Differentiation of Arthroderma spp. by random amplification of polymorphic DNA (RAPD) and Southern hybridization

To develop the molecular differentiation analysis of dermatophytes, we carried out RAPD and Southern hybridization analyses using genomic DNAs of six Arthroderma species, including A. fulvum, A. grubyi, A. gypseum, A. incurvatum, A. otae and A. racemosum. The RAPD analysis gave different band patterns specific to each of the six Arthroderma fungi. However, minor differences in the banding patterns were observed between the strains of plus (+) and minus (-) mating types of A. gypseum, A. fulvum and A. incurvatum. Southern blot analysis using a probe (1S) obtained from A. grubyi DNA gave specific bands only in the DNA samples of A. grubyi and A. incurvatum. On the other hand, Southern blot analysis using a probe (C3) obtained from A. otae DNA gave specific bands in all six Arthroderma species examined, and the size of the bands were specific to each species. These findings indicate that RAPD and Southern hybridization analyses are useful in the differentiation of these Arthroderma species.     

A method for rapid and complete substitution of the circulating erythrocytes in SCID mice with bovine erythrocytes and use of the substituted mice for bovine hemoprotozoa infections

We have previously developed an in vivo experimental system for a bovine hemoprotozoan parasite, in which SCID mice were periodically transfused with bovine red blood cells (Bo-RBCs), followed by infection with the parasite. The SCID mice prepared by the original method, however, had both mouse and bovine RBCs in the circulation, and their proportion always fluctuated significantly. In the present study, we aimed to deplete the mouse RBCs circulating in SCID mice and, thereby, to create SCID mice having complete Bo-RBC substitution. An anti-erythropoietin rabbit serum, an anti-mouse RBC rabbit serum and 23 monoclonal anti-mouse RBC rat antibodies were prepared for this purpose. They were examined, after administration into SCID mice, for their ability to decrease hematocrit value and also for any other adverse effect. A monoclonal antibody, clone 2E11, was found to have potent ability to induce clearance of the mouse RBCs in SCID mice without causing toxic effects. SCID mice receiving this antibody together with periodic transfusion of Bo-RBCs had their circulating RBCs completely substituted with Bo-RBCs. Infection of Bo-RBC-SCID mice with bovine hemoprotozoan parasites demonstrated that elimination of the mouse RBCs from Bo-RBC-SCID mice resulted in augmentation of parasite growth.     

Comparison of karyotype analysis and RT-PCR for AML1/ETO in 204 unselected patients with AML

Clinical isolates of Microsporum canis and M. gypseum from humans, dogs and cats were examined by random amplification of polymorphic DNA (RAPD) and Southern hybridization analyses. The RAPD band patterns of six clinical isolates of M. canis were identical to those of standard strains of Arthroderma otae. Of nine clinical isolates of M. gypseum seven and two isolates showed RAPD patterns identical to those of standard strains of A. gypseum and A. incurvatum respectively. Southern blot analysis using a probe (C3) obtained from A. otae DNA revealed that six clinical isolates of M. canis showed specific bands identical to those detected in the standard strains of A. otae. Of nine clinical isolates of M. gypseum, seven and two isolates showed bands hybridized by the C3 probe identical to those detected in A. gypseum and A. incurvatum respectively. Furthermore, the results from mating experiments on these nine clinical isolates of M. gypseum showed complete agreement with the results from RAPD and Southern hybridization analyses. These findings clearly indicate that RAPD and Southern hybridization analyses are very useful in the identification of clinical isolates of M. canis and M. gypseum.     

