title: Evaluation of Salmonella enterica serovar Typhi (Ty2 aroC-ssaV-) M01ZH09, with a defined mutation in the Salmonella pathogenicity island 2, as a live, oral typhoid vaccine in human volunteers.
abstract: Salmonella enterica serovar Typhi strains with mutations in the Salmonella pathogenicity island-2 (SPI-2) may represent an effective strategy for human vaccine development, and a vectoring system for heterologous antigens. S. Typhi (Ty2 aroC-ssaV-) M01ZH09 is an attenuated, live, oral typhoid vaccine harboring defined deletion mutations in ssaV, which encodes an integral component in the SPI-2 type III secretion system (TTSS), as well as a mutation in an aromatic biosynthetic pathway needed for bacterial growth in vivo (aroC). SPI-2 mutant vaccines have yet to be evaluated in a large, randomized human trial. A simplified or single-oral dose oral typhoid vaccine using the SPI-2 strategy would offer significant advantages over the currently licensed typhoid vaccines. We performed a double-blinded, placebo-controlled, dose-escalating clinical trial in 60 healthy adult volunteers to determine the tolerability and immunogenicity of a single dose of M01ZH09. Three groups of 20 healthy adult volunteers were enrolled; 16 in each group received a single oral dose of the freeze-dried vaccine at 5 x 10(7), 5 x 10(8) or 5 x 10(9)CFU in a bicarbonate buffer. Four volunteers in each cohort received placebo in the same buffer. Adverse events were infrequent and not statistically different between vaccine and placebo recipients, although two subjects in the mid-range dose and three subjects in the highest dose had temperature measurements >37.5 degrees C. No blood or urine cultures were positive for M01ZH09, and fecal shedding was brief. The immune response was dose-related; the highest vaccine dose (5 x 10(9)CFU) was the most immunogenic. All tested subjects receiving the highest dose had a significant ASC response (mean 118 spots/10(6) cells). A >or=4-fold increase in antibody titer for S. Typhi LPS or flagellin was detected in 75% of volunteers in the highest-dose cohort by day 28. The SPI-2 mutant vaccine, M01ZH09, is a promising typhoid vaccine candidate and deserves further study as a vectoring system for heterologous vaccine antigens.
authors.affiliation: University of Vermont College of Medicine, Department of Medicine, Unit of Infectious Diseases, 95 Carrigan Drive, 110 Stafford Building, Burlington, VT 05405, USA. beth.kirkpatrick@uvm.edu
authors.forename: B D
authors.initials: BD
authors.lastname: Kirkpatrick
authors.forename: Robin
authors.initials: R
authors.lastname: McKenzie
authors.forename: J Patrick
authors.initials: JP
authors.lastname: O'Neill
authors.forename: Catherine J
authors.initials: CJ
authors.lastname: Larsson
authors.forename: A Louis
authors.initials: AL
authors.lastname: Bourgeois
authors.forename: Janet
authors.initials: J
authors.lastname: Shimko
authors.forename: Matthew
authors.initials: M
authors.lastname: Bentley
authors.forename: Jill
authors.initials: J
authors.lastname: Makin
authors.forename: Steve
authors.initials: S
authors.lastname: Chatfield
authors.forename: Zoë
authors.initials: Z
authors.lastname: Hindle
authors.forename: Christine
authors.initials: C
authors.lastname: Fidler
authors.forename: Brad E
authors.initials: BE
authors.lastname: Robinson
authors.forename: Cassandra H
authors.initials: CH
authors.lastname: Ventrone
authors.forename: Nivedita
authors.initials: N
authors.lastname: Bansal
authors.forename: Colleen M
authors.initials: CM
authors.lastname: Carpenter
authors.forename: Deborah
authors.initials: D
authors.lastname: Kutzko
authors.forename: Sandra
authors.initials: S
authors.lastname: Hamlet
authors.forename: Casey
authors.initials: C
authors.lastname: LaPointe
authors.forename: David N
authors.initials: DN
authors.lastname: Taylor
mesh_terms: D000284:Administration, Oral; D000328:Adult; D004311:Double-Blind Method; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D010919:Placebos; D019779:Salmonella enterica / Q000235:genetics / Q000276:immunology*; D014436:Typhoid-Paratyphoid Vaccines / Q000008:administration & dosage / Q000009:adverse effects / Q000276:immunology*; D014774:Virulence / Q000235:genetics*
chemical_list: D010919:Placebos; D014436:Typhoid-Paratyphoid Vaccines