Zheng Quan Toh (Australia)
Murdoch Children's Research Institute Infection and ImmunityPresenter of 3 Presentations
MEASUREMENT OF HPV-SPECIFIC IGG AND IGM RESPONSES USING A PSEUDOVIRION-BASED ELISA METHOD (ID 1254)
Abstract
Introduction
The human papillomavirus (HPV) pseudovirion (PsV)-based neutralisation assay (PBNA) does not discriminate different antibody isotypes. Here, we examined the use of a PsV-based enzyme-linked immunosorbent assay (ELISA) to measure HPV-specific IgG and IgM antibody responses.
Methods
A cohort study was undertaken in 200 Fijian girls (15-19 years old) previously unvaccinated, or vaccinated with 1-3 doses of 4vHPV (Gardasil®, Merck Inc.) 6 years earlier. A booster dose of 2vHPV (Cervarix®, GSK) was given to all girls. Blood was taken pre- and 28 days following the 2vHPV booster dose. Neutralising antibody (NAb) responses were previously measured by a HPV PBNA. We measured the IgG and IgM response to HPV-16/18 using a PsV-based ELISA.
Results
Preliminary analyses to date (N=10/dosage group) showed significantly higher HPV16-IgG levels in girls previously vaccinated with 2 or 3 doses of 4vHPV compared with girls vaccinated with 1 dose or unvaccinated (p<0.05 in all cases): no significant differences in IgM antibody levels were found between all dosage groups. Following 2vHPV, HPV-specific IgG levels were significantly increased in all dosage groups, whereas previously unvaccinated girls also had significantly higher HPV-specific IgM levels (p<0.05). Girls previously vaccinated with 1 dose of 4vHPV boosted to a similar IgG level as girls previously vaccinated with 2 or 3 doses. Significant correlations were found between IgG, but not IgM and NAb (r=0.61, p<0.0001).
Conclusions
These results suggest that a PsV-based ELISA method may be used as an alternative to the PBNA for the measurement of HPV-specific antibody responses, including characterisation of antibody isotype and subclasses following vaccination. Further studies are needed in different settings to validate this approach.
SELECTIVE PERSISTENCE OF HPV CROSS-NEUTRALISING ANTIBODIES FOLLOWING REDUCED-DOSE HPV VACCINE SCHEDULES (ID 1198)
- Zheng Quan Toh (Australia)
- Jennie Kosasih (Australia)
- Fiona Russell (Australia)
- Rita Reyburn (Australia)
- James Fong (Fiji)
- Evelyn Tuivaga (Fiji)
- Felisita Ratu (Fiji)
- Cattram Nguyen (Australia)
- Silivia Mantanitobua (Fiji)
- Lien Anh Ha Do (Australia)
- Treve Menheniott (Australia)
- Suzanne M. Garland (Australia)
- Ian Frazer (Australia)
- Kim Mulholland (United Kingdom)
- Paul Licciardi (Australia)
Webcast
IMMUNE MEMORY RESPONSES FOLLOWING REDUCED-DOSE QUADRIVALENT HPV VACCINE IN ADOLESCENT FIJIAN GIRLS (ID 1192)
Abstract
Introduction
Data on immunological memory following reduced-dose human papillomavirus (HPV) vaccine schedules are limited. Immune memory cells such as memory B cells (Bmem) and T-follicular helper T cells (Tfh) are important for generation of long-term memory responses. We examined Bmem and Tfh 1-month following a booster dose of 2vHPV (Cervarix®, GSK) in girls who were previously unimmunised or received 1, 2 or 3 doses of 4vHPV (Gardasil®, Merck Inc.) 6 years earlier.
Methods
We conducted a cohort study in 200 Fijian girls (15-19 years old) previously unimmunised, or immunised with 1-3 doses of 4vHPV 6 years earlier. Blood was taken pre- and 28 days following the 2vHPV booster dose. To determine HPV vaccine type immune memory cells, we conjugated HPV16 or 18 pseudovirions with a fluorescently-labelled probe (Alexa Fluor® 488), and then measured the HPV-specific response by flow cytometry using the following markers for Bmem (CD19, CD27, CD38, IgM, IgG) and Tfh (CD4, CXCR5, CD278 and CD279) responses.
Results
Following a dose of 2vHPV, there were similar proportions of CD27+IgG+HPV16+/18+ populations in girls who were previously immunised with 1, 2 or 3 doses of 4vHPV 6 years earlier. All were higher than unimmunised girls, although this was not significant. A weak correlation was found between CD27+IgG+16/18+ and HPV16/18 neutralising antibodies when the data were pooled (r=0.22, p=0.03). Analyses for the comparison of other cell populations (CD27+IgM+16/18+; memory IgM B cells, CD27+CD38+; plasmablast, CD4+CXCR5+PD-1+ICOS-1+; Tfh) are ongoing.
Conclusions
Prior immunisation with 1, 2 or 3 doses of 4vHPV generated similar levels of CD27+IgG+16/18+ Bmem after a booster dose of 2vHPV, suggesting that 1 dose may efficiently prime immunological memory responses. Additional analyses of specific immune memory cell populations will provide a better understanding of the potential usefulness of single dose HPV schedules in the long-term.