The movement protein of cucumber mosaic virus traffics into sieve elements in minor veins of nicotiana clevelandii

The location of the 3a movement protein (MP) of cucumber mosaic virus (CMV) was studied by quantitative immunogold labeling of the wild-type 3a MP in leaves of Nicotiana clevelandii infected by CMV as well as by using a 3a-green fluorescent protein (GFP) fusion expressed from a potato virus X (PVX) vector. Whether expressed from CMV or PVX, the 3a MP targeted plasmodesmata and accumulated in the central cavity of the pore. Within minor veins, the most extensively labeled plasmodesmata were those connecting sieve elements and companion cells. In addition to targeting plasmodesmata, the 3a MP accumulated in the parietal layer of mature sieve elements. Confocal imaging of cells expressing the 3a-GFP fusion protein showed that the 3a MP assembled into elaborate fibrillar formations in the sieve element parietal layer. The ability of 3a-GFP, expressed from PVX rather than CMV, to enter sieve elements demonstrates that neither the CMV RNA nor the CMV coat protein is required for trafficking of the 3a MP into sieve elements. CMV virions were not detected in plasmodesmata from CMV-infected tissue, although large CMV aggregates were often found in the parietal layer of sieve elements and were usually surrounded by 3a MP. These data suggest that CMV traffics into minor vein sieve elements as a ribonucleoprotein complex that contains the viral RNA, coat protein, and 3a MP, with subsequent viral assembly occurring in the sieve element parietal layer.     

NK cell lysis of HIV-1-infected autologous CD4 primary T cells: requirement for IFN-mediated NK activation by plasmacytoid dendritic cells

In vivo, several mechanisms have been postulated to protect HIV-1-infected cells from NK surveillance. In vitro, previous research indicates HIV-1-infected autologous CD4(+) primary T cells are resistant to NK lysis. We hypothesized that NK lysis of HIV-1-infected target cells would be augmented by the presence of accessory cells and/or accessory cell factors. In this study, we show that stimulation of plasmacytoid dendritic cells (PDC) with the TLR9 agonist, CpG ODN 2216, triggered NK lysis of HIV-1-infected autologous CD4(+) primary T cells. PDC-stimulated NK lysis was dependent upon MHC class I (MHC-I) down-regulation on infected cells, and primary HIV-1 isolates that exhibited enhanced MHC-I down-regulation were more susceptible to NK-mediated lysis. PDC-stimulated NK lysis of HIV-1-infected autologous CD4(+) primary T cells was blocked by neutralizing Abs to type 1 IFN and was perforin/granzyme dependent. Overall, our data suggest that HIV-infected cells are not innately resistant to NK lysis, and that exogenous NK stimulation derived from PDC can trigger NK cytotoxicity against HIV-1-infected autologous CD4(+) primary T cells.     

Predation pressure in maize across Europe and in Argentina: an intercontinental comparison

Humankind draws important benefits from large-scale ecological processes termed ecosystem services, yet the status of several of them is declining. Reliable monitoring methods are essential for tracking the status of ecosystem services. Predation is the mainstay of natural pest control, a key ecosystem service. We used green plasticine caterpillars to monitor predation pressure, and to obtain baseline data on predator activity in transgenic Bt versus non-Bt maize fields in Old and New World countries. Predation pressure was measured at ground and canopy levels using an identical, small-plot experimental design in four European countries (Denmark, Slovakia, Romania and Italy) and Argentina. Total predation rate in maize was l l.7%d^-1 (min. 7.2%d^-1 in Argentina, max. 29.0%d^-1 in Romania). Artificial caterpillars were attacked both by invertebrates (mostly chewing insects with 42.0% of the attack marks, and ants with 7.1%, but also predatory and parasitoid wasps, spiders and slugs), and vertebrates (small mammals 25.5%, and birds 20.2%). Total predation at ground level (15.7%d^-1) was significantly higher than in maize canopies (6.0%d^-1) in all countries, except Argentina. We found no significant differences between predator pressure in Bt versus non-Bt maize plots. The artificial caterpillar method provided comparable, quantitative data on predation intensity, and proved to be suitable for monitoring natural pest control. This method usefully expands the existing toolkit by directly measuring ecological function rather than structure.     

Impact of Anti-Peroxynitrite-Damaged-Thymidine- Monophosphate Antibodies on Disease Activity in Patients with Systemic Lupus Erythematosus

Present study probes the role of peroxynitrite (ONOO^-)-modified thymidine-5′-monophosphate (TMP) in SLE patients with different disease activity scores according to the SLE Disease Activity Index (SLEDAI). Serum analysis showed significant increased number of subjects positive for anti-ONOO^--TMP-protein antibodies in SLE patients with different SLEDAI scores. Interestingly, the levels of these antibodies were significantly higher among SLE patients, whose SLEDAI scores were ≥20. In addition, a significant correlation was observed between the levels of anti-ONOO^--TMP-protein antibodies and the SLEDAI score (r = 0.595, p < 0.0001). In short, this study shows a positive association between anti-ONOO^--TMP-protein antibodies and SLEDAI. The stronger response observed in patients with higher SLEDAI scores suggests that anti-ONOO^--TMP-protein antibodies may be useful in evaluating the progression of SLE and in elucidating the mechanisms of disease pathogenesis.