Defining the Range of Pathogens Susceptible to Ifitm3 Restriction Using a Knockout Mouse Model

The interferon-inducible transmembrane (IFITM) family of proteins has been shown to restrict a broad range of viruses in vitro and in vivo by halting progress through the late endosomal pathway. Further, single nucleotide polymorphisms (SNPs) in its sequence have been linked with risk of developing severe influenza virus infections in humans. The number of viruses restricted by this host protein has continued to grow since it was first demonstrated as playing an antiviral role; all of which enter cells via the endosomal pathway. We therefore sought to test the limits of antimicrobial restriction by Ifitm3 using a knockout mouse model. We showed that Ifitm3 does not impact on the restriction or pathogenesis of bacterial (Salmonella typhimurium, Citrobacter rodentium, Mycobacterium tuberculosis) or protozoan (Plasmodium berghei) pathogens, despite in vitro evidence. However, Ifitm3 is capable of restricting respiratory syncytial virus (RSV) in vivo either through directly restricting RSV cell infection, or by exerting a previously uncharacterised function controlling disease pathogenesis. This represents the first demonstration of a virus that enters directly through the plasma membrane, without the need for the endosomal pathway, being restricted by the IFITM family; therefore further defining the role of these antiviral proteins.     

Schistosoma japonicum Soluble Egg Antigens Attenuate Invasion in a First Trimester Human Placental Trophoblast Model

Background

Schistosomiasis affects nearly 40 million women of reproductive age, and is known to elicit a pro-inflammatory signature in the placenta. We have previously shown that antigens from schistosome eggs can elicit pro-inflammatory cytokine production from trophoblast cells specifically; however, the influence of these antigens on other characteristics of trophoblast function, particularly as it pertains to placentation in early gestation, is unknown. We therefore sought to determine the impact of schistosome antigens on key characteristics of first trimester trophoblast cells, including migration and invasion.

Methods

First trimester HTR8/SVneo trophoblast cells were co-cultured with plasma from pregnant women with and without schistosomiasis or schistosome soluble egg antigens (SEA) and measured cytokine, cellular migration, and invasion responses.

Results

Exposure of HTR8 cells to SEA resulted in a pro-inflammatory, anti-invasive signature, characterized by increased pro-inflammatory cytokines (IL-6, IL-8, MCP-1) and TIMP-1. Additionally, these cells displayed 62% decreased migration and 2.7-fold decreased invasion in vitro after treatment with SEA. These results are supported by increased IL-6 and IL-8 in the culture media of HTR8 cells exposed to plasma from Schistosoma japonica infected pregnant women.

Conclusions

Soluble egg antigens found in circulation during schistosome infection increase pro-inflammatory cytokine production and inhibit the mobility and invasive characteristics of the first trimester HTR8/SVneo trophoblast cell line. This is the first study to assess the impact of schistosome soluble egg antigens on the behavior of an extravillous trophoblast model and suggests that schistosomiasis in the pre-pregnancy period may adversely impact placentation and the subsequent health of the mother and newborn.     

Mycobacterium ulcerans Disease: Experience with Primary Oral Medical Therapy in an Australian Cohort

Background

Mycobacterium ulcerans (MU) is responsible for disfiguring skin lesions and is endemic on the Bellarine peninsula of southeastern Australia. Antibiotics have been shown to be highly effective in sterilizing lesions and preventing disease recurrences when used alone or in combination with surgery. Our practice has evolved to using primarily oral medical therapy.

Methods

From a prospective cohort of MU patients managed at Barwon Health, we describe those treated with primary medical therapy defined as treatment of a M. ulcerans lesion with antimicrobials either alone or in conjunction with limited surgical debridement.

Results

From 1/10/2010 through 31/12/11, 43 patients were treated with exclusive medical therapy, of which 5 (12%) also underwent limited surgical debridement. The median patient age was 50.2 years, and 86% had WHO category 1 and 91% ulcerative lesions. Rifampicin was combined with ciprofloxacin in 30 (70%) and clarithromycin in 12 (28%) patients. The median duration of antibiotic therapy was 56 days, with 7 (16%) receiving less than 56 days. Medication side effects requiring cessation of one or more antibiotics occurred in 7 (16%) patients. Forty-two (98%) patients healed without recurrence within 12 months, and 1 patient (2%) experienced a relapse 4 months after completion of 8 weeks of antimicrobial therapy.

