Description:
<jats:title>Abstract</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>The ability of tick-borne agents to survive in stored blood bags is a key factor for their transmissibility by blood transfusion. The aim of this study was to evaluate the survival and potential infectivity of<jats:italic>Rickettsia conorii</jats:italic>(RC) in artificially contaminated canine whole blood (WB) and in leukoreduced whole blood (LR-WB) during the storage period.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p>RC was cultured on L929 cells. We used a one-week 25-cm<jats:sup>2</jats:sup>flask with 70–80% of L929 infected cells to prepare the bacterial inoculum by pelleting cells and suspending the pellet in the donors’ serum. We infected five 100 ml WB units with RC within 2 h from the collection and maintained it at room temperature for 4 h prior to refrigeration. We filtered 50 ml of each WB bag to obtain leukoreduced WB (LR-WB) at day 1 post-infection (dpi). We checked WB and LR-WB bags at 1, 4, 7, 14, 21, 28, 35 dpi for RC presence and viability through real-time PCR (rPCR) for DNA and mRNA, respectively, and by isolation. Identification of isolates was confirmed by indirect immunofluorescence and rPCRs.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>RC survived for the entire storage period in both whole and leukoreduced blood. All bags contained viable bacteria until 7 dpi; RC viability generally decreased over time, particularly in LR-WB bags where the isolation time was longer than in WB. Viable bacteria were still isolated at 35 dpi in 3 WB and 3 LR-WB.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>Leukoreduction reduced but did not eliminate RC in infected units. The survival and infectivity of RC in canine blood during the storage period may represent a threat for recipients.</jats:p></jats:sec>