Depletion of Human Papilloma Virus E6- and E7-Oncoprotein-Specific T-Cell Responses in Women Living With HIV

Background: Cervical cancer - caused by persistent High Risk Human Papilloma Virus (HR HPV) infections - is the second most common cancer affecting women globally. HIV infection increases the risk for HPV persistence, associated disease progression and malignant cell transformation. We therefore hypothesized that this risk increase is directly linked to HIV infection associated dysfunction or depletion of HPV-oncoprotein-specific T-cell responses. Methods: The 2H study specifically included HIV+ and HIV- women with and without cervical lesions and cancer to analyze HPV oncogene-specific T cell responses in relation to HPV infection, cervical lesion status and HIV status. Oncoprotein E6 and E7 specific T-cell responses were quantified for the most relevant types HPV16, 18 and 45 and control antigens (CMV-pp65) and M.tb-PPD in 373 women, using fresh peripheral blood mononuclear cells in an IFN-γ release ELISpot assay. Results: Overall, systemic E6- and E7-oncoprotein-specific T-cell responses were infrequent and of low magnitude, when compared to CMV-pp65 and M.tb-PPD (p < 0.001 for all HR HPV types). Within HIV negative women infected with either HPV16, 18 or 45, HPV16 infected women had lowest frequency of autologous-type-E6/E7-specific T-cell responses (33%, 16/49), as compared to HPV18 (46% (6/13), p = 0.516) and HPV45 (69% (9/13), p = 0.026) infected women. Prevalent HPV18 and 45, but not HPV16 infections were linked to detectable oncoprotein-specific T-cell responses, and for these infections, HIV infection significantly diminished T-cell responses targeting the autologous infecting genotype. Within women living with HIV, low CD4 T-cell counts, detectable HIV viremia as well as cancerous and precancerous lesions were significantly associated with depletion of HPV oncoprotein-specific T-cell responses. Discussion: Depletion of HPV-oncoprotein-specific T-cell responses likely contributes to the increased risk for HR HPV persistence and associated cancerogenesis in women living with HIV. The low inherent immunogenicity of HPV16 oncoproteins may contribute to the exceptional potential for cancerogenesis associated with HPV16 infections

gfp-Based N-Acyl Homoserine-...

stem functions via small, diffusible N-acyl homoserine lactone (AHL) signal molecules. The signals are synthesized from precursors by a synthase protein, &quot;I,&quot; and once they have reached a certain threshold concentration, they interact with a transcriptional activating &quot;R&quot; protein to induce expression of different target genes (for reviews see references 11, 13, and 43). Such regulatory systems operate as a quorum-sensing mechanism that allows bacteria to sense and express target genes in relation to their cell density. Several methods to detect the presence of AHL have been described. AHLs can be extracted from liquid cultures, purified to homogeneity by semipreparative high-performance liquid chromatography (HPLC), and identified by mass spectrometry and H nuclear magnetic resonance (NMR) spectroscopy (10). A number of bacterial sensor systems such as the pigment -developing Chromobacterium violaceum (30) and luxAB- and lacZ-based systems have been described (36, 50). Bioluminesce

Use of green fluorescent protein for online, single cell detection of bacteria introduced into activated sludge microcosms

A derivative of broad host-range plasmid RP4 was tagged with the green fluorescent protein (GFP) and this construct was used to mark various Gram-negative bacteria. Video recording of combined phase contrast and epifluorescence microscopy was employed to track the fate of individual marked cells after introduction into a sludge microcosm. Whether the introduced bacteria were laboratory strains or activated sludge isolates. they were found to be rapidly eliminated from the microcosms as a result of intense predation by protozoa. Furthermore, a method was developed that allows detection of GFP-tagged bacteria in fixed samples that are simultaneously used for in situ hybridisation with a eukaryote-specific rRNA-targeted oligonucleotide probe for visualisation of protozoa