Kinetic analysis of Human T-cell Leukemia Virus type 2 expression in chronically-infected cells and patient PBMCs

Introduction: The elucidation of the viral gene expression profile provides useful information in assessing the function of specific viral genes in the process of infection and cellular transformation. HTLV-2 pattern of mRNAs expression produces three major classes of mRNAs: unspliced genomic mRNA for Gag, protease and Pol proteins; singly spliced mRNAs encoding Env and the accessory proteins p28, p22/p20-1 and -2; and a doubly spliced mRNA for the regulatory proteins Tax, Rex and for the p10/p11 and p? accessory ones (Ref.1 and Fig. 1). To date, very little information has been obtained on the temporal regulation of different HTLV-2 transcripts expression in infected cells. Aim of this study was to investigate the kinetics of gene expression from HTLV-2 infected cell lines and from PBMCs of HTLV-2B infected subjects. The expression profile and kinetics of the different transcripts were analysed by real time RT-PCR using splice-junction-specific primers. Results: This approach was used to first determine the steady-state levels of expression for the different viral transcripts in three different cell lines in log phase of growth . Experiments performed indicated that gag/pol is the most abundant transcript. The expression level of env was comparable in the two T-cell lines, Mo-T and C344, infected by the 2A subtype, and was considerably higher than in the B-cells infected with HTLV-2B subtype, where p10/p11 and p? transcripts were below the limit of detection. We next investigated the kinetics of viral transcripts expression in infected BJAB-Gu cells. As in the previous experiment, the absolute copy number of gag/pol was the highest over the time period analysed . Among the accessory transcripts, p28,p22/p20-2 was the most abundant while other regulatory and accessory genes were lower. The analysis of fold variation, reported in g. 4B, indicated that tax/rex and p28, p22/p20-1 showed a biphasic profile with an early peak at 24 hours and a second one at 72 hours, whereas the transcripts gag/pol, env and p28,p22/p20-2 were expressed later.The kinetics of gene expression also was analysed from ex-vivo PBMCs of HTLV-2B infected subjects. Fig. 5 shows a typical pattern of expression. Also in this case, among the mRNAs species, gag/pol was consistently the most abundant transcript, p28, p22/p20-2 was approximately 15 fold lower than gag/pol, followed by tax/rex and p? that were present at approximately 25 fold lower than the unspliced mRNA coding for gag/pol . Very low levels of expression were found for p28, p22/p20-1, while env and p10/p11 transcripts were below the limit of detection. In Fig. 5B the fold variation analysis showed that the first mRNAs expressed were tax/rex and p28,p22/p20-1 with a peak at 4 hours followed by all the other transcripts that showed a later peak at 24 hours.These results indicate that tax/rex is the earliest transcript expressed, while the other genes, coding for accessory and structural proteins, are expressed in a later phase of the viral cycle. Conclusions: The expression of different HTLV-2 genes follows a distinct timing both in infected cell lines and PBMCs isolated from infected patients. The transcript tax/rex is the first to be expressed, thus indicating that it is necessary at the beginning of the infection cycle to transactivate and regulate viral and cellular transcripts. These results also suggest that the control of viral gene expression is highly regulated both in its kinetics and expression level

A Multi-Transistion CO Study of the "Antennae" Galaxies NGC4038/9

For the Antennae interacting galaxy pair, we have obtained high quality, fully sampled $^{12}$CO J=1-0, 2-1 and 3-2 maps of the regions surrounding the nuclei and the area of overlap between the two galaxies, with an angular resolution of 15" or 1.5 kpc. The $^{12}$CO J=1-0, 2-1, 3-2 emission all peak in the overlap region, which contains ~ 4 x 10^9 solar mass of molecular gas mass if the conventional X factor is used. Line emission at $^{13}$CO J=2-1 and 3-2 is detected at selected points in the two nuclei and the overlap region. Both the ^{12}CO/^{13}CO J=2-1 and 3-2 integrated intensity ratios are remarkably high in the overlap region. This is the first published case in which such high $^{12}$CO/$^{13}$CO J=2-1 and 3-2 ratios are found outside a galactic nucleus. Detailed LVG modeling indicates that the $^{12}$CO and ^{13}CO emission originate in different spatial components. Assuming a CO-to-H2 abundance ratio of $10^{-4}$, the X factor given by the LVG model is an order of magnitude lower than the conventional value for molecular clouds in the Milky Way. Accordingly, we suggest the possibility that the strong CO emission in the overlap region of the Antennae galaxies is associated with increased radiative efficiency, possibly caused by a large velocity dispersion within the individual molecular clouds. A comparison of the CO J=3-2 emission with the SCUBA 850 um continuum in the Antennae galaxies shows that the CO line emission contributes globally 46% of the 850 um continuum flux and that the ratio of $^{12}$CO J=3-2 to SCUBA 850 um flux varies by a factor of two across the system.Comment: Accepted by ApJ on Jan 2. 2003, and is also available on ApJ preprint site. To download the figures and tables, choose the format "other", then click on the "Download source" at the bottom of the format selector page. Some figures are in png or jpg format to save spac

