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After sample processing for RNA and DNA analysis, the leftover protein pellets are usually discarded due to the limited efficiency of pellet reconstitution/solubilisation. As the pelleted proteins are tightly packed, they are most often solubilised using chaotropic agents (e.g., guanidine hydrochloride or urea), detergents (e.g., SDS), salts (NaCl) or basic buffer (Tris). The aim of this study was to define and optimise the procedure for the efficient extraction of proteins from human peripheral blood mononuclear cells (PBMCs), obtained by a single blood draw and lysed in TRIzol reagent, by varying experimental conditions in terms of protein precipitation solvent (isopropanol or acetone), washing (with or without guanidine hydrochloride) and solubilisation solution (containing SDS, NaCl, urea and/or Tris). We evaluated the efficacy of the final, optimised protocol to solubilise both small cytoplasmic and larger transmembrane proteins, and the compatibility with methods employed for the subsequent analysis of protein posttranslational modifications, such as glycosylation. The optimised protocol for the extraction and isolation of post-TRIzol leftover proteins from PBMCs can be defined as follows: protein precipitation from the organic phase with ice-cold acetone, pellet washing with absolute ethanol and solubilisation in 1 % SDS, employing 20 min heating at 50ºC and vortexing.

Safe sample transport is of great importance for infectious diseases diagnostics. Various treatments and buffers are used to inactivate pathogens in diagnostic samples. At the same time, adequate sample preservation, particularly of nucleic acids, is essential to allow an accurate laboratory diagnosis. For viruses with single-stranded RNA genomes of positive polarity, such as foot-and-mouth disease virus (FMDV), however, naked full-length viral RNA can itself be infectious. In order to assess the risk of infection from inactivated FMDV samples, two animal experiments were performed. In the first trial, six cattle were injected with FMDV RNA (isolate A22/IRQ/24/64) into the tongue epithelium. All animals developed clinical disease within two days and FMDV was reisolated from serum and saliva samples. In the second trial, another group of six cattle was exposed to FMDV RNA by instilling it on the tongue and spraying it into the nose. The animals were observed for 10 days after exposure. All animals remained clinically unremarkable and virus isolation as well as FMDV genome detection in serum and saliva were negative. No transfection reagent was used for any of the animal inoculations. In conclusion, cattle can be infected by injection with naked FMDV RNA, but not by non-invasive exposure to the RNA. Inactivated FMDV samples that contain full-length viral RNA carry only a negligible risk of infecting animals. [ABSTRACT FROM AUTHOR]