measurement of the modification of the sensor surface refractive index. The surface of

such biosensors is commonly in metals (gold or platinum) and ligands grafted could

be of various origins (antibodies, cell receptors, glycans, aptamers). Antibody grafting

was the first applied for virus detection [25], but antibody independent assays were

soon proposed based on the grafting of viral cell receptors or target as for the glycans

in the case of influenza viruses [11], [26]. The limit of detection of such tools is highly

competitive and it was recently proven to be the first tool to allow for both viral

activity validation and complete viral particle counting [11] (see Figure 8.3).

8.3.2.2

Particle Counters

Viral particle counting technologies have been developed in the last twenty years

and could be referred to as particle counters for most of them. Such technologies

have been developed or adapted from other fields for the real-time quantification of

the total viral particles. They rely on various technologies involving either light

scattering, Coulter effect, or fluorescence in-flow detection [4]. Examples are given

in Figure 8.4.

FIGURE 8.4 Comparative studies of quantification strategies on viral preparations. a −

Lentivirus quantifications (data extracted from Heider et al. 2014 [ 4]). b − Ebolavirus

quantifications (data extracted from Rossi et al. 2015 [ 27]). c − Influenza virus of various

strain quantifications (data extracted from Transfiguracion et al. 2015 [ 3]).

Analytics and virus production processes

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