Search

Background: The arenavirus Junin virus (JUNV), causative agent of the argentine hemorrhagic fever, is able to modulate several signaling pathways involved in cell survival and multiplication., Objectives: We aimed to characterize the infection of rat osteoblasts (OBCs) with JUNV and its consequence on the modulation of osteogenic genes expression, thus studying the ability of this virus to induce cell differentiation. In addition, we evaluated the effect of purinergic agonists on viral replication., Method: Quantification of infectivity by plaque forming unit (PFU) assay, synthesis of viral proteins by western blot and immunofluorescence, and expression of osteogenic differentiation markers (ODM) by quantitative real-time polymerase chain reaction were employed., Results: Infection of OBCs with JUNV (MOI 0.01 PFU/cell) showed a peak of infectivity, reaching 1.5 × 105 PFU/mL at the second day post-infection (p.i.). A marked restriction in multiplication was detected at day 7 p.i. that did not impair the establishment of a persistent stage of infection in OBCs. Analysis of mRNAs corresponding to ODM such as alkaline phosphatase, bone sialo-protein, and bone morphogenetic proteins (BMPs) 4 and 6 revealed that only the levels of BMP-6 were significantly higher in infected cells. Treatment with the purinergic agonists ATPγS, UTP, ADP, or UDP diminished viral titer and reduced the expression of the viral nucleoprotein. Also, treatment with 10 μM ATPγS reduced the stimulation of BMP-6 expression induced by the infection., Conclusions: These data demonstrate that JUNV is capable of infecting OBCs and point out BMP-6 as a key factor during this process., (© 2019 S. Karger AG, Basel.)

In previous work, we demonstrated that the arenavirus Junín virus (JUNV) is able to activate Akt by means of the phosphatidylinositol-3-kinase (PI3K) survival pathway during virus entry. This work extends our study, emphasizing the relevance of this pathway in the establishment and maintenance of persistent infection in vitro. During the course of infection, JUNV-infected Vero cells showed a typical cytopathic effect that may be ascribed to apoptotic cell death. Treatment of infected cultures with Ly294002, an inhibitor of the PI3K/Akt pathway, produced an apoptotic response similar to that observed for uninfected cells treated with the drug. This result suggests that virus-induced activation of the PI3K/Akt pathway does not deliver a strong enough anti-apoptotic signal to explain the low proportion of apoptotic cells observed during infection. Also, inhibition of the PI3K/Akt pathway during the acute stage of infection did not prevent the establishment of persistence. Furthermore, treatment of persistently JUNV-infected cells with Ly294002 did not alter viral protein expression. These findings indicate that despite the positive modulation of the PI3/Akt pathway during Junín virus entry, this would not play a critical role in the establishment and maintenance of JUNV persistence in Vero cells.