The etiological agent of human amoebiasis is the protozoan parasite E. histolytica; the disease is still an endemic infection in some countries and the outcome of infection in the host infection can range from asymptomatic intestinal infection to intestinal or liver invasive forms of the disease. The invasive character of this parasite is multifactorial and mainly due to the differential expression of multiple pathogenic genes. The aim of the present work was to measure the differential expression of some genes in different specimens of patients with amoebic liver abscess (ALA) and specimens of genital amoebiasis (AG) by RT-qPCR. Results show that the expression of genes is different in both types of samples. Almost all studied genes were over expressed in both sets of patients; however, superoxide dismutase (Ehsod), serine threonine isoleucine rich protein (Ehstirp), peroxiredoxin (Ehprd) and heat shock protein 70 and 90 (Ehhsp-70, EHhsp-90) were higher in AG biopsies tissue. Furthermore, cysteine proteinases 5 and 2 (Ehcp5, Ehcp2), lectin (Ehgal/galnaclectin) and calreticulin (Ehcrt) genes directly associate with pathogenic mechanisms of E. histolytica had similar over expression in both AG and ALA samples. In summary the results obtained show that trophozoites can regulate the expression of their genes depending on stimuli or environmental conditions, in order to regulate their pathogenicity and ensure their survival in the host.

[This corrects the article DOI: 10.1371/journal.pone.0181962.].

BACKGROUND:This study aimed to determine the frequency of Entamoeba histolytica and Entamoeba dispar infection in school children in the community of Tlaltizapan, in order to understand the dynamics of infection within the school and family spheres of this population. Amoebiasis is an unsolved public health problem and an endemic disease in Mexico. The incidence rate varies depending on the state; the most affected states show the highest numbers of new cases of amoebiasis per year. Previously, we reported the molecular frequency of infection with E. histolytica and/or E. dispar in other rural communities of the state of Morelos.METHODS:Children from 3 schools were studied to estimate the frequency of intestinal parasites through microscopic examination of fresh stool samples. The number of studied individuals were 309 school children. The molecular characterization of E. histolytica or E. dispar was carried out by Polymerase Chain Reaction (PCR) using species-specific primers to amplify short tandem repeats (STR) in non-coding sequences associated with the tRNA gene; the amplified fragments were sequenced and analyzed.RESULTS:Eight different genotypes were obtained from E. dispar isolates with the molecular marker NKD3-D5. None of the cases in which the species E. histolytica was detected developed symptoms attributable to an invasive process of disease. Moreover, the parasitized condition appeared to have no significant impact on the development or nutritional status of affected children. Genotype 1, which corresponds to the reference strain E. dispar SAW760, considered a non-pathogenic amoeba, was the most prevalent.CONCLUSIONS:The comparison of the genotypes of Entamoeba species did not show a correlation between children and their relatives. In this community, the species Entamoeba dispar genotype 1 was the most widespread. Based on the indicators of growth, development and nutrition status, the studied community seems to be reasonably adapted to constant exposure to intestinal parasites, since there were no evidences of a serious impact of the parasitized condition on the children's health.

The role of calreticulin (CRT) in host-parasite interactions has recently become an important area of research. Information about the functions of calreticulin and its relevance to the physiology ofEntamoebaparasites is limited. The present work demonstrates that CRT of both pathogenicE. histolyticaand nonpathogenicE. disparspecies specifically interacted with human C1q inhibiting the activation of the classical complement pathway. Using recombinantEhCRT protein, we demonstrate that CRT interaction site and human C1q is located at the N-terminal region ofEhCRT. The immunofluorescence and confocal microscopy experiments show that CRT and human C1q colocalize in the cytoplasmic vesicles and near to the surface membrane of previously permeabilized trophozoites or are incubated with normal human serum which is known to destroy trophozoites. In the presence of peripheral mononuclear blood cells, the distribution ofEhCRT and C1q is clearly over the surface membrane of trophozoites. Nevertheless, the level of expression of CRTin situin lesions of amoebic liver abscess (ALA) in the hamster model is different in bothEntamoebaspecies; this molecule is expressed in higher levels inE. histolyticathan inE. dispar. This result suggests thatEhCRT may modulate some functions during the early moments of the host-parasite relationship.

