Slc43a2T cell metastasis from spleen to brain in RGNNV infected teleost.

Abstract

The origin of T cells in the teleost's brain is unclear. While viewing the central nervous system (CNS) as immune privileged has been widely accepted, previous studies suggest that T cells residing in the thymus but not in the spleen of the teleost play an essential role in communicating with the peripheral organs. Here, we identified nine T cell subpopulations in the thymus and spleen of orange-spotted grouper (Epinephelus coioices) through single-cell RNA-sequencing analysis. After viral CNS infection with red-spotted grouper nervous necrosis virus (RGNNV), the number of slc43a2T cells synchronously increased in the spleen and brain. During the infection tests in asplenic zebrafish (tlx1zebrafish model), no increase in the number of slc43a2T cells was observed in the brain. Single-cell transcriptomic analysis indicated that slc43a2T cells mature and functionally differentiate within the spleen and then migrate into the brain to trigger an immune response. This study suggests a novel route for T cell migration from the spleen to the brain during viral infection in fish.