IMPAIRED THROMBOPOIESIS AFTER STEM CELL INFECTION WITH JUNIN VIRUS

POZNER RG; PACIENZA N; NEGROTTO S; D'ATRI LP; URE A; TORRES O; ROMANOWSKI V; SCHATTNER M; GOMEZ RM

Ginebra, Suiza

Congreso; XXIst Congress of the International Society on Thrombosis and Haemostasis; 2007

IMPAIRED THROMBOPOIESIS AFTER STEM CELL INFECTION WITH JUNIN VIRUSR.G. Pozner, N. Pacienza, S. Negrotto, L.P. D´Atri, A. Ure, O. Torres, V. Romanowski, M. Schattner, R.M. Gomez. Haemostrasis and Trombosis, National Academy of Medicine, Buenos Aires; Biological Sciences, National University of La Plata, La Plata, ArgentinaIntroduction: Hematologic alterations are the main feature of Argentine hemorrhagic fever (AHF), a disease caused by Junin virus (JV). Although thrombocytopenia is a valuable diagnostic sign, the origin of this alteration remains unknown. In this study we evaluated the effect of JV on in vitro platelet (Plt) generation.Methods: Human umbilical cord CD34+ cells were infected with JV or an UV-inactivated strain (JVuv) at a MOI of 0.1 and stimulated with thrombopoitein. Seven days postinoculation (PI) viral infection was determined by RT-PCR, and 14 days PI Plt generated in culture were enumerated by flow cytometry and expressed in arbitrary units. A paired t-test was used to compare differences.Results: Viral RNA was detected only in samples inoculated with the infectious JV. Although megakaryocyte proliferation and viability were not modified by JV infection, the number of Plt generated from JV-infected cultures was significantly diminished compared to control samples (Table, n=4, * p<0.05). The JV impairment in Plt generation was mimicked by the toll like receptor-3 (TLR-3) agonist Poly (I:C) and type I IFN (Table, n=3). Considering that Src kinases inhibition improves Plt formation, we blocked Src kinases with PP2 but the inhibitory effect of JV infection was not prevented.Table: Plt Number Non infected 1342±72 JVuv 1318±80 JV 724±20* Poly (I:C) 10 mug/ml 679±53* IFN-alpha 100 U/ml 931±80* IFN-´eta 100 U/ml 815±55*Conclusions: The results suggest that stem cells are susceptible to be infected by JV inducing a defective Plt generation. TLR-3/IFN pathway may be the mechanism involved in thrombopoiesis inhibition suggesting that such alterations play a major role in the pathogenesis of AHF and perhaps in other viral-induced hemorrhagic diseases.