anti-LPS IgA Research Articles

Antimicrobial and immunomodulating activities of hesperidin and ellagic acid against diarrheic Aeromonas hydrophila in a murine model

AimsThe present study is designed to evaluate the in vitro and in vivo bactericidal and immunomodulating activities of hesperidin (HES) and ellagic acid (EA) against Aeromonas hydrophila. A hydrophila, an uncommon human pathogen, can cause invasive infections in immunocompromised individuals and common clinical presentations in acute gastrointestinal illness, soft-tissue infections and sepsis. The antimicrobial activities of medicinal plants against A. hydrophila have received only cursory attention. MethodsWe examined the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) values in vitro. Moreover, the effects of HES and EA against bacterial colonization were studied in vivo. Also, humoral immune response was tested against A. hydrophila-LPS or A. hydrophila-ECP antigen preparations and the intestinal histopathological alterations were studied. ResultsData revealed that the treatments with HES and EA each had antimicrobial activities against A. hydrophila. Both HES and EA treatments significantly increased anti-LPS IgM levels and reduced anti-LPS and anti-ECP IgA levels to their normal values in comparison to the infected group, which recorded significantly elevated levels two week post-infection. In conclusion, the present data suggest that HES and EA have antimicrobial and immunomodulating activities against murine A. hydrophila infections. SignificantThese data warrant clinical studies to delineate HES and EA roles in human infectious diseases.

Oral administration of LPS and lipoteichoic acid prepartum modulated reactants of innate and humoral immunity in periparturient dairy cows

The study evaluated the effects of repeated oral exposure to LPS and lipoteichoic acid (LTA) on immune responses of dairy cows. Thirty pregnant Holstein cows were randomly assigned to two treatment groups. Cows received orally either 2 ml of 0.85% sterile saline solution (control group), or 2 ml of sterile saline solution containing three doses of LPS from Escherichia coli 0111 : B4 along with a flat dose of LTA from Bacillus subtilis. Blood and saliva samples were collected and analyzed for serum amyloid A (SAA); LPS-binding protein (LBP); anti-LPS plasma IgA, IgG and IgM; TNF-α; and IL-1. Results showed greater concentrations of IgA in the saliva of treated cows compared with the controls (P < 0.01). Treated cows had lower plasma concentrations of anti-LPS IgA, IgG and IgM Abs, and TNF-α than the controls (P < 0.05). There was a tendency for the concentrations of plasma LBP (P = 0.06) and haptoglobin (P = 0.10) to be lesser in the treatment group, although no differences were found in the concentration of plasma SAA and IL-1 (P > 0.10). Overall, the results of this study indicate that repeated oral administration with LPS and LTA stimulates innate and humoral immune responses in periparturient dairy cows.

Impact of oral typhoid vaccination on the human gut microbiota and correlations with s. Typhi-specific immunological responses.

The resident microbial consortia of the human gastrointestinal tract play an integral role in modulating immune responses both locally and systemically. However, detailed information regarding the effector immune responses after vaccine administration in relation to the gastrointestinal microbiota is absent. In this study, the licensed oral live-attenuated typhoid vaccine Ty21a was administered in a clinical study to investigate whether oral immunization resulted in alterations of the microbiota and to identify whether a given microbiota composition, or subsets of the community, are associated with defined S. Typhi-specific immunological responses. The fecal microbiota composition and temporal dynamics were characterized using bacterial 16S rRNA pyrosequencing from individuals who were either immunized with the Ty21a typhoid vaccine (n = 13) or served as unvaccinated controls (n = 4). The analysis revealed considerable inter- and intra-individual variability, yet no discernible perturbations of the bacterial assemblage related to vaccine administration were observed. S. Typhi-specific cell mediated immune (CMI) responses were evaluated by measurement of intracellular cytokine production using multiparametric flow cytometry, and humoral responses were evaluated by measurement of serum anti-LPS IgA and IgG titers. Volunteers were categorized according to the kinetics and magnitude of their responses. While differences in microbial composition, diversity, or temporal stability were not observed among individuals able to mount a positive humoral response, individuals displaying multiphasic CMI responses harbored more diverse, complex communities. In line with this preliminary observation, over two hundred operational taxonomic units (OTUs) were found to differentiate multiphasic and late CMI responders, the vast majority of which classified within the order Clostridiales. These results provide an unprecedented view into the dramatic temporal heterogeneity of both the gut microbiota and host immune responses.