Differentiation of Australian isolates of Mycobacterium paratuberculosis using pulsed-field gel electrophoresis

OBJECTIVES: To examine strain variation amongst Australian isolates of Mycobacterium paratuberculosis. DESIGN: Pulsed field gel electrophoresis was optimised for differentiation of M paratuberculosis strains, and this typing technique was then applied to a collection of Australian isolates. PROCEDURE: DNAs from 35 Australian isolates of M paratuberculosis and a UK reference strain were digested with one or other of three restriction endonucleases. The banding patterns obtained after pulsed field gel electrophoresis of the DNA fragments were compared. RESULTS: The Australian isolates were divided into two groups on the basis of their DNA banding pattern. Both were different from the UK reference strain. Seven isolates from cattle in Victoria and the Northern Territory had the same pattern as five isolates from alpacas in Victoria and Western Australia. Another 20 isolates from cattle in Victoria, Western Australia and the Northern Territory had the same pattern as isolates from two sheep and a goat in New South Wales. CONCLUSION: Pulsed field gel electrophoresis was a useful tool for strain typing of M paratuberculosis, and could be used to study the transmission of strains in Australia.     

Molecular analysis of bovine spongiform encephalopathy and scrapie strain variation

Five mouse scrapie strains, a mouse-passaged scrapie isolate derived from a field case in sheep in Germany, and 2 mouse-passaged bovine spongiform encephalopathy (BSE) isolates were analyzed by immunoblot in regards to banding patterns of proteinase K-digested pathologic prion proteins (PrPres). To obtain reliable results, the photo-imager technique was used for measurement of staining band intensities. Distinct and reproducible profiles were observed for the different strains or isolates. A British and a German BSE isolate were similar, suggesting the same source of infection. The German scrapie isolate resembled scrapie strain ME7, which has frequently been isolated from sheep scrapie in the past. In selected strains or isolates, no influence of the mouse lines used was observed on PrPres profiles, nor were brain region-specific differences apparent. This investigation suggests that PrPres glycotyping can be an invaluable tool for the in vitro differentiation of BSE and scrapie isolates.     

Minisatellites corresponding to the human polycore probes 33.6 and 33.15 in the genome of the most 'primitive' known eukaryote Giardia lamblia

DNA fingerprinting has been widely used for genetic characterization and individual recognition in a range of species, from man and other mammals down the evolutionary scale to some lower eukaryotic parasites. These techniques utilise repetitive elements first characterised in the human genome, known as minisatellites, which display extensive allelic variability. Few biological or biochemical characteristics have been found that distinguish isolates of Giardia lamblia (Gl), or their apparent variations in virulence. We have characterized 21 Gl isolates in axenic culture using DNA fingerprinting with the human minisatellite probes, 33.6 and 33.15. Up to 12 variable bands per isolate were recognized in the size range of 2.5 to 15 kb by Southern blot hybridization of restriction endonuclease-digested Gl DNA. Most isolates demonstrated a distinct banding pattern or DNA fingerprint. The results suggest that this method may provide a basis for the detailed genotypic characterization of Gl which will be amenable to computer and statistical analysis for use in studies of virulence and epidemiology. Also, as Gl occupies a unique phylogenetic position as a member of the earliest known divergence from the eukaryotic line of descent, this study may provide a useful model for the study of other important eukaryotic pathogens, as it is rapidly becoming apparent that minisatellites are ubiquitous components of eukaryotic genomes.     

Theileria sergenti and T. buffeli: polymerase chain reaction-based marker system for differentiating the parasite species from infected cattle blood and infected tick salivary gland

Benign Theileria species in cattle. Theileria sergenti and T. buffeli, are morphologically indistinguishable. The polymerase chain reaction (PCR) was used to amplify the genes encoding the 33- and 34-kDa major piroplasm antigens (p33/34) of T. sergenti and T. buffeli from cattle blood infected with these parasites and tick salivary gland infected with T. sergenti. Following amplification, the p33 gene from T. sergenti and the p34 gene from T. buffeli were clearly differentiated using the restriction enzyme sites that were not shared between them. The oligonucleotide primer set, designed from the p33/34 genes, was specific for these Theileria species, since no amplification was detected with DNA from Babesia ovata, B. bovis, Anaplasma marginale, A. centrale, Eperythrozoon wenyoni, bovine white blood cells, and uninfected tick salivary glands. One tenth vol of the template prepared from either 25 microliters of blood with 0.5% parasitemia or individual tick salivary glands with six infected acini allowed sufficient amplification for differentiation of the two parasite species by restriction enzyme digestion. In addition, this system could be used to demonstrate the simultaneous, experimentally induced infection of cattle with T. sergenti and T. buffeli. The PCR-based marker system therefore provides a means to differentiate T. sergenti from T. buffeli in infected cattle blood and infected tick salivary glands. This system may also be useful for the characterization of other benign Theileria species in cattle.     

