Inhibition of HIV-1 by an anti-integrase single-chain variable fragment (SFv): delivery by SV40 provides durable protection against HIV-1 and does not require selection

Human immunodeficiency virus type I (HIV-1) encodes several proteins that a re packaged into virus particles. Integrase (IN) is an essential retroviral enzyme, which has been a target for developing agents to inhibit virus rep lication. In previous studies, we showed that intracellular expression of s ingle-chain variable antibody fragments (SFvs) that bind IN, delivered via retroviral expression vectors, provided resistance to productive HIV-1 infe ction in T-lymphocytic cells. In the current studies, we evaluated simian-v irus 40 (SV40) as a delivery vehicle for anti-IN therapy of HIV-1 infection . Prior work suggested that delivery using SV40 might provide a high enough level of transduction that selection of transduced cells might be unnecess ary. In these studies, an SV40 expression vector was developed to delivery SFv-IN (SV(Aw)). Expression of the SFv-IN was confirmed by Western blotting and immunofluorescence staining, which showed that >90% of SupT1 T-lymphoc ytic cells treated with SV(Aw) expressed the SFv-IN protein without selecti on. When challenged, HIV-1 replication, as measured by HIV-1 p24 antigen ex pression and syncytium formation, was potently inhibited in cells expressin g SV40-delivery SFv-IN. Levels of inhibition of HIV-1 infection achieved us ing this approach were comparable to those achieved using murine leukemia v irus (MLV) as a transduction vector, the major difference being that transd uction using SV40 did not require selection in culture whereas transduction with MLV did require selection. Therefore, the SV40 vector as gene deliver y system represents a novel therapeutic strategy for gene therapy to target HIV-1 proteins and interfere with HIV-1 replication.