The Influence of Virus Infection on the Extracellular pH of the Host Cell Detected on Cell Membrane

Abstract

Influenza virus infection can result in changes in the cellular ion levels at 2–3 h post-infection. More H+ is produced by glycolysis, and the viral M2 proton channel also plays a role in the capture and release of H+ during both viral entry and egress. Then the cells might regulate the intracellular pH by increasing the export of H+ from the intracellular compartment. Increased H+ export could lead indirectly to increased extracellular acidity. To detect changes in extracellular pH of both virus-infected and uninfected cells, pH sensors were synthesized using polystyrene beads (ϕ1 μm) containing Rhodamine B and Fluorescein isothiocyanate (FITC). The fluorescence intensity of FITC can respond to both pH and temperature. So Rhodamine B was also introduced in the sensor for temperature compensation. Then the pH can be measured after temperature compensation. The sensor was adhered to cell membrane for extracellular pH measurement. The results showed that the multiplication of influenza virus in host cell decreased extracellular pH of the host cell by 0.5–0.6 in 4 h after the virus bound to the cell membrane, compared to that in uninfected cells. Immunostaining revealed the presence of viral PB1 protein in the nucleus of virus-bound cells that exhibited extracellular pH changes, but no PB1 protein are detected in virus-unbound cells where the extracellular pH remained constant.

Extracellular pH and lung infections in cystic fibrosis

“…Its role is important, for example, in Candida albicans infections (not considered a relevant pathogen in CF (Chmiel et al, 2014)), where acidic pH and low cAMP levels favor its growth as yeast (Danhof et al, 2016;Hollomon et al, 2016). Some viruses, like influenza virus, acidify the pHe when they multiplicate (Liu et al, 2016). In addition, many neutrophilic bacterial strains change their intracellular ATP concentration in response to extracellular pH variations, adapting their cellular bioenergetics to the new environment (Albert and Brown, 2015).…”

Chemical reactivation of fluorescein isothiocyanate immunofluorescence-labeled resin-embedded samples

“…Since fluorescein isothiocyanate (FITC) had a high fluorescence quantum yield 13,14 and was widely used for monitoring pH values [15][16][17] and immunofluorescence labeling of biological tissues, [18][19][20][21][22] we chose FITC as one representative of pH-sensitive fluorescent probe to realize the idea. First, we investigated whether the fluorescence of FITC would be quenched during resin-embedding process, then further tested whether the quenched immunofluorescence could be reactivated.…”

Manipulation and Immobilization of a Single Fluorescence Nanosensor for Selective Injection into Cells

“…In our previous study, our group achieved pH measurement of an influenza virus-infected cell on the cell membrane using a fluorescence microsensor [29]. However, intracellular measurement was not achieved, since rapid injection of the selected microsensor into a specific cell was still too difficult.…”