Increasing incidence and comparison of nalidixic acid-resistant Salmonella enterica subsp. enterica serotype typhimurium isolates from humans and animals

We determined the resistance to quinolone of 309 Salmonella enterica subsp. enterica serotype Typhimurium strains isolated from humans and animals (cattle, pigs, or poultry) in 1995 or 1996. Nalidixic acid resistance increased from 8.5% in 1995 to 18.6% in 1996. The highest resistance levels correlated with a mutation at Ser-83 (or Asp-82). All strains remained ciprofloxacin susceptible. Human and animal isolates were compared by pulsed-field gel electrophoresis, and the banding patterns of the human isolates most closely matched those of the bovine isolates.     

Proteinase activity in the isolates of Trichomonas vaginalis according to their pathogenicity

Ten axenic isolates of Trichomonas vaginalis were subcutaneously injected to the BALB/c mice in order to assess their pathogenicity by means of so-called "mouse assay" method. All the isolates revealed neutral and acid proteinase activities both in their lysates and in culture media, but the specific activities of both proteinases in the severely pathogenic group were significantly higher than the mildly pathogenic group (p < 0.05). In the SDS-PAGE system in which the electrophoretic gels contained 0.4% gelatin as the substrate, five different banding patterns of trichomonal proteinases were detected, and the patterns were closely related with the pathogenicity of the isolates of T. vaginalis. All five bands might be regarded as cysteine proteinases group in the inhibitor assays. The cytotoxicity of the lysates of T. vaginalis to the target Chinese hamster ovarian (CHO) cell line was also significantly different according to the pathogenicity of the isolates, and generally lower in the lysates treated with cysteine proteinase inhibitors than in the control lysates. In summarizing the results, it might be considered that the proteinases of T. vaginalis showing five electrophoretic banding patterns are closely related with the pathogenicity and cytotoxicity of the isolates of T. vaginalis.     

Kinins and the events influenced by an angiotensin-converting enzyme inhibitor during neointima formation in the rat carotid artery

Sixty-one strains of bacteria capable of growth on 4-methyl benzoic acid (29 isolates) or naphthalene (32 isolates) as the sole source of carbon and energy were isolated from sediments and water samples from the River Tyne, UK. Random amplification of polymorphic DNA from genomic DNA extracted from the different strains demonstrated that 14 of the 4-methyl benzoate-degrading isolates were unique and the remainder fell into seven groups containing two or three isolates that produced identical banding patterns. Thirteen of the naphthalene-degrading isolates were unique and nine groups with two or three identical representatives encompassed all other isolates. Screening of the bacterial strains for the presence of genes homologous to xylE, nahC and bphC by polymerase chain reaction and dot blot hybridization demonstrated that most strains harboured xylE- and/or nahC-like genes and only a single isolate was found that did not harbour any of these genes. None of the isolates harboured bphC-like genes. It was concluded that, while considerable diversity existed in host strains isolated using a single simple enrichment procedure, the extradiol dioxygenase genes involved in aromatic ring cleavage, present in these strains, were conserved to a considerable degree.     

