PROJECT SUMMARY
Viruses are well-established causes of central nervous system (CNS) disease in the most vulnerable
populations, particularly in the young and immunocompromised. During CNS infection, the immune
response can inadvertently cause neuropathology, resulting in neuronal death and demyelination.
Mouse models of viral infection have served as a valuable tool for dissecting mechanisms of
demyelinating disease in the adult brain, and a rich body of literature has revealed a complex role for
the immune response in demyelination. However, we know little about how viruses disrupt myelination
in childhood, when both neurons, oligodendrocytes (OLs), and immune cells are actively maturing.
Thus, true myelin restoration remains an elusive therapeutic goal in demyelinating diseases at all ages.
The long-term goal is to identify mechanisms to support the preservation and repair of brain cells in the
very young. The overall objective of this project is to evaluate the response of oligodendrocyte
precursor cells (OPCs), which ultimately give rise to myelinating OLs, during a viral infection in the
developing brain. Using a juvenile mouse model of neuron-restricted virus infection, where OPCs/OLs
are bystanders to the antiviral immune response, we have found that OPCs expand dramatically during
infection, and infiltrating adaptive immune cells are primary drivers of this OPC response. The general
hypothesis is that OPCs are spurred to proliferate by infiltrating B cells during a juvenile infection, but
that full-fledged OPC differentiation is ultimately impeded by virally-infected neurons. The general
hypothesis will be tested via the following the specific aims: (1) determine the protective role of juvenile
immune cells in promoting OPC proliferation; and (2) define the role of OPC maturation in recovery
from demyelination during a juvenile infection. In Aim 1, we will use genetic and molecular approaches
to define how OPC proliferation and maturation are regulated by subsets of B cells over the course of a
juvenile infection. In aim 2, we will assess how virally-infected neurons regulate the differentiation of
newly-generated OPCs using in vivo and in vitro approaches. The expected outcomes are that we will
define cellular and molecular interactions that direct OPC fate during a juvenile viral infection.
Collectively, these results are expected to have a significant impact by providing a basis for the
development of therapies to preserve or restore myelination in the young brain. This research aligns
with NIND's mission by generating fundamental insights into interactions between the brain and
immune cells, and by applying that new knowledge to reduce the burden of neurological disease in the
most vulnerable populations.