RESUMO
BACKGROUND: Currently, widespread HIV testing is the best preventive action against further spread of the HIV epidemic. However, over 40% of the U.S. population has never been tested for HIV and 25% of those with HIV have never been tested. To increase testing rates, in 2006 the CDC advised healthcare settings to conduct testing on an opt-out basis. METHODS: Qualitative, semi-structured interviews with ten seropositive patients and ten seronegative were conducted to address the lack of studies investigating patients' acceptance of and attitude towards this and more novel testing models, e.g. incentivized or anonymous mandatory testing. Participants were asked about their HIV testing history and attitudes towards opt-out, incentivized, and mandatory anonymous HIV testing. RESULTS: Major themes were identified using grounded theory data analysis. All participants were receptive to opt-out testing, and saw the removal of separate written consent as beneficial as long as patients were given the opportunity to consent in some form. CONCLUSION: Ultimately, both mandatory and opt-out testing were equally indicated by participants as being the most effective testing model at increasing testing rates. A firm understanding of patients' perspectives allows for development of effective HIV testing initiatives that are patient-sensitive and can substantially reduce HIV infection rates.
RESUMO
Trypanosoma cruzi, a blood-borne parasite, is the etiological agent of Chagas disease. T. cruzi trypomastigotes, the infectious life cycle stage, can be detected in blood of infected individuals using PCR-based methods. However, soon after a natural infection, or during the chronic phase of Chagas disease, the number of parasites in blood may be very low and thus difficult to detect by PCR. To facilitate PCR-based detection methods, a parasite concentration approach was explored. A whole cell SELEX strategy was utilized to develop serum stable RNA aptamers that bind to live T. cruzi trypomastigotes. These aptamers bound to the parasite with high affinities (8-25 nM range). The highest affinity aptamer, Apt68, also demonstrated high specificity as it did not interact with the insect stage epimastigotes of T. cruzi nor with other related trypanosomatid parasites, L. donovani and T. brucei, suggesting that the target of Apt68 was expressed only on T. cruzi trypomastigotes. Biotinylated Apt68, immobilized on a solid phase, was able to capture live parasites. These captured parasites were visible microscopically, as large motile aggregates, formed when the aptamer coated paramagnetic beads bound to the surface of the trypomastigotes. Additionally, Apt68 was also able to capture and aggregate trypomastigotes from several isolates of the two major genotypes of the parasite. Using a magnet, these parasite-bead aggregates could be purified from parasite-spiked whole blood samples, even at concentrations as low as 5 parasites in 15 ml of whole blood, as detected by a real-time PCR assay. Our results show that aptamers can be used as pathogen specific ligands to capture and facilitate PCR-based detection of T. cruzi in blood.