An enzyme-linked immunosorbent assay (ELISA) for serological diagnosis of Neospora sp. infection in cattle

A kinetic enzyme-linked immunosorbent assay (ELISA) was developed and optimized for detection of antibodies to Neospora sp. in cattle. Sonicated tachyzoites of Neospora sp. isolated from an aborted bovine fetus were used as antigen. Variability in immunoblot patterns among positive sera, and the fact that all life stages of the parasites are unknown, justified use of a multiple-antigen ELISA to allow for maximum sensitivity. Immunoblot analysis revealed negligible cross-reactions between Toxoplasma gondii antigen and Neospora sp. antisera and between Neospora sp. antigen and antisera from various apicomplexan parasites. The maximum positive-to-negative Vmax (average maximum slope of the optical density over time) ratio was obtained using 200 ng/well of sonicated tachyzoite antigen and a 1:200 serum dilution. Using logistic regression to determine the optimal cutoff point between known infected and noninfected cattle, a sample-to-positive control Vmax ratio of 0.45 was found to maximize the percent correct classification, with an estimated sensitivity of 88.6% and specificity of 96.5%. Use of Neospora caninum antigen following the same protocol demonstrated no difference in ELISA interpretation. Comparison with an existing indirect immunofluorescent antibody (IFA) test showed the ELISA to be the more sensitive and specific test for serodiagnosis of Neospora infection in cattle.     

Evidence of genomic instability in Campylobacter jejuni isolated from poultry

Poultry isolates of Campylobacter jejuni derived from a survey of meat processing batches were genotyped by pulsed-field gel electrophoresis (PFGE) of chromosomal DNA to establish the clonal relationships between single-colony isolates. In the majority of batches studied, one or two genotype patterns predominated. However, in one batch (batch A), 21 single-colony isolates gave 14 different PFGE genotypes. The banding patterns obtained with SmaI were sufficiently different to distinguish between genotypes, although the patterns also produced many common bands. The question of whether these isolates represented different clones or had a common clonal ancestry was addressed by additional genotypic and phenotypic methods. Restriction length polymorphism of PCR products obtained from the flagellin genes showed an identical flagellin genotype for all of these isolates. In contrast, unrelated control isolates resulted in different flagellin genotypes. Moreover, all 14 different PFGE genotypes of batch A had identical Penner serotypes and identical or similar biotypes and phage types. It was concluded that the isolates were of clonal origin and that the diversity in the PFGE banding patterns had most likely originated from genomic rearrangements. However, the PFGE genotypes were shown to be stable upon subculturing in vitro and after in vivo passage in chickens, and natural transformation between isogenic mutants carrying antibiotic markers did not occur in vivo in a chick colonization model. The possible mechanisms for the hypothesized genomic recombinations and the conditions that allow, induce, or select for such events are discussed.     

Distribution and molecular analysis of Lyme disease spirochetes, Borrelia burgdorferi, isolated from ticks throughout California

Previous studies describing the occurrence and molecular characteristics of Lyme disease spirochetes, Borrelia burgdorferi, from California have been restricted primarily to isolates obtained from the north coastal region of this large and ecologically diverse state. Our objective was to look for and examine B. burdorferi organisms isolated from Ixodes pacificus ticks collected from numerous regions spanning most parts of California where this tick is found. Thirty-one isolates of B. burgdorferi were examined from individual or pooled I. pacificus ticks collected from 25 counties throughout the state. One isolate was obtained from ticks collected at Wawona Campground in Yosemite National Park, documenting the occurrence of the Lyme disease spirochete in an area of intensive human recreational use. One isolate from an Ixodes neotomae tick from an additional county was also examined. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis, immunoblot analysis, agarose gel electrophoresis, Southern blot analysis, and the polymerase chain reaction were used to examine the molecular and genetic determinants of these uncloned, low-passage-number isolates. All of the isolates were identified as B. burgdorferi by their protein profiles and reactivities with monoclonal and polyclonal antibodies, and all the isolates were typed by the polymerase chain reaction as North American-type spirochetes (B. burgdorferi sensu stricto). Although products of the ospAB locus were identified in protein analyses in all of the isolates, several isolates contained deleted forms of this locus that would result in the expression of chimeric OspA-OspB proteins. The analysis of OspC demonstrated that this protein was widely conserved among the isolates but was also quite variable in its molecular mass and the amount of it that was expressed.     

