Identifying and validating the presence of Guanine-Quadruplexes (G4) within the blood fluke parasite Schistosoma mansoni

Schistosomiasis is a neglected tropical disease that currently affects over 250 million individuals worldwide. In the absence of an immunoprophylactic vaccine and the recognition that mono-chemotherapeutic control of schistosomiasis by praziquantel has limitations, new strategies for managing disease burden are urgently needed. A better understanding of schistosome biology could identify previously undocumented areas suitable for the development of novel interventions. Here, for the first time, we detail the presence of G-quadruplexes (G4) and putative quadruplex forming sequences (PQS) within the Schistosoma mansoni genome. We find that G4 are present in both intragenic and intergenic regions of the seven autosomes as well as the sex-defining allosome pair. Amongst intragenic regions, G4 are particularly enriched in 3´ UTR regions. Gene Ontology (GO) term analysis evidenced significant G4 enrichment in the wnt signalling pathway (p<0.05) and PQS oligonucleotides synthetically derived from wnt-related genes resolve into parallel and anti-parallel G4 motifs as elucidated by circular dichroism (CD) spectroscopy. Finally, utilising a single chain anti-G4 antibody called BG4, we confirm the in situ presence of G4 within both adult female and male worm nuclei. These results collectively suggest that G4-targeted compounds could be tested as novel anthelmintic agents and highlights the possibility that G4-stabilizing molecules could be progressed as candidates for the treatment of schistosomiasis.

Lack of evidence for vertical transmission of SAV 3 using gametes of Atlantic salmon, Salmo salar L., exposed by natural and experimental routes

Pancreas disease (PD) is an important cause of losses in farmed salmonids in Norway, the United Kingdom and Ireland. As the spread of salmonid alphavirus (SAV), the causal agent, to naïve populations is of major concern to the farming industry, it is important to uncover the transmission routes of the virus. This study was conducted to investigate the potential for vertical transmission of SAV subtype 3. Progeny of broodstock with signs of late-stage PD and persistent RT-PCR signals for SAV were followed from fertilization to smoltification in an experimental facility. Fertilized ova were either not disinfected or taken through one of three different disinfection regimes. Also, ova and milt from uninfected broodfish from a different population were exposed to a cell-cultured strain of SAV 3 immediately before fertilization to simulate a viraemic phase in parent fish. A group of uninfected controls were also included in the study. Fertilized ova from bath exposed and negative control groups were double disinfected. Following fertilization, experimental fish went through a normal freshwater phase. However, fry were stressed at first feeding to enhance replication of possibly latent virus. Smoltification was induced by an artificial light regime, and experimental fish were followed to the late smoltification phase. Selected samples were investigated by real-time RT-PCR for SAV, by histology for evidence of PD and by serology for neutralising antibodies against SAV. All analysed samples of progeny were negative. This result shows that SAV 3 is not readily transmitted vertically from parents to offspring. Additional negative PCR results from salmon sampled in commercial hatcheries support these findings. Also, recent studies have shown that risk factors for the horizontal transmission route explain the vast majority of PD outbreaks in Norway. It is concluded that if it happens at all, vertical transmission is of minor importance in the spread of SAV 3.

Aquatic birnavirus infection activates the transcription factor NF-kappaB via tyrosine kinase signalling leading to cell death

Our previous studies found that infectious pancreatic necrosis virus (IPNV) induces host apoptotic cell death, possibly through a newly synthesized protein trigger. Here, we examine whether IPNV infection can induce NF-kappaB activation through tyrosine kinase signalling of CHSE-214 cell death (host cell death). Using the electrophoretic mobility shift assay (EMSA) to detect transcription factor activation, we found that NF-kappaB is apparently activated 6-8 h post-IPNV infection. Using genistein (100 microg mL(-1); a tyrosine kinase inhibitor) to determine whether NF-kappaB activation requires tyrosine kinase activation, we found genistein blocks NF-kappaB activation at 8 h post-infection (p.i), and either enhances cell viability up to 50% at 12 h p.i. or blocks DNA fragmentation at 24 h p.i. Furthermore, the proteasome inhibitors PSI-I and PSI-II (both at 40 microm) also effectively blocked the NF-kappaB activation as well as stimulating a 30% increase in cell viability (30% decrease in apoptosis) at 8 and 12 h p.i. Taken together our data suggest that IPNV may induce NF-kappaB activation through tyrosine kinase signalling, which may be associated with induction of apoptosis.

