Publications

Rapid rebound of plasma viremia in patients after interruption of long-term combination antiretroviral therapy (cART) suggests persistence of low-level replicating cells or rapid reactivation of latently infected cells. To further characterize rebounding virus, we performed extensive longitudinal clonal evolutionary studies of HIV env C2-V3-C3 regions and exploited the temporal relationships of rebounding plasma viruses with regard to pretreatment sequences in 20 chronically HIV-1-infected patients having undergone multiple 2-week structured treatment interruptions (STI). Rebounding virus during the short STI was homogeneous, suggesting mono- or oligoclonal origin during reactivation. No evidence for a temporal structure of rebounding virus in regard to pretreatment sequences was found. Furthermore, expansion of distinct lineages at different STI cycles emerged. Together, these findings imply stochastic reactivation of different clones from long-lived latently infected cells rather than expansion of viral populations replicating at low levels. After treatment was stopped, diversity increased steadily, but pretreatment diversity was, on average, achieved only >2.5 years after the start of STI when marked divergence from preexisting quasispecies also emerged. In summary, our results argue against persistence of ongoing low-level replication in patients on suppressive cART. Furthermore, a prolonged delay in restoration of pretreatment viral diversity after treatment interruption demonstrates a surprisingly sustained evolutionary bottleneck induced by punctuated antiretroviral therapy.

The liganded vitamin D receptor (VDR) is thought to play an important role in controlling cardiac function. Specifically, this system has been implicated as playing an antihypertrophic role in the heart. Despite this, studies of VDR in the heart have been limited in number and scope. In the present study, we used a combination of real-time polymerase chain reaction, Western blot analysis, immunofluorescence, and transient transfection analysis to document the presence of functional VDR in both the myocytes and fibroblasts of the heart, as well as in the intact ventricular myocardium. We also demonstrated the presence of 1-alpha-hydroxylase and 24-hydroxylase in the heart, 2 enzymes involved in the synthesis and metabolism of 1,25 dihydroxyvitamin D. VDR is shown to interact directly with the human B-type natriuretic peptide gene promoter, a surrogate marker of the transcriptional response to hypertrophy. Of note, induction of myocyte hypertrophy either in vitro or in vivo leads to an increase in VDR mRNA and protein levels. Collectively, these findings suggest that the key components required for a functional 1,25 dihydroxyvitamin D-dependent signaling system are present in the heart and that this putatively antihypertrophic system is amplified in the setting of cardiac hypertrophy.