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Open Access Safety and Colonization of Two Novel virG(icsA)-based Live Shigella sonnei Vaccine Strains in Rhesus Macaques (Macaca mulatta)

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Shigella are gram-negative bacterium that cause bacillary dysentery (shigellosis). Symptoms include diarrhea and discharge of bloody mucoid stools, accompanied by severe abdominal pain, nausea, vomiting, malaise, and fever. Persons traveling to regions with poor sanitation and crowded conditions become particularly susceptible to shigellosis. Currently a vaccine for Shigella has not been licensed in the United States, and the organism quickly becomes resistant to medications. During the past 10 y, several live attenuated oral Shigella vaccines, including the strain WRSS1, have been tested in humans with considerable success. These Phase I vaccines lack the gene for the protein VirG also known as IcsA, which enables the organism to disseminate in the host target tissue. However, 5% to 20% of the vaccinated volunteers developed mild fever and brief diarrhea, and the removal of additional virulence-associated genes from the vaccine strain may reduce or eliminate these side effects. We administered 2 Shigella sonnei vaccines, WRSs2 and WRSs3, along with WRSS1 to compare their rates of colonization and clinical safety in groups of 5 rhesus macaques. The primate model provides the most physiologically relevant animal system to test the validity and efficacy of vaccine candidates. In this pilot study using a gastrointestinal model of infection, the vaccine candidates WRSs2 and WRSs3, which have additional deletions in the enterotoxin and LPS modification genes, provided better safety and comparable immunogenicity to those of WRSS1.

Document Type: Research Article

Affiliations: The Walter Reed Army Institute of Research, co-located with the Naval Medical Research Center, Silver Spring, MD, USA.

Publication date: February 1, 2008

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  • Comparative Medicine (CM), an international journal of comparative and experimental medicine, is the leading English-language publication in the field and is ranked by the Science Citation Index in the upper third of all scientific journals. The mission of CM is to disseminate high-quality, peer-reviewed information that expands biomedical knowledge and promotes human and animal health through the study of laboratory animal disease, animal models of disease, and basic biologic mechanisms related to disease in people and animals.

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