Conclusion

Our experience demonstrates the efficacy and safety of primary oral medical management of MU infection with oral rifampicin-based regimens. Further research is required to determine the optimal and minimum durations of antibiotic therapy, and the most effective antibiotic dosages and formulations for young children.     

Speed of Human Biological Form and Motion Processing

Recent work suggests that biological motion processing can begin within ~110 ms of stimulus onset, as indexed by the P1 component of the event-related potential (ERP). Here, we investigated whether modulation of the P1 component reflects configural processing alone, rather than the processing of both configuration and motion cues. A three-stimulus oddball task was employed to evaluate bottom-up processing of biological motion. Intact point-light walkers (PLWs) or scrambled PLWs served as distractor stimuli, whereas point-light displays of tool motion served as standard and target stimuli. In a second experiment, the same design was used, but the dynamic stimuli were replaced with static point-light displays. The first experiment revealed that dynamic PLWs elicited a larger P1 as compared to scrambled PLWs. A similar P1 increase was also observed for static PLWs in the second experiment, indicating that these stimuli were more salient than static, scrambled PLWs. These findings suggest that the visual system can rapidly extract global form information from static PLWs and that the observed P1 effect for dynamic PLWs is not dependent on the presence of motion cues. Finally, we found that the N1 component was sensitive to dynamic, but not static, PLWs, suggesting that this component reflects the processing of both form and motion information. The sensitivity of P1 to static PLWs has implications for dynamic form models of biological motion processing that posit temporal integration of configural cues present in individual frames of PLW animations.     

Late Diagnosis and Entry to Care after Diagnosis of Human Immunodeficiency Virus Infection: A Country Comparison

Background

Testing for HIV infection and entry to care are the first steps in the continuum of care that benefit individual health and may reduce onward transmission of HIV. We determined the percentage of people with HIV who were diagnosed late and the percentage linked into care overall and by demographic and risk characteristics by country.

Methods

Data were analyzed from national HIV surveillance systems. Six countries, where available, provided data on two late diagnosis indicators (AIDS diagnosis within 3 months of HIV diagnosis, and AIDS diagnosis within 12 months before HIV diagnosis) and linkage to care (≥1 CD4 or viral load test result within 3 months of HIV diagnosis) for people diagnosed with HIV in 2009 or 2010 (most recent year data were available).

Principal Findings

The percentage of people presenting with late stage disease at HIV diagnosis varied by country, overall with a range from 28.7% (United States) to 8.8% (Canada), and by transmission categories. The percentage of people diagnosed with AIDS who had their initial HIV diagnosis within 12 months before AIDS diagnosis varied little among countries, except the percentages were somewhat lower in Spain and the United States. Overall, the majority of people diagnosed with HIV were linked to HIV care within 3 months of diagnosis (more than 70%), but varied by age and transmission category.

Conclusions

Differences in patterns of late presentation at HIV diagnosis among countries may reflect differences in screening practices by providers, public health agencies, and people with HIV. The percentage of people who received assessments of immune status and viral load within 3 months of diagnosis was generally high.     

A Small Molecule Inhibitor of Polycomb Repressive Complex 1 Inhibits Ubiquitin Signaling at DNA Double-strand Breaks

Polycomb-repressive complex 1 (PRC1)-mediated histone ubiquitylation plays an important role in aberrant gene silencing in human cancers and is a potential target for cancer therapy. Here we show that 2-pyridine-3-yl-methylene-indan-1,3-dione (PRT4165) is a potent inhibitor of PRC1-mediated H2A ubiquitylation in vivo and in vitro. The drug also inhibits the accumulation of all detectable ubiquitin at sites of DNA double-strand breaks (DSBs), the retention of several DNA damage response proteins in foci that form around DSBs, and the repair of the DSBs. In vitro E3 ubiquitin ligase activity assays revealed that PRT4165 inhibits both RNF2 and RING 1A, which are partially redundant paralogues that together account for the E3 ubiquitin ligase activity found in PRC1 complexes, but not RNF8 nor RNF168. Because ubiquitylation is completely inhibited despite the efficient recruitment of RNF8 to DSBs, our results suggest that PRC1-mediated monoubiquitylation is required for subsequent RNF8- and/or RNF168-mediated polyubiquitylation. Our results demonstrate the unique feature of PRT4165 as a novel chromatin-remodeling compound and provide a new tool for the inhibition of ubiquitylation signaling at DNA double-strand breaks.