Murine antibody response to intranasally administered enterotoxigenic Escherichia coli colonization factor CS6

Lorimier, Arthur J. de; Byrd, Wyatt; Hall, Eric R.; Vaughan, William M; Tang, Douglas B.; Roberts, Zachary J.; McQueen, C.; Cassels, Frederick J.

doi:10.1016/s0264-410x(03)00101-4

Cited by 20 publications

(13 citation statements)

References 30 publications

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“…This nonfimbrial surface antigen is present either alone or in association with CS4 or CS5 on ETEC strains producing either ST or both enterotoxin types (7,24,42). Based on the high prevalence of CS6-positive ETEC, CS6 has been examined as a vaccine antigen and has been administered by different immunization routes, including the oral (5,14,32,36), transcutaneous (9,43), and intranasal routes (3,4). These vaccines have been based on oral live attenuated strains expressing CS6 (36,37) or recombinant CS6 antigen, and different routes and formulations have been used for immunization (3,43).…”

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confidence: 99%

Mucosal and Systemic Immune Responses in Patients with Diarrhea Due to CS6-Expressing Enterotoxigenic Escherichia coli

Qadri

Ahmed

et al. 2007

Infect Immun

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Colonization factor CS6 expressed by enterotoxigenic Escherichia coli (ETEC) is a nonfimbrial polymeric protein. A substantial proportion of ETEC strains isolated from patients in endemic settings and in people whotravel to regions where ETEC is endemic are ETEC strains expressing CS6, either alone or in combination with fimbrial colonization factor CS5 or CS4. However, relatively little is known about the natural immune responses elicited against CS6 expressed by ETEC strains causing disease. We studied patients who were hospitalized with diarrhea (n ‫؍‬ 46) caused by CS6-expressing ETEC (ETEC expressing CS6 or CS5 plus CS6) and had a disease spectrum ranging from severe dehydration (27%) to moderate or mild dehydration (73%). Using recombinant CS6 antigen, we found that more than 90% of the patients had mucosal immune responses to CS6 expressed as immunoglobulin (IgA) antibody-secreting cells (ASC) or antibody in lymphocyte supernatant (ALS) and that about 57% responded with CS6-specific IgA antibodies in feces. More than 80% of the patients showed IgA seroconversion to CS6. Significant increases in the levels of anti-CS6 antibodies of the IgG isotype were also observed in assays for ASC (75%), ALS (100%), and serum (70%). These studies demonstrated that patients hospitalized with the noninvasive enteric pathogen CS6-expressing ETEC responded with both mucosal and systemic antibodies against CS6. Studies are needed to determine if the anti-CS6 responses protect against reinfection and if protective levels of CS6 immunity are induced by vaccination.Enterotoxigenic Escherichia coli (ETEC) strains are noninvasive enteropathogens which colonize the small intestine by means of colonization factors (CFs) and are the single most common cause of bacterial diarrhea in children in developing countries, as well as in adults, including travelers (24, 41). After colonization, the bacteria cause watery diarrhea due to production of heat-stable toxin (ST) (6) and/or heat-labile enterotoxin (LT) (30). CFs are antigens that are known to provide protection against infection with ETEC expressing homologous CFs (7,15,32,34). Although ETEC can express more than 25 different CFs, 7 of these CFs are more prevalent than others (7). CS6 has been shown to promote binding of ETEC to rabbit and human enterocytes but not to cultured intestinal cells and other human-derived tissue (11). It is one of the most common CFs, and in some studies CS6 has been found to be present on more than 30% of the strains isolated from patients with ETEC diarrhea, as well as from military and civilian travelers to countries where ETEC is endemic (24,28,29,41,42). This nonfimbrial surface antigen is present either alone or in association with CS4 or CS5 on ETEC strains producing either ST or both enterotoxin types (7,24,42). Based on the high prevalence of CS6-positive ETEC, CS6 has been examined as a vaccine antigen and has been administered by different immunization routes, including the oral (5, 14, 32, 36), transcutaneous (9, 43), and intranasal routes (3...

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confidence: 99%

Mucosal and Systemic Immune Responses in Patients with Diarrhea Due to CS6-Expressing Enterotoxigenic Escherichia coli

Qadri

Ahmed

et al. 2007

Infect Immun

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“…So far, more than 25 CFs have been identified (Qadri et al, 2005;Gaastra & Svennerholm, 1996). Among them, CS6 is detected in 30% of the clinical isolates globally (de Lorimier et al, 2003). Our previous studies also demonstrated that CS6 is one of the most prevalent CFs among the clinical ETEC isolates obtained from hospitalized diarrhoeal patients (Ghosal et al, 2007;Sabui et al, 2010).…”

Section: Introductionmentioning

confidence: 88%

“…Our previous studies also demonstrated that CS6 is one of the most prevalent CFs among the clinical ETEC isolates obtained from hospitalized diarrhoeal patients (Ghosal et al, 2007;Sabui et al, 2010). Based on the high prevalence of CS6 positive ETEC, CS6 has been proposed as an important vaccine candidate (de Lorimier et al, 2003;Ghosal et al, 2007;Sabui et al, 2010).…”