Molecular gas in the central regions of the latest-type spiral galaxies

Using the IRAM 30m telescope, we have surveyed an unbiased sample of 47 nearby spiral galaxies of very late (Scd-Sm) Hubble-type for emission in the CO(1-0) and CO(2-1) lines. The sensitivity of our data (a few mK) allows detection of about 60% of our sample in at least one of the CO lines. The median detected H2 mass is 1.4\times 10^7 \msun within the central few kpc, assuming a standard conversion factor. We use the measured line intensities to complement existing studies of the molecular gas content of spiral galaxies as a function of Hubble-type and to significantly improve the statistical significance of such studies at the late end of the spiral sequence. We find that the latest-type spirals closely follow the correlation between molecular gas content and galaxy luminosity established for earlier Hubble types. The molecular gas in late-type galaxies seems to be less centrally concentrated than in earlier types. We use Hubble Space Telescope optical images to correlate the molecular gas mass to the properties of the central galaxy disk and the compact star cluster that occupies the nucleus of most late-type spirals. There is no clear correlation between the luminosity of the nuclear star cluster and the molecular gas mass, although the CO detection rate is highest for the brightest clusters. It appears that the central surface brightness of the stellar disk is an important parameter for the amount of molecular gas at the galaxy center. Whether stellar bars play a critical role for the gas dynamics remains unclear, in part because of uncertainties in the morphological classifications of our sample.Comment: 27 pages, 15 figures, accepted by A&

Molecular gas and star formation in the Tidal Dwarf Galaxy VCC 2062

The final, definitive version of this paper has been published in A&A, Vol 590, A92, June 2016, doi: 10.1051/0004-6361/201527887. Reproduced with permission from Astronomy & Astrophysics, © ESO.The physical mechanisms driving star formation (SF) in galaxies are still not fully understood. Tidal dwarf galaxies (TDGs), made of gas ejected during galaxy interactions, seem to be devoid of dark matter and have a near-solar metallicity. The latter makes it possible to study molecular gas and its link to SF using standard tracers (CO, dust) in a peculiar environment. We present a detailed study of a nearby TDG in the Virgo Cluster, VCC 2062, using new high-resolution CO(1--0) data from the Plateau de Bure, deep optical imaging from the Next Generation Virgo Cluster Survey (NGVS), and complementary multiwavelength data. Until now, there was some doubt whether VCC 2062 was a true TDG, but the new deep optical images from the NGVS reveal a stellar bridge between VCC 2062 and its parent galaxy, NGC 4694, which is clear proof of its tidal origin. Several high-resolution tracers (\halpha, UV, 8~\mi, and 24~\mi) of the star formation rate (SFR) are compared to the molecular gas distribution as traced by the CO(1-0). Coupled with the SFR tracers, the NGVS data are used with the CIGALE code to model the stellar populations throughout VCC 2062, yielding a declining SFR in the recent past, consistent with the low \halpha/UV ratio, and a high burst strength. HI emission covers VCC 2062, whereas the CO is concentrated near the HI maxima. The CO peaks correspond to two very distinct regions: one with moderate SF to the NE and one with only slightly weaker CO emission but with nearly no SF. Even where SF is clearly present, the SFR is below the value expected from the surface density of the molecular and the total gas as compared to spiral galaxies and other TDGs. After discussing different possible explanations, we conclude that the low surface brightness is a crucial parameter to understand the low SFR.Peer reviewe

