Аннотация:One of the developing HIV1 cure approaches is inhibition of interactions between viral proteins and their cellular partners. Consequently, the search for new cellular participants of HIV1 replication is still relevant. SFPQ protein (splicing factor, prolineand glutaminerich) is considered as one of HIV1 integrase part-ners but its role in the viral replication is obscure. To determinethe step in the virus life cycle that is affected by SFPQ, we trans-duced HEK 293T cells with normal, increased and reduced SFPQ levels with an HIV-based lentiviral vector and analyzed the efficiency of early replication stages using qPCR approaches. We showed that changes in the SFPQ level did not affect reverse transcription whereas influenced both integration and postinte-grational DNA repair. Using pulldown assay we studied binding of recombinant SFPQ protein with HIV1 reverse transcriptase and integrase as well as a cellular integrase partner Ku70, which is involved in the postintegrational repair [Anisenko AN et al.(2017) Sci Rep, 7:5649]. SFPQ was shown to interact with both integrase and Ku70 but not with reverse transcriptase. In addition, we established dissociation constant of integrase and SFPQ.Thus, we demonstrated for the first time the functional role of SFPQ in HIV1 integration and postintegrational repair, as well as characterized its interactions with viral proteins. This work is supported by Russian Foundation for Basic Research, grant 200400437