Serologic study of two clusters of infection due to Campylobacter jejuni

Occupational Exposure to Swine, Poultry, and Cattle and Antibody Biomarkers of Campylobacter jejuni Exposure and Autoimmune Peripheral Neuropathy

INTRODUCTION

Foodborne Campylobacter jejuni infection has been associated with an increased risk of autoimmune peripheral neuropathy, but risks of occupational exposure to C. jejuni have received less attention. This study compared anti-C. jejuni IgA, IgG, and IgM antibody levels, as well as the likelihood of testing positive for any of five anti-ganglioside autoantibodies, between animal farmers and non-farmers. Anti-C. jejuni antibody levels were also compared between farmers with different animal herd or flock sizes. The relationship between anti-C. jejuni antibody levels and detection of anti-ganglioside autoantibodies was also assessed.

METHODS

Serum samples from 129 Agricultural Health Study swine farmers (some of whom also worked with other animals) and 46 non-farmers, all from Iowa, were analyzed for anti-C. jejuni antibodies and anti-ganglioside autoantibodies using ELISA. Information on animal exposures was assessed using questionnaire data. Anti-C. jejuni antibody levels were compared using Mann-Whitney tests and linear regression on log-transformed outcomes. Fisher's Exact Tests and logistic regression were used to compare likelihood of positivity for anti-ganglioside autoantibodies.

RESULTS

Farmers had significantly higher levels of anti-C. jejuni IgA (p < 0.0001) and IgG (p = 0.02) antibodies compared to non-farmers. There was no consistent pattern of anti-C. jejuni antibody levels based on animal herd or flock size. A higher percentage of farmers (21%) tested positive for anti-ganglioside autoantibodies compared to non-farmers (9%), but this difference was not statistically significant (p = 0.11). There was no significant association between anti-C. jejuni antibody levels and anti-ganglioside autoantibodies.

CONCLUSIONS

The findings provide evidence that farmers who work with animals may be at increased risk of exposure to C. jejuni. Future research should include longitudinal studies of exposures and outcomes, as well as studies of interventions to reduce exposure. Policies to reduce occupational exposure to C. jejuni should be considered.

Assessment of the duration of protection in Campylobacter jejuni experimental infection in humans

A human Campylobacter jejuni infection model provided controlled exposure to assess vaccine efficacy and investigate protective immunity for this important diarrheal pathogen. A well-characterized outbreak strain, C. jejuni 81-176, was investigated using a volunteer experimental infection model to evaluate the dose range and duration of protection. Healthy Campylobacter-seronegative adults received C. jejuni strain 81-176 via oral inoculation of 10(5), 10(7), or 10(9) CFU (5 adults/dose), which was followed by clinical and immunological monitoring. Based on dose range clinical outcomes, the 10(9)-CFU dose (n = 31) was used to assess homologous protection at 28 to 49 days (short-term veterans [STV]; n = 8) or 1 year (long-term veterans [LTV]; n = 7) after primary infection. An illness dose effect was observed for naïve subjects (with lower doses, 40 to 60% of the subjects were ill; with the 10(9)-CFU dose, 92% of the subjects were ill) along with complete protection for the STV group and attenuated illness for the LTV group (57%). Partial resistance to colonization was seen in STV (25% of the subjects were not infected; 3-log-lower maximum excretion level). Systemic and mucosal immune responses were robust in naïve subjects irrespective of the dose or the severity of illness. In contrast, in STV there was a lack of circulating antibody-secreting cells (ASC), reflecting the local mucosal effector responses. LTV exhibited comparable ASC responses to primary infection, and anamnestic fecal IgA responses likely contributed to self-resolving illness prior to antibiotic treatment. Campylobacter antigen-dependent production of gamma interferon by peripheral blood mononuclear cells was strongly associated with protection from illness, supporting the hypothesis that TH1 polarization has a primary role in acquired immunity to C. jejuni. This study revealed a C. jejuni dose-related increase in campylobacteriosis rates, evidence of complete short-term protection that waned with time, and immune response patterns associated with protection.