Intermittent parenteral administration of endotoxin triggers metabolic and immunological alterations typically associated with displaced abomasum and retained placenta in periparturient dairy cows

This study sought to investigate the effects of induced intermittent endotoxemia on plasma mediators of carbohydrate and lipid metabolism, humoral immunity, and clinical health status in periparturient dairy cows. Sixteen pregnant Holstein cows were blocked by parity and day of calving, and were randomly allocated to 1 of 2 different treatment groups. Eight cows were infused intravenously (i.v.) with 100mL of sterile saline and served as the control group (CON). The other 8 cows were infused i.v. with 100mL of sterile saline containing 3 increasing doses of lipopolysaccharide (LPS), from Escherichia coli O111:B4, for 3 consecutive weeks during the 2 wk before and 1 wk after parturition as follows: (1) 0.01μg of LPS/kg of body weight (BW) on d −14 and −10; (2) 0.05μg of LPS/kg of BW on d −7 and −3; and (3) 0.1μg of LPS/kg of BW on d 3 and 7 postpartum. Nine blood samples were collected during the experimental period (i.e., from −14 to 28 d postpartum) and analyzed for calcium, zinc, iron, copper, glucose, lactate, β-hydroxybutyrate (BHBA), nonesterified fatty acids (NEFA), cholesterol, insulin, cortisol, serum amyloid A (SAA), lipopolysaccharide-binding protein (LBP), haptoglobin (Hp), and anti-LPS IgA, IgG, and IgM. Results showed that intermittently induced endotoxemia decreased feed intake and milk production and triggered alterations in plasma cholesterol, BHBA, Hp, Ca, Cu, and anti-LPS IgG and IgM. All of these changes were associated with a greater number of cows affected by metabolic disorders such as left displaced abomasum (LDA, 2 from 8 LPS cows vs. 0 from 8 CON cows) and retained placenta (RP; 4 from 8 LPS cows vs. 0 from 8 CON cows). In addition, the discriminant analysis differently clustered the cow responses within LPS group, each corresponding to LDA, RP, and the cows displaying no clinical health problems (LPS-NO). The stepwise selection procedure of the best discriminant variables revealed that plasma Ca and anti-LPS IgG, as well as glucose and cortisol, were the best discriminating variables for cows affected by LDA, whereas NEFA and cholesterol better discriminated for cows affected by RP. This analysis also revealed that the cluster of plasma variables including plasma Cu, SAA, BHBA, and anti-LPS IgA were the best discrimination for the LPS-NO group. In conclusion, our results indicate a role of endotoxemia, during the periparturient period, in development of metabolic and immune disturbances, as well as in the etiopathology of displaced abomasum and retained placenta in dairy cows.

Antigen-specific IgA B memory cell responses to Shigella antigens elicited in volunteers immunized with live attenuated Shigella flexneri 2a oral vaccine candidates

We studied the induction of antigen-specific IgA memory B cells (B(M)) in volunteers who received live attenuated Shigella flexneri 2a vaccines. Subjects ingested a single oral dose of 10(7), 10(8) or 10(9) CFU of S. flexneri 2a with deletions in guaBA (CVD 1204) or in guaBA, set and sen (CVD 1208). Antigen-specific serum and stool antibody responses to LPS and Ipa B were measured on days 0, 7, 14, 28 and 42. IgA B(M) cells specific to LPS, Ipa B and total IgA were assessed on days 0 and 28. We show the induction of significant LPS-specific IgA B(M) cells in anti-LPS IgA seroresponders. Positive correlations were found between anti-LPS IgA B(M) cells and anti-LPS IgA in serum and stool; IgA B(M) cell responses to IpaB were also observed. These B(M) cell responses are likely play an important role in modulating the magnitude and longevity of the humoral response.

