Characterization of CD8⁺ T cells in immune-privileged organs of ZIKV-infected Ifnar1^-/- mice

Zika virus (ZIKV) infection caused neurological complications and male infertility, leading to the accumulation of antigen-specific immune cells in immune-privileged organs (IPOs). Thus, it is important to understand the immunological responses to ZIKV in IPOs. We extensively investigated the ZIKV-specific T cell immunity in IPOs in Ifnar1(-/-) mice, based on an immunodominant epitope E294-302 tetramer. The distinct kinetics and functions of virus-specific CD8+ T cells infiltrated into different IPOs were characterized, with late elevation in the brain and spinal cord. Single epitope E294-302-specific T cells can account for 20-60% of the total CD8+ T cells in the brain, spinal cord, and testicle and persist for at least 90 days in the brain and spinal cord. The E294-302-specific TCR alpha beta s within the IPOs are featured with the majority of clonotypes utilizing TRAV9N-3 paired with diverse TRBV chains, but with distinct alpha beta paired clonotypes in 7 and 30 days post-infection. Specific chemokine receptors, Ccr2 and Ccr5, were selectively expressed in the E294-302-specific CD8(+ )T cells within the brain and testicle, indicating an IPO-oriented migration of virus-specific CD8(+) T cells after infection. Overall, this study adds to the understanding of virus-specific CD8(+) T cell responses for controlling and clearing ZIKV infection in IPOs.IMPORTANCE The immune-privileged organs (IPOs), such as the central nervous system and testicles, presented pathogenicity and inflammation after Zika virus (ZIKV) infection with infiltrated CD8(+)T cells. Our data show that CD8(+) T cells keep up with virus increases and decreases in immune-privileged organs. Furthermore, our study provides the first ex vivo comparative analyses of the composition and diversity related to TCR alpha/beta clonotypes across anatomical sites and ZIKV infection phases. We show that the vast majority of TCR alpha/beta clonotypes in tissues utilize TRAV9N-3 with conservation. Specific chemokine expression, including Ccr2 and Ccr5, was found to be selectively expressed in the E294-302-specific CD8(+) T cells within the brain and testicle, indicating an IPO-oriented migration of the virus-specific CD8(+) T cells after the infection. Our study adds insights into the anti-viral immunological characterization and chemotaxis mechanism of virus-specific CD8(+) T cells after ZIKV infection in different IPOs.