Figure 4: (a) The titer of neutralizing antibodies (NAb) against adenoviral (Ad), and (b) the titer of NAb against recombinant adeno-associated viral (rAAV2), or self-complementary AAV (scAAV2) vectors, in the serum, saline- (GBSS) and Ad-injected joint fluid, rAAV- or scAAV-injected joint fluid, or contralateral uninjected joint fluid. *Significantly greater than serum Ad/AAV2 NAb titers. There were no significant differences in NAb titers between types of AAV2 vectors (i.e., rAAV2 versus scAAV2). Both Ad and AAV2 vectors induce the sustained NAb production in the injected joint fluid and the transient NAb production in the serum and contralateral joint fluid.