Immunogenicity and protective efficacy of recombinant Campylobacter jejuni flagellum-secreted proteins in mice

Immunogenicity and protective efficacy of three Campylobacter jejuni flagellum-secreted proteins, FlaC, FspA1, and FspA2, were compared by use of a mouse model. Mice were immunized intranasally with each protein with or without LTR192G as the adjuvant and challenged intranasally with C. jejuni 81-176 or CG8486. All three proteins were immunogenic, although FspA1 induced the highest levels of serum immunoglobulin G (IgG) and fecal IgA. Although immunogenic, FlaC provided only 18% protection against disease from C. jejuni 81-176. Immunization with FspA1 resulted in 57.8% protection without adjuvant or 63.8% protection with adjuvant against homologous challenge with 81-176. Alternatively, immunization with FspA2 provided 38.4% (without adjuvant) or 47.2% (with adjuvant) protection against disease from homologous challenge with CG8486. In contrast to FspA2, FspA1 provided some heterologous protection against C. jejuni CG8486 when delivered with (31.2%) or without (44.8%) LTR192G. These results suggest that FspA1 may be a good subunit vaccine candidate against C. jejuni disease.

Immunoscreening protocols for the identification of clinically useful antibodies and antigens

The antigen-antibody interaction is a powerful tool for the immuno-screening of several diseases, including cancer and genetic disorders. The high specificity of monoclonal antibodies (mAbs) enables them to target antigens and form complexes that can be detected with enzymes, radionuclides, fluorescent dyes or other markers. The antibody molecule, which has an antigen binding site, can be used as an intact molecule or as a fragment, for example, F(ab)(2), Fab, Fv or scFv. Similarly, the antigen can also be varied. In this review, immuno-screening techniques that can be used to detect clinically relevant antibody-antigen interactions will be discussed.

Retrospective analysis of the first clonal outbreak of nalidixic acid-resistant Shigella sonnei shigellosis in Israel

Reported here is a retrospective molecular analysis of the isolates recovered from the first outbreak of nalidixic acid (NA)-resistant Shigella sonnei shigellosis to occur in Israel. The outbreak affected 94 children. In the retrospective analysis, a total of 13 NA-resistant isolates and five NA-susceptible isolates recovered during the outbreak period were examined. Restriction fragment length polymorphism profiles obtained by digestion with BamHI, PvuI, HinfI or SmaI yielded identical profiles for all 18 isolates. All NA-resistant strains had an identical plasmid profile, but this profile differed from that displayed by the susceptible strains. In all of the NA-resistant strains a 304 bp fragment in the gyrA gene coding for a region associated with NA resistance was sequenced and showed a single point mutation, Ser83-->Phe. In this outbreak, the isolates of NA-resistant Shigella sonnei belonged to a single clone and NA resistance was associated with a point mutation in the gyrA gene.

Antibody responses to Campylobacter infections determined by an enzyme-linked immunosorbent assay: 2-year follow-up study of 210 patients

An enzyme-linked immunosorbent assay (ELISA) was adapted to measure immunoglobulin G (IgG), IgM, and IgA classes of human serum antibody to Campylobacter jejuni and Campylobacter coli. Heat-stable antigen, a combination of C. jejuni serotype O:1,44 and O:53 in the ratio 1:1, was used as a coating antigen in the ELISA test. A total of 631 sera from 210 patients with verified Campylobacter enteritis were examined at various intervals after infection, and a control group of 164 sera were tested to determine the cut-off for negative results. With a 90th percentile of specificity, IgG, IgM, and IgA showed a sensitivity of 71, 60, and 80%, respectively. By combining all three antibody classes, the sensitivity was 92% within 35 days after infection, whereas within 90 days after infection, a combined sensitivity of 90% was found (IgG 68%, IgM 52%, and IgA 76%). At follow-up of the patients, IgG antibodies were elevated 4.5 months after infection but exhibited a large degree of variation in antibody decay profiles. IgA and IgM antibodies were elevated during the acute phase of infection (up to 2 months from onset of infection). The antibody response did not depend on Campylobacter species or C. jejuni serotype, with the important exception of response to C. jejuni O:19, the serotype most frequently associated with Guillain-Barré syndrome. All of the patients infected with this serotype had higher levels of both IgM (P = 0.006) and IgA (P = 0.06) compared with other C. jejuni and C. coli serotypes.

