bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence ofMycobacterium bovisBCG Vaccination on Cellular Immune Response of Guinea Pigs Challenged withMycobacterium tuberculosis
Authors: Ordway Diane , Henao-Tamayo Marcela , Shanley Crystal , Smith Erin E. , Palanisamy Gopinath , Wang Baolin , Basaraba Randall J. , Orme Ian M. 
Published: May 2008

ABSTRACTMycobacterium bovisbacillus Calmette-Guérin (BCG) currently remains the only licensed vaccine for the prevention of tuberculosis. In this study, we used a newly described flow cytometric technique to monitor changes in cell populations accumulating in the lungs and lymph nodes of naïve and vaccinated guinea pigs challenged by low-dose aerosol infection with virulentMycobacterium tuberculosis. As anticipated, vaccinated guinea pigs controlled the growth of the challenge infection more efficiently than controls did. This early phase of bacterial control in immune animals was associated with increased accumulation of CD4 and CD8 T cells, including cells expressing the activation marker CD45, as well as macrophages expressing class II major histocompatibility complex molecules. As the infection continued, the numbers of T cells in the lungs of vaccinated animals waned, whereas the numbers of these cells expressing CD45 increased. Whereas BCG vaccination reduced the influx of heterophils (neutrophils) into the lungs, an early B-cell influx was observed in these vaccinated animals. Overall, vaccine protection was associated with reduced pathology and lung damage in the vaccinated animals. These data provide the first direct evidence that BCG vaccination accelerates the influx of protective T-cell and macrophage populations into the infected lungs, diminishes the accumulation of nonprotective cell populations, and reduces the severity of lung pathology.
Opa Protein Repertoires of Disease-Causing and Carried Meningococci
Authors: Callaghan Martin J. , Buckee Caroline , McCarthy Noel D. , Ibarz Pavón Ana Belén , Jolley Keith A. , Faust Saul , Gray Stephen J. , Kaczmarski Edward B. , Levin Michael , Kroll J. Simon , Maiden Martin C. J. , Pollard Andrew J. 
Published: May 2008

ABSTRACT

The meningococcal Opa proteins play an important role in pathogenesis by mediating invasion of human cells. The aim of this investigation was to determine whether carried and disease-associated meningococci possess different Opa repertoires and whether the diversity of these proteins is associated with clinical severity of disease. Opa repertoires in 227 disease-associated meningococci, isolated in the United Kingdom over a period of 6 years, were compared to the repertoires in 190 asymptomatically carried meningococci isolated in the United Kingdom from a contemporary, nonepidemic period. Multidimensional scaling (MDS) was employed to investigate the association between Opa repertoires and multilocus sequence typing (MLST) genotypes. Associations with clinical severity were also analyzed statistically. High levels of diversity were observed in
opa
alleles, variable regions, and repertoires, and MDS revealed that MLST genotypes were strongly associated with particular Opa repertoires. Individual Opa proteins or repertoires were not associated with clinical severity, though there was a trend toward an association with the
opaD
locus. Meningococcal Opa repertoire is strongly linked to MLST genotype irrespective of epidemiological sampling and therefore correlates with invasiveness. It is not, however, strongly associated with severity of meningococcal disease.
Multiplex Real-Time PCR Assay for Rapid Identification ofMycobacterium tuberculosisComplex Members to the Species Level
Authors: Pinsky Benjamin A. , Banaei Niaz 
Published: May 2008

ABSTRACTThe species identification of members of theMycobacterium tuberculosiscomplex is critical to the timely initiation of both appropriate antibiotic therapy and proper public health control measures. However, the current commercially available molecular assays identify mycobacteria only to the complex level and are unable to differentiateM. tuberculosisfrom the closely relatedM. bovisandM. bovisBCG. We describe here a rapid and robust two-step, multiplex, real-time PCR assay based on genomic deletions to definitively identifyM. tuberculosis, M. bovis, M. bovisBCG, and other members of the complex. When tested against a panel of well-characterized mycobacterial reference strains, the assay was both sensitive and specific, correctly identifying all strains. We applied this assay to 60 clinical isolates previously identified asM. tuberculosiscomplex and found 57M. tuberculosisisolates and 3M. bovisBCG isolates from patients who had received intravesical BCG. Furthermore, analysis of 15 clinical specimens previously identified asM. bovisby spoligotyping revealed an isolate ofM. tuberculosisthat had been misidentified. We propose that this assay will allow the routine identification ofM. tuberculosiscomplex members in the clinical laboratory.
Rapid, Novel, Specific, High-Throughput Assay for Diagnosis of
Loa loa
Infection
Authors: Burbelo Peter D. , Ramanathan Roshan , Klion Amy D. , Iadarola Michael J. , Nutman Thomas B. 
Published: May 2008

