bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neutrophils Select Hypervirulent CovRS Mutants of M1T1 Group A Streptococcus during Subcutaneous Infection of Mice
Authors: Li Jinquan , Liu Guanghui , Feng Wenchao , Zhou Yang , Liu Mengyao , Wiley James A. , Lei Benfang 
Published: January 2014

ABSTRACT

Pathogen mutants arise during infections. Mechanisms of selection for pathogen variants are poorly understood. We tested whether neutrophils select mutations in the two-component regulatory system CovRS of group A
Streptococcus
(GAS) during infection using the lack of production of the protease SpeB (SpeB activity negative [SpeB
A−
]) as a marker. Depletion of neutrophils by antibodies RB6-8C5 and 1A8 reduced the percentage of SpeB
A−
variants (SpeB
A−
%) recovered from mice infected with GAS strain MGAS2221 by >76%. Neutrophil recruitment and SpeB
A−
% among recovered GAS were reduced by 95% and 92%, respectively, in subcutaneous MGAS2221 infection of CXCR2
−/−
mice compared with control mice. In air sac infection with MGAS2221, levels of neutrophils and macrophages in lavage fluid were reduced by 49% and increased by 287%, respectively, in CXCR2
−/−
mice compared with control mice, implying that macrophages play an insignificant role in the reduction of selection for SpeB
A−
variants in CXCR2
−/−
mice. One randomly chosen SpeB
A−
mutant outcompeted MGAS2221 in normal mice but was outcompeted by MGAS2221 in neutropenic mice and had enhancements in expression of virulence factors, innate immune evasion, skin invasion, and virulence. This and nine other SpeB
A−
variants from a mouse all had nonsynonymous
covRS
mutations that resulted in the SpeB
A−
phenotype and enhanced expression of the CovRS-controlled secreted streptococcal esterase (SsE). Our findings are consistent with a model that neutrophils select spontaneous
covRS
mutations that maximize the potential of GAS to evade neutrophil responses, resulting in variants with enhanced survival and virulence. To our knowledge, this is the first report of the critical contribution of neutrophils to the selection of pathogen variants.
Identification of Point Mutations in Clinical Staphylococcus aureus Strains That Produce Small-Colony Variants Auxotrophic for Menadione
Authors: Dean Melissa A. , Olsen Randall J. , Long S. Wesley , Rosato Adriana E. , Musser James M. 
Published: January 2014

ABSTRACT

Staphylococcus aureus
small-colony variants (SCVs) are implicated in chronic and relapsing infections that are difficult to diagnose and treat. Despite many years of study, the underlying molecular mechanisms and virulence effect of the small-colony phenotype remain incompletely understood. We sequenced the genomes of five
S. aureus
SCV strains recovered from human patients and discovered previously unidentified nonsynonymous point mutations in three genes encoding proteins in the menadione biosynthesis pathway. Analysis of genetic revertants and complementation with wild-type alleles confirmed that these mutations caused the SCV phenotype and decreased virulence for mice.
CsrA (BB0184) Is Not Involved in Activation of the RpoN-RpoS Regulatory Pathway in Borrelia burgdorferi
Authors: Ouyang Zhiming , Zhou Jianli , Norgard Michael V. 
Published: January 2014

ABSTRACT

Borrelia burgdorferi
encodes a homologue of the bacterial carbon storage regulator A (CsrA). Recently, it was reported that CsrA contributes to
B. burgdorferi
infectivity and is required for the activation of the central RpoN-RpoS regulatory pathway. However, many questions concerning the function of CsrA in
B. burgdorferi
gene regulation remain unanswered. In particular, there are conflicting reports concerning the molecular details of how CsrA may modulate
rpoS
expression and, thus, how CsrA may influence the RpoN-RpoS pathway in
B. burgdorferi
. To address these key discrepancies, we examined the role of CsrA in differential gene expression in the Lyme disease spirochete. Upon engineering an inducible
csrA
expression system in
B. burgdorferi
, controlled hyperexpression of CsrA in a merodiploid strain did not significantly alter the protein and transcript levels of
bosR
,
rpoS
, and RpoS-dependent genes (such as
ospC
and
dbpA
). In addition, we constructed isogenic
csrA
mutants in two widely used infectious
B. burgdorferi
strains. When expression of
bosR
,
rpoS
,
ospC
, and
dbpA
was compared between the
csrA
mutants and their wild-type counterparts, no detectable differences were observed. Finally, animal studies indicated that the
csrA
mutants remained infectious for and virulent in mice. Analyses of
B. burgdorferi
gene expression in mouse tissues showed comparable levels of
rpoS
transcripts by the
csrA
mutants and the parental strains. Taken together, these results constitute compelling evidence that CsrA is not involved in activation of the RpoN-RpoS pathway and is dispensable for mammalian infectious processes carried out by
B. burgdorferi
.
Induction of Virulence Gene Expression in Staphylococcus aureus by Pulmonary Surfactant
Authors: Ishii Kenichi , Adachi Tatsuo , Yasukawa Jyunichiro , Suzuki Yutaka , Hamamoto Hiroshi , Sekimizu Kazuhisa 
Published: January 2014

