Are immunoenzymatic tests for intestinal protozoans reliable when used on archaeological material?

Intestinal protozoans found in ancient human samples have been studied primarily by microscopy and immunodiagnostic assays. However, such methods are not suitable for the detection of zoonotic genotypes. The objectives of the present study were to utilize immunoenzimatic assays for coproantigen detection of Cryptosporidium sp., Giardia duodenalis, and Entamoeba histolytica/Entamoeba dispar in sixty ancient human and animal samples collected from 14 archaeological sites in South America, and to carry out a critical analysis of G. duodenalis according to results obtained from three diagnostic methodologies: microscopy, immunodiagnostic tests (immunoenzymatic and immunofluorescence), and molecular biology (PCR and sequencing). More than half (31/60) of the samples analyzed using immunoenzymatic tests were positive for at least one of the intestinal protozoans, with 46.6% (28/60) corresponding to G. duodenalis, 26.6% (16/60) to Cryptosporidium sp., and 5% (3/60) to E. histolytica/E. dispar. Cryptosporidium sp. and G. duodenalis coinfection was observed in 15% (9/60) of the samples, whereas all three protozoans were found in 5% (3/60) of samples. In the Northeast Region of Brazil, by immunoenzymatic tests there is evidence that G. duodenlais and Cryptosporidium sp. have infected humans and rodents for at least 7150 years. However, for G. duodenalis, the results from the three diagnostic tests were discordant. Specifically, despite the efficiency of the molecular biology assay in the experimental models, G. duodenalis DNA could not be amplified from the ancient samples. These results raise the following question: Are all ancient samples positive for coproantigen of G. duodenalis by immunoenzymatic tests truly positive? This scenario highlights the importance of further studies to evaluate the sensitivity and specificity of the immunoenzymatic method in the archaeological context.

The Architecture of Thiol Antioxidant Systems among Invertebrate Parasites.

The use of oxygen as the final electron acceptor in aerobic organisms results in an improvement in the energy metabolism. However, as a byproduct of the aerobic metabolism, reactive oxygen species are produced, leaving to the potential risk of an oxidative stress. To contend with such harmful compounds, living organisms have evolved antioxidant strategies. In this sense, the thiol-dependent antioxidant defense systems play a central role. In all cases, cysteine constitutes the major building block on which such systems are constructed, being present in redox substrates such as glutathione, thioredoxin, and trypanothione, as well as at the catalytic site of a variety of reductases and peroxidases. In some cases, the related selenocysteine was incorporated at selected proteins. In invertebrate parasites, antioxidant systems have evolved in a diversity of both substrates and enzymes, representing a potential area in the design of anti-parasite strategies. The present review focus on the organization of the thiol-based antioxidant systems in invertebrate parasites. Differences between these taxa and its final mammal host is stressed. An understanding of the antioxidant defense mechanisms in this kind of parasites, as well as their interactions with the specific host is crucial in the design of drugs targeting these organisms.

Paleoparasitological analysis of the extinct Myotragus balearicus Bate 1909 (Artiodactyla, Caprinae) from Mallorca (Balearic Islands, Western Mediterranean).

Myotragus balearicus (Artiodactyla, Caprinae) is an extinct caprine endemic of the Eastern Balearic Islands or Gymnesics (i.e., Mallorca, Menorca and surrounding islets, Western Mediterranean Sea). In spite of its small size, c. 50cm height at the shoulder, it was the largest mammal inhabiting these islands until the human arrival, and it had peculiar short legs and frontal vision. It disappeared between 2830 and 2210calBCE. The coprolites here studied were recovered from Cova Estreta, in Pollença, Mallorca. The samples were subjected to microscopic examination and enzyme-linked immunosorbent assays (ELISA) for E. histolytica/E. dispar, Giardia intestinalis and Cryptosporidium parvum. This study provides new paleoparasitological data from an extinct animal species of the Holocene period. The microscopy revealed one sample containing uninucleated-cyst of Entamoeba sp., whereas ELISA detected nine positive samples for Cryptosporidium sp. The finding of these protozoans can help in the discussion of its extinction cause and demonstrates the antiquity and the evolutionary history of host-parasite relationships between protozoa and caprines since the Messinian.

