Project Summary
Diarrhea is the second leading cause of death in children aged <5 years in developing countries, more than
AIDS, malaria, and measles combined. Our long-term goal is to develop effective vaccines against diarrheal
bacteria. The objective of this industrial partnership project is to combine expertise and leadership from
academic vaccine research and industrial vaccine development and manufacturing to accelerate the
development of MecVax, a multivalent cross-protective subunit vaccine for enterotoxigenic Escherichia coli
(ETEC). ETEC bacteria are one of the top five causes of children's diarrhea and the most common cause of
travelers' diarrhea. ETEC is listed as a category B priority pathogen (NIH) and a serious threat of antibiotic
resistance (CDC), and causes >220 million diarrhea clinical cases annually, resulting in stunting and poor
cognitive development in diarrheal children, 1,065,000 years lost due to disability (YLD), 6,894,000 years to
disability-adjusted life-years (DALY), and about 100,000 deaths (many are children < 5 years). ETEC is also a
primary cause of diarrhea in young animals and causes significant economic losses worldwide.
Currently, there are no licensed vaccines against ETEC diarrhea. The development of effective vaccines for
ETEC is a top priority for WHO, UNICEF, and many other public health institutions. By applying an innovative
vaccinology platform, we have constructed two polyvalent proteins and developed a protein-based multivalent
ETEC vaccine candidate, MecVax. MecVax is the only ETEC vaccine candidate that induces protective
antibodies against both ETEC toxins (LT and STa) and the seven most important ETEC adhesins (CFA/I, CS1 -
CS6). Since ETEC bacteria producing LT and/or STa toxin are associated with all ETEC diarrhea cases and
strains expressing adhesin CFA/I or CS1 - CS6 cause > 66% of ETEC clinical cases, the synergy of antitoxin
and anti-adhesin immunity from MecVax provides truly broad protection against ETEC children's diarrhea and
travelers' diarrhea. MecVax is demonstrated to broadly protect against ETEC clinical diarrhea and colonization
of small intestines preclinically. The central goal of this milestone-oriented vaccine development project is to
optimize MecVax vaccine formulation, analytical development, and production processing. The rationale is that
the completion of this application will identify MecVax optimal formulation, optimize upstream and downstream
processing and analytical development, and manufacture vaccine cGLP products, - essential to accelerate
MecVax development. To achieve these goals, we will 1) evaluate MecVax protection against ETEC adherence
and enterotoxicity at different antigen doses, adjuvants, buffers, and shelving conditions, 2) optimize analytical
assays and upstream and downstream processing, 3) manufacture and test MecVax master cell banks, and 4)
perform product production engineering runs and submit MecVax pre-IND application.
The positive impact is that an effective ETEC vaccine will save nearly 100,000 lives and prevent >200 million
diarrheal clinical cases each year, and reduce long-term negative nutritional and developmental impacts.