ABSTRACT

We performed a genomewide analysis using a next-generation sequencer to investigate the effect of pulmonary surfactant on gene expression in
Staphylococcus aureus
, a clinically important opportunistic pathogen. RNA sequence (RNA-seq) analysis of bacterial transcripts at late log phase revealed 142 genes that were upregulated >2-fold following the addition of pulmonary surfactant to the culture medium. Among these genes, we confirmed by quantitative reverse transcription-PCR analysis that mRNA amounts for genes encoding ESAT-6 secretion system C (EssC), an unknown hypothetical protein (NWMN_0246; also called pulmonary surfactant-inducible factor A [PsiA] in this study), and hemolysin gamma subunit B (HlgB) were increased 3- to 10-fold by the surfactant treatment. Among the major constituents of pulmonary surfactant, i.e., phospholipids and palmitate, only palmitate, which is the most abundant fatty acid in the pulmonary surfactant and a known antibacterial substance, stimulated the expression of these three genes. Moreover, these genes were also induced by supplementing the culture with detergents. The induction of gene expression by surfactant or palmitate was not observed in a disruption mutant of the
sigB
gene, which encodes an alternative sigma factor involved in bacterial stress responses. Furthermore, each disruption mutant of the
essC
,
psiA
, and
hlgB
genes showed attenuation of both survival in the lung and host-killing ability in a murine pneumonia model. These findings suggest that
S. aureus
resists membrane stress caused by free fatty acids present in the pulmonary surfactant through the regulation of virulence gene expression, which contributes to its pathogenesis within the lungs of the host animal.
Genomic Portrait of the Evolution and Epidemic Spread of a Recently Emerged Multidrug-Resistant Shigella flexneri Clone in China
Authors: Zhang Nan , Lan Ruiting , Sun Qiangzheng , Wang Jianping , Wang Yiting , Zhang Jin , Yu Deshan , Hu Wanfu , Hu Shoukui , Dai Hang , Du Pengcheng , Wang Haiyin , Xu Jianguo 
Published: January 2014

ABSTRACT

Shigella flexneri
is the major cause of shigellosis in developing countries. A new
S. flexneri
serotype, Xv, appeared in 2000 and replaced serotype 2a as the most prevalent serotype in China. Serotype Xv is a variant of serotype X, with phosphoethanolamine modification of its O antigen mediated by a plasmid that contained the
opt
gene. Serotype Xv isolates belong to sequence type 91 (ST91). In this study, whole-genome sequencing of 59
S. flexneri
isolates of 14 serotypes (serotypes 1 to 4, Y, Yv, X, and Xv) indicated that ST91 arose around 1993 by acquiring multidrug resistance (MDR) and spread across China within a decade. A comparative analysis of the chromosome and
opt
-carrying plasmid pSFXv_2 revealed independent origins of 3 serotype Xv clusters in China, with different divergence times. Using 18 cluster-dividing single-nucleotide polymorphisms (SNPs), SNP typing divided 380 isolates from 3 provinces (Henan, Gansu, and Anhui) into 5 SNP genotypes (SGs). One SG predominated in each province, but substantial interregional spread of SGs was also evident. These findings suggest that MDR is the key selective pressure for the emergence of the
S. flexneri
epidemic clone and that
Shigella
epidemics in China were caused by a combination of local expansion and interregional spread of serotype Xv.
Detection of Campylobacter in Stool and Determination of Significance by Culture, Enzyme Immunoassay, and PCR in Developing Countries
Authors: Platts-Mills James A. , Liu Jie , Gratz Jean , Mduma Esto , Amour Caroline , Swai Ndealilia , Taniuchi Mami , Begum Sharmin , Peñataro Yori Pablo , Tilley Drake H. , Lee Gwenyth , Shen Zeli , Whary Mark T. , Fox James G. , McGrath Monica , Kosek Margaret , Haque Rashidul , Houpt Eric R. 
Published: January 2014