[Analysis of intestinal ameobiasis in patients with diarrhea by adhesin antigen test and direct microscopy]. / Ishalli Hastalarda Baðýrsak Amebiyazýnýn Adezin Antijen Testi ve Direkt Mikroskopi ile Incelenmesi.

OBJECTIVE: In this study, we aimed to research the frequency of intestinal amebiasis in patients who applied with diarrhea retrospectively for a year and compare direct microscopic analysis and ELISA adhesin antigen test for Entamoeba histolytica procedures. METHODS: The fecal matter sample of 259 patients with diarrhea who applied to the Sivas Numune Hospital Microbiology Laboratory between February 2012 and March 2013 were studied. Samples were evaluated with direct microscopic analysis and Entamoeba histolytica adhesin antigen test (E. histolytica II, Techlab, Blacksburg, USA). RESULTS: In the patients who applied to our laboratory with an amebiasis diagnosis, the mean age was detected as 40.12±19, and the positivity range of the Entamoeba histolytica adhesin antigen test was detected as 25.1% (n=65). In ELISA adhesin test-positive patients 24.6% (n=16) trophozoites, cyst, abundant leukocytes and erythrocytes were detected, and in 6 patients (3.1%), ELISA adhesin antigen test was negative. There was no difference between males and females (p>0.05), but between-season difference was detected (p<0.05). CONCLUSION: Direct microscopic analysis may be inadequate in the differential diagnosis of E. histolytica/ and E. dispar and discrimination of Entamoeba cyst and/or trophozoites from other cellular elements (esp. leukocytes). Furthermore, we thought that the E. histolytica monoclonal ELISA adhesin test is useful for the differential diagnosis of pathogenic E. histolytica and nonpathogenic E. dispar.

PREVALENCE OF Entamoeba histolytica/Entamoeba dispar IN THE CITY OF CAMPINA GRANDE, IN NORTHEASTERN BRAZIL / Prevalência de Entamoeba histolytica/Entamoeba dispar na cidade de Campina Grande, Nordeste do Brasil

There is a clear need to perform epidemiological studies to find the true prevalence of Entamoeba histolytica around the world. The evaluation of this prevalence has been hindered by the existence of two different species which are morphologically identical, but genetically different, namely E. histolytica, which causes amebiasis, and E. dispar, which is non-pathogenic. In Brazil, the E. dispar has been detected in communities in the Southeastern (SE) and Northeastern (NE) regions with poor sanitation. However, individuals infected with E. histolytica have been identified in other regions. There is an absence of reports on the prevalence of these parasites in the state of Paraíba, which also has areas with poor sanitary conditions where a high prevalence of the E. histolytica/E. dispar complex has been detected in children from urban slums. The present study evaluated the prevalence of E. histolytica and E. dispar in 1,195 asymptomatic children between two and 10 years of age, living in a sprawling urban slum in Campina Grande, in the state of Paraíba, in Northeastern Brazil. These children were examined and their feces samples were analyzed microscopically. A total of 553 children tested positive for the E. histolytica/E. dispar complex, and 456 of the positive samples were tested with the E. histolytica II® ELISA kit. All 456 samples were negative for the presence of the adhesin E. histolytica specific antigen. The evidence suggests that in this community E. histolytica is absent and E. dispar is the dominant species.

