Marcela Pasetti
University of Maryland, Baltimore, MD·Microbiology & Immunology
Shigella bacteria cause diarrhea and dysentery around the world, and toddlers in low- and middle-income countries suffer most; repeated episodes can leave lasting health damage, and the bacteria often resist multiple antibiotics. No vaccine is approved.
- Fields
Microbiology & Immunology
Medicine & Clinical Research
Public Health & Epidemiology
- Topics
Shigella
shigellosis
dysentery
- Grants
- 4 known grants, through May 2028
What they work on
- Optimize process development, formulation and scale-up of two-strain O-polysaccharide conjugates in which Shigella sugar is linked to IpaB, an invasion protein shared across Shigella species, made by cell-free protein expression.
- Test immune responses and protection of the O-polysaccharide-IpaB conjugates against Shigella flexneri 2a and Shigella sonnei in mice given a lethal lung challenge and in guinea pigs with rectal and colon infection.
- Identify the immune features behind protection by transferring antibodies into animals and running laboratory assays of antibody function against Shigella.
- Produce and characterize the conserved Shigella proteins IpaB, IpaH and VirG using cell-free protein synthesis and test them alone or combined with alum adjuvant for broad protection across Shigella types in mice and guinea pigs.
- Determine which step of Shigella invasion each protein-specific antibody blocks, using antibody transfer in mouse and guinea pig infection models together with cell-culture infection assays.
- Profile blood antibodies and T- and B-cell responses to Shigella proteins in Malawian infants followed from birth to two years, using a systems serology platform, and compare infected with uninfected children to find correlates of protection.
- Characterize breast-milk antibodies by systems serology to define how maternal immunity shields infants during the first months of life.
- Engineer human monoclonal antibodies against Shigella proteins with maximal antibacterial function, starting from blood cells of mothers with the strongest immunity.
- Define how pregnancy alters vaccine-induced antibody and B- and T-cell responses, and which antibody properties govern transfer across the placenta and into breast milk.
More about the research
Most candidates rely on the O-antigen, the sugar coat that differs across more than fifty disease-causing Shigella types, and these have disappointed in children under three. Work in this lab asks two linked questions: which immune components actually protect young children, and can vaccines built from bacterial proteins shared across all Shigella types protect broadly. A parallel line of work studies how a mother's immunization shapes her infant's immunity.
Why it matters
Shigella is a leading cause of childhood diarrheal death and is increasingly drug resistant, with no licensed vaccine. A protein-carrier or protein-only vaccine that works in toddlers could protect the children most at risk and reduce reliance on antibiotics, and engineered human antibodies could offer treatment where resistance has made drugs fail. Defining which maternal antibodies reach infants and how they shape infant vaccine responses could improve how vaccines are given during pregnancy.
Known grants
From NIH and NSF research grants. Labs often have other funding we can't see.
Closest labs
Jonathan Herman
University of California-Los Angeles, CA·Microbiology & Immunology·Early-career
Define functional antibody correlates of protection in malaria-exposed PfSPZ vaccinees, and how pre-existing anti-malarial antibodies affect vaccination, using serum from vaccination and controlled human malaria infection trials.
Anthony Maurelli
University of Florida, FL·Public Health & Epidemiology
Develop and validate sensitive, specific and reproducible digital PCR methods for detecting Shigella species in wastewater, optimizing extraction using authentic and synthetic wastewater spiked with lab-grown strains.
Pamela Wong
University of Michigan, MI·Microbiology & Immunology
Profile the immune responses raised by the combined nanoemulsion plus RIG-I-agonist adjuvant paired with multiple SARS-CoV-2 antigens, comparing injection and mucosal routes, to identify optimal formulations and delivery.
The school
University of Maryland, Baltimore: 23 labs on PI Pages, $1.5B a year on research, 79 research doctorates a year.
Reach out
A start for your email. Fill in the brackets.