Environmental Effects on Late-Type Galaxies in Nearby Clusters

The transformations taking place in late-type galaxies in the environment of rich clusters of galaxies at z=0 are reviewed. From the handful of late-type galaxies that inhabit local clusters, whether they were formed in-situ and survived as such, avoiding transformation or even destruction or if they are newcomers that recently infall from outside, we can learn an important lesson on the latest stages of galaxy evolution. We start by reviewing the observational scenario, covering the broadest possible stretch of the electromagnetic spectrum, from the gas tracers, the star formation tracers, the old star tracers and the dust. Strong emphasis is given to the three nearby, well studied clusters Virgo, A1367 and Coma, representative of different evolutionary stages, from unrelaxed, spiral rich (Virgo) to relaxed, spiral poor clusters (Coma). We continue by providing a review of models of galaxy interactions relevant to clusters of galaxies. Prototypes of various mechanisms and processes are discussed and their typical time-scales are given in an Appendix. Observations indicate the presence of healthy late-type galaxies falling into nearby clusters individually or belonging to massive groups. More rare are infalling galaxies belonging to compact groups where significant pre-processing might take place. Once entered the cluster, they loose their gas and quench their star formation activity, becoming anemics. Observations and theory agree in indicating that the interaction with the intergalactic medium is responsible for the gas depletion. This process, however, cannot be at the origin of the cluster lenticular galaxy population. Physical and statistical properties of S0 in nearby clusters and at higher redshift, indicate that they originate from spiral galaxies transformed by gravitational interactions.Comment: Review paper accepted for publication on PASP, high resolution version of the figures available on the GOLDMine webpage: http://goldmine.mib.infn.it/papers.htm

An HST Survey of the mid-UV Morphology of Nearby Galaxies

(Abbreviated) We present an imaging survey of 37 nearby galaxies observed with HST/WFPC2 in the mid-UV F300W filter and in F814W. 11 galaxies were also imaged in F255W. These galaxies were selected to be detectable with WFPC2 in one orbit, and cover a wide range of Hubble types and inclinations. The mid-UV spans the gap between our groundbased optical/NIR images and far-UV images available from the Astro/UIT missions. Our first qualitative results are: (1) Early-type galaxies show a significant decrease in surface brightness going from the red to the mid-UV, and in some cases the presence of dust lanes. Some galaxies would be classified different when viewed in the mid-UV, some become dominated by a blue nuclear feature or point source. (2) Half of the mid-type spiral and star-forming galaxies appear as a later morphological type in the mid-UV, as Astro/UIT also found in the far-UV. Some- times these differences are dramatic. The mid-UV images show a considerable range in the scale and surface brightness of individual star-forming regions. Almost all mid-type spirals have their small bulges bi-sected by a dust-lane. (3) Most of the heterogeneous subset of late-type, irregular, peculiar, and merging galaxies display F300W morphologies that are similar to those seen in F814W, but with differences due to recognizable dust features absorbing the bluer light, and due to UV-bright hot stars, star-clusters, and star-forming ridges. In the rest-frame mid-UV, early- to mid-type galaxies are more likely to be misclassified as later types than vice versa. This morphological K-correction explains only part of the excess faint blue galaxies seen in deep HST fields.Comment: 30 pages, LateX (AASTeX5.0), 2 figures and 3 tables included, mid-UV atlas and pan-chromatic atlas provided as 63 JPG figures. Full resolution PS version (~100Mb) available upon request. Accepted for publication in ApJ

Co-infection by human immunodeficiency virus type 1 (HIV-1) and human T cell leukemia virus type 1 (HTLV-1): does immune activation lead to a faster progression to AIDS?

<p>Abstract</p> <p>Background</p> <p>Recent data have shown that HTLV-1 is prevalent among HIV positive patients in Mozambique, although the impact of HTLV-1 infection on HIV disease progression remains controversial. Our aim was to determine the phenotypic profile of T lymphocytes subsets among Mozambican patients co-infected by HIV and HTLV-1.</p> <p>Methods</p> <p>We enrolled 29 patients co-infected by HTLV-1 and HIV (co-infected), 59 patients mono-infected by HIV (HIV) and 16 healthy controls (HC), respectively.</p> <p>For phenotypic analysis, cells were stained with the following fluorochrome-labeled anti-human monoclonal antibodies CD4-APC, CD8-PerCP, CD25-PE, CD62L-FITC, CD45RA-FITC. CD45RO-PE, CD38-PE; being analysed by four-colour flow cytometry.</p> <p>Results</p> <p>We initially found that CD4⁺T cell counts were significantly higher in co-infected, as compared to HIV groups. Moreover, CD4⁺T Lymphocytes from co-infected patients presented significantly higher levels of CD45RO and CD25, but lower levels of CD45RA and CD62L, strongly indicating that CD4⁺T cells are more activated under HTLV-1 plus HIV co-infection.</p> <p>Conclusion</p> <p>Our data indicate that HTLV-1/HIV co-infected patients progress with higher CD4⁺T cell counts and higher levels of activation markers. In this context, it is conceivable that in co-infected individuals, these higher levels of activation may account for a faster progression to AIDS.</p