Protective Anti‐Lipopolysaccharide Monoclonal IgA Antibodies Interferes with Salmonella Motility and Invasion of Epithelial cells, Independent of Bacterial Agglutination

Mucosal immunity to enteric bacterial pathogens, including Salmonella enterica serovar Typhimurium (S.Typhimurium) and Shigella flexneri is mediated by secretory IgA (SIgA) antibodies directed against bacterial lipopolysaccharide (LPS). It has long been assumed that these antibodies protect intestinal epithelial cells from microbial colonization and invasion by simply promoting bacterial agglutination and entrapment in mucus. In this study, we challenge this paradigm by demonstrating that protective, serotype‐specific, anti‐LPS monoclonal IgA antibodies (IgA mAbs) at sub‐agglutinating concentrations interfere with bacterial motility and type three‐mediated secretion of proteins necessary for invasion of epithelial cells. These effects occurred within minutes of antibody exposure and at IgA concentrations sufficient to coat less than 5% of the bacterial LPS. By scanning electron microscopy we observed anti‐LPS IgA mAbs induced dramatic morphological changes in the surface topology of the bacterial outer membranes, suggesting motility arrest and inhibition of type‐three secretion may be the result of physical changes in the LPS layer. These data reveal a novel and previously unrecognized capacity of SIgA to effectively “disarm” microbial pathogens on mucosal surfaces and render them unable to colonize or invade host intestinal epithelial cells. This work was supported by New Investigator funds from the Wadsworth Center, New York State Department of Health.

Oral Ingestion of Phosphorylated Dextrin Stimulates Antibody Responses in Mice

Corn dextrin with an average degradation degree of 16.7, or molecular mass of 2,700, was covalently introduced with 4.5 mol of phosphoric acid per mole by dry-heating with sodium phosphate. The effect on immunoglobulin production of the phosphorylated dextrin in mice that orally ingested lipopolysaccharide (LPS) from Salmonella typhimurium was investigated. No significant difference in body weight gain was observed between mice fed a phosphorylated dextrin-containing diet and those fed a control (dextrin-containing) diet. Fecal and intestinal anti-LPS immunoglobulin (Ig) A, intestinal and serum anti-LPS IgG, and fecal and intestinal total IgA levels were significantly higher in the mice given the phosphorylated dextrin. In contrast, serum and intestinal levels of IgM specific to the LPS were similar between the two groups. Moreover, spleen cells from mice fed the phosphorylated dextrin-added diet had significantly higher levels of anti-LPS IgG and IgA than those from mice on the control diet. These results suggest that dietary phosphorylated dextrin protects against local and systemic invasions of pathogenic microorganisms in mice.

A positive association of peripheral arterial occlusive disease (PAD) and Chlamydophila (Clamydia) pneumoniae

The relationship between Chlamydophila pneumoniae (Cp) infection and peripheral arterial occlusive disease (PAD) was studied by analyzing clinical samples from 95 patients with PAD and 100 controls. The following investigations were conducted: IgG and IgA against lipopolysaccharide (LPS) and against purified Cp-specific antigens from elementary bodies (EB) with ELISA; anti-EB IgG, with MIF; Cp DNA in arterial biopsy and peripheral blood mononuclear cells with heminested PCR; LPS with ELISA; and bacteria culture in HEp-2 cells from arterial biopsy. A significantly higher ratio of anti-EB IgG was detected in patients. There were no significant differences in anti-LPS IgG, anti-LPS IgA and anti-EB IgA between cases and controls. Cp DNA findings in the vascular wall biopsy showed significant differences between cases and controls. We obtained results that significantly involve Cp infection with PAD through the detection of anti-EB IgG from serum and bacterial DNA from arterial biopsy.

