Giardia duodenalis flavohemoglobin is a target of 5-nitroheterocycle and benzimidazole compounds acting as enzymatic inhibitors or subversive substrates.

Giardia duodenalis causes giardiasis in humans, companion, livestock and wild animals. Control of infection involves drugs as benzimidazoles (e.g.

Giardipain-1, a protease secreted by Giardia duodenalis trophozoites, causes junctional, barrier and apoptotic damage in epithelial cell monolayers.

The adhesion of Giardia duodenalis trophozoites to intestinal epithelial cells allows the onset and maintenance of giardiasis. During these interactions, epithelial cells can be committed to apoptosis by enzymes secreted by the parasites, including cysteine proteases that are increasingly identified as virulence factors in parasitic protozoa. In this work, a monoclonal antibody (mAb1G3) raised against G.

Expression and secretion of the Giardia duodenalis variant surface protein 9B10A by transfected trophozoites causes damage to epithelial cell monolayers mediated by protease activity.

Giardia duodenalis is the protozoan parasite responsible for most cases of parasitic diarrhea worldwide. The pathogenic mechanisms of giardiasis have not yet been fully characterized. In this context parasite's excretory/secretory products have been related to the damage induced by the parasite on enterocytes.

Albendazole induces oxidative stress and DNA damage in the parasitic protozoan Giardia duodenalis.

The control of Giardia duodenalis infections is carried out mainly by drugs, among these albendazole (ABZ) is commonly used. Although the cytotoxic effect of ABZ usually involves binding to β-tubulin, it has been suggested that oxidative stress may also play a role in its parasiticidal mechanism. In this work the effect of ABZ in Giardia clones that are susceptible or resistant to different concentrations (1.

Giardia fatty acyl-CoA synthetases as potential drug targets.

Giardiasis caused by Giardia intestinalis (syn. G. lamblia, G.

An antioxidant response is involved in resistance of Giardia duodenalis to albendazole.

Albendazole (ABZ) is a therapeutic benzimidazole used to treat giardiasis that targets β-tubulin. However, the molecular bases of ABZ resistance in Giardia duodenalis are not understood because β-tubulin in ABZ-resistant clones lacks mutations explaining drug resistance. In previous work we compared ABZ-resistant (1.

Induction of protection in murine experimental models against Trichinella spiralis: an up-to-date review.

The parasitic nematode Trichinella spiralis, an aetiological agent of the disease known as trichinellosis, infects wild and domestic animals through contaminated pig meat, which is the major source for Trichinella transmission. Prevention of this disease by interrupting parasite transmission includes vaccine development for livestock; however, major challenges to this strategy are the complexity of the T. spiralis life cycle, diversity of stage-specific antigens, immune-evasion strategies and the modulatory effect of host responses.

A prime-boost vaccination of mice with attenuated Salmonella expressing a 30-mer peptide from the Trichinella spiralis gp43 antigen.

Protection against Trichinella infections has been achieved using various parasite antigens and adjuvants. Recently, we reported that immunization of mice with an attenuated Salmonella strain displaying a 30-mer peptide (residues 210-239) from the Trichinella spiralis gp43 antigen using the ShdA autotransporter induced partial protection against T. spiralis infection.

Proteomic and transcriptional analyses of genes differentially expressed in Giardia duodenalis clones resistant to albendazole.

In this study we performed proteomic and transcriptional analyses to identify and characterize genes differentially expressed in Giardia duodenalis clones resistant to albendazole. The expression of proteins and their corresponding mRNAs was analyzed in clones resistant in vitro to different concentrations of albendazole (1.35, 8.

Trichinella spiralis: intranasal immunization with attenuated Salmonella enterica carrying a gp43 antigen-derived 30mer epitope elicits protection in BALB/c mice.

Trichinellosis is a public health problem and is considered an emergent/re-emergent disease in various countries. The etiological agent of trichinellosis is the nematode Trichinella, which infects domestic animals such as pigs and horses, as well as wild animals and humans. A veterinary vaccine could be an option to control the disease in domestic animals.

A helminth cestode parasite express an estrogen-binding protein resembling a classic nuclear estrogen receptor.

The role of an estrogen-binding protein similar to a known mammalian estrogen receptor (ER) is described in the estradiol-dependent reproduction of the helminth parasite Taenia crassiceps. Previous results have shown that 17-β-estradiol induces a concentration-dependent increase in bud number of in vitro cultured cysticerci. This effect is inhibited when parasites are also incubated in the presence of an ER binding-inhibitor (tamoxifen).

Hypochlorous acid scavenging activities of thioallyl compounds from garlic.

The hypochlorous acid (HOCl) scavenging capacities of 10 garlic compounds containing modifications in the thioallyl group (-S-CH2CH ═ CH2) were determined by a catalase protection assay, and the corresponding structure-activity relationships using molecular descriptors were calculated. This scavenging activity was enhanced by increasing the number of S atoms or by the alanyl group (-CH2CH-NH2-COOH) and decreased in the absence of the C ═ C bond or in the presence of a sulfoxide group in the thioallyl group. Interestingly, S-allylcysteine and its corresponding sulfoxide (alliin) showed the highest and lowest HOCl-scavenging capacities, respectively.

