. HYR vaccine seed viruses are produced by co-inoculation of two viruses in ovo. The two viral parents are the WT virus, which is currently circulating and causes disease in a population in a given year, and the HYR donor virus, which is well adapted for growth in embryonated chicken eggs and develops high viral titers.
This study compared the influenza virus type A infectivity of four pairs of H1N1pdm, four pairs of H3N2 subtype viruses, and their HYR viruses, all prepared previously in our lab. Furthermore, we determined if there is a correlation between virus infectivity for influenza virus type A, influenza virus reassortants, and other parameters currently being used to determine yield.
This study showed that most HYR of both subtypes, H1N1 pdm and H3N2, had higher EID50 compared to their parent WT. We found that 2.9% of infectivity can be explained by HA concentration, while 39% can be explained by HA titer. We also found that 25% of HA titer variations can be explained by HA concentration.
In conclusion, the EID50 does not seem a good indication of yield during vaccine development compared to other methods.
Alrashidy, Amna, "Comparison Between Virus Infectivity for Influenza Virus A Wild Type Strains and Their High Yielding Virus Reassortants and Other Determinants of Yield During Vaccine Strain Development" (2021). NYMC Student Theses and Dissertations. 30.