title: Comparison of the protective effects of killed Burkholderia pseudomallei and CpG oligodeoxynucleotide against live challenge.
abstract: Melioidosis is a fatal disease caused by Burkholderia pseudomallei. Currently there is no vaccine available. Synthetic oligodeoxynucleotides with unmethylated CpG dinucleotide motifs (CpG ODN) can stimulate vertebrate immune cells and clear certain pathogens that are susceptible to a strong Th1 response. In our previous study, pretreatment with CpG ODN alone or CpG-ODN with cationic liposomes for 2-10 or 30 days before B. pseudomallei infection in mice conferred 80-100% protection. In the present study we investigated the protective effect of CpG-ODN together with heat-killed (HK) or paraformaldehyde-killed B. pseudomallei (PP). HK or PP were used to immunize BALB/c mice twice at 15-day intervals before intra-peritoneal challenge with 5LD50 of B. pseudomallei and observed for 30 days. We found that PP could significantly protect mice (60%) with an increased survival time (24.8±11.63 days) while in the HK and PBS groups, all infected mice died within 6 days. Although either CpG ODN or PP conferred significant protection, giving them in combination did not enhance it further. Serum IFN-γ levels on day-5 (before challenge) of the PP and PP+CpG ODN groups were significantly higher than those of the PBS control group. The results further support the importance of IFN-γ in host protection against B. pseudomallei and suggest further study on paraformaldehyde-killed bacteria as a component of a future B. pseudomallei vaccine.
authors.affiliation: Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand; Melioidosis Research Center, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
authors.forename: Apichaya
authors.initials: A
authors.lastname: Puangpetch
authors.affiliation: Department of Microbiology & Immunology, Canadian Center for Vaccinology, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Pediatrics, Canadian Center for Vaccinology, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Robert
authors.initials: R
authors.lastname: Anderson
authors.affiliation: Department of Microbiology & Immunology, Canadian Center for Vaccinology, Dalhousie University, Halifax, Nova Scotia, Canada; Department of Pediatrics, Canadian Center for Vaccinology, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: Yan Y
authors.initials: YY
authors.lastname: Huang
authors.affiliation: Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand; Melioidosis Research Center, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
authors.forename: Rojana
authors.initials: R
authors.lastname: Saengsot
authors.affiliation: Department of Biochemistry, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand; Melioidosis Research Center, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
authors.forename: Rasana W
authors.initials: RW
authors.lastname: Sermswan
authors.affiliation: Department of Microbiology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand; Melioidosis Research Center, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand. Electronic address: sura_wng@kku.ac.th.
authors.forename: Surasakdi
authors.initials: S
authors.lastname: Wongratanacheewin
mesh_terms: D000276:Adjuvants, Immunologic / Q000008:administration & dosage; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001428:Bacterial Vaccines / Q000276:immunology*; D016957:Burkholderia pseudomallei / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007371:Interferon-gamma / Q000097:blood; D008297:Male; D008554:Melioidosis / Q000517:prevention & control*; D008807:Mice, Inbred BALB C; D009838:Oligodeoxyribonucleotides / Q000276:immunology*; D014613:Vaccines, Attenuated / Q000276:immunology
chemical_list: D000276:Adjuvants, Immunologic; D000907:Antibodies, Bacterial; D001428:Bacterial Vaccines; C408982:CPG-oligonucleotide; D007074:Immunoglobulin G; D009838:Oligodeoxyribonucleotides; D014613:Vaccines, Attenuated; D007371:Interferon-gamma
keywords: Burkholderia pseudomallei; CpG oligodeoxynucleotide; Heat-killed Burkholderia pseudomallei; Paraformaldehyde-killed Burkholderia pseudomallei