ABSTRACT

Campylobacter
is a common bacterial enteropathogen that can be detected in stool by culture, enzyme immunoassay (EIA), or PCR. We compared culture for
C. jejuni/C. coli
, EIA (ProSpecT), and duplex PCR to distinguish
Campylobacter jejuni/C. coli
and non-
jejuni/coli Campylobacter
on 432 diarrheal and matched control stool samples from infants in a multisite longitudinal study of enteric infections in Tanzania, Bangladesh, and Peru. The sensitivity and specificity of culture were 8.5% and 97.6%, respectively, compared with the results of EIA and 8.7% and 98.0%, respectively, compared with the results of PCR for
C. jejuni/C. coli
. Most (71.6%) EIA-positive samples were positive by PCR for
C. jejuni/C. coli
, but 27.6% were positive for non-
jejuni/coli Campylobacter
species. Sequencing of 16S rRNA from 53 of these non-
jejuni/coli Campylobacter
samples showed that it most closely matched the 16S rRNA of
C. hyointestinalis
subsp.
lawsonii
(56%),
C. troglodytis
(33%),
C. upsaliensis
(7.7%), and
C. jejuni/C. coli
(2.6%).
Campylobacter
-negative stool spiked with each of the above-mentioned
Campylobacter
species revealed reactivity with EIA. PCR detection of
Campylobacter
species was strongly associated with diarrhea in Peru (odds ratio [OR] = 3.66,
P
< 0.001) but not in Tanzania (OR = 1.56,
P
= 0.24) or Bangladesh (OR = 1.13,
P
= 0.75). According to PCR,
Campylobacter jejuni/C. coli
infections represented less than half of all infections with
Campylobacter
species. In sum, in infants in developing country settings, the ProSpecT EIA and PCR for
Campylobacter
reveal extremely high rates of positivity. We propose the use of PCR because it retains high sensitivity, can ascertain burden, and can distinguish between
Campylobacter
infections at the species level.
Concordance of PCR and Culture from Nasal Swabs for Detection of Methicillin-Resistant Staphylococcus aureus in a Setting of Concurrent Antistaphylococcal Antibiotics
Authors: Shenoy Erica S. , Noubary Farzad , Kim JiYeon , Rosenberg Eric S. , Cotter Jessica A. , Lee Hang , Walensky Rochelle P. , Hooper David C. 
Published: January 2014

ABSTRACT

The effect of concurrent administration of antibiotics on the detection of methicillin-resistant
Staphylococcus aureus
(MRSA) remains unresolved. Here, we assessed the concordance of paired nasal swabs processed using commercial PCR and culture and found high concordance in both the absence and presence of antibiotics with activity against MRSA (93.7% [95% confidence interval [CI], 88.1%, 96.8%] and 90.9% [95% CI, 84.8%, 94.7%], respectively), although PCR was more likely to be positive in the presence of antibiotics. (This study has been registered at
ClinicalTrials.gov
under registration no. NCT01234831.)
Phenotypic and Genotypic Characterization of Canadian Clinical Isolates of Vibrio parahaemolyticus Collected from 2000 to 2009
Authors: Banerjee Swapan K. , Kearney Ashley K. , Nadon Celine A. , Peterson Christy-Lynn , Tyler Kevin , Bakouche Laurene , Clark Clifford G. , Hoang Linda , Gilmour Matthew W. , Farber Jeffrey M. 
Published: January 2014

ABSTRACT

Vibrio parahaemolyticus
is the leading bacterial cause of food-borne illness due to the consumption of contaminated seafood. The aim of the present study was to determine the population of its subtypes and establish a better understanding of the various types of
V. parahaemolyticus
strains that are causing human illness in Canada. The subtypes for 100 human clinical isolates of
V. parahaemolyticus
collected between 2000 and 2009 were determined by performing serotyping, ribotyping, pulsed-field gel electrophoresis, and multilocus sequence typing. Within this panel of strains, there was a high level of diversity (between 22 and 53 subtypes per method), but the presence of predominant clones with congruent subtypes between the various methods was also observed. For example, all 32 isolates belonging to sequence type 36 (ST36) were from serogroup O4, while 31 of them were ribotype EcoVib235-287, and 24 of the 32 were SfiI pulsed-field gel electrophoresis (PFGE) pattern VPSF1.0001. With regard to the presence of known virulence genes, 74 of the 100 isolates were PCR positive for the presence of the thermostable direct hemolysin (
tdh
); and 59 of these 74 strains also contained the second virulence marker, the
tdh
-related hemolysin (
trh
). The detection of
trh
was more predominant (81%) among the clinical isolates, and only four (4%) of the clinical isolates tested negative for the presence of both
tdh
and
trh
. This database, comprising 100 clinical isolates of
V. parahaemolyticus
strains from Canada, forms a baseline understanding of subtype diversity for future source attribution and other epidemiologic studies.
Association of Herpes Simplex Virus pU
L
31 with Capsid Vertices and Components of the Capsid Vertex-Specific Complex
Authors: Yang Kui , Wills Elizabeth , Lim Han Young , Zhou Z. Hong , Baines Joel D. 
Published: January 2014