Economics of gastrointestinal parasitism of cattle

Understandably, cattle are raised for profit, as beef and/or dairy. Anything that negates that equation results in a loss to the producer and to the livestock economy. Thus, parasites negatively affect the economy of the industry. Worldwide, gastrointestinal nematode parasites, especially Ostertagia ostertagi, and those of the respiratory tract (Dictyocaulus viviparus) have a potentially major impact on herd health. In the past 10-15 years, anthelmintic (AH) drug development and the strategic use of AH have positively balanced the economic equation, so that overall, parasitism in cattle is often observed or determined to be subclinical or economical. Other control measures, such as better pasture management, are also being developed to enhance herd health and the cattle economy. The determination of the economic impact of parasitism has thus become less apparent, to the extent that measures, such as performance parameters, must be used to measure differences between treated and untreated animals or herds. These include weight gain, reproduction, lactation and forage use. To determine the effectiveness of control measures, field trials are designed to measure these parameters by the demonstration of improved performance. Because these trials are conducted in a competitive mode, results are often debated by competitors and by the scientific community because of study design. Variables must then be taken into consideration in the interpretation of results. It is now well known that, with the generation of new AH and appropriately-timed administration, parasitism of well-managed herds has been reduced to subclinical levels. Thus, we are now in the process of fine-tuning the positive effect of these control measures for enhanced production. Understandably, beef and dairy producers have 'production of high quality commodities' at a cost-effective level as a common goal. Successful cattlemen calculate expenditures and income by line item including veterinary expenses and cost and labor in administration of AH. Return is based on performance. Again, nematode parasites can disturb the equation enough to make production less profitable or even unprofitable. Most USA beef cattle producers believe that worm parasites do have an effect on cattle health and production so that 77% use AH and the market impact is that AH have become integrated into cattle herd health programs. However, to be most cost-effective, programs must be strategic but flexible with scheduling tailored for the region and the cattle operation. Other technologies should eventually provide rapid identification of worm populations by species and numbers and recognition of individual animal response to parasites and inheritance of that trait by their progeny. Computerized programs for analysis of seasonality of the epidemiology of gastrointestinal parasites and of herd performance could predict appropriate timing and cost benefit for control measures. Modes of AH administration are being developed which are more reliable and convenient in terms of delivery and labor. Control measures must also include better pasture management with less impact on the environment and to justify investment in land. In addition, successful producers are better educated, more cost-conscious, consumer-oriented, sensitive to the environment and attuned to the economics of parasitism.     

Investigation of the sequence of colonization and candidemia in nonneutropenic patients

Among neutropenic patients with hematologic malignancies, candidemia has been shown to arise typically from autoinfection after colonization. In patients without neutropenia, we examined the similarities of strains colonizing or infecting various body sites and those subsequently causing Candida bloodstream infections. Strain similarity was examined by karyotyping and restriction endonuclease analysis of genomic DNA (REAG) by using two restriction enzymes (SfiI and BssHII). The banding patterns of 42 isolates from 19 patients were independently evaluated in a blinded fashion by three observers. The interobserver reliability measured with a generalized kappa statistic was 0.59 for karyotyping, 0.84 for REAG with SfiI, and 0.88 for REAG with BssHII (P < 0.001 for each). REAG classified the initial colonizing or infecting isolate and subsequent blood isolates as identical in 16 patients (84%). The mean duration of colonization or infection prior to a positive blood culture was 5 and 23 days in patients infected with related and unrelated isolates, respectively (P = 0.14; 95% confidence interval = -14.5 to 50.5). Karyotyping results matched the REAG results for isolates from 14 of the 19 patients (74%). In patients infected with identical isolates, the initial isolate was most frequently recovered from the urine (n = 5) or vascular catheter tips (n = 4). In the five subjects with organisms showing disparate results between the methods, karyotyping revealed different banding patterns, whereas REAG suggested that the isolates were identical. Candida colonization or infection with an identical strain frequently precedes bloodstream infection in nonneutropenic patients. Future studies should evaluate whether patients at high risk for candidemia and who have vascular catheter or urine samples that are positive for a Candida on culture should be treated empirically.     

