Integration of the proviral DNA into the genome of infected cells is a key
step of HIV-1 replication. Integration is catalyzed by the viral enzyme int
egrase (IN). 6-oxocytidine-containing oligonucleotides were found to be eff
icient inhibitors of integrase in vitro. The inhibitory effect is sequence-
specific and strictly requires the presence of the 6-oxocytidine base. It i
s due to the impairment of the integrase binding to its substrate and does
not involve an auto-structure of the oligonucleotide.