Immunogens of interest for the diagnosis of Campylobacter jejuni infections

In order to identify the C. jejuni immunogens of interest for the diagnosis of Campylobacter infections, we analyzed the humoral response of 153 patients by using complement fixation (CF) and western blot assays. A first group of 79 sera was from C. jejuni infected patients suffering from enteritis (n=16), Guillain-Barré syndrome (GBS) (n=40) and arthritis (n=23). A second group of 49 sera was from healthy blood donors and a third group consisted of 25 sera from children under 4 years old. Using the CF test, 88.6% of the C. jejuni infected patients were seropositive versus 28.5% of the healthy blood donors and none of the children. The Western blot assay allowed detection of antibodies directed against seven selected antigens ranging from 14 to 67 kDa. Three of these antigens with a molecular size of 29, 37 and 43 kDa were detected by 86.0%, 84.8% and 91.1% of the C. jejuni infected patients, respectively. These three antigens seem to be good candidates for the development of assays suitable for direct and indirect diagnosis of Campylobacter infections.

Bactericidal properties of Campylobacter jejuni-specific immunoglobulin M antibodies in commercial immunoglobulin preparations

Campylobacter jejuni is one of the most common enterocolitis-causing microorganisms worldwide. It is of particular importance in immunodeficient patients, who frequently are prone to develop extraintestinal manifestations. Since these cases respond poorly to antibiotic treatment, a supportive immunomodulating therapy including the administration of C. jejuni-specific immunoglobulins would be desirable. In the present study, nine commercial immunoglobulin preparations for intravenous use were tested for the presence of C. jejuni lipopolysaccharide (LPS)- and outer membrane protein (OMP)-specific antibodies by using immunoblot and enzyme-linked immunosorbent assay techniques. The immunoglobulin G (IgG) antibody reactivities against these antigens were comparable in eight of nine tested immunoglobulin preparations. Only in one preparation were C. jejuni OMP- and LPS-specific IgM antibodies found. In this preparation the immunoblot test revealed a strong reactivity against both flagellin and a major OMP. Moreover, all immunoglobulin preparations recognized OMPs of C. jejuni serotypes Lior 4, 9, 11, and 29 equally strongly, while the reactivity to an anti-Lior 36 isolate was less marked. Furthermore, the bactericidal properties of three immunoglobulin preparations were tested by means of chemiluminescence signaling in and bacterial killing by human polymorphonuclear leukocytes (PMNL). The results show that the IgM preparation enhanced Campylobacter-triggered chemiluminescence signaling in PMNL as well as killing of C. jejuni by PMNL, while the other immunoglobulin preparations did not do so. These results suggest that the administration of immunoglobulin preparations containing C. jejuni-specific IgM antibodies would be beneficial for patients with severe C. jejuni infections.

Immunogenicity and protective efficacy of a prototype Campylobacter killed whole-cell vaccine in mice

The immunogenicity and efficacy of an experimental inactivated Campylobacter jejuni whole-cell (CWC) vaccine were evaluated in mice. Mice were orally immunized in a three-dose primary series (48-h intervals) at doses of 10(5), 10(7), or 10(9) CWC vaccine particles alone or in combination with 25 micrograms of a mucosal adjuvant, the heat-labile enterotoxin of Escherichia coli (LT). The comparative immunogenicities of both formulations were assessed on the basis of the generation of antigen-specific antibodies in serum and intestinal secretions, and efficacy was determined by measuring the degrees of protection afforded against intestinal colonization and systemic dissemination of challenge organisms. Campylobacter-specific intestinal immunoglobulin (Ig) A responses were dependent on the use of LT, whereas IgA and IgG responses in serum were not. Colonization resistance was induced over a broad range of vaccine doses when LT was included. However, only the highest dose of CWC alone gave comparable levels of protection. Both formulations provided equivalent protection against systemic spread of challenge organisms. These results indicate that both whole-cell vaccine formulations deserve further evaluation as candidate vaccines and also highlight the potential value of mucosal adjuvants, like LT, in enteric vaccine development.