A prevalência mundial de Entamoeba histolytica não está bem estabelecida. Este fato deve-se à complicação derivada da existência de duas espécies morfologicamente idênticas, mas geneticamente diferentes: a E. histolytica que causa amebíases e a E. dispar descrita como não patogênica. No Brasil, em comunidades com precárias condições sanitárias e endêmicas para várias parasitoses, localizadas nas regiões Sudeste (SE) e Nordeste (NE), somente E. dispar tem sido encontrada, porém outras regiões, apresentam indivíduos infectados por E. histolytica. Na região agreste do Estado da Paraíba (NE) que apresenta as mesmas precárias condições sanitárias, não tem sido reportada prevalência específica destes parasitos, embora fosse encontrada alta prevalência do complexo E. dispar/E. histolytica em crianças em favela urbana. O presente estudo foi realizado em favela da cidade de Campina Grande, Estado da Paraíba, onde 1.195 crianças de dois a 10 anos sem sintomatologia foram examinadas. Amostras de fezes destas crianças foram analisadas microscopicamente, encontrando-se 553 positivas para o complexo E. dispar/E. histolytica. Do total de amostras positivas, 456 foram submetidas à pesquisa do antígeno especifico para E. histolytica pelo teste ELISA E. histolytica II®,obtendose resultado negativo para a presença do antígeno adesina específico de E. histolytica, em todas as amostras testadas. Os resultados sugerem que nesta comunidade não há infecção por E. histolytica, e que E. dispar é a espécie dominante na região.

Frequency of amoebiasis and other intestinal parasitoses in a settlement in Ilheus City, State of Bahia, Brazil

Introduction: This study evaluated the frequency of intestinal parasites, emphasizing the identification and differentiation of Entamoeba spp. Methods: Multiplex polymerase chain reaction (PCR), coproantigen tests and morphometric analysis were performed for Entamoeba spp. differentiation. Results: The overall frequency of intestinal parasites was 65%. Entamoeba histolytica was detected by the coproantigen test, and the PCR showed that Entamoeba dispar predominated in the population. In contrast, morphometric analysis was important for identifying Entamoeba hartmanni. Conclusions: It is possible to identify the causative agent of amoebiasis and to differentiate this agent from other species by combining techniques. .

Evidence of gene conversion in genes encoding the Gal/GalNac lectin complex of Entamoeba.

The human gut parasite Entamoeba histolytica, uses a lectin complex on its cell surface to bind to mucin and to ligands on the intestinal epithelia. Binding to mucin is necessary for colonisation and binding to intestinal epithelia for invasion, therefore blocking this binding may protect against amoebiasis. Acquired protective immunity raised against the lectin complex should create a selection pressure to change the amino acid sequence of lectin genes in order to avoid future detection. We present evidence that gene conversion has occurred in lineages leading to E. histolytica strain HM1:IMSS and E. dispar strain SAW760. This evolutionary mechanism generates diversity and could contribute to immune evasion by the parasites.

Entamoeba invadens, encystation process and enolase.

The reptilian parasite Entamoeba invadens is accepted as a model for the study of the Entamoeba encystation process. Here we describe the production and characterization of a mAb (B4F2), generated against a component of the E. invadens cyst wall. This mAb specifically recognizes a 48-kDa protein present in cytoplasmic vesicles of cells encysting for 24 h. In mature cysts (96 h), the antigen was detected on the cyst surface. By two-dimensional electrophoresis and mass spectrometry analysis, the B4F2 specific antigen was identified as enolase. Levels of enolase mRNA were increased in encysting cells and the B4F2 mAb was found to inhibit cyst formation. Therefore, these results strongly suggest a new role for enolase in E. invadens encystation, and the B4F2 mAb will be useful tool to study its role in the differentiation process.

Comparison of multiplex-PCR and antigen detection for differential diagnosis of Entamoeba histolytica.

