Melissa Kapulu: Malaria transmission and human infection studies
The efficacy of vaccine developed in naïve population (UK or US) often drops dramatically when used in endemic populations, where individuals are exposed to the vaccine disease target. The Human Malaria Infection Model looks at naturally acquired immunity and correlates of protection. Furthermore, scientists in affected areas build capacity and knowledge base, and integration of scientific thought and processes.
My name is Melissa Kapulu, I am a post-doctoral research scientist based at the KEMRI Wellcome Trust Research Programme, Kilifi campus. My area of research is based largely on malaria and looking at immunology, transmission dynamics and epidemiology. I mainly focus on immune epidemiology of transmission stages as well as establishing platforms and models that can be used to interrogate immunity.
Broadly speaking, human infection studies in the last 5-10 years have largely shifted to lower/middle income countries. These are studies that have largely been undertaken in naïve populations in developed countries, and there is now a need to set up these models in endemic regions. The reason for this is that in endemic regions there is naturally acquired immunity or pre-existing immunity.
The body of knowledge that has grown in the last 20 years is that when a vaccine is developed let say for instance in the United Kingdom or in the US, it is tested to look at efficacy in human infection studies in the US, in a naïve population. It will give great results of maybe 60-80% efficacy. But as soon as that vaccine moves to an endemic population, the vaccine efficacy dwindles, by anything from 10-50%. There are modulating circumstances based on the fact that individuals are exposed to a plethora of illnesses, including the actual vaccine disease target. Therefore it is very important that during the development pipeline of a vaccine, you do look at efficacy within the setting that vaccine will be used.
In our case we’ve established the Human Malaria Infection Model to look at naturally acquired immunity because that is key to understand how immunity develops in the context of, for instance, past exposure, and that will give us answers on what potential correlates of protection one can garner when you are looking at various vaccine targets. In addition to looking at potential correlates of protection, you can also look at potential other secondary targets which can then be developed into potential second generation vaccines.
One might ask: why does this matter? Why invest time, effort and money into this? This is important. It matters because it builds capacity in the local context. It matters because it provides establishment of key scientific findings, establishment of key scientific processes happening in lower to middle income countries. This is very key if we are going to have a situation where solutions are coming from areas that are actively affected by these disease processes. It is key that scientists in areas that are affected play a role, in coming up with solutions that could benefit not just the local context but even the wider context. I believe in strong collaborations between North and South, and South and South. The fact that you would be able to establish such studies in a South setting comparably to a North setting is very important: it builds capacity, it builds knowledge base - there are a lot of insights we can gain by doing these studies in settings in the South - and also it allows for integration of scientific thought, integration of scientific processes that would otherwise not organically happen if there was no investment in effort and time to set these studies up in areas that are important.
My research and my research interests fit in broadly and widely into translational medicine. I feel like I am at the bridge between basic science and translational science. What we gain from insights when chopping up a mosquito in the lab to look at whether or not it’s got parasites will have an effect on how that then gets translated into whether or not an intervention is to be tested in that particular mosquito strain. I believe that, in broad as well as narrow terms, in terms of translational research, that is a whole process which encompasses both basic, as well as moving into translational research. For translational medicine, to come up with potential correlates of protection, potential targets for vaccine development, potential models and mechanisms to test various interventions, that is really key in trying to translate our science from the bench to the field.
This interview was recorded in May 2019.