Section: Introductionmentioning

confidence: 94%

Characterization of oligomeric assembly of colonization factor CS6 from enterotoxigenic Escherichia coli

et al. 2016

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The widely distributed colonization factor (CF) CS6 of enterotoxigenic Escherichia coli (ETEC) has gained importance over the years in terms of its structure and function. CS6 is an afimbrial assembly in contrast to the other ETEC CFs, which are mostly fimbrial. A recent study predicted a linear fibre model for recombinant chimeric CS6 and formation of oligomers in solution. In this study, we characterized the oligomeric assembly of CS6, purified from a clinical ETEC isolate and identified its existence in the WT strain. We found that purified CS6 forms a continuous array of higher order oligomers composed of two tightly associated subunits, CssA and CssB in an equal (1:1) stoichiometry. This oligomerization occurs by formation of (CssA-CssB) n complex where 'n' increases with the concentration. The diameter of CS6 oligomers also proportionally increases with concentration. More significantly, we showed CS6 oligomers to be spherical in shape instead of being linear fibres as predicted earlier and this was further confirmed by electron microscopy. We also showed CS6 assembled on the bacterial surface in the form of an oligomeric complex. This process depends on the expression of properly folded CssA and CssB together, guided by the chaperone CssC and usher CssD. In conclusion, our results provide evidence for the existence of concentration-dependent, spherical oligomers of CS6 comprising both the structural subunits in equal stoichiometry and the CS6 oligomeric complex on the ETEC surface.

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“…Individual microtiter wells (Nunc immunoplates) were coated with 100 l of a 1.0-g/ml PBS solution of CS6 antigen, incubated overnight at 37°C, washed with PBS, and blocked with 0.1% bovine serum albumin (BSA) (Sigma). The CS6 antigen was generated at bench scale using the identical fermentation and purification process as for the cGMP (vaccine) lot, with a purity of Ͼ95% as determined by sodium dodecyl sulfatepolyacrylamide gel electrophoresis and densitometric scanning (10). Threefold serial dilutions of sera were made (starting dilution of 1:5), and plates were incubated at room temperature (RT) for 90 minutes.…”

Section: Methodsmentioning

confidence: 99%

Randomized Clinical Trial Assessing the Safety and Immunogenicity of Oral Microencapsulated Enterotoxigenic Escherichia coli Surface Antigen 6 with or without Heat-Labile Enterotoxin with Mutation R192G

Lapa

Sincock

Ananthakrishnan

et al. 2008

Clin Vaccine Immunol

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An oral, microencapsulated anti-colonization factor 6 antigen (meCS6) vaccine, with or without heat-labile enterotoxin with mutation R192G (LT R192G ) (mucosal adjuvant), against enterotoxigenic Escherichia coli (ETEC) was evaluated for regimen and adjuvant effects on safety and immunogenicity. Sixty subjects were enrolled into a three-dose, 2-week interval or four-dose, 2-day interval regimen. Each regimen was randomized into two equal groups of meCS6 alone (1 mg) or meCS6 with adjuvant (2 g of LT R192G ). The vaccine was well tolerated and no serious adverse events were reported. Serologic response to CS6 was low in all regimens (0 to 27%). CS6-immunogloublin A (IgA) antibody-secreting cell (ASC) responses ranged from 36 to 86%, with the highest level in the three-dose adjuvanted regimen; however, the magnitude was low. As expected, serologic and ASC LT responses were limited to adjuvanted regimens, with the exception of fecal IgA, which appeared to be nonspecific to LT administration. Further modifications to the delivery strategy and CS6 and adjuvant dose optimization will be needed before conducting further clinical trials with this epidemiologically important class of ETEC.The significant worldwide burden of diarrheal disease due to enterotoxigenic Escherichia coli (ETEC) in children of developing countries has been well documented (5,32,39,45). In addition, military and civilian travelers are at high risk of acquiring ETEC-associated diarrhea when visiting regions where it is endemic (1, 6, 15, 19, 21), which prompts ongoing vaccine development. Prevalence surveys have documented the significant contribution of CS6-ETEC (ETEC containing surface antigen 6; 10 to 37% of ETEC isolates) relative to the overall global ETEC burden (13,29,33,36,37,42,46,47). Based on this information, this unique nonfimbrial colonization factor (CF) was selected as a target antigen for vaccine development (17,18,24,25,27,32,43,48).ETEC vaccine development has been based on two strategies: blocking adherence and/or toxin activity (32, 39). CFs are necessary for ETEC to adhere to the intestinal mucosal lining. After adherence, heat-labile toxin (LT), heat-stable toxin (ST), or both are expressed, resulting in watery diarrhea. The mucosal adjuvant LT is immunogenic but causes unacceptable gastrointestinal toxicity (3,28). LT R192G is a mutant form of LT which retains immunogenicity and adjuvanticity with greatly reduced toxicity, as documented by in vitro assays, animal models, and clinical trials (3,11,14).Incorporation of CFs into poly(DL-lactide-co-glycolide) (PLG) microspheres has been attempted in order to improve antigen delivery and uptake at mucosal inductive sites (30). In a previous study, microencapsulated CS6 (meCS6) was safe and well tolerated when delivered orally as either a 1-or 5-mg dose in a three-dose, 2-week interval regimen (23). The highest immune responses were observed in subjects (n ϭ 5) receiving the 1-mg dose in a buffered solution, with 80% antibody-se-

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Murine antibody response to intranasally administered enterotoxigenic Escherichia coli colonization factor CS6

Cited by 20 publications

References 30 publications

Mucosal and Systemic Immune Responses in Patients with Diarrhea Due to CS6-Expressing Enterotoxigenic Escherichia coli

Mucosal and Systemic Immune Responses in Patients with Diarrhea Due to CS6-Expressing Enterotoxigenic Escherichia coli

Characterization of oligomeric assembly of colonization factor CS6 from enterotoxigenic Escherichia coli

Randomized Clinical Trial Assessing the Safety and Immunogenicity of Oral Microencapsulated Enterotoxigenic Escherichia coli Surface Antigen 6 with or without Heat-Labile Enterotoxin with Mutation R192G

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