Amebiasis is an infection caused by Entamoeba histolytica. However, differentiation between E. histolytica and Entamoeba dispar, which are morphologically identical species, is essential for treatment decision, precaution of the invasive disease and public health. The purpose of the present study was to evaluate a Multiplex -PCR for detection and differentiation of E. histolytica from E. dispar from fresh stool samples in comparison with the coproantigen commercial ELISA. Microscopic examination of stools using the Coprotest method, detection of stool antigen by enzyme-linked immunosorbent assay kit and a home made Multiplex-PCR, were used for the diagnosis of amoebiasis infection. Analysis of the 127 stools samples by microscopy examination demonstrated that only 27 (21%) samples were positive for E. histolytica/E. dispar complex. Among these stool samples, 11 were positive by Multiplex-PCR, with nine presenting the diagnostic fragment characteristic of E. dispar (96 bp) and two presenting diagnostic fragment of E. histolytica (132 bp). Among negative samples detected by microscopic examination, three positive samples for E. dispar and one positive for E. histolytica by Multiplex-PCR was observed. This denotes a low sensibility of microscopic examination when a single stool sample is analyzed. Assay for detection of E. histolytica antigen was concordant with multiplex-PCR in relation to E. histolytica. Statistical analysis comparing the sensibility tests was not done because of the low number of E. histolytica cases. The results demonstrate the importance of the specific techniques use for the differentiation between E. histolytica and E. dispar.

Comparison of multiplex-PCR and antigen detection for differential diagnosis of Entamoeba histolytica

Amebiasis is an infection caused by Entamoeba histolytica. However, differentiation between E. histolytica and Entamoeba dispar, which are morphologically identical species, is essential for treatment decision, precaution of the invasive disease and public health. The purpose of the present study was to evaluate a Multiplex -PCR for detection and differentiation of E. histolytica from E. dispar from fresh stool samples in comparison with the coproantigen commercial ELISA. Microscopic examination of stools using the Coprotest method, detection of stool antigen by enzyme-linked immunosorbent assay kit and a home made Multiplex-PCR, were used for the diagnosis of amoebiasis infection. Analysis of the 127 stools samples by microscopy examination demonstrated that only 27 (21 percent) samples were positive for E. histolytica/E. dispar complex. Among these stool samples, 11 were positive by Multiplex-PCR, with nine presenting the diagnostic fragment characteristic of E. dispar (96 bp) and two presenting diagnostic fragment of E. histolytica (132 bp). Among negative samples detected by microscopic examination, three positive samples for E. dispar and one positive for E. histolytica by Multiplex-PCR was observed. This denotes a low sensibility of microscopic examination when a single stool sample is analyzed. Assay for detection of E. histolytica antigen was concordant with multiplex-PCR in relation to E. histolytica. Statistical analysis comparing the sensibility tests was not done because of the low number of E. histolytica cases. The results demonstrate the importance of the specific techniques use for the differentiation between E. histolytica and E. dispar.

A novel nested multiplex polymerase chain reaction (PCR) assay for differential detection of Entamoeba histolytica, E. moshkovskii and E. dispar DNA in stool samples.

BACKGROUND: E. histolytica, a pathogenic amoeba, is indistinguishable in its cyst and trophozoite stages from those of non-pathogenic E. moshkovskii and E. dispar by light microscopy. We have developed a nested multiplex PCR targeting a 16S-like rRNA gene for differential detection of all the three morphologically similar forms of E. histolytica, E. moshkovskii and E. dispar simultaneously in stool samples. RESULTS: The species specific product size for E. histolytica, E. moshkovskii and E. dispar was 439, 553 and 174 bp respectively, which was clearly different for all the three Entamoeba species. The nested multiplex PCR showed a sensitivity of 94% and specificity of 100% for the demonstration of E. histolytica, E. moshkovskii and E. dispar DNA in stool samples. The PCR was positive for E. histolytica, E. moshkovskii and E. dispar in a total of 190 out of 202 stool specimens (94% sensitive) that were positive for E. histolytica/E. dispar/E. moshkovskii by examination of stool by microscopy and/or culture. All the 35 negative control stool samples that were negative for E. histolytica/E. dispar/E. moshkovskii by microscopy and culture were also found negative by the nested multiplex PCR (100% specific). The result from the study shows that only 34.6% of the patient stool samples that were positive for E. histolytica/E. dispar/E. moshkovskii by examination of stool by microscopy and/or culture, were actually positive for pathogenic E. histolytica and the remaining majority of the stool samples were positive for non-pathogenic E. dispar or E. moshkovskii as demonstrated by the use of nested multiplex PCR. CONCLUSION: The present study reports a new nested multiplex PCR strategy for species specific detection and differentiation of E. histolytica, E. dispar and E. moshkovskii DNA in stool specimens. The test is highly specific, sensitive and also rapid, providing the results within 12 hours of receiving stool specimens.

