*Review* **Protective to a T: The Role of T Cells during Zika Virus Infection**

**Ryan D. Pardy 1,2 and Martin J. Richer 1,2,\***


Received: 4 July 2019; Accepted: 2 August 2019; Published: 3 August 2019

**Abstract:** CD4 and CD8 T cells are an important part of the host's capacity to defend itself against viral infections. During *flavivirus* infections, T cells have been implicated in both protective and pathogenic responses. Given the recent emergence of Zika virus (ZIKV) as a prominent global health threat, the question remains as to how T cells contribute to anti-ZIKV immunity. Furthermore, high homology between ZIKV and other, co-circulating *flaviviruses* opens the possibility of positive or negative effects of cross-reactivity due to pre-existing immunity. In this review, we will discuss the CD4 and CD8 T cell responses to ZIKV, and the lessons we have learned from both mouse and human infections. In addition, we will consider the possibility of whether T cells, in the context of *flavivirus*-naïve and *flavivirus*-immune subjects, play a role in promoting ZIKV pathogenesis during infection.

**Keywords:** zika virus; flaviviruses; T cells; host-pathogen interactions