ABSTRACT

The ability to diagnose
Loa loa
infection readily and accurately remains a demanding task. Among the available diagnostic methods, many are impractical for point-of-care field testing. To investigate whether luciferase immunoprecipitation systems (LIPS) can be used for rapid and specific diagnosis of
L. loa
infection, a LIPS assay was developed based on immunoglobulin G (IgG) and IgG4 subclass antibodies to a recombinant
L. loa
SXP-1 (designated LlSXP-1) antigen and tested with sera from healthy controls or patients with proven infection with
L. loa, Mansonella perstans, Onchocerca volvulus, Strongyloides stercoralis
, or
Wuchereria bancrofti
. A LIPS test measuring IgG antibody against LlSXP-1 readily differentiated
L. loa
-infected from uninfected patients and demonstrated markedly improved sensitivity and specificity compared with an LlSXP-1 IgG4-based enzyme-linked immunosorbent assay (67% sensitivity and 99% specificity). No significant immunoreactivity was observed with
S. stercoralis
-infected sera, but a small number of patients infected with
O. volvulus, M. perstans
, or
W. bancrofti
showed positive immunoreactivity. Measuring anti-IgG4-specific antibodies to LlSXP-1 showed a significant correlation (
r
∼ 0.85;
P
< 0.00001) with the anti-IgG results but showed no advantage over measuring the total IgG response alone. In contrast, a rapid LIPS format (called QLIPS) in which the tests are performed in less than 15 minutes under nonequilibrium conditions significantly improved the specificity for cross-reactive
O. volvulus
patient sera (100% sensitivity and 100% specificity). These results suggest that LIPS (and the even more rapid test QLIPS) represents a major advance in the ability to diagnose
L. loa
infection and may have future applications for point-of-care diagnostics.
Capsular Polysaccharide Synthesis Regions in
Klebsiella pneumoniae
Serotype K57 and a New Capsular Serotype
Authors: Pan Yi-Jiun , Fang Han-Chi , Yang Hui-Ching , Lin Tzu-Lung , Hsieh Pei-Fang , Tsai Feng-Chiao , Keynan Yoav , Wang Jin-Town 
Published: May 2008

ABSTRACT

Community-acquired pyogenic liver abscess caused by
Klebsiella pneumoniae
is an emerging infectious disease. We explored the capsular polysaccharide synthesis (
cps
) regions of three non-K1, non-K2
K. pneumoniae
strains, A1142, A7754, and A1517, from Taiwanese patients experiencing pyogenic liver abscess. Two of the strains, A1142 and A7754, belonged to capsular serotype K57, while the third belonged to a new capsular serotype, different from the previously reported 77 serotypes. Deletion and complementation experiments suggested that a unique K57 gene, a homologue of
wzy
, was essential for K57 capsular synthesis and confirmed that this gene cluster was a genetic coding region for K57. Compared to K1 and K2 strains, the three strains were all serum sensitive, suggesting that host factors might also be involved in the three patients. PCR using primers from specific genes for K57 was more sensitive and specific than traditional serotyping. The remaining strain, A1517, did not react to the antisera from any of the 77 serotypes, and none of the 77 reference strains reacted to the serum against this strain. Moreover, PCR analyses using various primer pairs from the serotype-specific open reading frames did not reveal cross-reactivity to any of the 77 reference strains, suggesting that this strain likely represents a new capsular type. We conclude that sequences from these two
cps
regions are very useful in detecting K57 and the new
cps
genotype.
Atomic Force Microscopy Investigation of Vaccinia Virus Structure
Authors: Kuznetsov Y. , Gershon P. D. , McPherson A. 
Published: May 2008

ABSTRACTVaccinia virus was treated in a controlled manner with various combinations of nonionic detergents, reducing agents, and proteolytic enzymes, and successive products of the reactions were visualized using atomic force microscopy (AFM). Following removal of the outer lipid/protein membrane, a layer 20 to 40 nm in thickness was encountered that was composed of fibrous elements which, under reducing conditions, rapidly decomposed into individual monomers on the substrate. Beneath this layer was the virus core and its prominent lateral bodies, which could be dissociated or degraded with proteases. The core, in addition to the lateral bodies, was composed of a thick, multilayered shell of proteins of diverse sizes and shapes. The shell, which was readily etched with proteases, was thoroughly permeated with pores, or channels. Prolonged exposure to proteases and reductants produced disgorgement of the viral DNA from the remainders of the cores and also left residual, flattened, protease-resistant sacs on the imaging substrate. The DNA was readily visualized by AFM, which revealed some regions to be “soldered” by proteins, others to be heavily complexed with protein, and yet other parts to apparently exist as bundled, naked DNA. Prolonged exposure to proteases deproteinized the DNA, leaving masses of extended, free DNA. Estimates of the interior core volume suggest moderate but not extreme compaction of the genome.
Deoxynucleoside Triphosphate Incorporation Mechanism of Foamy Virus (FV) Reverse Transcriptase: Implications for Cell Tropism of FV
Authors: Santos-Velazquez Jose , Kim Baek 
Published: May 2008