Ocorrência de Entamoeba histolytica/Entamoeba dispar em pacientes ambulatoriais de Recife, PE / Occurrence of Entamoeba histolytica/Entamoeba dispar in ambulatory patients of Recife, PE

Este trabalho teve como objetivo determinar a ocorrência das espécies Entamoeba histolytica/Entamoeba dispar em amostras clínicas de pacientes ambulatoriais de Pernambuco. Neste estudo, foi utilizado o teste imunoenzimático específico para Entamoeba histolytica, que entre os 213 pacientes não identificou nenhuma amostra fecal positiva. Estes resultados confirmam Entamoeba dispar é a espécie dominante nesta região.

The objective this study was to determine the occurrence of the species Entamoeba histolytica/Entamoeba díspar in clinical samples of ambulatory patients in Pernambuco. A specific assay for Entamoeba histolytica was used in this study, which identified no positive fecal samples among the 213 patients. These results confirm that E. dispar is the dominant species in Pernambuco State.

Comparison of a stool antigen detection kit and PCR for diagnosis of Entamoeba histolytica and Entamoeba dispar infections in asymptomatic cyst passers in Iran.

The present study was conducted to compare stool antigen detection with PCR for the diagnosis of Entamoeba sp. infection in asymptomatic cyst passers from Iran. Entamoeba dispar and, in one case, E. moshkovskii were the Entamoeba spp. found in the amebic cyst passers. There was a 100% correlation between the results from the TechLab E. histolytica II stool antigen kit and those from nested PCR. We concluded that E. dispar is much more common in asymptomatic cyst passers in Iran and that antigen detection and PCR are comparable diagnostic modalities.

Diagnostic methods for differentiation of Entamoeba histolytica and Entamoeba dispar in carriers: performance and clinical implications in a non-endemic setting.

Unpreserved faecal samples, suspected to contain Entamoeba histolytica/Entamoeba dispar cysts or trophozoites on the basis of microscopic examination, and serum samples from 416 patients were collected in a prospective study to determine whether stool antigen assays and detection of antibodies in serum are reliable methods to distinguish between carriers of E. histolytica and E. dispar in comparison to the reference test: real-time PCR. In 283 patients (68%) DNA of E. histolytica or E. dispar was amplified by real-time PCR: 6 patients with amoebic colitis (2%), 19 carriers of E. histolytica (6.7%), and 258 carriers of E. dispar (91.2%). In 133 patients (31%) no DNA of E. histolytica or E. dispar could be amplified in the stool samples. This patient group was used as control for the evaluation of diagnostic tests. Using real-time PCR as a reference test, the sensitivity and specificity of (1) the Entamoeba test for the diagnosis of E. histolytica/E. dispar carrier were 59% and 98%, (2) E. histolytica II for the diagnosis of E. histolytica carrier was 71% and 100%, and (3) serology for the diagnosis of E. histolytica infection was 83.3% and 95.2%, respectively. Applied to carriers that did not originate from an endemic country the sensitivity of serology for E. histolytica infection was 90% and specificity was 98.8%. In comparison to real-time PCR the performances of Entamoeba test and E. histolytica II lacked sensitivity for a reliable diagnosis of E. histolytica/E. dispar infection in a non-endemic setting. In carriers of E. histolytica/E. dispar from non-endemic countries the high specificity of serology can be used to establish the diagnosis of E. histolytica infection if antibodies are present.

