Prebiotic chemicals-amino acid and phosphorus-in the coma of comet 67P/Churyumov-Gerasimenko.

The importance of comets for the origin of life on Earth has been advocated for many decades. Amino acids are key ingredients in chemistry, leading to life as we know it. Many primitive meteorites contain amino acids, and it is generally believed that these are formed by aqueous alterations. In the collector aerogel and foil samples of the Stardust mission after the flyby at comet Wild 2, the simplest form of amino acids, glycine, has been found together with precursor molecules methylamine and ethylamine. Because of contamination issues of the samples, a cometary origin was deduced from the (13)C isotopic signature. We report the presence of volatile glycine accompanied by methylamine and ethylamine in the coma of 67P/Churyumov-Gerasimenko measured by the ROSINA (Rosetta Orbiter Spectrometer for Ion and Neutral Analysis) mass spectrometer, confirming the Stardust results. Together with the detection of phosphorus and a multitude of organic molecules, this result demonstrates that comets could have played a crucial role in the emergence of life on Earth.

Hepatitis C virus window-phase infections: closing the window on hepatitis C virus.

BACKGROUND: The detection of hepatitis C virus (HCV) infection is of major importance for the prevention of transfusion-transmitted hepatitis. The testing of donations by nucleic acid testing (NAT) techniques may not be feasible or economic. Combined antigen and antibody assays are now available, and the performance of two combined assays on window-phase donations is evaluated. STUDY DESIGN AND METHODS: Three panels of antibody-negative plasma samples from HCV NAT-only-positive donors were characterized for HCV status by quantitative reverse transcription-polymerase chain reaction, a commercial third-generation HCV antibody assay (Ortho), and combined antigen and antibody assays (Bio-Rad MONOLISA and Murex). RESULTS: All 142 plasma samples were antibody negative by Ortho third-generation HCV. A total of 112 samples (79%) were found to contain HCV RNA; 32 were detected by the Bio-Rad assay (29%), whereas 56 (50%) were detected by the Murex assay. Of 45 samples with viral loads of greater than 10(6), 32 (71%) were positive in the Bio-Rad combination assay and 44 (98%) were positive in the Murex assay. Interestingly none of the 3a genotypes were detected by the Bio-Rad MONOLISA, including eight donations that were greater than 10(6) IU per mL. CONCLUSIONS: Combined antigen and antibody testing provides a useful improvement on the sole reliance on antibody testing for detection of HCV infection; however, it remains less sensitive than NAT for detecting viremic donors and may be genotype susceptible.