ABSTRACT

pU
L
34 and pU
L
31 of herpes simplex virus (HSV) comprise the nuclear egress complex (NEC) and are required for budding at the inner nuclear membrane. pU
L
31 also associates with capsids, suggesting it bridges the capsid and pU
L
34 in the nuclear membrane to initiate budding. Previous studies showed that capsid association of pU
L
31 was precluded in the absence of the C terminus of pU
L
25, which along with pU
L
17 comprises the capsid vertex-specific complex, or CVSC. The present studies show that the final 20 amino acids of pU
L
25 are required for pU
L
31 capsid association. Unexpectedly, in the complete absence of pU
L
25, or when pU
L
25 capsid binding was precluded by deletion of its first 50 amino acids, pU
L
31 still associated with capsids. Under these conditions, pU
L
31 was shown to coimmunoprecipitate weakly with pU
L
17. Based on these data, we hypothesize that the final 20 amino acids of pU
L
25 are required for pU
L
31 to associate with capsids. In the absence of pU
L
25 from the capsid, regions of capsid-associated pU
L
17 are bound by pU
L
31. Immunogold electron microscopy revealed that pU
L
31 could associate with multiple sites on a single capsid in the nucleus of infected cells. Electron tomography revealed that immunogold particles specific to pU
L
31 protein bind to densities at the vertices of the capsid, a location consistent with that of the CVSC. These data suggest that pU
L
31 loads onto CVSCs in the nucleus to eventually bind pU
L
34 located within the nuclear membrane to initiate capsid budding.

IMPORTANCE
This study is important because it localizes pU
L
31, a component previously known to be required for HSV capsids to bud through the inner nuclear membrane, to the vertex-specific complex of HSV capsids, which comprises the unique long region 25 (U
L
25) and U
L
17 gene products. It also shows this interaction is dependent on the C terminus of U
L
25. This information is vital for understanding how capsids bud through the inner nuclear membrane.
Evidence of
In Utero
Transmission of Classical Scrapie in Sheep
Authors: Spiropoulos John , Hawkins Stephen A. C. , Simmons Marion M. , Bellworthy Susan J. 
Published: January 2014

ABSTRACT

Classical scrapie is one of the transmissible spongiform encephalopathies (TSEs), a group of fatal infectious diseases that affect the central nervous system (CNS). Classical scrapie can transmit laterally from ewe to lamb perinatally or between adult animals. Here we report detection of infectivity in tissues of an unborn fetus, providing evidence that
in utero
transmission of classical scrapie is also possible.
Relocation of the NIb Gene in the Tobacco Etch Potyvirus Genome
Authors: Majer Eszter , Salvador Zaira , Zwart Mark P. , Willemsen Anouk , Elena Santiago F. , Daròs José-Antonio 
Published: January 2014

ABSTRACT

Potyviruses express most of their proteins from a long open reading frame that is translated into a large polyprotein processed by three viral proteases. To understand the constraints on potyvirus genome organization, we relocated the viral RNA-dependent RNA polymerase (NIb) cistron to all possible intercistronic positions of the
Tobacco etch virus
(TEV) polyprotein. Only viruses with NIb at the amino terminus of the polyprotein or in between P1 and HC-Pro were viable in tobacco plants.
Stability of the Parainfluenza Virus 5 Genome Revealed by Deep Sequencing of Strains Isolated from Different Hosts and following Passage in Cell Culture
Authors: Rima Bert K. , Gatherer Derek , Young Daniel F. , Norsted Hanna , Randall Richard E. , Davison Andrew J. 
Published: January 2014