Infection by human immunodeficiency virus-1 is not a risk factor for amebiasis.

The purpose of this study was to determine whether HIV-1 infected patients in our community were more susceptible to Entamoeba histolytica and Entamoeba dispar infection than non-HIV-infected individuals. The prevalence and frequency of invasive amebiasis was determined in 203 HIV+/AIDS subjects and 140 close relatives or sexual partners, all of whom were HIV-. Anti-E. histolytica antibodies (IgG, IgA) were assessed as indicators of E. histolytica invasive infection. Polymerase chain reaction (PCR) was used for the characterization of the Entamoeba species. The prevalence estimated with PCR data showed that E. histolytica infection was more common in the HIV+/AIDS group (25.32%), than in HIV- contacts (18.46%). E. histolytica + E. dispar infection was more frequent in HIV+/AIDS patients (13.3%), than in HIV- contacts (0.7%). E. histolytica and/or E. dispar infection was highly prevalent in HIV+/AIDS patients (34.1%) without evidence of recent or current invasive disease. Contacts of HIV+/AIDS patients who were infected with E. histolytica were asymptomatic cyst passers. Our results suggest that E. histolytica strains prevalent in the studied community appear to be of low pathogenic potential.

Intestinal antilectin immunoglobulin A antibody response and immunity to Entamoeba dispar infection following cure of amebic liver abscess.

We followed 93 subjects with amebic liver abscess (ALA) and 963 close associate controls at 3-month intervals for 36 months to characterize intestinal and humoral antibody responses to the amebic galactose-inhibitable lectin and to determine whether immunity developed to Entamoeba histolytica or Entamoeba dispar infection following cure of ALA. We found that ALA subjects had a higher prevalence and level of intestinal antilectin immunoglobulin A (IgA) and serum anti-LC3 (cysteine-rich recombinant lectin protein) IgA and IgG antibodies, P < 0.01 and P < 0.05, respectively, compared to controls. The intestinal antilectin IgA antibody response was sustained over a longer time period in ALA subjects (71.8% remained positive at 18 months and 52.6% at 36 months, P < 0.001 compared to 17.6% and 10.3% of controls, respectively). ALA subjects were highly immune to E. dispar infection throughout the study (0% infected at 6 and 36 months, compared to 6.5% and 4.9% of control subjects, respectively, P < 0.05). Upon entry into the study, 6.3% of ALA subjects were infected with E. histolytica; the incidence of new E. histolytica infections in controls (as determined by culture) was too low (1.4%) to determine whether ALA subjects exhibited immunity to new infections. We found that stool cultures every 3 months markedly underestimated the occurrence of new E. histolytica infections, as 15.3% of controls seroconverted after 12 months of follow-up. Unfortunately, under the field conditions present in Durban, South Africa, enzyme-linked immunosorbent assay for detection of lectin antigen in stool yielded unreliable results. In summary, subjects cured of ALA exhibited sustained mucosal IgA antibody responses to the amebic galactose-inhibitable lectin and a high level of immunity to E. dispar infection. Determination of immunity to E. histolytica following cure of ALA will require the use of more sensitive and reliable diagnostic methods.

Appearance of a stage-specific immunodominant glycoprotein in encysting Entamoeba invadens.

The appearance of cyst-specific proteins in encysting Entamoeba invadens and their immunogenicity were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and immunoblotting using an axenic encystation system in vitro. A rabbit antiserum against trophozoites of E. invadens reacted with a number of proteins of cysts after 1-4 days of incubation. Thus, a number of cyst proteins remained antigenically unchanged as common antigens of the two forms after transformation from trophozoites to cysts. A rabbit antiserum against cysts also reacted with the trophozoite proteins as well as the cyst proteins. The most interesting result was that the rabbit anticyst serum reacted predominantly with an 88-kDa protein of cysts after 1 day of incubation. The 88-kDa protein reacted with the anticyst serum absorbed with trophozoite proteins and was thus cyst-specific. The reactivity of the 88-kDa protein of cysts with the absorbed anticyst serum decreased as encystation proceeded. When soluble and particulate fractions prepared from cysts after 1 day of incubation were examined by electrophoresis and immunoblotting, the 88-kDa protein that had reacted with the absorbed anticyst serum was found to be present in the particulate fraction, which was rich in cell-wall fragments, and stained with periodic acid-Schiff's reagent, indicating that it is a glycoprotein. The results indicate that encystation is accompanied by appearance of the cyst-specific 88-kDa glycoprotein, which is immunodominant and most abundantly expressed in cysts after 1 day of incubation and appears to be associated with the cyst wall.