Persistent, recurring diarrhea in a colony of orangutans (Pongo pygmaeus) caused by multiple strains of Campylobacter spp

A colony of 10 orangutans (Pongo pygmaeus) experienced persistent, recurring diarrhea caused by multiple infections with Campylobacter jejuni and C. coli. Infections appeared to have occurred through several mechanisms, including fecal-oral transmission between orangutans, and possibly transmission by houseflies contaminated with the organisms from nearby chicken feces. Among the 14 fecal and environmental C. jejuni isolates, 4 different antibiotic susceptibility profiles were detected; there were also 4 different profiles among the 8 isolates of C. coli. In 5 orangutans, there were back-to-back infections by different strains of C. jejuni, suggesting that a single C. jejuni infection may not confer protective immunity against heterologous strains circulating in the same vicinity. Transmission was effectively interrupted by environmental modifications and a 7-day course of oral erythromycin.

Modulation of mucosal immunity against Campylobacter jejuni by orally administered cytokines

The effect of oral recombinant interleukin (rIL) treatment on the course of Campylobacter jejuni infection and the development of mucosal immunity in mice was investigated. rIL-2, rIL-5, and rIL-6 were administered to mice at 24 and 6 h before infection and at 0, 24, and 48 h after infection with C. jejuni HC, and the subsequent development of an immune response and intestinal colonization resistance were determined. In this model, orally administered cytokines retained their biological activities with no apparent side effects. Following infection, initial bacterial counts in fecal samples collected from cytokine-treated and untreated mice were similar. However, within 48 h of infection a greater than 3-log-unit reduction in the number of C. jejuni shed in the feces was found for rIL-6-treated animals. Colonization levels were similarly reduced in rIL-5-treated mice, although the rate of clearance was somewhat slower. In contrast, rIL-2 treatment had no significant effect on colonization levels compared with that in controls. Oral rIL-6 treatment was also associated with enhanced intestinal and systemic Campylobacter-specific immunoglobulin A responses compared with those observed in either rIL-5- or rIL-2-treated animals. Upon rechallenge, initial colonization in all cytokine-treated groups was approximately 2 log units lower than that in controls. However, local infection was controlled only in rIL-2-treated mice over time. rIL-5 and rIL-6 treatment had only a marginal effect on colonization resistance following rechallenge. On the basis of these results, it appears that rIL-5 or rIL-6 may function to modulate the induction and/or expression of anti-C. jejuni immunity through different mechanisms.

The relative importance of Shigella in the aetiology of childhood gastroenteritis in Saudi Arabia

The role of shigella infection in childhood gastroenteritis was studied over a 2-year period. Shigella species were found in the faecal specimens of 70 (1%) of 7369 children with gastroenteritis, but in only 1 (0.1%) of 1130 controls. S. flexneri was the commonest isolate (51%), followed by S. sonnei (37%). Most shigella species were isolated during the winter. The prevalence of shigellosis was highest for children 1-5 years of age but equal for both sexes. Fever, abdominal cramps, vomiting, and bloody diarrhoea were the predominant clinical features. Of the shigella isolates, 73% were resistant to cotrimoxazole, 43% to ampicillin, and 41% to chloramphenicol. One-third of isolates were resistant to greater than or equal to 3 antibiotics. All isolates were susceptible to nalidixic acid. The illness was mild and self-limiting and most patients recovered without antimicrobial therapy.

Immune response to Campylobacter jejuni and Campylobacter coli in a cohort of children from birth to 2 years of age

A cohort of 111 children from Bangui, Central African Republic, was surveyed for enteric Campylobacter infections from birth to the age of 2 years; stools were examined biweekly in these children until 6 months of age and at least four times per year thereafter until 2 years of age and after each diarrheal episode. Blood samples were obtained at birth and at 3, 6, 9, 12, 18, and 24 months of age. Antibodies against glycine-extracted membrane antigens, purified flagella, and cholera toxin (CT) were assayed by an enzyme-linked immunosorbent assay. The results showed that titers of antibody against the three tested antigens increased in children between 6 and 12 months of age and that nearly all children were immunized by the age of 2 years. A significant fall in anti-flagellum (P less than 0.001) and anti-glycine extract antibodies (P less than 0.001) occurred between birth and age 3 months, and children who had Campylobacter infections during the first 6 months of life had significantly (P less than 0.02) less anti-flagellum antibodies at birth than did those who did not have Campylobacter infections during that time. Three-month-interval stratification showed that CT antibody titers at birth were significantly lower in children who developed Campylobacter infection than in controls (P = 0.05). Comparison of the immune response to a single Campylobacter episode showed that 46.6% of children with asymptomatic carriage did not respond to CT while only 5% of children with diarrhea-producing infection did not respond to CT (P less than 0.01), compared with 30% (P = 0.065) and 56% (P less than 0.01), respectively, of the age-matched controls. Antibodies to flagella seem to protect against enteric colonization by Campylobacter jejuni and Campylobacter coli.

