Plasma extracellular vesicles (EVs), especially exosome-like vesicles (ELVs), are being increasingly explored as a source of potential noninvasive disease biomarkers. The discovery of blood-based biomarkers associated with ELVs requires methods that isolate high yields of these EVs without significant contamination with highly abundant plasma proteins and lipoproteins. The rising interest in blood-based EV-associated biomarkers has led to the rapid development of novel EV isolation methods. However, the field suffers from a lack of standardization and often, new techniques are used without critical evaluation. Size exclusion chromatography (SEC) has become the method of choice for rapid isolation of relatively pure EVs from plasma, yet it has technical limitations for certain downstream applications. The recently released exoEasy kit (Qiagen) is a new membrane affinity spin column method for the isolation of highly pure EVs from biofluids with the potential to overcome most of the limitations of SEC. By using multiple complementary techniques we assessed the performance of the exoEasy kit in isolating ELVs from 2 ml of human plasma and compared it with the SEC qEV column (Izon Science). Our data show that exoEasy kit isolates a heterogenous mixture of particles with a larger median diameter, broader size range and a higher yield than the SEC qEV column. The exclusive presence of small RNAs in the particles and the total RNA yield were comparable to the SEC qEV column. Despite being less prone to low density lipoprotein contamination than the SEC qEV column, the overall purity of exoEasy kit EV preparations was suboptimal. The low particle-protein ratio, significant amount of albumin, very low levels of exosome-associated proteins and propensity to triglyceride-rich lipoprotein contamination suggest isolation of mainly non-ELVs and co-isolation of plasma proteins and certain lipoproteins by the exoEasy kit. We demonstrate that performance of exoEasy kit for the isolation of ELVs for biomarker discovery is inferior to the SEC qEV column. This comprehensive evaluation of a novel EV isolation method contributes to the acceleration of the discovery of EV-associated biomarkers and the development of EV-based diagnostics.

Several sulfated polysaccharides (dextran sulfate, pentosan polysulfate, fucoidan, and carrageenans) proved to be potent inhibitors for herpes simplex virus, human cytomegalovirus, vesicular stomatitis virus, Sindbis virus, and human immunodeficiency virus. They were moderately inhibitory to vaccinia virus but not inhibitory to adenovirus, coxsackievirus, poliovirus, parainfluenza virus, and reovirus. These results indicate that, with the exception of parainfluenza virus, enveloped viruses are specifically susceptible to the inhibitory activity of sulfated polysaccharides.

The (S)- and (R)-enantiomers of acyclic purine nucleoside phosphonate analogs (i.e., 3-hydroxy-2-phosphonomethoxypropyl [HPMP] derivatives, 3-fluoro-2-phosphonomethoxypropyl [FPMP] derivatives, and 2-phosphonomethoxypropyl [PMP] derivatives of adenine [A], 2-aminopurine, 2,6-diaminopurine [DAP], and guanine [G]) have been synthesized and evaluated for antiviral activity. As a rule, the HPMP derivatives proved effective against DNA viruses but not RNA viruses or retroviruses. In particular, (S)-HPMPA, (S)-HPMPDAP, and (R)- and (S)-HPMPG were exquisitely inhibitory to herpes simplex virus type 1 (50% effective concentrations, 0.63, 0.22, 0.10, and 0.66 microM, respectively). The FPMP and PMP derivatives showed marked inhibitory activities against retroviruses but not DNA viruses. The (S)-enantiomer of FPMPA and the (R)-enantiomer of PMPA were approximately 30- to 100-fold more effective against human immunodeficiency virus and Moloney murine sarcoma virus (MSV) than their enantiomeric counterparts. In contrast, both (S)- and (R)-enantiomers of the DAP and G derivatives proved equally effective against retroviruses, except for (R)-PMPDAP, which was 15- to 40-fold more inhibitory than (S)-PMPDAP. (R)-PMPDAP emerged as the most potent and selective inhibitor of MSV-induced transformation of murine C3H/3T3 cells and human immunodeficiency virus-induced cytopathicity in MT-4 and CEM cells (50% effective concentration, approximately 0.1 to 0.6 microM). When administered intraperitoneally at a single dose as low as 2 mg/kg, (R)-PMPDAP efficiently decreased MSV-induced tumor formation in newborn NMRI mice and significantly increased the survival time of MSV-infected mice. In addition, upon oral administration to MSV-infected mice, (R)-PMPDAP showed marked antiretroviral efficacy.