NOD2 Responds to Dengue Virus Type 2 Infection in Macrophage-like Cells Interacting with MAVS Adaptor and Affecting IFN-α Production and Virus Titers

In pathogen recognition, the nucleotide-binding domain (NBD) and leucine rich repeat receptors (NLRs) have noteworthy functions in the activation of the innate immune response. These receptors respond to several viral infections, among them NOD2, a very dynamic NLR, whose role in dengue virus (DENV) infection remains unclear. This research aimed to determine the role of human NOD2 in THP-1 macrophage-like cells during DENV-2 infection. NOD2 levels in DENV-2 infected THP-1 macrophage-like cells was evaluated by RT-PCR and Western blot, and an increase was observed at both mRNA and protein levels. We observed using confocal microscopy and co-immunoprecipitation assays that NOD2 interacts with the effector protein MAVS (mitochondrial antiviral signaling protein), an adaptor protein promoting antiviral activity, this occurring mainly at 12 h into the infection. After silencing NOD2, we detected increased viral loads of DENV-2 and lower levels of IFN-α in supernatants from THP-1 macrophage-like cells with NOD2 knock-down and further infected with DENV-2, compared with mock-control or cells transfected with Scramble-siRNA. Thus, NOD2 is activated in response to DENV-2 in THP-1 macrophage-like cells and participates in IFN-α production, in addition to limiting virus replication at the examined time points.

MDR1 protein (ABC-C1) Over Expression in Giardia Intestinalis Incubated with Albendazole and Nitazoxanide

BACKGROUND

Giardia intestinalis is a worldwide parasite. Drugs used for the treatment of giardiasis are metronidazole, albendazole and nitazoxanide. The development of drug resistance is an obstacle to the effective treatment. Resistance mechanisms in some parasites involve the participation of ATP-binding cassette (ABC) transporter superfamily.

PURPOSE

To find if the ATP-binding cassette genes are overexpressed in trophozoites treated with albendazole or nitazoxanide.

METHODS

A search for ATP-binding cassette genes in Giardia sequence database (GiardiaDB) was done and six genes were selected. Trophozoites treated with albendazole or nitazoxanide and the expression of these six ABC genes was quantitated by real-time RT-PCR. The ABC-C1 gene was selected, and a fragment cloned. The ABC-C1 protein was expressed, and polyclonal antibodies were elicited in mice to detect the protein in treated trophozoites, finally a docking analysis was performed for ABC-C1 and tizoxanide interaction.

RESULTS

Bioinformatics analysis showed that the ATP-binding cassette (ABC) topology is present in the six proteins. The qRT-PCR revealed that the ABC-C1 gene was overexpressed in cells incubated with nitazoxanide or albendazole. Confocal analysis showed that ABC-C1 protein levels increased in trophozoites with both treatments but was higher with nitazoxanide. The mark was detected heavily in the periphery of the cells. Using a docking analysis, it was found that the nitazoxanide metabolite, tizoxanide was docked close to the ATP-binding region as well as in the exit tunnel, located in the transmembrane region.

CONCLUSION

These findings in Giardia intestinalis, support the possible role of ABC-C1 in drug efflux.

Socio-spatial organization reveals paternity and low kinship in the Honduran white bat (Ectophylla alba) in Costa Rica

Ectophylla alba is a tent-making bat that roosts in mixed-sex clusters comprising adults and offspring. Our goal was to determine the genetic identity of individuals belonging to different roosting groups. We tested the hypothesis of kin selection as a major force structuring group composition. We used 9 microsatellites designed for E. alba to determine the genetic identity and probability of parentage of individuals. We analyzed parentage and kinship using the software ML-Relate, GenAIEx, and Cervus. The obtained relationship probabilities (0.5) revealed a clear maternal relationship between female adults and offspring with allele compatibility, and at least 5 relationships between male adults and pups. We found a low degree of relatedness within roosting groups. Between roosting groups at different sites, the mean probability of a half-sibling relationship ranged from 0.214 to 0.244 and, for full-sibling relationship, from 0.383 to 0.553. Genetically, adult individuals were poorly related within clusters, and kinship as an evolutionary force could not explain group membership.

