Peste des Petits Ruminants virus virulence is associated with an early inflammatory profile in the tonsils and cell cycle arrest in lymphoid tissue

Field observations show that the severity of infection with Peste des Petits Ruminants virus (PPRV) is highly dependent on the viral strains and the host infected, but the mechanisms behind these variations are not well understood. Here we compare immune response in Saanen goats infected with high (MA08) and low (IC89) virulent PPRV strains. Analyses revealed a differential immune response: early activation of type I interferon (IFN-I) responses only with MA08, but comparable IFN-I expression levels with MA08 and IC89 at later stages. Additionally, only the MA08 strain triggered inflammatory and myeloid cell-related responses in the tonsils, as well as a disseminated early and marked suppression of lymphocyte proliferation evidenced by cell cycle arrest. CD4 T cells were found to be most affected in terms of depletion in the peripheral blood. Massive infection of the tonsils, particularly for the highly virulent strains, seems to induce epithelial lesions that promotes the inflammatory responses. These findings underscore the importance of understanding strain-specific differences for appropriate surveillance and control of PPR.