3 research outputs found
Eikonal phase retrieval: Unleashing the fourth generation sources potential for enhanced propagation based tomography on biological samples
The evolution of synchrotrons towards higher brilliance beams has increased
the possible sample-to-detector propagation distances for which the source
confusion circle does not lead to geometrical blurring. This makes it possible
to push near-field propagation driven phase contrast enhancement to the limit,
revealing low contrast features which would otherwise remain hidden under an
excessive noise-to-signal ratio. Until today this possibility was hindered, in
most objects of scientific interest, by the simultaneous presence of strong
phase gradient regions and low contrast features. The strong gradients, when
enhanced with the now possible long propagation distances, induce such strong
phase effects that the linearisation assumptions of current state-of-the-art
single-distance phase retrieval filters are broken, and the resulting image
quality is jeopardized. Our work provides an innovative algorithm which
efficiently performs the phase retrieval task over the entire near-field range,
producing images of exceptional quality for mixed objects
The Envelope Cytoplasmic Tail of HIV-1 Subtype C Contributes to Poor Replication Capacity through Low Viral Infectivity and Cell-to-Cell Transmission.
The cytoplasmic tail (gp41CT) of the HIV-1 envelope (Env) mediates Env incorporation into virions and regulates Env intracellular trafficking. Little is known about the functional impact of variability in this domain. To address this issue, we compared the replication of recombinant virus pairs carrying the full Env (Env viruses) or the Env ectodomain fused to the gp41CT of NL4.3 (EnvEC viruses) (12 subtype C and 10 subtype B pairs) in primary CD4+ T-cells and monocyte-derived-macrophages (MDMs). In CD4+ T-cells, replication was as follows: B-EnvEC = B-Env>C-EnvEC>C-Env, indicating that the gp41CT of subtype C contributes to the low replicative capacity of this subtype. In MDMs, in contrast, replication capacity was comparable for all viruses regardless of subtype and of gp41CT. In CD4+ T-cells, viral entry, viral release and viral gene expression were similar. However, infectivity of free virions and cell-to-cell transmission of C-Env viruses released by CD4+ T-cells was lower, suggestive of lower Env incorporation into virions. Subtype C matrix only minimally rescued viral replication and failed to restore infectivity of free viruses and cell-to-cell transmission. Taken together, these results show that polymorphisms in the gp41CT contribute to viral replication capacity and suggest that the number of Env spikes per virion may vary across subtypes. These findings should be taken into consideration in the design of vaccines