PATH Malaria Vaccine Initiative (MVI) Creates New Central “Reference” Lab, Standardizing Ability to Measure Performance of Malaria Vaccine Formulations

By Eric Akasa

In response to a critical gap in developing malaria vaccines, the PATH Malaria Vaccine Initiative (MVI) announced a new collaboration Monday with the International AIDS Vaccine Initiative (IAVI) and Imperial College London to measure the capacity of different vaccine candidates in human clinical testing to elicit an immune response aimed at protecting against deadly malaria parasites.

“Until now, malaria vaccine scientists have struggled to directly compare the cellular immune response elicited in humans by one vaccine to that of another, and this has hampered the ability to prioritize a portfolio of vaccine candidates,” says David C. Kaslow, MD, director of MVI. “We are fortunate to have in IAVI and Imperial College London partners with a track record of developing validated human immunological assays. Through this new collaboration, we look forward to being able to make better informed decisions about if and how various malaria vaccines elicit immune responses at the cellular level in humans.” He adds.

One obstacle to comparing the cell-mediated immunity elicited by different malaria vaccine candidates has been the lack of uniform validated techniques and processes among the various laboratories used by MVI and its collaborators specifically to evaluate T-cell immunity. Previously, AIDS vaccine researchers faced similar challenges. In an effort to identify a more consistent understanding of how multiple vaccine candidates were performing at a cellular level, IAVI and its Human Immunology Laboratory (HIL) at Imperial College London refined and validated specific tests, or assays, that measure vaccine-induced, cell-mediated immunity. The HIL is accredited in Good Clinical Laboratory Practices (GCLP), an internationally recognized quality standard.

In 2006, the wider scientific community cited in its Malaria Vaccine Technology Roadmap the development of a standard set of assays with standardized procedures to enable comparisons of the immune responses of vaccines. This was one of several priority areas critical to accelerating the pace of malaria vaccine development. Kaslow noted that this new collaboration directly addresses the need identified in the Roadmap as well as a critical gap faced in managing a portfolio of malaria vaccine projects, that is, the need for fully comparable data to guide transparent, objective, data-driven portfolio decisions.

“We are pleased that IAVI can contribute to informed, data-driven decisions on vaccine approaches,” notes Margaret McGlynn, President and Chief Executive Officer of IAVI. “Many of the methods and strategies employed in AIDS vaccine development could be of use in efforts to develop a malaria vaccine. Our collaboration will allow investments in AIDS vaccine R&D to benefit efforts to prevent another disease of great relevance to global health.” She adds.

Under the agreement, IAVI and its laboratory partner at Imperial College London will focus on providing two types of assays for MVI and its collaborators as they move vaccine candidates into clinical trials: the Interferon-gamma ELISpot assay and a multi-color flow cytometry assay. These tests will be used to detect the disease-fighting cells, or T cells, that may be present in the blood of volunteers after vaccination.

“These tests can provide quantitative information, such as how many cells responded to the vaccine, along with qualitative information, such as the different cell types that were stimulated,” says Professor Gavin Screaton, Head of the Department of Medicine at Imperial College London. “Both types of information can be important in determining the power of the overall vaccine-induced immune response.” Gavin adds.

“We’re delighted to be hosting this work at Imperial, which builds on our longstanding fruitful association with IAVI,” he said. “We’re also looking forward to working more closely with MVI as part of our commitment to vaccine research and international health.” He continues.

MVI’s Kaslow said the tests will help MVI prioritize investments and allow scientists to refine vaccine strategies by showing whether a particular formulation, delivery approach, or vaccine adjuvant elicits a superior cell-mediated immune response. However, he emphasized that results from the assays are just one piece of evidence that MVI will use to guide Go/No-go decisions in malaria vaccine development. He noted that while the collaboration with IAVI and Imperial College London will provide MVI with a central “reference” laboratory for measuring cell-mediated immune responses, MVI encourages malaria vaccine developers to continue performing their own tests as well.

“At MVI, we need standardization of these assays because when we analyze the results from various trials and look at the data on cell-mediated immunity, we need to be sure that any differences are not caused by variations in how the tests were done,” Kaslow observes.