UBIQUITIN OF Entamoeba histolytica INDUCE ANTIBODY RESPONSE IN PATIENTS WITH INVASIVE AMOEBIASIS

Entamoeba histolytica causes amoebic liver abscess (ALA) in humans. The injury of target cells by Entamoeba histolytica includes processes controlled by the ubiquitin Ehub. Previously, we found immunodominance of Ehub glycan moieties using immunized rabbits. In this work, we analyzed dominance of antibodies to the glycoprotein Ehub in the sera from 52 patients with ALA. Controls were sera from 20 healthy people living in endemic areas with high seroprevalence of antibodies to amoebas, and 20 patients with alcoholic hepatitis (AH) to rule out the cross-reaction of Ehub with autoantibodies induced by liver damage. Antigens were trophozoite extract, glycoprotein Ehub and the recombinant protein rEhub. The sera from healthy volunteers and patients with AH do not have antibodies to glycoprotein Ehub. Surprisingly, only the antibodies from patients with ALA recognized the glycoprotein Ehub, and some sera gave a faint reaction with the recombinant protein, especially because evolutionarily, the ubiquitin is conserved between species. This is the first report demonstrating that antibodies to ubiquitin Ehub are induced exclusively in patients with invasive amoebiasis, and the antibody response is mainly to the glycoprotein, indicating glycans are immunodominant. Inhibitors of the Ehub glycans could be potential treatment for amoebiasis by selectively damaging trophozoites. This article is protected by copyright. All rights reserved.

Glycan moieties in Entamoeba histolytica ubiquitin are immunodominant

The ubiquitin-proteasome system plays a central role performing several functions to maintain parasite homeostasis. We have reported the partial characterization of N-linked glycosylation profile in E. histolytica ubiquitin (EhUb). Here we examined the immunogenicity and antigenicity of carbohydrates in EhUbiquitin. Rabbits were immunized with purified EhUbiquitin or purified recombinant rUb expressed by E. coli. Using Western Blot, we explored the immunogenicity and antigenicity of protein portion and carbohydrates moiety. Interestingly, immunized rabbits produced antibodies to both Ub glycoprotein and rUb; but antibodies against carbohydrates were immunodominant, rather than antibodies to the protein moiety of EhUbiquitin. In addition, we observed that antibodies to protein moiety are not conserved in serum unless antigen is continually administrated. Conversely, anti-Ub glycoprotein antibodies are well maintained in circulation. In humans, infection with Entamoeba histolytica induces strong IgG anti-Ub response. The human antibodies recognize both, the protein moieties and the glycosylated structure. Entamoeba histolytica ubiquitin is immunogenic and antigenic. The glycan moieties are immunodominant and induces IgG. These data open the door to use carbohydrates as potential targets for diagnose tests, drugs and vaccine to prevent this parasitic disease.

Expression of DC-SIGN in peripheral blood dendritic cells of patients with typical, slow, and rapid progression to AIDS

The main access route for human immunodeficiency virus (HIV) into the lymph nodes is through the mucosa. Once there, dendritic cells (DCs) are the first cells to interact with the virus. Then, DCs can uptake and transport to the lymph nodes, beginning a disseminated infection. Interaction between the virus and DCs is mediated by the receptor DC-SIGN. This study seeks to determine any relationship between HIV-AIDS immunopathology and DC-SIGN expression levels in DCs from typical, rapid, and slow progressors. A DC separation system was implemented using peripheral blood mononuclear cells from infected subjects. The study included 27 patients classified as typical, rapid, and slow progressors according to their clinical and epidemiological files. Finally, quantification of DC-SIGN was achieved by real-time PCR and by applying the Relative Quantification Scheme (DeltaDeltaCt). We isolated DCs from peripheral blood of 27 HIV-infected patients. Nineteen were considered as typical progressors, five as slow progressors, and three as rapid progressors. No significant differences were observed on the expression levels of DC-SIGN among the three groups of patients. Even if there are differences in expression levels among the analyzed patients, we did not find any significant differences in DC-SIGN expression among the three included groups. We therefore cannot conclude that the expression level of the receptor is related with the progression to AIDS.

Antiviral therapy: inhibition of Hepatitis C Virus expression by RNA interference directed against the NS5B region of the viral genome

BACKGROUND

Hepatitis C virus (HCV) is a major public health problem with 170 million chronically infected people throughout the world. Currently, the only treatment available consists of a combination of pegylated interferon (INF-alpha) and ribavirin, but only half of the patients treated show a sufficient antiviral response. Thus there is a great need for the development of new treatments for HCV infections. RNA interference (RNAi) represents a new promising approach to develop effective antiviral drugs and has been extremely effective against HCV gene expression in short-term cell culture. Our aim was to determine the effect of RNAi directed against the NS5B-HCV region on HCV expression in a human hepatoma cell line that expresses HCV-subgenomic replicon (Huh7 HCV replicon cells).

METHODS

We transfected Huh7 HCV replicon cells with different concentrations of RNAi (100-200 nM) targeting the NS5B region of the viral genome. 2-6 days post-transfection HCV-RNA was quantified by semiquantitative and real-time RT-PCR, and HCV NS5B protein levels were assayed by western blot. Cell viability was also quantified by MTT assay.

RESULTS

Our results indicate that the NS5B-siRNAs used in this study can specifically inhibit HCV-RNA replication and protein expression (more than 90%) compared to control cells.

CONCLUSIONS

Synthetic siRNA against NS5BHCV inhibited HCV replication and viral proteins levels and thereby becomes a powerful strategy to combat hepatitis C virus.

Mouse mammary tumor virus-like gene sequences in breast cancer samples of Mexican women

BACKGROUND

Previous reports related the presence of mouse mammary tumor virus (MMTV)-like gene sequences to human breast carcinoma. The aim of this study was to determine whether MMTV-like env gene sequences are present in breast cancer samples of Mexican women and in breast and lung cancer cell lines.

METHODS

Using specific primers for MMTV, we tested 3 breast cancer cell lines, 4 non-small lung cancer cell lines and 119 breast cancer samples from Mexican women.

RESULTS

MMTV-like gene sequences were amplified in the lung cancer cell INER-51, but not in the MCF-7 cell line that has been used as a positive control in other reports and in 5 of 119 (4.2%) breast cancer biopsy tissues. Furthermore, the identity of sequences of PCR products from INER-51 and a breast cancer-positive sample are 98 and 99% when compared with the env region of MMTV (GenBank accession No. AY161347).

CONCLUSION

These results indicate that MMTV-like gene sequences are present in the Mexican population.

High affinity binding of the large T protein of polyoma virus to a genomic mouse DNA sequence

We purified a fragment of mouse DNA to which the large T protein of polyoma virus was bound in chromatin prepared from transformed mouse cells. This sequence, which is not repeated to a measurable extent within the mouse genome, does not show any significant homology to the viral ori region, except in a short region, which comprises a sequence related to the consensus for recognition by large T proteins ((A,T)GPuGGC). This region of pCG4 was confirmed by in vitro binding assays to be essential for T antigen binding.