Marfan syndrome: diagnosis of cardiovascular manifestations]

BACKGROUND: Despite the availability of several different markers for Epstein--Barr virus (EBV) serology, the EBV status of some patients cannot be resolved from a single serum sample with routine testing. To avoid the requirement of follow-up samples, supplementary tests have to be used in these cases. OBJECTIVE: To evaluate the usefulness of avidity and immunoblot assays as supplementary tests for the diagnosis of acute EBV infections. STUDY DESIGN: Three groups of samples for which a definite diagnosis on the EBV status could not be obtained with the routine serological tests were further examined by an EBV IgG avidity assay, by an immunoblot based on a lysate of EBV infected cells, and by a second immunoblot based on recombinant EBV antigens. The three groups consisted of 38 samples with negative/borderline EB nuclear antigen 1 (EBNA-1) antibodies, negative/borderline EBV IgM and positive EBV IgG; 10 samples with indeterminate EBNA-1 and/or EBV IgM assays because of control antigen reactions; and 4 samples with positive EBV IgM results that were not plausible. RESULTS: The avidity assay differentiated between acute and past infections for all samples. In contrast, some cases remained unresolved with both the recombinant and the lysate immunoblot. Two samples were incorrectly classified with the lysate immunoblot. Interpretation of the lysate immunoblot banding patterns was complicated when anticellular antibodies were present. CONCLUSION: Avidity testing appears to be the confirmatory method of choice to differentiate between acute and past EBV infections.     

Evaluation of serotyping, biotyping, plasmid banding pattern analysis, and HEp-2 vacuolation factor assay in the epidemiological investigation of Bacillus cereus emetic-syndrome food poisoning

To assess the value of the plasmid banding patterns, the vacuolation factor (VF) assay, biotyping, and serological typing as epidemiological markers for strains of Bacillus cereus causing emetic-syndrome illness, 43 isolates from five outbreaks and an additional 76 strains isolated in food-poisoning outbreaks caused by other enteric pathogens were examined by these techniques, and the results were compared. Thirty-eight (88%) of the 43 outbreak strains produced vacuolation responses in HEp-2 cells and were all starch-hydrolysis negative. The other 76 strains associated with outbreaks caused by other food-poisoning bacteria gave all negative VF production results except four strains, and 56 (74%) of these strains produced positive reactions in starch hydrolysis tests. Starch hydrolysis emerged as a convenient screen for VF production, because no starch hydrolysis-positive strains produced VF. With the exception of one isolate, all 38 VF-positive isolates from emtic-syndrome outbreaks were serotype H.1. Isolates from four of the five outbreaks revealed identical plasmid banding patterns in each outbreak, whereas only three of eight serotype H.1 strains from the fifth outbreak exhibited indistinguishable plasmid banding patterns. These results suggest that the plasmid banding pattern analysis may be of value in discriminating between isolates of the same serotype, and establishing if an outbreak arises from a common food source. In conclusion, the vacuolation factor assay combined with the plasmid banding patterns proved to be a valuable tool for the epidemiological investigation of emetic-syndrome outbreaks caused by B. cereus. Moreover, these methods are particularly useful for laboratories that do not have ready access to serotyping facilities.     

