Protein antibody markers of pneumococcal carriage in support of protein and whole cell vaccine trial design using panproteomic antibody screening

Dr Joseph Campo, Director of Operations
Antigen Discovery, Inc (ADI)  (USA) Dr Joesph Campo 200x200px

Professor Andrew Pollard, University of Oxford (UK)
Mrs Merryn Voysey, University of Oxford (UK)
Professor Shrijana Shrestha, Patan Academy of Health Sciences (Nepal) 

Pneumococcal disease is a serious illness that can result in death. In many countries, children are given a vaccine to protect them against pneumococcal disease which is caused by a bacterial infection. There are more than 90 different types (‘serotypes’) of the bacteria. The vaccine only covers a 10-12 of these serotypes. New vaccines being developed may protect against all types of pneumococcal disease.

New vaccines are tested in clinical trials to show that they are effective. One way of doing this is to measure if the bacteria is present (‘carried’) in the nasal passages of children who have been vaccinated. The bacteria are commonly ‘carried’ in the nasal passages without causing disease, and this is the way it spreads to other people. If a vaccine can stop carriage, it will also stop the spread of disease.

Unfortunately, tests of nasal swabs for bacteria often miss detecting carriage. Carriage occurs only for a short period of time and the swab may not be taken at the time the bacteria were present. Thus, many carriage events are missed.

Another method of testing vaccines is to measure antibodies. However, the new vaccines (‘protein’ vaccines) produce different antibodies from the older (‘polysaccharide’) vaccines and so the old tests are no longer useful.

This study aims to use blood samples taken one month apart from children in a vaccine study in Nepal, and test for new protein antibodies. There are 2,200 different proteins that can be tested all at once using a new test called a protein microarray. The children in the study also had nasal swabs taken, so we will be able to see if those children carrying the bacteria also had high levels of antibodies. This study will enable us to know which protein antibodies could be used in future assessment of vaccines which contain pneumococcal proteins. These new vaccines could improve protection in both developing countries with the highest burden of disease, but could also be important in improving protection against meningitis and pneumonia in the U.K.