Rabeprazole inhibits several functions of Entamoeba histolytica related with its virulence

Amoebiasis is a human parasitic disease caused by Entamoeba histolytica. The parasite can invade the large intestine and other organs such as liver; resistance to the host tissue oxygen is a condition for parasite invasion and survival. Thioredoxin reductase of E. histolytica (EhTrxR) is a critical enzyme mainly involved in maintaining reduced the redox system and detoxifying the intracellular oxygen; therefore, it is necessary for E. histolytica survival under both aerobic in vitro and in vivo conditions. In the present work, it is reported that rabeprazole (Rb), a drug widely used to treat heartburn, was able to inhibit the EhTrxR recombinant enzyme. Moreover, Rb affected amoebic proliferation and several functions required for parasite virulence such as cytotoxicity, oxygen reduction to hydrogen peroxide, erythrophagocytosis, proteolysis, and oxygen and complement resistances. In addition, amoebic pre-incubation with sublethal Rb concentration (600 μM) promoted amoebic death during early liver infection in hamsters. Despite the high Rb concentration used to inhibit amoebic virulence, the wide E. histolytica pathogenic-related functions affected by Rb strongly suggest that its molecular structure can be used as scaffold to design new antiamoebic compounds with lower IC₅₀ values.

Prevalence of Human Papillomavirus in Women from the State of Michoacan, Mexico, Showed High Frequency of Unusual Virus Genotypes

BACKGROUND

Human papillomaviruses (HPVs), the leading cause of cervical cancer, are distributed worldwide, with high prevalence in developing countries.

OBJECTIVE

The objective of the study is to know the prevalence and genotypes of HPV in women from the state of Michoacán and the Women's Hospital in Morelia, Michoacán.

MATERIALS AND METHODS

Cervical smear samples (159,288) were subjected to HPV detection by hybrid capture 2. A subsample of 484 patients from the Women's Hospital was studied by Papanicolaou test and linear array HPV genotyping, and when positive, patients were also examined by colposcopy and histopathology.

RESULTS

The overall prevalence for HPV in Michoacán State was 7.74%; 7.11% in 2009, 6.46% in 2010, 9.58% in 2011, and 8.43% in 2012. The highest prevalence was found in the age groups < 25 and 25-34 years. The prevalence at the Women's Hospital was 8.51%. Cytological examination revealed normal cytology in 64.44% of samples, 26.66 % with low-grade and 8.88 % with high-grade squamous intraepithelial lesion (HSIL). However, by colposcopy, normal tissue appearance was found only in 26.66%; 51% were reclassified as low-grade squamous intraepithelial lesion, 17.77% as HSIL, and in 4.4% atrophy was observed. The most prevalent genotype in single infections was HPV59, followed by HPV51 and HPV45. Double infections occurred with the following genotypes: 52-53, 51-59, 61-67, 66-11, 16-62, 53-62, 59-CP6108, 45-66, and 45-51. Triple infections were identified as: 6-31-39, 51-59-62, 51-62-81, 54-55-59, 16-58-71, and 16-59-62.

CONCLUSIONS

The prevalent genotype found among women from Michoacán, HPV59, was different to the rest of the country. The high prevalence of HPV59 could be due to cases imported to Michoacán by agricultural workers migrating to the USA or may be associated to ethnicity differences. Implications of this finding for immunization programs should be explored.

Detection of Paragonimus mexicanus (Trematoda) metacercariae in crabs from Oaxaca, Mexico

Metacercariae of Paragonimus mexicanus were collected in crabs Tehuana guerreroensis (Rathbun, 1933) in the municipality of Putla, Oaxaca, Mexico. Metacercariae were found in 20.8% of the crabs collected, with an average of 1.9 metacercarie per crab. Stained metacercariae showed the specific characteristics of P. mexicanus by morphology and sequencing a fragment of the 28S ribosomal gene obtained by PCR. These findings reveal that T. guerreroensis is an intermediate host for P. mexicanus; this new report is relevant considering the potential risk of transmission in the states of Oaxaca and Guerrero, Mexico.