Campylobacter jejuni isolations from Mexican and Swedish patients, with repeated symptomatic and/or asymptomatic diarrhoea episodes

The presence of different Campylobacter jejuni serotypes in Swedish patients with diarrhoea and in Mexican patients with or without diarrhoea was investigated with special reference to repeated isolations during the course of infection and to symptomatic and asymptomatic episodes. The study included 136 C. jejuni isolates from 62 Mexican children and 173 isolates from 68 Swedish patients. The bacteria were serotyped for heat-stable (HS) and heat-labile (HL) antigen. Swedish patients, all with symptoms, were in general only infected with one serotype and were rarely reinfected. Mexican patients on the other hand were in general infected with mixed serotypes and frequently reinfected without symptoms with new, different serotypes, a finding which is in concordance with a theory of an induced immunity to surface antigens.

Human serum antibody response in Campylobacter jejuni enteritis as measured by enzyme-linked immunosorbent assay

An ELISA for detection of IgG, IgA, and IgM antibody using an acid-glycine extract from Campylobacter jejuni as antigen was developed. To determine the value of this assay for the diagnosis of acute Campylobacter jejuni infections, the IgG, IgA, and IgM immune response against Campylobacter jejuni was investigated at various timepoints after infection in patients with culture-proven infection. A total of 112 sera from 46 patients and 78 sera from a control group were tested. All but one of the 46 patients with culture-proven Campylobacter jejuni enteritis developed IgG antibodies against Campylobacter jejuni. IgA and IgM ELISA both showed 97% specificity, and sensitivity of 63% and 30% respectively. IgG antibody titers generally remained at a constant level for more than 50 days, whereas IgA and IgM antibody titers declined more rapidly to normal values within 30 to 50 days after onset of clinical symptoms. Detection of Campylobacter jejuni specific IgA antibodies in a single serum sample provided the most useful assay for serological diagnosis of Campylobacter jejuni enteritis. The presence of Campylobacter jejuni specific IgM antibodies was the sole diagnostic criterion in three cases. Serological diagnosis of Campylobacter jejuni enteritis should therefore include both IgA and IgM antibody determination.

The epidemiology of shigellosis in Israel

Analysis of Shigella isolates referred for serotyping to the Central Shigella Reference Laboratory has revealed a slight predominance of S. sonnei (47%) over S. flexneri (44%) in Israel. In female patients, the predominance of S. sonnei isolates was more accentuated (54 v. 37.5% for S. flexneri). On the other hand, an increased incidence of S. flexneri was observed in military personnel (59 v. 32% for S. sonnei), and even more so in the Arab population (69 v. 19%). Incidence peaked in summer (July, August) for all subgroups.

Campylobacter jejuni antibodies in Nigerian children

Titers of complement-fixing (CF) antibody to Campylobacter jejuni were demonstrated in 87 (36.7%) of 237 infants 6 to 15 months old in Jos, Nigeria. Of the total number of children examined, 81 had acute diarrhea and 27 of them (33.3%) were found to have CF antibodies in their serum. The remaining 156 children were asymptomatic, and 60 (38.4%) of them had CF antibodies. In the diarrheal group, 27 of 75 children 6 to 8 months old were CF antibody positive. There was no significant difference in the incidence of CF C. jejuni antibodies in the diarrheal and nondiarrheal infants (P greater than 0.05). Also, infants 9 to 15 months old had a higher incidence of CF antibodies (46.5%) than those 6 to 8 months of age (25%). The data suggest that the infants whose sera were CF antibody positive had had an exposure to C. jejuni. All 33 infants 6 to 8 months of age who had no diarrhea were CF antibody negative.