ABSTRACT
Here, we investigated the pre-steady-state deoxynucleoside triphosphate (dNTP) incorporation kinetics of primate foamy virus (PFV) reverse transcriptase (RT) in comparison with those of HIV-1 and MuLV RTs. PFV RT displayed a drastic reduction in primer extension at low dNTP concentrations where HIV-1 RT remains highly active, indicating a low dNTP binding affinity in the case of PFV RT. Indeed, kinetic analysis showed that, as observed with MuLV RT, PFV RT exhibits ∼10 to 80 times lower dNTP binding affinity than HIV-1 RT. These three RTs, however, show similar catalytic activities. In conclusion, PFV RT displays mechanistic distinctions in comparison to HIV-1 RT and shares close similarity to MuLV RT.
Asparagine 631 Variants of the Chicken Mx Protein Do Not Inhibit Influenza Virus Replication in Primary Chicken Embryo Fibroblasts or In Vitro Surrogate Assays
Authors: Benfield Camilla T. O. , Lyall Jon W. , Kochs Georg , Tiley Laurence S. 
Published: May 2008

ABSTRACT
Whether chicken Mx inhibits influenza virus replication is an important question with regard to strategies aimed at enhancing influenza resistance in domestic flocks. The Asn631 polymorphism of the chicken Mx protein found in the Shamo (SHK) chicken line was previously reported to be crucial for the antiviral activity of this highly polymorphic chicken gene. Our aims were to determine whether cells from commercial chicken lines containing Asn631 alleles were resistant to influenza virus infection and to investigate the effects that other polymorphisms might have on Mx function. Unexpectedly, we found that the Asn631 genotype had no impact on multicycle replication of influenza virus (A/WSN/33 [H1N1]) in primary chicken embryo fibroblast lines. Furthermore, expression of the Shamo (SHK) chicken Mx protein in transfected 293T cells did not inhibit viral gene expression (A/PR/8/34 [H1N1], A/Duck/England/62 [H4N6], and A/Duck/Singapore/97 [H5N3]). Lastly, in minireplicon systems (A/PR/8/34 and A/Turkey/England/50-92/91 [H5N1]), which were highly sensitive to inhibition by the murine Mx1 and human MxA proteins, respectively, Shamo chicken Mx also proved ineffective in the context of avian as well as mammalian cell backgrounds. Our findings demonstrate that Asn631 chicken Mx alleles do not inhibit influenza virus replication of the five strains tested here and efforts to increase the frequency of Asn631 alleles in commercial chicken populations are not warranted. Nevertheless, chicken Mx variants with anti-influenza activity might still exist. The flow cytometry and minireplicon assays described herein could be used as efficient functional screens to identify such active chicken Mx alleles.
Identification of Residues outside of the Receptor Binding Domain That Influence the Infectivity and Tropism of Porcine Endogenous Retrovirus
Authors: Argaw Takele , Figueroa Mariel , Salomon Daniel R. , Wilson Carolyn A. 
Published: May 2008

ABSTRACT
Identification of determinants of human tropism of porcine endogenous retrovirus (PERV) is critical to understanding the risk of transmission of PERV to recipients of porcine xenotransplantation products. Previously, we showed that a chimeric envelope cDNA encoding the 360 N-terminal residues of the human-tropic PERV envelope class A (PERV-A) SU and the 130 C-terminal residues of the pig-tropic PERV-C SU and all of TM (PERV-A/C) showed a 100-fold decrease in infectivity titer on human cells (M. Gemeniano, O. Mpanju, D. R. Salomon, M. V. Eiden, and C. A. Wilson, Virology 346:108-117, 2006). To identify residues important for human cell infection, we performed site-directed mutagenesis on each of the nine residues, singly or in combination, that distinguish the C-terminal region of PERV-C from PERV-A. Of the nine amino acids, two single-amino-acid substitutions, Q374R and I412V, restored the infectivity of human cells to the chimeric PERV-A/C to a titer equivalent to that of PERV-A. In contrast, PERV-A/C mutant envelope Q439P resulted in undetectable infection of human cells and an approximately 1,000-fold decrease in control pig cells. Mutation of K441R rescued mutants that carried Q439P, suggesting an incompatibility between the proline residue at this position and the presence of KK in the proteolytic cleavage signal. We confirmed this incompatibility with vectors carrying PERV-A envelope mutant R462K that were also rendered noninfectious. Finally, tropism of vectors carrying PERV-C envelope mutants with only four amino acid changes in the C terminus of PERV-C envelope, NHRQ436YNRP plus K441R, was shifted to one similar to that of PERV-A. Our results show an important and previously unrecognized role for infectivity and tropism for residues at the C terminus of SU.
Visualization of the Externalized VP2 N Termini of Infectious Human Parvovirus B19
Authors: Kaufmann Bärbel , Chipman Paul R. , Kostyuchenko Victor A. , Modrow Susanne , Rossmann Michael G. 
Published: May 2008