Theophylline-induced mesenteric periarteritis in F344/N rats

Burkholderia pseudomallei is a free-living organism that causes the potentially lethal tropical infection melioidosis. The disease is endemic in many parts of eastern Asia and northern Australia. The presence of two distinct biotypes in soil can be reliably distinguished by their ability to assimilate L-arabinose. Whereas some soil isolates could utilize this substrate (Ara+), the remaining soil isolates and all clinical isolates tested so far could not (Ara-). Only the Ara- isolates were virulent in animal models. We have raised a murine monoclonal antibody (MAb) that can readily distinguish Ara- from Ara+ biotypes. The MAb reacted with a high molecular weight component present only on the Ara- biotype. With this MAb, clinical and soil Ara- isolates gave identical positive reactions in agglutination, immunofluorescence, ELISA and immunoblot assays. Using these same assay systems, the soil Ara+ biotype did not react with the MAb. Similar but distinct immunoblot patterns were also noted when these two Ara biotypes were probed with sera from patients with melioidosis or with polyclonal immune rabbit sera. These data showed that the Ara- biotype from both clinical and environmental isolates is antigenically different from its Ara+ environmental counterpart. The SDS-PAGE protein and lectin-binding profiles of both groups of Ara- isolates were also found to be different from those of the Ara+ biotype.     

Multiplex PCR for simultaneous detection of the most frequent T cell receptor-delta gene rearrangements in childhood ALL

A rapid and simple multiplex polymerase chain reaction (PCR) is described that is capable of identifying the six most frequent rearrangements of the T cell receptor (TCR)-delta gene segments in childhood acute lymphoblastic leukemia (ALL). The PCR products amplified in a single reaction are of different size for each TCR-delta gene rearrangement. Therefore, they are readily and unambiguously distinguished after agarose gel electrophoresis and assigned to a specific V-D-J gene rearrangement. There is no need for labor-intensive and time-consuming Southern blot hybridization or nested PCR. To evaluate the multiplex assay we chose 45 DNA samples of childhood ALL analyzed beforehand for TCR-delta gene rearrangements by Southern blot and single PCR of which 30 showed TCR-delta gene rearrangements. The multiplex PCR results corresponded to the Southern blot and single PCR analyses. The described multiplex PCR enables the detection of clonal markers in about 50% of patients in order to monitor minimal residual disease (MRD) in prospective studies with a high turnover of samples.     

The effect of different TP53 mutations on the chromosomal stability of a human colonic adenoma derived cell line with endogenous wild type TP53 activity, before and after DNA damage

The idiopathic inflammatory bowel diseases, ulcerative colitis and Crohn's disease, are chronic disorders that appear to arise from an aberrant interaction of environmental, genetic, and immunologic factors. The aim of this study was to examine the immune reactivity of a spontaneously colitic mouse strain, C3H/HeJBir, to epithelial, food, and enteric bacterial Ags. Serum Ab responses of colitic C3H/HeJBir and noncolitic parental C3H/HeJ mice were measured by enhanced chemiluminescence Western blotting. No reactivity to epithelial or food Ags was detected. However, the sera from C3H/HeJBir mice had a reproducible banding pattern on Western blot to bacterial Ags, whereas sera from C3H/HeJ mice did not. Only a small, highly selected number of enteric bacterial Ags were recognized. There were major differences in the degree of recognition of different bacterial strains, marked by remarkably few Abs to Ags of the major anaerobes of the bacterial flora. The serum Abs detected on immunoblot were primarily IgG2a, suggesting a Th1 response. Comparison of sera reactivity to histopathologic severity showed an inverse relationship: one third of young C3H/HeJBir mice during the peak of colitis produced Abs to bacterial Ags, while later in life, when the colitis had resolved, 96% produced Abs. These data are consistent with an abnormal immune reactivity to enteric bacterial flora in C3H/HeJBir mice, a reactivity that is highly selective considering the abundant bacterial Ags present in the colon lumen. We postulate that this reactivity plays a role in the pathogenesis of colitis in these mice.