Volunteer studies of deletion mutants of Vibrio cholerae O1 prepared by recombinant techniques

Abstract

Vibrio cholerae 01 A-Bvaccine strain JBK 70 and A-B' CVD 101 prepared by recombinant DNA techniques from pathogenic El Tor Inaba N16961 and classical Ogawa 395, respectively, were fed to 38 volunteers in single doses of 104 to 1010. Although severe diarrhea did not occur in any vaccinee, more than one-hplf developed mild diarrhea. These attenuated strains colonized well and elicited prominent vibriocidal and antitoxic (CVD 101) antibody responses. Recipients of a single dose of JBK 70 were significantly protected when challenged with 106 wild-type N16961. Diarrhea occurred in 7 of 8 controls but in only 1 of 10 vaccinees (P < 0.003, 89% vaccine efficacy), demonstrating the potency of immune mechanisms that do not involve cholera antitoxin. Further derivatives were prepared to explore the pathogenesis of the residual diarrhea, considering that either intestinal colonization by the vaccine itself or accessory toxins might be responsible. CVD 102, an auxotrophic mutant of CVD 101, did not cause diarrhea but colonized poorly and elicited feeble immune responses. Derivatives of JBK 70 and CVD 101 (CVD 104 and 105) deleted of genes encoding the El Tor hemolysin still caused mild diarrhea. Genetically engineered strains can be colonizing, highly immunogenic, and protective single-dose oral vaccines, but they must be further attenuated before they can be considered for use as public health tools.

A new methodology for modelling of health risk from urban flooding exemplified by cholera – case Dhaka, Bangladesh

“…The 2007 outbreak in Dhaka was caused by a hyperinfective clone, V. cholerae O1 El Tor, which is believed to have a yearly cycle mediated via the aquatic environment and during the outbreak transmitted via the faecal-oral route . Faeces from cholera patients typically contain 10 7 -10 8 V. cholerae per gram (Dizon et al, 1967;Levine et al, 1988). Hence, it only takes a relatively small number of seriously ill patients to contaminate the sewage and drainage systems in Dhaka and lead to secondary infections via contamination of drinking water or via direct contact with the mixture of surface and drainage water during flooding.…”

Transcriptional upregulation of inflammatory cytokines in human intestinal epithelial cells following Vibrio cholerae infection

“…The major enterotoxin CT has been demonstrated to strongly promote the production of interleukin (IL)-6 by rat IEC-6 epithelial cells [8], and CT treatment of rat IEC-17 cells stimulated both IL-1 and IL-6 secretion [9]. V. cholerae vaccine strains caused symptoms consistent with inflammation in human volunteers [10]. Reports suggest that certain V. cholerae strains, as well as CT, may stimulate a modest intestinal inflammatory response [3,7].…”

Colonization of professional divers by toxigenic Vibrio cholerae O1 and V. cholerae non-O1 at dive sites in the United States, Ukraine and Russia

“…Three catagories of isolates were used in this study: (1) isolates recovered from divers from whom blood was drawn; (2) isolates recovered from divers from whom blood was not drawn, but the diver belonged to a diving team from which at least one blood sample was drawn; and (3) isolates recovered from water or sediment samples collected at the diving sites. Table 1 Sources of V. cholerae O1 and non-O1 strains isolated in this study 139 Each whole cell antigen preparation that was made in this study, following methods decribed elsewhere [11], was allowed to react with all sera available from one diving team, if it was isolated during that training dive.…”

“…For detection of PCR product, 5/zl of amplified DNA and molecular mass markers (100 bp DNA ladder, Bethesda Research Laboratories, Bethesda, MD) were subjected to electophoresis in a 1% agarose gel stained with ethidium bromide (0.5 /zg/ml) and photographed under UV exposure. Strains of V. cholerae O1 were also tested for cholera toxin by ELISA following the method described by Levine et al [11].…”