A new MAP kinase protein involved in estradiol-stimulated reproduction of the helminth parasite Taenia crassiceps.

MAP kinases (MAPK) are involved in the regulation of cellular processes such as reproduction and growth. In parasites, the role of MAPK has been scarcely studied. Here, we describe the participation of an ERK-like protein in estrogen-dependent reproduction of the helminth parasite Taenia crassiceps.

Encystation commitment in Giardia duodenalis: a long and winding road.

Cholesterol and bile salts are relevant modulators of Giardia encystation. Although several molecules within signaling cascades have been identified, and changes in their expression observed during giardial encystation, their underlying interactions leading to expression of cyst wall markers (CWPs and precursors of the GalNAc homopolymer) are not well defined. Recent experimental data and the completion of the Giardia Genome Project Database (GiardiaDB) allow us now to consider the role of bile salts as "natural stimuli" and the potential involvement of a Raf/MEK/ERK pathway mediating cholesterol-regulated expression of cyst-specific genes.

On the spread of the novel influenza A (H1N1) virus in Mexico.

A novel influenza A H1N1 virus of swine origin is responsible for the influenza epidemic affecting Mexico, the United States of America (USA), and 39 other countries. While the origin of this emerging pathogen remains uncertain, an increase in the reported incidence of respiratory diseases was noted during March 2009 at the town of La Gloria, in the southeastern state of Veracruz, Mexico. So far, this is the first community in which a case of novel influenza A H1N1 virus has been identified.

New tools provide further insights into Giardia and Cryptosporidium biology.

The ubiquity and importance of Giardia and Cryptosporidium as pathogens are reflected in the increasing number of publications concerning these organisms, but they are not the only reason why researchers are increasingly turning their attention to studying Giardia and Cryptosporidium. As new tools and databases become available, it is now possible to investigate fundamental issues related to their biology and relationship with their hosts. In this article, we highlight recent advances in research and outline questions arising that need to be addressed as a way of focusing the attention of the research and health communities and encouraging further dialogue and collaboration.

In vitro resistance to 5-nitroimidazoles and benzimidazoles in Giardia duodenalis: variability and variation in gene expression.

The susceptibility of Giardia duodenalis trophozoites exposed in vitro to sublethal concentrations of metronidazole (MTZ) and albendazole (ABZ) may exhibit inter-culture (variability) and intra-culture (variation) differences in drug susceptibility. It was previously reported that MTZ-resistant trophozoites may display changes in pyruvate:ferredoxin oxidoreductase (PFOR) expression while changes at the beta-tubulin molecule are apparently absent in ABZ-resistant cultures. To assess the levels of gene expression of these molecules, we obtained cloned cultures growing at concentrations up to 23 microM MTZ (WBRM23) and up to 8muM ABZ (WBRA8) and gene sequence and expression of pfor and beta-tubulin loci were compared with these of drug-susceptible clone WB1.

Ultrastructural study of the encystation and excystation processes in Naegleria sp.

An important aspect of the biology of Naegleria sp. is the differentiation processes that occur during encystation and excystation. We studied these using both fluorescence and transmission electron microscopy techniques.

Seroepidemiology of giardiasis in Mexico.

Prevalence of antibodies against Giardia duodenalis was determined by enzyme-linked immunosorbent assay in serum samples from a national serologic survey of Mexico that included all geographic areas and socioeconomic and demographic data for each person sampled. The country was divided into four regions on the basis of development (high, medium high, medium low, and low). Of 3,461 serum samples tested, 1,914 (55.

Differential activation of mast cells by antigens from Trichinella spiralis muscle larvae, adults, and newborn larvae.

Mast cell (MC) hyperplasia and activation are prominent features in Trichinella spiralis infection. Indeed a temporal correlation has been shown between the kinetics of intestinal mastocytosis, release of inflammatory mediators from MC, and adult worm loss, which constitutes a major component of the defense against T. spiralis infection.

Identification of nucleoli in the early branching protist Giardia duodenalis.

Giardia duodenalis has been described as 'anucleolated'. In this work we analysed the subcellular distribution of several nucleolar markers in Giardia nuclei using silver and immunostaining techniques for electron and confocal laser microscopy as well as expression of epitope-tagged proteins in transgenic trophozoites. We identified anteronuclear fibrogranular structures corresponding to nucleolar organising regions with recruited ribonucleoprotein complexes, rRNA and epitope-tagged fibrillarin and rRNA-pseudouridine synthase (CBF5).

Giardia duodenalis: adhesion-deficient clones have reduced ability to establish infection in Mongolian gerbils.

The role of Giardia duodenalis surface molecules in the attachment of trophozoites to epithelial cells has been established through the dual strategies of characterizing G. duodenalis clones with deficient adhesion and blocking experiments with surface-specific monoclonal antibodies. Also, the infectivity of the analyzed clones was tested using Mongolian gerbils as experimental model.

Contributions to the study of Trichinella spiralis TSL-1 antigens in host immunity.

The observation on different hosts infected with Trichinella spiralis that recognized similar muscle larvae (ML) antigens and the fact that different monoclonal antibodies (mAb) had a similar reactivity to ML components prompted a proposal to define a useful classification system for these antigens. For this purpose, an international workshop provided a platform for the classification of T. spiralis antigens.