Comparison of antigen-capture ELISA to stool-culture methods for the detection of asymptomatic Entamoeba species infection in Kafer Daoud, Egypt.

We performed a prospective field study in the village of Kafer Daoud in Menofia, Egypt to compare the fecal culture method with enzyme linked immuno assay (ELISA) for detection of 170 kDa lectin antigen in feces for diagnosis of asymptomatic Entamoeba histolytica and Entamoeba dispar infection. All subjects with E. histolytica or E. dispar infection detected by culture also had positive ELISA for amebic antigen in their feces and an additional 57 Entameoba infections missed by culture were detected by ELISA (P < 0.001 compared to culture). The presence of fecal anti-lectin IgA antibodies and serum anti-LC3 (recombinant cysteine-rich lectin protein) IgG antibodies were positive predictors for E. histolytica infection (P < 0.03). Of interest, infection with Trichomonas hominis but not Blastocystis hominis was positively associated with E. histolytica infection (P < 0.05). In conclusion, ELISA for detection of fecal lectin antigen is a more sensitive method than fecal culture for detecting asymptomatic E. histolytica infection.

Development of monoclonal antibodies specifically recognizing the cyst stage of Entamoeba histolytica.

Protozoan cysts were isolated according to a two-step sucrose gradient procedure. Pure cysts of Entamoeba histolytica, in fixed and native states, were injected into BALB/c mice intraperitoneally for immunization. The spleens of these animals were used for fusion with AG8 mouse myeloma cells. Hybridomas were obtained and tested for the recognition of E. histolytica, E. dispar, E. coli, E. hartmanni, Endolimax nana, Jodamoeba biitschlii, and Giardia lamblia. Three monoclonal antibodies were identified that reacted only with cysts and trophozoites of E. histolytica. These can be used for differentiation and identification of E. histolytica in feces.

Prospective study of Entamoeba dispar infection in a cohort of mothers and their infants: relationship to serum antibody response.

The sera of cohorts of newborn infants and their mothers, characterized as cyst passers of Entamoeba with nonpathogenic zymodemes (E. dispar) and seropositive for amoebic antigens, were analyzed. Both cohorts were followed for a period of 12 months by microscopic examination of feces and determination of serum anti-amoebic antibody titers using the indirect hemagglutination assay. Control groups (noncyst passer mothers and their infants) were included and followed. To characterize antigens involved in the induction of IgG and IgA antibody responses, Western blots of serum from all participants were tested and immunoplots of the frequency of antigenic recognition were constructed. Results of clinical follow-up and microscopic examination of feces showed that during the 12-month period none of the cyst passer mothers had episodes of diarrhea attributable to E. histolytica invasion; five of 21 children of cyst passer mothers became infected during the study, five of five infected children developed serum antiamebic antibodies (titers 1:64-1:128); none of the cohort of children from cyst passer mothers had diarrhea due to E. histolytica. Western blot analysis showed that there are antigenic fractions that induce serum antibodies of the IgG and IgA classes against E. dispar very early in the host-parasite relationship. Our results suggest that mechanisms of antibody induction different from intestinal invasion may be operating in amebic infection. Intestinal absorption of antigen, systemic reflection of secretory antibody response, and priming of newborns by maternal anti-idiotypic antibody transfer are discussed.