FIG. 3.
Autologous and heterologous neutralization efficiencies of sera from mice immunized with HIV-VLPAs. The HIV-1 neutralization assay was performed on CCR5-expressing U87 cells against autologous and heterologous primary isolates, clade A Ugandan and clade B Italian HIV-1 isolates, respectively. Ten TCID50 of each isolate were pretreated with serial dilutions of the immune sera, collected at the end of the complete immunization schedule, from the mouse groups immunized with 20 μg of HIV-VLPAs via the i.p. or the i.n. route. The neutralization activities of serum antibodies, at different dilutions, induced via the i.p. (A and C) or the i.n. (B and D) route are represented as percentages of the virus replication in control samples (vertical bars). Fifty percent neutralization has been considered the lowest limit for scoring the test positive. In all the panels the kinetics of virus growth during the 7-day neutralization assay is shown (lines). Each serum dilution was evaluated in triplicate, and the reported results include the cumulative data from two independent experiments with three mice per group per experiment.