Recombinant single-chain variable fragment and single domain antibody piezoimmunosensors for detection of HIV1 virion infectivity factor

In this paper recombinant single-chain fragments (scFv-4BL), and single domain antibodies (4BL-VH) and (4BL-VHD) generated against HIV1 virion infectivity factor (Vif) are used to develop piezoimmunosensors for HIV1 recognition. Mixed self assembled monolayers were generated at the surface of gold coated crystal sensors to which scFv-4BL, 4BL-VH, or 4BL-VHD were immobilized. Impedance analysis was used to discriminate interfering signals from frequency variation data and to increase the sensor sensitivity. The elimination of interfering signals enabled the quantification of the amount of immobilized protein and gave some indication on the viscoelasticity of immobilized biofilms. All the modified sensors were able to specifically recognize HIV1 Vif in liquid samples. The results indicate that lower sensitivities are obtained with 4BL-VH single domain antibodies, possibly due to its higher hydrophobic character. The sensitivity obtained when using scFv-4BL was reestablished when using the more hydrophilic 4BL-VHD single domain. 4BL-VHD piezoimunosensors were effective in recognizing HIV1 Vif from protein mixtures and from cell extracts of human embryonic kidney cells expressing HIV1 Vif. The results presented in this paper demonstrate the potential applicability of the developed piezoimmunosensors to monitor HIV1 infection evolution.