Levels of immunoglobulins of isotype IgG and IgG2 in subjects lacking formation of IgG antibodies against lipopolysaccharide of Chlamydia

In some patients with antibodies against LPS antigen of Chlamydia, specific immunoglobulins G are not present. The findings of isolated anti-LPS IgA/IgM antibodies are to be considered as possibly non-specifically or "false" positive. The aim of this study was to investigate if there is any difference in the level of total immunoglobulins of isotypes IgG and IgG2 in probands with isolated positivity anti-LPS IgA (i.e. without simultaneous presence of specific IgG; n = 34) as compared with a control group of subjects presenting positive anti-LPS IgA and IgG antibodies (n = 44). Antibodies against LPS antigen of Chlamydia were determined by ELISA method ("Chlamydien--rELISA", medac, Germany). Total immunoglobulin levels were determined by nephelometry using the following kits: "Immunoglobulin G Reagent, ARRAY Systems", Beckman Coulter, USA and "Human IgG2 Subclass Beckman ARRAY Kits", The Binding Site, UK. The measured values were related to the age-dependent laboratory standard values and the differences between the tested groups were statistically evaluated (chi(2) test). Decreased total IgG have been demonstrated in 4 (11.8 %) probands and in 5 (11.4 %) subjects of the control group; increased total IgG were found in 2 (5.9 %) probands and in 1 (2.3 %) subject of the control group. Decreased levels of total IgG2 were not determined in any proband and were found in 1 (2.3 %) subject of the control group. Increased levels of IgG2 were registered in 12 (35.3 %) probands and in 15 (34.1 %) control subjects. No statistically significant differences were found between the two groups. It can be concluded that no relationship was proved between the levels of total IgG and IgG2 and the absence of formation of specific anti-Chlamydia-LPS IgG. Further research will be necessary for the elucidation of this phenomenon (e.g. the presence of specific anti-LPS IgG in immunocomplexes).

Stimulatory effect of a dietary casein phosphopeptide preparation on the mucosal IgA response of mice to orally ingested lipopolysaccharide from Salmonella typhimurium.

The effect on immunoglobulin production of a commercially available casein phosphopeptide preparation (CPP-III) consisting mainly of bovine alpha s2-casein (1-32) and beta-casein (1-28) in mice that had orally ingested lipopolysaccharide (LPS) from Salmonella typhimurium was investigated. No significant difference in body weight gain was observed between the mice fed on the CPP-III-added diet and those fed on the control diet. The mice fed on the CPP-III-added diet exhibited similar serum and intestinal IgG, IgM, and IgE responses towards LPS to those fed on the control diet. In contrast, fecal and intestinal anti-LPS IgA and total IgA in mice fed on the CPP-III-added diet were significantly higher than in those fed on the control diet. Spleen cells from mice fed on the CPP-III-added diet produced larger amounts of IgA, IL-5, and IL-6 than cells from mice fed on the control diet. These results suggest that dietary casein phosphopeptide may protect a host from invasion of the intestinal mucosa by food-born pathogenic microorganisms.

Antibodies to chlamydial lipopolysaccharides in unstable angina pectoris

Patients with coronary artery disease frequently have elevated antibody titers against Chlamydia pneumoniae, but whether antichlamydial antibody titers are correlated with prognosis in unstable angina remains unclear. We therefore investigated the sera of 1,096 patients with unstable angina regarding immunoglobulin (Ig) IgG, IgA, and IgM antibody titers against chlamydial lipopolysaccharides (LPS) and the concentrations of C-reactive protein (CRP) and troponin T (TnT). Anti-LPS IgG titers were increased in 45% of patients at enrollment and in 48% of patients at discharge (p <0.0001). Anti-LPS IgA titers were increased in 27% of patients at enrollment and in 33% of patients at discharge (p <0.0001). Patients who subsequently died had significantly lower IgM titers at enrollment than patients without events (p = 0.016). IgG, IgA, or IgM titers did not correlate with concentrations of CRP or TnT. In this large-scale study of patients with unstable angina, we frequently found elevated antichlamydial antibody titers. Patients with low IgM anti-LPS titers were at risk for subsequent death. However, there was no correlation between antichlamydial antibody titers and CRP or TnT.

