Title of PhD project / theme
Development of a novel 24-plex quantitative microsphere-based assay for assessment of antibodies against pneumococcal vaccines.
Supervisory team
Nagasaki University supervisor (lead):
Lead: Assoc Prof Bhim Gopal Dhoubhadel (b-gopal@nagasaki-u.ac.jp)
Asst Prof Kentaro Kato (katoken@nagasaki-u.ac.jp)
LSHTM supervisor:
Prof Shunmay Yeung (Shunmay.Yeung@lshtm.ac.uk, Faculty of Infectious and Tropical Diseases)
Advisors:
Prof Stefan Flasche (LSHTM)
Prof Koya Ariyoshi (NU)
Prof Konosuke Morimoto (NU)
Asst Prof Ganchimeg Bayarsaikhan (NU)
Brief description of project / theme
Pneumococcus (Streptococcus pneumoniae) is a major human pathogen that causes deadly diseases, e.g., pneumonia and meningitis, mostly in elderly and young children. This pathogen has almost 100 different serotypes; however, only 24 serotypes are covered in the vaccines: 23-valent pneumococcal polysaccharide (PPV23) vaccine and 10- or 13-valent pneumococcal conjugate (PCV10 or PCV13) vaccine. Protective antibody production of each vaccine serotype is not equal, and few of these serotypes are still prevalent among vaccinated adults and children (Djennad A, EClinicalMedicine, 2018). Knowing which vaccine serotype protects and which does not in population, helps us to design new effective vaccines in future (Toh ZQ, Vaccines, 2021).
This PhD project will focus on the development of an innovative test for the detection of anti-pneumococcal antibodies following vaccination. There are two potential phases to explore in this project. The first is to develop a novel 24-plex microsphere-based immunoassay for quantitative assessment of antibodies against the 24 vaccine serotypes applicable both in serum and saliva. This multiplex assay dramatically reduces the requirement of serum volume, workload, and the cost than conventional ELISA as 24 different antibodies can be analysed in a single well. Recently, Pfizer has developed a 13-plex assay for PCV13 serotypes based on the similar method (Pavliakova D, mSphere, 2018). However, in our new assay, we will not only extend the coverage of vaccine serotypes but also use a novel chemistry for the conjugation of the antigens to the microspheres so that the assay will be safer to perform, have less cross-reactivity with non-specific antibodies, and can assess a wider range of antibody levels than that of Pfizer’s one.
The second is to explore the potential of saliva samples as an alternative to blood samples. At present, antibodies against pneumococcal vaccines are checked in blood samples. It is challenging to get blood samples particularly from children and elderly people due to its invasive procedure, and it is difficult to carry out in the field. In comparison to blood, saliva can be a safer, convenient, and efficient method of specimen for antibody assessment. Therefore, the second objective of this study is to answer whether saliva can be used instead of blood in assessment of antibody response of pneumococcal vaccines. We will use the clinical samples from PPV23 vaccinated adults in Japan and PCV10 vaccinated children in Nepal for this study.
This 24-plex assay will be a cornerstone for the advancement of our present capacity of pneumococcal research in Nagasaki. At present we have the nanofluidic real-time PCR assay that can detect 50 serotypes, including all vaccine serotypes. This nanofluidic assay has enabled us to carry out pneumococcal research in Vietnam, Afghanistan, Japan, and Nepal (Dhoubhadel BG, PLOS ONE, 2014; Zabihullah R, Emerg Infect Dis, 2017; Suzuki M, Lancet Infect Dis, 2017). Besides broadening our research capacity, this proposed new assay will enable us to assess the pneumococcal vaccine immunity faster, cheaper, and in a non-invasive manner, which potentially can have a huge global health impact on prevention of pneumococcal diseases in resource limited regions.
The role of LSHTM and NU in this collaborative project
NU will provide the PhD candidate an opportunity to develop a high throughput assay and apply it to the clinical samples. At LSHTM, the candidate can take some relevant courses. Project supervisors in NU and LSHTM will facilitate connections and collaborations for the candidate with relevant faculties in both schools.
Particular prior educational requirements for a student undertaking this project
Medical doctor or MSc in medical microbiology. Experience in diagnostic/molecular biology, or immunology is desirable.
Skills we expect a student to develop/acquire whilst pursuing this project
- Skills on development and validation of multiplex microsphere-based Luminex assay
- Co-ordinating enrolment, data management, and logistics of the cross-sectional study
- Data analysis skill
- Academic writing for publication and PhD thesis
- Transferable skills (Vitae Researcher Development Framework)