ABSTRACT
The structures of infectious human parvovirus B19 and empty wild-type particles were determined by cryoelectron microscopy (cryoEM) to 7.5-Å and 11.3-Å resolution, respectively, assuming icosahedral symmetry. Both of these, DNA filled and empty, wild-type particles contain a few copies of the minor capsid protein VP1. Comparison of wild-type B19 with the crystal structure and cryoEM reconstruction of recombinant B19 particles consisting of only the major capsid protein VP2 showed structural differences in the vicinity of the icosahedral fivefold axes. Although the unique N-terminal region of VP1 could not be visualized in the icosahedrally averaged maps, the N terminus of VP2 was shown to be exposed on the viral surface adjacent to the fivefold β-cylinder. The conserved glycine-rich region is positioned between two neighboring, fivefold-symmetrically related VP subunits and not in the fivefold channel as observed for other parvoviruses.
Synthesis of Genomic and Subgenomic RNA in Mosquito Cells Infected with Two Sindbis Virus nsP4 Mutants: Influence of Intracellular Nucleoside Triphosphate Concentrations
Authors: Li Mei-Ling , Kwan Tzu-Yu , Simmonds H. Anne , Stollar Victor 
Published: May 2008

ABSTRACT
Cells infected with Sindbis virus (SV) make two positive-strand RNAs, a genomic-length RNA (G) RNA and a subgenomic (SG) RNA. In cells infected with SVstd, and in general in cells infected with wt alphaviruses, more SG RNA is made than G RNA. How the balance between synthesis of G RNA and SG RNA is regulated is not known. SVpzf and SVcpc are nsP4 mutants of SV which, in mosquito cells, make more G RNA than SG RNA. When low concentrations of pyrazofurin (inhibits the synthesis of UTP and CTP) were added to SVpzf-infected cells, the yield of virus was increased, and the ratio of SG/G RNA was changed from <1 to >1. These effects were reversed by uridine. In SVcpc-infected cells, but not in SVstd-infected cells, synthesis of viral RNA was inhibited by the addition of either uridine or cytidine, and viral yields were lowered. Our findings suggest that the activities of the viral RNA-synthesizing complexes in cells infected with SVpzf or SVcpc, in contrast to those in SVstd-infected cells, are sensitive to high concentrations of UTP or CTP. Using a cell-free system that synthesizes both SG and G RNA, we measured viral RNA synthesis as a function of the UTP/CTP concentrations. The results indicated that the presence of the SVpzf mutations in nsP4 and the SG promoter produced a pattern quite different from that seen with the SVstd nsP4 and SG promoter. As the UTP/CTP concentrations were increased, the SVpzf system, in contrast to the SVstd system, made more G RNA than SG RNA, reflecting the situation in cells infected with SVpzf.
Different Mechanisms of Cell Entry by Human-Pathogenic Old World and New World Arenaviruses
Authors: Rojek Jillian M. , Sanchez Ana B. , Nguyen Ngoc Thao , de la Torre Juan-Carlos , Kunz Stefan 
Published: May 2008