Mucosal and systemic immune responses in humans after primary and booster immunizations with orally administered invasive and noninvasive live attenuated bacteria.

The mucosal and systemic immune responses after primary and booster immunizations with two attenuated live oral vaccine strains derived from a noninvasive (Vibrio cholerae) and an invasive (Salmonella typhi) enteric pathogen were comparatively evaluated. Vaccination with S. typhi Ty21a elicited antibody-secreting cell (ASC) responses specific for S. typhi O9, 12 lipopolysaccharide (LPS), as well as significant increases in levels of immunoglobulin G (IgG) and IgA antibodies to the same antigen in serum. A strong systemic CD4(+) T-helper type 1 cell-mediated immune (CMI) response was also induced. In contrast to results with Ty21a, no evidence of a CMI response was obtained after primary immunization with V. cholerae CVD 103-HgR in spite of the good immunogenicity of the vaccine. Volunteers who received a single dose of CVD 103-HgR primarily developed an IgM ASC response against whole vaccine cells and purified V. cholerae Inaba LPS, and seroconversion of serum vibriocidal antibodies occurred in four of five subjects. Serum IgG anti-cholera toxin antibody titers were of lower magnitude. For both live vaccines, the volunteers still presented significant local immunity 14 months after primary immunization, as revealed by the elevated baseline antibody titers at the time of the booster immunization and the lower ASC, serum IgG, and vibriocidal antibody responses after the booster immunization. These results suggest that local immunity may interfere with colonization of the gut by both vaccine strains at least up to 14 months after basis immunization. Interestingly, despite a low secondary ASC response, Ty21a was able to boost both humoral (anti-LPS systemic IgG and IgA) and CMI responses. Evidence of a CMI response was also observed for one of three volunteers given a cholera vaccine booster dose. The direct comparison of results with two attenuated live oral vaccine strains in human volunteers clearly showed that the capacity of the vaccine strain to colonize specific body compartments conditions the pattern of vaccine-induced immune responses.

Separation of Broad Spectrum Anti-LPS IgA From Human Milk Using LPS Chitosan Affinity Chromatography

An affinity chromatography technique was developed for separation of broad spectrum antilipopolysaccharide (LPS) IgA antibodies from human milk. The affinity column was prepared by immobilizing LPS from Escherichia coli O111:B4 on to porous chitosan beads using glutaraldehyde activation. IgA separated from human milk using a Jacalin column was cycled through the LPS-chitosan column at a slow rate. Bound IgA was eluted with glycineHCl, pH 2.6, and presence of IgA in the eluate was confirmed by radial immunodiffusion (RID) and by visualization on sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). Column binding capacity was 0.22 mg of LPS-specific IgA ml−1. The stability of immobilized LPS was confirmed upon repeated uses of the column with negligible leaching of the ligand. The affinity purified anti-LPS IgA accounted for 12.3% of Jacalin purified IgA and was found to cross-react highly with E. coli O128:B12, and Klebsiella pneumoniae using LPS-ELISA, demonstrating the use of this technique for purification of broad spectrum, cross reactive immunoglobulins. There is a great potential for application of this technique in preparation of antibodies for prevention of enteric gram-negative infections in high risk individuals. The low cost column material used (chitosan beads) makes large scale utilization of this technique more practical.

Immunization against the colonization factor antigen I of enterotoxigenic Escherichia coli by administration of a bivalent Salmonella typhimurium aroA strain.