Protein synthesis factors (RF1, RF2, RF3, RRF, and tmRNA) and peptidyl-tRNA hydrolase rescue stalled ribosomes at sense codons

During translation, ribosomes stall on mRNA when the aminoacyl-tRNA to be read is not readily available. The stalled ribosomes are deleterious to the cell and should be rescued to maintain its viability. To investigate the contribution of some of the cellular translation factors on ribosome rescuing, we provoked stalling at AGA codons in mutants that affected the factors and then analyzed the accumulation of oligopeptidyl (peptides of up to 6 amino acid residues, oligopep-)-tRNA or polypeptidyl (peptides of more than 300 amino acids in length, polypep-)-tRNA associated with ribosomes. Stalling was achieved by starvation for aminoacyl-tRNA(Arg4) upon induced expression of engineered lacZ (β-galactosidase) reporter gene harboring contiguous AGA codons close to the initiation codon or at internal codon positions together with minigene ATGAGATAA accompanied by reduced peptidyl-tRNA hydrolase (Pth). Our results showed accumulations of peptidyl-tRNA associated with ribosomes in mutants for release factors (RF1, RF2, and RF3), ribosome recycling factor (RRF), Pth, and transfer-messenger RNA (tmRNA), implying that each of these factors cooperate in rescuing stalled ribosomes. The role of these factors in ribosome releasing from the stalled complex may vary depending on the length of the peptide in the peptidyl-tRNA. RF3 and RRF rescue stalled ribosomes by "drop-off" of peptidyl-tRNA, while RF1, RF2 (in the absence of termination codon), or Pth may rescue by hydrolyzing the associated peptidyl-tRNA. This is followed by the disassembly of the ribosomal complex of tRNA and mRNA by RRF and elongation factor G.

[The origin of the genetic variability of influenza viruses]

To better understand the significant variability displayed by influenza viruses, we need to be aware not only of its genetic characteristics, but also of the effect this genetic makeup has on proteins associated with viral replication and antigenicity. The origin of such diversity is due first and foremost to its segmented genome that allows segment reassortment (antigenic shift) and second to the error prone viral polymerase (antigenic drift) responsible of copying the genes enclosed in these segments. These two combined mechanisms confer a genetic plasticity that often leads to the emergence of new influenza viruses in nature.

Characterization of chaperonin 10 (Cpn10) from the intestinal human pathogen Entamoeba histolytica

Entamoeba histolytica is the causative agent of amoebiasis, a poverty-related disease that kills an estimated 100 000 people each year. E. histolytica does not contain "standard mitochondria", but harbours mitochondrial remnant organelles called mitosomes. These organelles are characterized by the presence of mitochondrial chaperonin Cpn60, but little else is known about the functions and molecular composition of mitosomes. In this study, a gene encoding molecular chaperonin Cpn10--the functional partner of Cpn60--was cloned, and its structure and expression were characterized, as well as the cellular localization of its encoded protein. The 5' untranslated region of the gene contains all of the structural promoter elements required for transcription in this organism. The amoebic Cpn10, like Cpn60, is not significantly upregulated upon heat-shock treatment. Computer-assisted protein modelling, and specific antibodies against Cpn10 and Cpn60, suggest that both proteins interact with each other, and that they function in the same intracellular compartment. Thus, E. histolytica appears to have retained at least two of the key molecular components required for the refolding of imported mitosomal proteins.

A novel ADP/ATP transporter in the mitosome of the microaerophilic human parasite Entamoeba histolytica

Recent data suggest that microaerophilic and parasitic protozoa, which lack oxidative phosphorylation, nevertheless contain mitochondrial homologs [1-6], organelles that share common ancestry with mitochondria. Such widespread retention suggests there may be a common function for mitochondrial homologs that makes them essential for eukaryotic cells. We determined the mitochondrial carrier family (MCF) complement of the Entamoeba histolytica mitochondrial homolog, also known as a crypton [5] or more commonly as a mitosome [3]. MCF proteins support mitochondrial metabolic energy generation, DNA replication, and amino-acid metabolism by linking biochemical pathways in the mitochondrial matrix with those in the cytosol [7]. MCF diversity thus closely mirrors important facets of mitochondrial metabolic diversity. The Entamoeba histolytica mitosome has lost all but a single type of MCF protein, which transports ATP and ADP via a novel mechanism that is not reliant on a membrane potential. Phylogenetic analyses confirm that the Entamoeba ADP/ATP carrier is distinct from archetypal mitochondrial ADP/ATP carriers, an observation that is supported by its different substrate and inhibitor specificity. Because many functions of yeast and human mitochondria rely on solutes transported by specialized members of this family, the Entamoeba mitosome must contain only a small subset of these processes requiring adenine nucleotide exchange.

