Isoelectric points of viruses

Abstract

Viruses as well as other (bio-)colloids possess a pH-dependent surface charge in polar media such as water. This electrostatic charge determines the mobility of the soft particle in an electric field and thus governs its colloidal behaviour which plays a major role in virus sorption processes. The pH value at which the net surface charge switches its sign is referred to as the isoelectric point (abbreviations: pI or IEP) and is a characteristic parameter of the virion in equilibrium with its environmental water chemistry. Here, we review the IEP measurements of viruses that replicate in hosts of kingdom plantae, bacteria and animalia. IEPs of viruses are found in pH range from 1AE9 to 8AE4; most frequently, they are measured in a band of 3AE5 < IEP < 7. However, the data appear to be scattered widely within single virus species. This discrepancy is discussed and should be considered when IEP values are used to account for virus sorption processes.

Long-range attractive forces extending from the alumina’s nanolayer surface in aqueous solutions

“…The average strength of electric field in aqueous solution at 25°C with v e of 40 μm/s (Table 12), and ζ(MS2) = − 40.4 ± 3.7 mV [34] at pH7 can be estimated at 12.8 V/cm, which is in good agreement with the value of 15.2 V/cm created by nanoalumina fibers grafted onto microglass fibers [1].…”

“…In the case where clean colloidal particles are suspended in absolute pure water, the point of zero charge (PZC), which is characteristic to the particle's surface, can be determined. The IEP and the PZC do not necessarily differ in the presence of monovalent ions; however, the PZC is very difficult to measure experimentally [34]. MS2 (ATCC 15597-B1) and fr (ATCC 15767-B1) bacteriophages are icosahedral in shape with a diameter of 26-27 nm [35] and 19 nm [37], respectively.…”

“…The IEP value of MS2 bacteriophage in different environments, based on the averaging of 10 measurements, shows a mean IEP value of 3.5 ± 0.6 and with the discrepancy in IEP (ΔIEP) of 1.8 from 2.2 to 4.0 [34]. Recent studies by Duek et al [35] and Chrysikopoulos et al [36] determined the alteration of the IEP by a change in water chemistry (e.g., ionic strength or ionic composition) with IEP of the former case in the range from less than 2 at ionic strengths of 0.0 mM and 2.6 mM to IEP of 4.4 in the latter case that was measured in double distilled water.…”

The mechanism for bacteriophage f2 removal by nanoscale zero-valent iron

“…Bacteriophage f2 is an icosahedral, positive-sense single-stranded RNA virus that infects the bacterium E. coli. The pI of bacteriophage f2 is 4.0 as published (Michen and Graule, 2010). It is extremely similar to bacteriophage MS2.…”

Iron oxide amended biosand filters for virus removal

“…These differences were also attributed to echovirus-12 having a higher IEP (echoviruses have IEP of 5-6.4) than MS2 and PRD-1, which have similar IEPs of 3.5-3.9 and 4.2, respectively [58].…”