UBC Theses and Dissertations

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UBC Theses and Dissertations

Neonatal immunization with Listeria monocytogenes induces T cells with an adult-like avidity, sensitivity, and TCR-Vbeta repertoire, and does not adversely impact the response to boosting Smolen, Kinga Krystyna


Neonates are highly susceptible to infection and respond suboptimally to most vaccines. However, our previous studies have shown that a protective Th1-type immune response to neonatal Listeria monocytogenes (Lm) immunization can be induced. In this study, we investigated the impact of neonatal Lm immunization and boosting on the key parameters of the T cell response. We found that immunized murine neonates reached maximum antigen-specific CD8⁺ T cell expansion after only a single immunization, while adults required a booster dose to reach their maximal response. Antigen-specific CD4⁺ expansion in both age groups however required a booster dose to reach its peak. Neither functional avidity nor sensitivity of antigen-specific CD8⁺ and CD4⁺ T cells differed between mice immunized as neonates or adults. The range of different TCR Vβ chains employed in the response was also similar in both age groups. Lastly, neonatal immunization and subsequent boosting did not decrease protection, as both immunized neonates and adults remained well protected after one or after multiple doses. Overall, our data provide further evidence in support of immunization at birth as a feasible public health strategy to combat early life infections, and that Lm in particular represents an attractive vehicle to do so.

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