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Luminescence signals are expressed as relative light models (RLU). between HT-PBNA titers and anti-HPV 16 L1 antibody-levels determined by a Luminex bead-based GST-capture assay for these 35 sera and a Kappa-value of 0.72, with only 3 discordant sera in the low titer range. In addition to natural low titer antibody responses the high sensitivity of the HT-PBNA also allows detection of cross-neutralizing antibodies induced by commercial HPV L1-vaccines and experimental L2-vaccines. When analyzing the WHO international requirements for HPV 16 and 18 we decided an analytical sensitivity of 0.864 and 1.105 mIU, respectively. == Introduction == Human papillomaviruses (HPV) are causally involved in the induction of cervical malignancy and its precursor lesions. Currently, 12 HPV types are classified as carcinogenic ON-01910 (rigosertib) to humans and an additional 8 types as probably or possibly carcinogenic to human[1]. Worldwide, the ten HPV types recognized most frequently in cervical malignancy are HPV 16, 18, 33, 45, 31, 58, 52, 35, 59 and 56[2]. HPV contamination is recognized as an absolute requirement for the transformation process in cervical malignancy[3],[4], but host cell cofactors also play a role. Built around the recognition of the HPV causality in cervical malignancy development, two commercial vaccines, Gardasil and Cervarix targeting the two most prevalent carcinogenic HPV types 16 and 18 were licensed in the EU in 2006 and 2007, respectively[5],[6]. Both vaccines employ the major capsid protein L1 in form of virus-like particles (VLPs) as antigen and are highly effective in preventing infections by HPV types 16 and 18 as well as cervical intraepithelial neoplasias induced by these viruses[7],[8]. The mode of action ON-01910 (rigosertib) of both vaccines is considered to be the induction of neutralizing antibodies directed against L1 surface loops of the viral capsid. With more than six years history on papillomavirus prophylactic vaccination, monitoring long term development of protective titers of neutralizing antibodies is usually of increasing importance. Thus, there is a need for the evaluation of such antibody responses, specifically for functional assays analyzing neutralizing antibodies. Papillomaviruses cannot be replicated in simple cell culture systems. Therefore, in the past a number of functional assays have been developed to measure antibody-mediated neutralization of papillomaviruses. These assays involved the use of authentic viruses[9][10]and so called pseudovirions with an encapsidated reporter construct[11],[12],[13]. In addition, neutralizing antibodies have been measured more indirectly e.g. by a hemagglutination inhibition assay[14]or by competition of binding of a neutralizing monoclonal antibody[15]. The current gold standard for measuring neutralizing anti-HPV antibodies is a manually performed pseudovirion-based neutralization assay (manPBNA;[16]) using secreted alkaline phosphatase (SEAP) as reporter. Although infectious ON-01910 (rigosertib) pseudovirions of different PV types can be very easily produced, the manPBNA remains tedious and variable, restricting its applicability mainly to small sample figures. Several arguments make a case for the need of a high-throughput neutralization assay with improved sensitivity: (i) requirement of larger serum sample figures for follow-up studies on current vaccines, (ii) detection of cross-neutralizing antibodies induced by the commercial vaccines, and (iii) monitoring the effect of simplified vaccination techniques. Also, induction of neutralizing antibodies by second generation vaccines, e.g. based on the L2 protein needs to be assessed. Finally, large level neutralization assays would allow addressing questions on naturally occurring protective immunity against HPV infections. Especially in respect to antibody responses against natural papillomavirus infections there are high demands for sensitivity and reproducibility in a neutralization assay. To date, high-throughput detection of HPV capsid-specific antibodies has been possible only with the aid of surrogate detection assays such as ELISA and competitive Luminex immunoassay (cLIA) using VLPs as antigen. Here we describe the adaptation of the PBNA to a high-throughput (HT) setting. We developed a purely add-on system in which the serial dilution of serum samples is separated from your cell-based assay, providing a high degree of flexibility. The high-throughput assay demonstrates high robustness with little intra- and inter-assay day variability. Also, the HT-PBNA shows higher sensitivity compared to the manually performed assay using SEAP as reporter. In its current format, the neutralization titer of 110 serum samples for seven HPV types can be determined in a single run. The HT-PBNA will allow the execution of large studies on vaccine- and naturally-induced immunity against HPV Rabbit Polyclonal to PDLIM1 infections. == Materials and Methods == == Human Sera == Base line.