Susceptibility of Campylobacter jejuni to strain-specific bactericidal activity in sera of infected patients

Campylobacter jejuni is a common cause of inflammatory enteritis, which in normal hosts is usually self-limited and resolves without antibiotic therapy. C. jejuni bacteremia is very rare. We examined sera for bactericidal activity that might be important in limiting the extent of C. jejuni infection in man. We studied the ability of nonimmune sera and homologous and heterologous immune sera from infected patients to kill different fresh case isolates of C. jejuni in vitro. The reduction of the log10 concentration of viable C. jejuni (log10 killing) by fresh sera from nonimmune donors was only 0.2. Log10 killing by homologous acute sera varied from 0 to 3.8 (mean, 1.8). Convalescent sera showed remarkable log10 killing of only homologous C. jejuni, with values of 2.7 to 4.4 (mean, 3.7). The bactericidal effects of acute and convalescent sera were abrogated by heat and EDTA chelation, indicating mediation by complement. The role of classical complement pathway activation was supported by chelating sera with magnesium EGTA [ethylene glycol-bis(beta-aminoethyl ether)-N, N, N', N'-tetraacetic acid] and by reconstitution experiments with heat-inactivated sera, C2-deficient serum, and purified C2. The requirement of specific antibody for the serum bactericidal effect was indicated by the loss of bactericidal activity when immune sera were absorbed with homologous but not heterologous whole C. jejuni isolates. The presence of specific antibodies was further documented by agglutination of only homologous C. jejuni suspensions by heat-inactivated immune sera. Studies with polymorphonuclear leukocytes suggested that ingestion and killing of two C. jejuni strains were modest and variable in the presence of heat-inactivated homologous serum. In summary, the data document a potent serum bactericidal effect that develops rapidly and specifically during C. jejuni enteritis and may be an important factor in host defense against C. jejuni.

Typing of heat-stable and heat-labile antigens of Campylobacter jejuni and Campylobacter coli by coagglutination

A coagglutination system has been devised for typing heat-stable and heat-labile antigens of Campylobacter jejuni and C. coli. The use of protein A-positive Staphylococcus aureus cells carrying Campylobacter sp. serotype antibody and the treatment of Campylobacter sp. cells with DNase in the antigen suspension permitted rapid and specific coagglutination of rough (autoagglutinable) as well as smooth cultures. Cells of S. aureus were sensitized with Campylobacter sp. serotype antisera. Four to five types of sensitized S. aureus cells were pooled. A strain of Campylobacter sp. was first tested with the pools and then typed with the individual reagents of the reactive pool. After the described procedures, 68 serotype strains tested blindly as unknowns were correctly typed according to their heat-stable or heat-labile antigens. The two most commonly used typing schemes which are based separately on the heat-stable or the heat-labile antigens as assayed by passive hemagglutination and slide agglutination, respectively, can be utilized simultaneously in the coagglutination system for strain characterization. The coagglutination system is simple, yields results rapidly, conserves typing reagents, and offers the flexibility of formulating the pools of reagents according to the experimental design or the prevalence of serotypes in a geographic location. It should be a practical system for the typing of Campylobacter spp. in public health or clinical laboratories.

Human serum antibody response to Campylobacter jejuni infection as measured in an enzyme-linked immunosorbent assay

An enzyme-linked immunosorbent assay was adapted to measure immunoglobulin A (IgA), IgG, and IgM classes of human serum antibody to Campylobacter jejuni. Sera were tested from healthy controls, from ill persons at various intervals after exposure to an epidemiologically implicated vehicle for Campylobacter sp. enteritis, from persons exposed to these same vehicles who remained well, and from persons who chronically drank raw milk. The major antigens in the C. jejuni acid-washed antigen preparations from three different strains all migrated at about 30,000 and 63,000. Persons with Campylobacter enteritis developed rising serum IgA, IgG, and IgM antibodies during the second week after infection; IgG and IgM elevations persisted longer than did IgA. Exposed persons who remained well showed similar, but lower, antibody rises. Chronic raw milk drinkers had elevated IgG levels, but not IgM or IgA levels, whether or not they were acutely exposed to an implicated vehicle.