FIG. 7.
Comparison of the abilities of antisera raised against initial purified HPV-11 VLPs and against reassembled VLPs to neutralize HPV-11 virus. Serial log10 dilutions of anti-HPV-11 antiserum (10−3 to 10−7) raised against initial purified HPV-11 VLPs or reassembled VLPs were incubated with HPV-11 virions before addition to HaCaT cells. Control experiments without added virions (lane C) or virions added to cells without preincubation with serum (lane V) were also run. Six days postinfection, the cells were harvested and the presence of the E1∧E4 spliced message, diagnostic of HPV-11 infection, was determined by RT-PCR. PCR products were separated on 2% agarose gels, stained with ethidium bromide, and examined under UV light for the presence of the ∼0.6-kb E1∧E4 band (a). PCR amplification of β-actin was performed on all cDNA samples as an internal control (b). The expected size of the β-actin band is ∼0.6 kb. Lane S contains molecular size markers.