An expression plasmid (pCFA-1) carrying the cfaB gene that codes for the enterotoxigenic Escherichia coli (ETEC) fimbrial adhesin colonization factor antigen I (CFA/I) subunit was constructed and used to transform a derivative of the attenuated Salmonella typhimurium aroA vaccine strain SL3261 carrying an F'lacIq. Treatment of the transformed strain with isopropyl-beta-D-thiogalactopyranoside (IPTG) resulted in elevated in vitro expression of the CFA/I subunit. Although flagellar function and lipopolysaccharide (LPS) synthesis were similar in both the parental and the recombinant strains, spleen colonization was reduced in the recombinant strain. All BALB/c mice parenterally inoculated with the recombinant strain developed significant anti-CFA/I and anti-LPS serum antibody titers (P < 0.05). Moreover, 2 of 5 mice orally inoculated with the engineered Salmonella strain developed anti-CFA/I intestinal IgA (P > 0.05) while 4/5 of the same mice developed anti-LPS IgA (P < 0.05). The results indicate that the vaccine strain elicited an antibody response against the bacterial host both after oral and intravenous immunization while the response against the CFA/I antigen was significant only after inoculation by the intravenous route.

Shigella lipopolysaccharide antibodies in pediatric populations.

Shigellosis is the most common cause of bacterial dysentery. To study the specific immunity to the two major groups causing shigellosis, we assayed antibodies to lipopolysaccharide (LPS) by enzyme-linked immunoadsorbent assay to both Shigella sonnei and Shigella flexneri 2a serotypes in the following populations: (1) women immediately after delivery and their infants to assess the transfer of passive immunity by placenta and the presence of secretory antibodies in breast milk; (2) children of different ages; and (3) the kinetics of antibody production in pediatric patients, who had culture-proved shigellosis. The sera of these women showed variable concentrations of antibodies of all three isotypes to LPS of S. sonnei and S. flexneri 2a. These serotype-specific antibodies were not cross-reactive. Transfer of IgG anti-LPS across the placenta was significantly correlated with concentration of the specific antibody in the mother (S. sonnei, r = 0.96; S. flexneri, r = 0.84). Varying concentrations of anti-LPS IgA were present in colostrum, which was correlated with serum anti-LPS IgA titers in the case of S. sonnei (r = 0.44; P < 0.05) but not S. flexneri (r = 0.17). Healthy children between the ages of 6 months and 4 years in our population had undetectable or relatively low titers of anti-S. sonnei IgG. More children had detectable antibody titers to S. flexneri 2a than to S. sonnei. The relatively high concentrations of these natural antibodies are particularly noteworthy because there is a far lower incidence (< 10% of patients) with S. flexneri than with S. sonnei disease in this population.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum antibodies to Porphyromonas gingivalis in children.

Serum samples from 41 periodontally healthy children aged 1 to 16 years were examined by ELISA for the presence of antibodies against a glass bead-EDTA cell surface extract (GBE) and LPS of Porphyromonas gingivalis strain ATCC 33277. P. gingivalis was detected by immunofluorescence, using a species-specific monoclonal antibody, in 41% (17/41) of the children, and isolated from a single subject (2.4%). IgM, IgG, and IgA against GBE were detected in respectively 39/41 (95%), 41/41 (100%), and 27/41 (66%) of the sera. In 22/39 sera, the IgG titer was below 50% that of a reference pool of adult sera (RP). In 13/41, the IgM titer was higher than that of the RP, mostly in the deciduous dentition group. Detectable IgA titers were always below 67% that of the RP. A polarized distribution of the children appeared, separating 21 non- and low IgA responders (IgA titer below 10% that of the RP) from the remaining 20 subjects. Anti-LPS IgG, IgM, and IgA were detected in 41/41 (100%), 39/41 (95%), and 23/38 (61%) respectively of the children. In 32/41 sera, the anti-LPS IgG titer was below 50% that of the RP, while in 20/39 sera, IgM titers were higher. A clearcut dichotomy in IgA response was observed, allowing us to distinguish non-IgA responders (39%) and IgA responders to LPS (61%). Our results indicate that serum antibodies to P. gingivalis are highly prevalent in children, suggesting that an active primary immune response and a secondary immune response are well underway.(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of parenteral immunization on the intestinal immune response to Salmonella typhi Ty21a as measured using peripheral blood lymphocytes

