Wilke: Difference between revisions

[[Image:Wilke_newsicon_09162009.png|left|150px]] Even though highly active antiretroviral therapy (HAART) can reduce HIV-1 virus load to clinically undetectable levels, the virus never completely disappears and ultrasensitive assays can detect small quantities of virus in all patients on HAART. The exact origin of this virus is unknown. Many researchers assume that it is produced by latently infected CD4+ T cells that reactivate. We analyzed HIV-1 sequences isolated from resting CD4+ T cells, activated CD4+ T cells, and blood plasma using a population-genetics approach. Our analysis showed that sequences from resting and activated CD4+ T cells formed a single population, whereas some of the virus in the blood plasma seemed genetically distinct from the virus in CD4+ T cells. This result shows that circulating CD4+ T cells are not the only source of residual viremia, and it suggests that a novel cellular source may contribute significantly to ongoing virus production under HAART. This research was featured by [http://www.sciencedaily.com/releases/2009/08/090825082656.htm Science Daily].

[[Image:Wilke_newsicon_06152009.png|left|150px]] In 1994, Akashi proposed that translationally optimal codons, codons that are translated with relatively low error rate, should preferentially be located at important sites in coding sequences. This signal would be the consequence of translational-accuracy selection, i.e., selection to minimize the amount of non-functional or misfolded protein produced by translation errors. Traditionally, the importance of a site under Akashi's test has been assessed by evolutionary conservation. The July issue of Mol. Biol. Evol. contains a study by Zhou et al. <cite>Zhou_et_al_2009</cite> that correlates the location of optimal codons with sites that are important for protein structure. The study finds that there is a tendency of optimal codons to appear at structurally important sites in a wide range of organisms. The study lends further credence to the mistranslation-induced protein-misfolding hypothesis, which argues that much of the selection pressure on coding sequences stems from the toxic effects of mistranslated and misfolded proteins.

[[Image:Wilke_newsicon_05202009.png|left|150px]] The spectrum of anti-HIV drugs was recently extended by a new class of drugs, the integrase inhibitors. The first drug of this class that received FDA approval is Raltegravir. Clinical data show that when previously untreated patients start treatment on Raltegravir, their viral load declines more rapidly than it does in patients who take instead the reverse-transcriptase inhibitor Efavirenz. This spring, Antiviral Therapy published a modeling study by Sedaghat et al. <cite>Sedaghat_et_al_2009a</cite> that discusses the possible mechanisms responsible for this accelerated decline in viral load. The study argues that the accelerated decline is likely not caused by greater antiviral efficiency of Raltegravir compared to Efavirenz. Instead, because Raltegravir acts later in the viral life cycle than Efavirenz, at the beginning of Raltegravir therapy fewer cells have progressed to a state where the drug can not inhibit virus production, and hence the viral load declines faster. The study is a follow-up to a paper published in 2008 in Proc. Natl. Acad. Sci. USA <cite>Sedaghat_et_al_2008b</cite>.