ABSTRACT
The Old World arenavirus Lassa virus (LASV) is the causative agent of severe viral hemorrhagic fever (VHF) in humans and is the most prevalent human pathogen among arenaviruses. The present study investigated the largely unknown mechanisms of cell entry of LASV, a process know to be mediated solely by the virus envelope glycoprotein (GP). To circumvent biosafety restrictions associated with the use of live LASV, we used reverse genetics to generate a recombinant variant of the prototypic arenavirus lymphocytic choriomeningitis virus (LCMV) expressing the LASV GP (rLCMV-LASVGP). The rescued rLCMV-LASVGP grew to titers comparable to that of LCMV and showed the receptor binding characteristics of LASV. We used rLCMV-LASVGP to characterize the cellular mechanisms of LASV entry in the context of a productive arenavirus infection. The kinetics of pH-dependent membrane fusion of rLCMV-LASVGP resembled those of the human-pathogenic New World arenavirus Junin virus (JUNV) and other enveloped viruses that use clathrin-mediated endocytosis for entry. However, rLCMV-LASVGP entered cells predominantly via a clathrin-, caveolin-, and dynamin-independent endocytotic pathway similar to the one recently described for LCMV. Productive infection of rLCMV-LASVGP was only mildly affected by a dominant negative mutant of Rab5 and was independent of Rab7, suggesting an unusual mechanism of delivery to endosomes. In addition, rLCMV-LASVGP infection was independent of actin but required intact microtubules. Our data indicate that LASV enters cells via a pathway distinct from the one used by human-pathogenic New World arenaviruses.
Induction of Plasma (TRAIL), TNFR-2, Fas Ligand, and Plasma Microparticles after Human Immunodeficiency Virus Type 1 (HIV-1) Transmission: Implications for HIV-1 Vaccine Design
Authors: Gasper-Smith Nancy , Crossman Deanna M. , Whitesides John F. , Mensali Nadia , Ottinger Janet S. , Plonk Steven G. , Moody M. Anthony , Ferrari Guido , Weinhold Kent J. , Miller Sara E. , Reich Charles F. , Qin Li , Self Stephen G. , Shaw George M. , Denny Thomas N. , Jones Laura E. , Pisetsky David S. , Haynes Barton F. 
Published: May 2008

ABSTRACT

The death of CD4
+
CCR5
+
T cells is a hallmark of human immunodeficiency virus (HIV) infection. We studied the plasma levels of cell death mediators and products—tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL), Fas ligand, TNF receptor type 2 (TNFR-2), and plasma microparticles—during the earliest stages of infection following HIV type 1 (HIV-1) transmission in plasma samples from U.S. plasma donors. Significant plasma TRAIL level elevations occurred a mean of 7.2 days before the peak of plasma viral load (VL), while TNFR-2, Fas ligand, and microparticle level elevations occurred concurrently with maximum VL. Microparticles had been previously shown to mediate immunosuppressive effects on T cells and macrophages. We found that T-cell apoptotic microparticles also potently suppressed in vitro immunoglobulin G (IgG) and IgA antibody production by memory B cells. Thus, release of TRAIL during the onset of plasma viremia (i.e., the eclipse phase) in HIV-1 transmission may initiate or amplify early HIV-1-induced cell death. The window of opportunity for a HIV-1 vaccine is from the time of HIV-1 transmission until establishment of the latently infected CD4
+
T cells. Release of products of cell death and subsequent immunosuppression following HIV-1 transmission could potentially narrow the window of opportunity during which a vaccine is able to extinguish HIV-1 infection and could place severe constraints on the amount of time available for the immune system to respond to the transmitted virus.
Virological Consequences of Early Events following Cell-Cell Contact between Human Immunodeficiency Virus Type 1-Infected and Uninfected CD4
+
Cells
Authors: Ruggiero Eliana , Bona Roberta , Muratori Claudia , Federico Maurizio 
Published: May 2008

ABSTRACT

Human immunodeficiency virus type 1 (HIV-1)-infected cells transmit viral products to uninfected CD4
+
cells very rapidly. However, the natures of the transmitted viral products and the mechanism of transmission, as well as the relative virological consequences, have not yet been fully clarified. We studied the virological events occurring a few hours after contact between HIV-1-infected and uninfected CD4
+
cells using a coculture cell system in which the virus expression in target cells could be monitored through the induction of a green fluorescent protein reporter gene driven by HIV-1 long terminal repeats. Within 16 h of coculture, we observed two phenomena not related to the cell-free virus infection, i.e., the formation of donor-target cell fusions and a fusion-independent internalization of viral particles likely occurring at least in part through intercellular connections. Both events depended on the expression of Env and CD4 in donor and target cells, respectively, whereas the HIV-1 internalization required clathrin activity in target cells. Importantly, both phenomena were also observed in cocultures of primary CD4
+
lymphocytes, while primary macrophages supported only HIV-1 endocytosis. By investigating the virological consequences of these events, we noticed that while fused cells released infectious HIV-1 particles, albeit with reduced efficiency compared with donor cells, no virus expression was detectable upon HIV-1 endocytosis in target cells. In sum, the HIV-1 transmission following contact between an HIV-1-infected and an uninfected CD4
+
cell can occur through different mechanisms, leading to distinguishable virological outcomes.