Los genes humanos MHC clase I (Mica y MICB) estan localizados dentro de la region de los genes de clase I del HLA en elcromosoma 6. Su organizacion, expresion y productos difieren considerablemente de los genes clasicos del HLA clase I. Lasproteinas MIC son consideradas como marcadores de estres en epitelio y fibroblastos, actuando como moleculassenalizadoras que son reconocidas por celulas asesinas naturales (NK) a traves de un receptor denominado (NKG2D).Modelos moleculares actuales por difraccion de rayos X han permitido conocer la union de la proteina MICA con el receptorNKG2D formando complejos. Las moleculas de MICA parecen ser altamente flexibles y polimorficas, aunque la relevanciafuncional y las implicaciones de su polimorfismo tienen que ser todavia discutidas

Cutaneous amebiasis is the least common clinical form of human amebiasis in Mexico, sexual amebiasis was only occasionally observed before the late 1980s. However, in the last few decades, most of the documented cases of cutaneous amebiasis from around the world are sexually transmitted. We present two cases of sexually transmitted genital amebiasis. The molecular characterization of the Entamoeba species in the affected tissues underlines the importance of an etiological diagnosis using specific and sensitive techniques that avoid the rapid destruction of tissues and the irreversible sequelae to the anatomy and function of the affected organs. In addition, for those interested in the study of the human-amoebic disease relationship and its epidemiology, the detection of a new, mixed infection in an invasive case of amebiasis reveals new perspectives in the study of the extraordinarily complex host-parasite relationship in amebiasis.

In accordance with the 1997 documents of the World Health Organization (WHO), amoebiasis is defined as the infection by the protozoan parasite Entamoeba histolytica with or without clinical manifestations. The only known natural host of E. histolytica is the human with the large intestine as major target organ. This parasite has a very simple life cycle in which the infective form is the cyst, considered a resistant form of parasite: The asymptomatic cyst passers and the intestinal amoebiasis patients are the transmitters; they excrete cysts in their feces, which can contaminate food and water sources. E. histolytica sensu stricto is the potentially pathogenic species and E. dispar is a commensal non-pathogenic Entamoeba. Both species are biochemical, immunological and genetically distinct. The knowledge of both species with different pathogenic phenotypes comes from a large scientific debate during the second half of the 20(th) century, which gave place to the rapid development of diagnostics technology based on molecular and immunological strategies. During the last ten years, knowledge of the new epidemiology of amoebiasis in different geographic endemic and non-endemic areas has been obtained by applying mostly molecular techniques. In the present work we highlight novelties on human infection and the disease that can help the general physician from both endemic and non-endemic countries in their medical practice, particularly, now that emigration is undoubtedly a global phenomenon that is modifying the previous geography of infectious diseases worldwide.

1 Department of Experimental Medicine, Faculty of Medicine, National Autonomous University of Mexico (UNAM), Mexico City, 04510, Mexico; E-Mails: cerritos@miranda.ecologia.unam.mx (R.C.); rojasvelazquezliliana@gmail.com (L.R.); patricia_morans@yahoo.com (P.M.); egori1900@prodigy.net.mx (E.G.); avaladezs17@yahoo.com.mx (A.V.); ericghdz@yahoo.com.mx (E.H.); lizbthangy@yahoo.com.mx (A.L.); oswpartida@yahoo.com.mx (O.P.) 2 Department of Zoology, ENCB, National Polytechnic Institute (IPN), Mexico City, 11340, Mexico 3 Department of Morphology, Laboratory of Parasitology, Federal University of Sergipe, Aracaju, Sergipe, 49100-000, Brazil; E-Mail: dolabella@ufs.br 4 Department of Infectomic and Molecular Pathogenesis, (CINVESTAV), Mexico City, 07360, Mexico; E-Mail: mineko@cinvestav.mx 5 Department of Chemistry and Biological Science, University of Sonora (UNISON), Hermosillo, Sonora, 83000, Mexico; E-Mail: valenzuela.o@gmail.com 6 Department of Parasitology, Institute for Biological Sciences, Federal University of Minas Gerais, Minas Gerais, Belo Horizonte, 31270-901, Brazil; E-Mail: felix@icb.ufmg.br

For over 30 years it has been established that the Entamoeba histolytica protozoan included two biologically and genetically different species, one with a pathogenic phenotype called E. histolytica and the other with a non-pathogenic phenotype called Entamoeba dispar. Both of these amoebae species can infect humans. E. histolytica has been considered as a potential pathogen that can cause serious damage to the large intestine (colitis, dysentery) and other extraintestinal organs, mainly the liver (amebic liver abscess), whereas E. dispar is a species that interacts with humans in a commensal relationship, causing no symptoms or any tissue damage. This paradigm, however, should be reconsidered or re-evaluated. In the present work, we report the detection and genotyping of E. dispar sequences of DNA obtained from patients with amebic liver abscesses, including the genotyping of an isolate obtained from a Brazilian patient with a clinical diagnosis of intestinal amebiasis that was previously characterized as an E. dispar species. The genetic diversity and phylogenetic analysis performed by our group has shown the existence of several different genotypes of E. dispar that can be associated to, or be potentiality responsible for intestinal or liver tissue damage, similar to that observed with E. histolytica.