Peste des petits ruminants virus (PPRV) modulates caprine dendritic cell function and induces immunosuppression through IL-10 upregulation

Peste des petits ruminants (PPR) is a WOAH notifiable disease affecting sheep and goats, caused
by Peste des petits ruminants virus (PPRV), a morbillivirus of the Paramyxoviridae family. Infection
with PPRV leads to immunosuppression, creating conditions for opportunistic infections that can
result in animal mortality. Although goats generally exhibit more severe clinical signs than sheep,
the underlying mechanisms driving this species-specific difference remain poorly understood.
Dendritic cells (DC), which play a pivotal role in initiating immune responses, are among the
immune targets of PPRV in small ruminants. In this study, we examined the impact of PPRV on
caprine immune cells, focusing on CD14+ monocytes and monocyte-derived dendritic cells
(MoDC). Our findings indicate that PPRV infects goat monocytes without preventing their differentiation
into DC. Infected MoDC displayed increased expression of maturation markers and
reduced phagocytic activity, suggesting a transition toward an activated phenotype. However,
mixed lymphocyte reaction assays revealed that PPRV-infected MoDCs have a diminished capacity
to promote T cell proliferation. This impaired function was associated with elevated IL-10 production
and reduced conjugation between DCs and T cells. Overall, PPRV infection induces an atypical
maturation stage in goat MoDCs, characterized by partial activation but impaired antigen presentation.
These findings demonstrate that PPRV-driven modulation of DC function contributes to
the immunosuppression observed during PPRV infection in goats.