A stable isotope-mass spectrometric method for measuring human spermatogenesis kinetics in vivo

PURPOSE

Currently it is thought to take 60 to 70 days to produce and ejaculate human sperm. This estimate is derived mainly from a single older, descriptive, kinetic analysis of spermatogenesis. We developed a noninvasive method to assess germ cell turnover time accurately in vivo using stable isotope labeling and gas chromatography/mass spectrometry analyses. We confirmed the postulated length of a normal cycle of spermatogenesis.

MATERIALS AND METHODS

A total of 11 men with normal sperm concentrations ingested (2)H(2)O daily for 3 weeks. Semen samples were collected every 2 weeks for up to 90 days. Label incorporation into sperm DNA was quantified by gas chromatography/mass spectrometry, allowing calculation of the percent of new cells present. A cycle of sperm production was determined as the lag time until labeled sperm appeared in the ejaculate.

RESULTS

Labeled sperm were detected after a mean +/- SD of 64 +/- 8 days (range 42 to 76). In 1 subject the time lag was 42 days but it was at least 60 in all other subjects. In most subjects plateau labeling in sperm was not attained. In 2 subjects the rise and fall of the labeling curve was steep and reached greater than 85% new cells, suggesting rapid washout of old sperm in the epididymal reservoir.

CONCLUSIONS

This direct kinetic assessment confirms a course of spermatogenesis that is on the shorter side of traditional estimates based on prior analyses. In addition, the variability observed in healthy men suggests that characteristics such as the epididymal reservoir effect may influence the modeling of in vivo spermatogenesis.

Development of a subunit vaccine for infectious pancreatic necrosis virus using a baculovirus insect/larvae system

Various attempts to develop a vaccine against infectious pancreatic necrosis virus (IPNV) have not yielded consistent results. Thus, at present, no commercial vaccine is available that can be used with confidence to immunize fry of salmon and trout. We generated a cDNA clone of the large genome segment A of an IPNV Sp strain and expressed all structural protein genes in insect cells and larvae using a baculovirus expression system. Green fluorescent protein was also coexpressed as a reporter molecule. High yields of IPNV proteins were obtained and the structural proteins self assembled to form virus-like particles (VLPs). We tested the immunogenicity of the putative VLP antigen in immersion vaccine experiments (two concentrations) in rainbow trout (Oncorhynchus mykiss) fry, and by intraperitoneal immunisation of Atlantic salmon (Salmo salar) pre-smolts using an oil adjuvant formulation. Rainbow trout were challenged by immersion using either the Sp or the VR-299 strain of IPNV two or three weeks post-vaccination, while Atlantic salmon were bath challenged with Sp strain after two months, after parr-smolt transformation. In the rainbow trout fry challenged two weeks post-immunization, cumulative mortality rates three weeks post challenge were 14 % in the fry that had received the highest dose versus 8 % in the control groups. No indication of protection was seen in repeated trials using a lower dose of antigen and challenge three weeks post-immunisation. The cumulative mortality rate of intraperitoneally immunised Atlantic salmon post-smolts four weeks post challenge was lower (56%) than in the control fish (77%), showing a dose-response pattern.

[Characterization of fatty acids and mycolic acid degradation products in mycobacterial species of major incidence in Argentina]

The human immunodeficiency virus (HIV) epidemic has altered the epidemiological profile of tuberculosis in both industrialized and developing countries. Serious diseases caused by mycobacteria other that M. tuberculosis, mostly belonging to the M. avium-intracellulare complex (MAC), have become very common in association with severe immunosuppression. The increase in mycobacterial disease complexity has stimulated the development of more rapid and efficient methods of diagnosis. In the present study we characterized the cellular fatty acids and the mycolic acid cleavage product from most frequent mycobacteria species in Argentina using gas chromatography in order to develop a rapid technique for their identification. Fatty acids and mycolic acids extracted from saponified mycobacterial cells were examined as methyl esters by capillary has chromatography. The major constituent fatty acids in all species, with the exception of M. smegmatis, were octadecenoic (18:1) and hexadecanoic (16:1) acids. The fatty acids and mycolic acid cleavage product profiles from the studied species were quantitatively but not qualitatively different. Tuberculostearic acid was found in all species. Significantly different amounts of some fatty acids (p < 0.01) were observed among clinical isolates of M. tuberculosis, M. bovis and MAC. Traces of 2-eicosanol were detected in the M. tuberculosis H37Rv strain. Although a limited number of strains and species were tested, preliminary results indicate that this method could be used to characterize mycobacterial cultures.