Respiratory and intestinal infections of infants between 1 and 6 months of life account for greater than 2 million deaths annually worldwide. Prominent among these infections is influenza virus, with one third of all infants infected in the first year of life. While wide-spread use of vaccines has been one of the greatest success stories in medicine, the vast majority of vaccines, including those for influenza, are not licensed for children <6 months of age, arguably a critical window for mortality and morbidity. The goal of our proposed studies is to identify adjuvants that can promote effective and safe adaptive immune responses in neonates. Given the significant morbidity and mortality that results from infection of human neonates with influenza, we have chosen inactivated influenza virus as our vaccination target. The guiding hypothesis for the optimization strategy for vaccination against influenza virus is that in the neonate, the inactivated influenza virus vaccine fails to provide th signals necessary for optimal/appropriate dendritic cell maturation and, as a result, fails to promote an effective adaptive immune response. The reduced ability of neonatal dendritic cells (DC) to undergo appropriate maturation in response to activating stimuli represents a major hurdle in vaccine efficacy in the neonate. Strategies that promote TLR signaling, a major regulator of DC maturation, is thus a rational approach to enhance vaccination. As TLR are also expressed on other cell types, including T and B cells, direct engagement of TLR on lymphocytes provides an additional avenue for TLR mediated amplification of the immune response. An important aspect of this application is the use of nonhuman primates, which is vital given the differences in distribution and function in TLR in primates versus mice. To our knowledge, our proposed study would be the first of its kind to develop the infant nonhuman primate for use in the optimization of influenza vaccines. The mechanistic studies that can be carried out using this model will almost certainly provide novel and important insights that cannot be gained using rodent models.
Aim1. To determine the ability of R848 and flagellin to modulate the humoral and cell mediated vaccine responses in neonates. Neonatal or adult AGM will be vaccinated with inactivated influenza virus in the presence or absence of flagellin, R848, or flagellin+R848. After boosting, animals will be challenged with influenza virus and viral burden and disease will be assessed over a 14 day period. In addition, virus-specific T and B cell responses will be assessed at d14 post challenge.
Aim 2. To determine the ability of flagellin and R848 to directly promote activation of neonate dendritic cells, T cells, and B cells.
In aim two we propose studies to determine the mechanistic basis of the adjuvant effect of the TLR agonists on the adaptive immune response. Since it is also possible that flagellin and R848 will have direct effects on lymphocytes, we will determine the ability of the TLR agonists to impact neonatal T and B cell activation/function.

Public Health Relevance

Although infants represent a highly susceptible group for serious influenza infections, successful vaccination in this population remains an unrealized goal. These studies utilize TLR ligands as an approach to generate protective immune responses in neonates. Given the high degree of similarity in the function and distribution of TLR in non-human primates, this model will be used for these mechanistic analyses.

National Institute of Health (NIH)
National Institute of Allergy and Infectious Diseases (NIAID)
Research Project (R01)
Project #
Application #
Study Section
Vaccines Against Microbial Diseases (VMD)
Program Officer
Salomon, Rachelle
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
Wake Forest University Health Sciences
Schools of Medicine
United States
Zip Code
Holbrook, Beth C; Aycock, S Tyler; Machiele, Emily et al. (2018) An R848 adjuvanted influenza vaccine promotes early activation of B cells in the draining lymph nodes of non-human primate neonates. Immunology 153:357-367
Westcott, Marlena M; Clemens, Elene A; Holbrook, Beth C et al. (2018) The choice of linker for conjugating R848 to inactivated influenza virus determines the stimulatory capacity for innate immune cells. Vaccine 36:1174-1182
Holbrook, Beth C; D'Agostino Jr, Ralph B; Tyler Aycock, S et al. (2017) Adjuvanting an inactivated influenza vaccine with conjugated R848 improves the level of antibody present at 6months in a nonhuman primate neonate model. Vaccine 35:6137-6142
Holbrook, Beth C; D'Agostino Jr, Ralph B; Parks, Griffith D et al. (2016) Adjuvanting an inactivated influenza vaccine with flagellin improves the function and quantity of the long-term antibody response in a nonhuman primate neonate model. Vaccine 34:4712-4717
Holbrook, Beth C; Kim, Jong R; Blevins, Lance K et al. (2016) A Novel R848-Conjugated Inactivated Influenza Virus Vaccine Is Efficacious and Safe in a Neonate Nonhuman Primate Model. J Immunol 197:555-64
Holbrook, Beth C; Hayward, Sarah L; Blevins, Lance K et al. (2015) Nonhuman primate infants have an impaired respiratory but not systemic IgG antibody response following influenza virus infection. Virology 476:124-33
Kim, Jong R; Holbrook, Beth C; Hayward, Sarah L et al. (2015) Inclusion of Flagellin during Vaccination against Influenza Enhances Recall Responses in Nonhuman Primate Neonates. J Virol 89:7291-303
Alexander-Miller, Martha A (2014) Vaccines against respiratory viral pathogens for use in neonates: opportunities and challenges. J Immunol 193:5363-9
Parks, Griffith D; Alexander-Miller, Martha A (2013) Paramyxovirus activation and inhibition of innate immune responses. J Mol Biol 425:4872-92