Protein import, replication, and inheritance of a vestigial mitochondrion

Mitochondrial remnant organelles (mitosomes) that exist in a range of "amitochondrial" eukaryotic organisms represent ideal models for the study of mitochondrial evolution and for the establishment of the minimal set of proteins required for the biogenesis of an endosymbiosis-derived organelle. Giardia intestinalis, often described as the earliest branching eukaryote, contains double membrane-bounded structures involved in iron-sulfur cluster biosynthesis, an essential function of mitochondria. Here we present evidence that Giardia mitosomes also harbor Cpn60, mtHsp70, and ferredoxin and that despite their advanced state of reductive evolution they have retained vestiges of presequence-dependent and -independent protein import pathways akin to those that operate in mammalian mitochondria. Although import of IscU and ferredoxin is still reliant on their amino-terminal presequences, targeting of Giardia Cpn60, IscS, or mtHsp70 into mitosomes no longer requires cleavable presequences, a derived feature from their mitochondrial homologues. In addition, we found that division and segregation of a single centrally positioned mitosome tightly associated with the microtubular cytoskeleton is coordinated with the cell cycle, whereas peripherally located mitosomes are inherited into daughter cells stochastically.

Mitosomes of Entamoeba histolytica are abundant mitochondrion-related remnant organelles that lack a detectable organellar genome

The existence of mitochondrion-related relict organelles (mitosomes) in the amitochondrial human pathogen Entamoeba histolytica and the detection of extranuclear DNA-containing cytoplasmic structures (EhKOs) has led to the suggestion that a remnant genome from the original mitochondrial endosymbiont might have been retained in this organism. This study reports on the mutually exclusive distribution of Cpn60 and extranuclear DNA in E. histolytica and on the distribution of Cpn60-containing mitosomes in this parasite. In situ nick-translation coupled to immunofluorescence microscopy failed to detect the presence of DNA in mitosomes, either in fixed parasite trophozoites or in partially purified organellar fractions. These results indicate that a remnant organellar genome has not been retained in E. histolytica mitosomes and demonstrate unequivocally that EhKOs and mitosomes are distinct and unrelated cellular structures.

Mitochondrial remnant organelles of Giardia function in iron-sulphur protein maturation

Giardia intestinalis (syn. lamblia) is one of the most widespread intestinal protozoan pathogens worldwide, causing hundreds of thousands of cases of diarrhoea each year. Giardia is a member of the diplomonads, often described as an ancient protist group whose primitive nature is suggested by the lack of typical eukaryotic organelles (for example, mitochondria, peroxisomes), the presence of a poorly developed endomembrane system and by their early branching in a number of gene phylogenies. The discovery of nuclear genes of putative mitochondrial ancestry in Giardia and the recent identification of mitochondrial remnant organelles in amitochondrial protists such as Entamoeba histolytica and Trachipleistophora hominis suggest that the eukaryotic amitochondrial state is not a primitive condition but is rather the result of reductive evolution. Using an in vitro protein reconstitution assay and specific antibodies against IscS and IscU--two mitochondrial marker proteins involved in iron-sulphur cluster biosynthesis--here we demonstrate that Giardia contains mitochondrial remnant organelles (mitosomes) bounded by double membranes that function in iron-sulphur protein maturation. Our results indicate that Giardia is not primitively amitochondrial and that it has retained a functional organelle derived from the original mitochondrial endosymbiont.

Dystrophin isoform Dp7l is present in lamellipodia and focal complexes in human astrocytoma cells U-373 MG

Dp71 is the most abundant product of the dmd gene in the brain. There are at least 2 isoforms derived from alternative splicing of exon 78 (Dp71d, which contains exon 78 and Dp71f, the spliced isoform) but the precise localization and function of each isoform is still unknown. In the present study, we demonstrate by RT-PCR that the Dp71f isoform is present in an astrocytoma cell line U-373 MG, and its subcellular localization was determined in the cytoplasm, particularly in perinuclear areas, with lower amounts towards the periphery but increasing in the leader borders of lamellipodia and focal complexes. Double labeling indirect immunofluorescence showed that Dp71f colocalized with actin-like beta-dystroglycan and beta-1 integrin. We also demonstrated by triple labeling that Dp71f was colocalized with actin and two members of integrin complexes, alpha-actinin and vinculin, in focal complexes. Ventral plasma membranes were enriched and in those containing focal complex proteins, we found colocalization of Dp71f, actin and vinculin. It is concluded that U-373 MG cells express Dp71f as part of lamellipodia and focal complex proteins, and possibly connected via distroglycan complexes to integrin complexes.