Bound Lectin Latex

The enveloped glycoprotein gp120 of human immunodeficiency virus type 1 (HIV-1) is a mannose-rich glycoprotein that strongly interacts with some lectins such as Con A. Akashi et al. [19] and Hayakawa et al. [20] described covalent immobilization of Con A and other mannose-specific lectins onto modified polystyrene nanospheres (360 nm in diameter) in order to capture HIV-1 virion. As shown in Fig. 5, polystyrene beads were functionalized by carboxylic acid groups brought by poly(ferf-butyl methacrylate), which allow covalent binding of lectins by reaction with their amino groups using carbodiimide activation. Interaction between Con A-immobilized latex particles and HIV-1 virions led to aggregation of the nanospheres allowing their separation from noncaptured virions by centrifugation. 0.3 |g of Con A/cm2 [19] and 0.91 |g of Con A/ cm2 [20] were assessed. Results indicated that HIV-1 capture activity of Con A-immobilized nanospheres was dose dependent. A significant reduction of the viral infectious activity—up to 2 x 103—was reached at 2 mg/mL concentration [20]. Furthermore, identical activity in HIV-1 capture was obtained with the other tested mannose-specific lectins whereas no HIV-1 capture activity was detectable with galactose-specific lectin [19]. Authors concluded that both selection of immobilized lectins and diameter of nanospheres are determining parameters for the capture activity and selectivity. Indeed, interaction between Con A and gp 120 is not as specific as that with anti-gp 120 antibodies, since lectins recognize the oligosaccharide chain of gp 120.

The efficiency of lectin-immobilized latex particles in biomedical applications is not clear because of the low specificity of the interaction with HIV-1 virion, which could be canceled under in vivo conditions. Indeed, other biological components, including oligosaccharide moieties, should present higher affinities for lectins than HIV-1 virion. Moreover, Con A is known to exhibit various toxicities in vivo. Nevertheless, the Con A-latex nanospheres could be used in ex vivo experiments or for basic research applications such as a chromato-graphic matrix to purify or concentrate enveloped viruses.

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