The effects of parenteral administration of a killed typhoid vaccine on the intestinal immune response to live orally administered Salmonella typhi Ty21a in human subjects was assessed using an assay of in vitro specific antibody production by circulating peripheral blood lymphocytes (PBL). Previous priming with the parenterally administered vaccine had no effect on secondary immune responses to a live oral vaccine in humans with this response not differing in magnitude or duration from that following the primary oral vaccination course (p = 0.38). Following the primary PBL anti-LPS IgA response to an oral course of live vaccine in all subjects (6/6), boosting with a single oral dose of live vaccine resulted in 0/6 responders, while 2/11 subjects responded after a single dose of parenteral vaccine. No additional responses were evident after the second parenterally administered booster dose. PBL IgG and IgM responses were also demonstrated following oral vaccination, with 1/6 and 2/6 subjects parenterally vaccinated demonstrating IgM PBL responses after the first and second vaccination respectively. This study confirmed that parenteral vaccination did not impair the PBL IgA immune response to a secondary course of live orally administered organisms, and that multiple parenteral booster doses did not induce primary or secondary recirculation of antigen-specific PBL.

Field trial of oral cholera vaccines in Bangladesh: evaluation of anti-bacterial and anti-toxic breast-milk immunity in response to ingestion of the vaccines

In a field trial conducted in Bangladesh, ingestion of either B subunit-killed whole cell (BS-WC) or killed whole cell (WC) oral cholera vaccines by mothers was associated with a 47% reduction of the risk of cholera in their non-vaccinated children aged under 36 months. Because vaccine-induced breast-milk immunity seemed a possible explanation for these findings, we evaluated anti-lipopolysaccharide (LPS) and anti-cholera toxin (CT) IgA antibody responses in breast milk collected during the trial from 53 lactating women who ingested three doses of BS-WC, WC, or an Escherichia coli K12 strain (K12). Despite induction of moderate vibriocidal (1.4 to 2.0-fold) and anti-CT (4.5-fold) serum antibody responses, the vaccines did not elicit significant rises of anti-LPS or anti-CT IgA breast-milk antibodies. The failure of the vaccines to elicit significant levels of breast-milk anti-cholera antibodies suggests an alternative explanation for protection of young children by maternal vaccination, such as interruption of maternal-child transmission of Vibrio cholerae 01.

Protection of weaned rabbits against experimental Escherichia coli O103 intestinal infection by oral formalin-killed vaccine

In an attempt to vaccinate young weaned rabbits against life-threatening enterocolitis caused by Escherichia coli of the O103 serogroup, 32 New Zealand male rabbits were divided into three groups. One group remained unvaccinated as a control (Group C), and each of the other groups received one of two types of vaccine prepared with E. coli strain O103/10 cultured either in trypticase-soy broth (Group A) or in Minca agar (Group B). Bacteria were killed by formalin and administered per os for 10 consecutive days after weaning at a daily dose of 4 × 10 9 organisms. Six days after the last administration, all the animals were challenged with 1 × 10 4 virulent E. coli O103/10 and the experimental infection was monitored for 26 days. All rabbits in Group A were protected from symptoms of disease and remained alive, whereas two rabbits in Group B developed clinical signs and one died. Protection did not correlate with local or general responses to lipopolysaccharide (LPS) O103, as judged by measurement of anti-LPS O103 IgA in faeces or serum, or by serum agglutinating antibodies. Numbers of E. coli and E. coli O103 were significantly lower in vaccinated animals of Group A as compared with animals of the control group. The differences between both vaccine regimens may be partially explained by a different expression of the adhesins of strain O103/10, depending on the medium used to prepare the vaccine.