Eight to ten week old female New Zealand White (NZW) rabbits were immunized subcutaneously with saline (naïve) or 1/4th (5 μg each HPV16 and HPV18 VLP) the human dose equivalent of Cervarix® at W0, W4 and W12. Eight to ten week old female NZW rabbits were selleck kinase inhibitor immunized subcutaneously with 5 μg each of the indicated in
house L1 VLP (or 5 μg each of HPV16, HPV18, HPV39 and HPV58 for the tetravalent preparation). VLP were absorbed onto 3% alhydrogel (250:1 (v/v), Superfos Biosector) for 1–2 h at room temperature under gentle rotation. For the final preparation of the rabbit inoculum, the VLP-alhydrogel mix was diluted in sodium phosphate buffer pH 6.5 (final concentration 2.7 mM NaH2PO4 and 3.3 mM Na2HPO4) with 150 mM NaCl, alhydrogel (250 μg/mL Al3+), Sigma Adjuvant System (25 μg/mL monophosphoryl lipid), and incubated with gentle rotation at room temperature for a minimum of 15 min. Rabbits received additional immunizations at W4 and W12. In all cases, serum samples were collected prior to the first immunization (pre-immunization) and two weeks Selleck BMS777607 following both the second and third doses. All animal husbandry and
regulated procedures were carried out in strict accordance with UK Home Office guidelines and governed by the Animals (Scientific Procedures) Act 1986 which complies with the EC Directive 2010/63/EU and performed under licences PPL 80/2537 and PPL 70/6562-3 granted only after review of all the procedures in the licence by the local Animal Welfare and Ethical Review Bodies. L1L2 pseudoviruses representing Alpha-7 and Alpha-9 HPV genotypes and BPV, and carrying a luciferase reporter, were expressed from transiently transfected 293TT cells, purified and characterized as previously described [20] and [36]. The equivalent of a Tissue Culture Infectious Dose 50% (TCID50) was estimated using the Spearman-Karber equation and a standardized input of 300 TCID50 was used for all pseudoviruses. Serum samples were
else serially diluted and the 80% reciprocal neutralization titer estimated by interpolation. Heparin (H-4784; Sigma–Aldrich, UK) was included as a positive inhibitor control and as an indicator of inter-assay reproducibility. The median (Inter-quartile range, IQR) inhibitory concentrations (μg/mL) were as follows: HPV16 11.9 (9.5–22.3; n = 7), HPV31 5.1 (3.3–8.1; 6), HPV33 13.1 (7.4–19.4; 6), HPV35 3.1 (2.9–4.9; 6), HPV52 25.2 (13.6–31.9; 6), HPV58 8.2 (3.6–19.4; 6), HPV18 3.9 (3.4–5.0; n = 6) HPV39 5.8 (4.0–7.2; 5), HPV45 3.7 (3.5–3.9; 6), HPV59 13.6 (11.7–16.3; 6), HPV68 7.0 (6.5–12.1; 6) and BPV 73.5 (59.1–75.9; 5). Serial dilutions of selected final bleed rabbit sera were pre-incubated for 1hr at room temperature with 2 μg of L1 VLP (HPV16, HPV31, HPV33 or HPV58), followed by addition of 300 TCID50 of L1L2 pseudoviruses representing the same HPV genotypes for 1 h at room temperature, before being transferred to 293TT cells for 72 h at 37 °C.