ABSTRACT
The strain diversity of a rubulavirus, parainfluenza virus 5 (PIV5), was investigated by comparing 11 newly determined and 6 previously published genome sequences. These sequences represent 15 PIV5 strains, of which 6 were isolated from humans, 1 was from monkeys, 2 were from pigs, and 6 were from dogs. Strain diversity is remarkably low, regardless of host, year of isolation, or geographical origin; a total of 7.8% of nucleotides are variable, and the average pairwise difference between strains is 2.1%. Variation is distributed unevenly across the PIV5 genome, but no convincing evidence of selection for antibody-mediated evasion in hemagglutinin-neuraminidase was found. The finding that some canine and porcine, but not primate, strains are mutated in the SH gene, and do not produce SH, raised the possibility that dogs (or pigs) may not be the natural host of PIV5. The genetic stability of PIV5 was also demonstrated during serial passage of one strain (W3) in Vero cells at a high multiplicity of infection, under conditions of competition with large proportions of defective interfering genomes. A similar observation was made for a strain W3 mutant (PIV5VΔC) lacking V gene function, in which the dominant changes were related to pseudoreversion in this gene. The mutations detected in PIV5VΔC during pseudoreversion, and also those characterizing the SH gene in canine and porcine strains, predominantly involved U-to-C transitions. This suggests an important role for biased hypermutation via an adenosine deaminase, RNA-specific (ADAR)-like activity.

IMPORTANCE
Here we report the sequence variation of 16 different isolates of parainfluenza virus 5 (PIV5) that were isolated from a number of species, including humans, monkeys, dogs, and pigs, over 4 decades. Surprisingly, strain diversity was remarkably low, regardless of host, year of isolation, or geographical origin. Variation was distributed unevenly across the PIV5 genome, but no convincing evidence of immune or host selection was found. This overall genome stability of PIV5 was also observed when the virus was grown in the laboratory, and the genome stayed remarkably constant even during the selection of virus mutants. Some of the canine isolates had lost their ability to encode one of the viral proteins, termed SH, suggesting that although PIV5 commonly infects dogs, dogs may not be the natural host for PIV5.
Caring at the end of life: do cancer caregivers differ from other caregivers?
Authors: Girgis Afaf , Abernethy Amy P , Currow David C 
Published: January 2014

ObjectiveCancer is one of the most common health conditions in receipt of informal caregiving. This study compares key characteristics of caregivers who cared for someone with cancer until death with caregivers of people with other life-limiting illnesses and their care recipients irrespective of health service utilisation.MethodData were analysed from annual state-wide South Australian Health Omnibus Surveys (2000–2007) involving 14 624 respondents, regarding end of life care. Descriptive and comparative data are presented.ResultsAlmost a third of respondents (32%; participation rate 72%) had someone close to them die from an ‘expected’ death in the preceding 5 years. One in 10 (10%) respondents reported providing hands-on care predominantly for someone with cancer. Compared with non-cancer caregivers, cancer caregivers cared for someone who was significantly younger (mean age 66 (95% CI 64 to 67) years vs 74 (95% CI 72 to 77) years; one-way analysis of variance p<0.0001) and were more likely to report having a hospice/palliative care service involved in the care of the deceased (65% (95% CI 63 to 67) compared with 39% (95% CI 37 to 42). In the Australian context, this may mean contact with inpatient, outpatient and community-based services.There were no differences between the needs which caregivers perceived to be unmet or the perceptions that no additional supports were required between the two groups.ConclusionsInformal caregivers perform a critical social and economic role in care provision. Cancer caregivers are a proportionally larger cohort than non-cancer caregivers. With the increasing incidence of cancer, the sustainability of a voluntary cancer caregiving workforce will be reliant upon minimising the burden of care.
Superior outcomes for military ankylosing spondylitis patients treated with anti-TNF
Authors: Rees Jonathan D , Bennett A N , Harris D , Jones T 
Published: January 2014

ObjectivesThe British military has a cohort of patients with ankylosing spondylitis (AS) characterised by young age and short disease duration. Many of the most severely affected AS patients have been treated since 2005 at Headley Court with anti-tumour necrosis factor (anti-TNF) therapy in accordance with National Institute of Health and Care Excellence guidance. We wanted to prospectively determine both the safety and efficacy of this new treatment in our British military population and compare this with relevant civilian study outcome data.MethodsAll AS patients commenced on anti-TNF therapy at Headley Court were prospectively monitored for treatment efficacy and side effects. Outcome measures used included the Bath Ankylosing Spondylitis Disease Activity Index. Our results were compared with a civilian comparison group (NHS) and relevant landmark clinical trial data.ResultsOur patients were younger (mean age 34.7 years) and had a shorter duration (mean disease duration 6.9 years) than the civilian (NHS) comparison group. Our safety data were extremely benign with only two patients suffering minor side effects (local injection site reaction). Furthermore, our outcome data were superior to both NHS routine care and to landmark clinical studies.DiscussionPrior to this study, there were no data on military AS populations receiving anti-TNF therapy. The study confirms British military patients tolerate this therapy extremely well and receive greater benefit from this treatment than that seen in any published study to date. We believe that this confirms that young age and short disease duration are good prognostic factors in the treatment of AS with anti-TNF therapy.