Evaluation of HPV-16 and HPV-18 specific antibody measurements in saliva collected in oral rinses and merocel® sponges

Background: Current Human papillomavirus (HPV) L1 VLP vaccines protect against HPV-16 and HPV-18-associated cancers, in females and males. Although correlates of protection have not been identified, HPV-specific antibodies at sites of infection are thought to be the main mechanism of protection afforded by vaccination. Oral sampling has gained increased attention as a potential alternative to serum in monitoring immunity to vaccination and understanding local immunity in oral cancers. Methods: Serum was collected via venipuncture, and saliva was collected via oral rinses and Merocel (R) sponges from healthy volunteers: 16 unvaccinated females, 6 females (ages 24-41) and 6 mid-adult aged males (ages 27-45) recipients of three doses of the HPV-16/18/6/11 vaccine (Gardasil (R)). Mid-adult male vaccine trial participants were compared to female participants. Samples were tested for anti-HPV-16 and anti-HPV-18 immunoglobulin G levels by an Ll virus-like particle-based enzyme-linked immunosorbent assay (ELISA). Results: All vaccinated participants had detectable serum anti-HPV-16 and anti-HPV-18 antibodies. Optimal standard concentration range and sample serial dilutions for oral rinses were determined. The standard curve was not affected by the type of solution examined. Reproducibility of HPV-16 and HPV-18 antibody titers in mouthwash (overall CV < 10%) or in Merocel (R) extraction buffer was robust (CV < 13%). Excellent assay linearity (R-2 > 0.9) was observed for sera spiked controls in both solutions. HPV-16 and HPV-18 specific antibodies were detectable in saliva from vaccine recipients, both in mouthwash and in Merocel (R) sponges but levels were several logs lower than those in serum. Conclusions: This study confirms the application of HPV-16 and HPV-18 ELISAs currently used in seroepidemiological studies of immunogenicity of HPV vaccines for use with oral samples. Oral samples may be a useful resource for the detection of HPV-16 and HPV-18-specific antibodies in saliva following vaccination. ARTICLE INFO Article history: Received 7 December 2017 Received in revised form 8 March 2018 Accepted 10 March 2018 Available online 6 April 2018 Keywords: HPV vaccine Mouthwash Saliva Human papillomavirus (C) 2018 Elsevier Ltd. All rights reserved.