A Novel Vaccine for Listeriosis Infection
Listeriosis is an infectious disease caused by the bacterial pathogen Listeria monocytogenes. Although the average number of cases is moderate in the United States (1600-2500/year), listeriosis is a significant health concern due to its exceptionally high fatality rate. Indeed, listeriosis is the 3rd deadliest foodborne illness and costs $2.8 billion/year. Listeriosis infection leads to more than 90% hospitalization, which most often involve the intensive care unit. The risk and severity of the disease are significantly increased among the elderly (about 80% of listeriosis cases) and pregnant women and their newborns (about 20% of listeriosis cases). Clinical manifestations include septicemia, meningoencephalitis, miscarriage, stillbirth, and severe infection of neonates with a fatality rate of 16-25% and 13% long-term neurologic deficits, despite treatment. Currently, there is no approved listeriosis vaccine, and previous attempts were developed using live attenuated vaccine strains, which are contraindicated in these high-risk populations. With increasing incidence of listeriosis and the emergence of antibiotic-resistance among L. monocytogenes strains, a vaccine for preventing or treating L. monocytogenes infection is needed.
Researchers at The Ohio State University, led by Dr. Stephanie Seveau, have developed an experimental listeriosis vaccine. The technology strategically implements a safer approach to listeriosis vaccination by utilizing a subunit vaccine, rather than a live-attenuated vaccine. The vaccine comprises a novel, non-toxic listeriolysin O polypeptide (LLOT) and an experimental adjuvant cholera toxin (CT). The adjuvant β subunit of CT is approved for human use in the US. The LLOT was rationally designed according to properties of LLO, including its deleterious effects on animals, unique immune-stimulating signature, and major role in listeriosis pathogenesis. When tested in vivo, the vaccine was efficient in protecting mice against L. monocytogenes infection. Because all virulent Listeria strains produce LLO, the vaccine is expected to be protective of all Listeria strains.