bluuebunny/crossref_metadata_2025_split huggingface dataset:
The megaplasmid pCER270 of
Bacillus cereus
emetic strain affects the timing of the sporulation process, spore resistance properties, and germination
Authors: Perchat Stéphane , Nevers Alicia , Kranzler Markus , Ehling-Schulz Monika , Lereclus Didier , Gohar Michel 
Published: August 2024

ABSTRACT

The
Bacillus cereus
group includes closely related spore-forming Gram-positive bacteria. In this group, plasmids play a crucial role in species differentiation and are essential for pathogenesis and adaptation to ecological niches. The
B. cereus
emetic strains are characterized by the presence of the pCER270 megaplasmid, which encodes the non-ribosomal peptide synthetase for the production of cereulide, the emetic toxin. This plasmid carries several genes that may be involved in the sporulation process. Furthermore, a transcriptomic analysis has revealed that pCER270 influences the expression of chromosome genes, particularly under sporulation conditions. In this study, we investigated the role of pCER270 on spore properties in different species of the
B. cereus
group. We showed that pCER270 plays a role in spore wet heat resistance and germination, with varying degrees of impact depending on the genetic background. In addition, pCER270 ensures that sporulation occurs at the appropriate time by delaying the expression of sporulation genes. This regulation of sporulation timing is controlled by the pCER270-borne Rap-Phr system, which likely regulates the phosphorylation state of Spo0A. Acquisition of the pCER270 plasmid by new strains could give them an advantage in adapting to new environments and lead to the emergence of new pathogenic strains.

IMPORTANCE

The acquisition of new mobile genetic elements, such as plasmids, is essential for the pathogenesis and adaptation of bacteria belonging to the
Bacillus cereus
group. This can confer new phenotypic traits and beneficial functions that enable bacteria to adapt to changing environments and colonize new ecological niches. Emetic
B. cereus
strains cause food poisoning linked to the production of cereulide, the emetic toxin whose synthesis is due to the presence of plasmid pCER270. In the environment, cereulide provides a competitive advantage in producing bacteria against various competitors or predators. This study demonstrates that pCER270 also regulates the sporulation process, resulting in spores with improved heat resistance and germination capacity. The transfer of plasmid pCER270 among different strains of the
B. cereus
group may enhance their adaptation to new environments. This raises the question of the emergence of new pathogenic strains, which could pose a serious threat to human health.
Nitrate assimilation compensates for cell wall biosynthesis in the absence of
Aspergillus fumigatus
phosphoglucose isomerase
Authors: Gong Xiufang , Zhou Yao , Qin Qijian , Wang Bin , Wang Linqi , Jin Cheng , Fang Wenxia 
Published: August 2024

ABSTRACT

Phosphoglucose isomerase (PGI) links glycolysis, the pentose phosphate pathway (PPP), and the synthesis of cell wall precursors in fungi by facilitating the reversible conversion between glucose-6-phosphate (Glc6p) and fructose-6-phosphate (Fru6P). In a previous study, we established the essential role of PGI in cell wall biosynthesis in the opportunistic human fungal pathogen
Aspergillus fumigatus
, highlighting its potential as a therapeutic target. In this study, we conducted transcriptomic analysis and discovered that the Δ
pgi
mutant exhibited enhanced glycolysis, reduced PPP, and an upregulation of cell wall precursor biosynthesis pathways. Phenotypic analysis revealed defective protein
N
-glycosylation in the mutant, notably the absence of glycosylated virulence factors DPP V and catalase 1. Interestingly, the cell wall defects in the mutant were not accompanied by activation of the MpkA-dependent cell wall integrity (CWI) signaling pathway. Instead, nitrate assimilation was activated in the Δ
pgi
mutant, stimulating glutamine synthesis and providing amino donors for chitin precursor biosynthesis. Blocking the nitrate assimilation pathway severely impaired the growth of the Δ
pgi
mutant, highlighting the crucial role of nitrate assimilation in rescuing cell wall defects. This study unveils the connection between nitrogen assimilation and cell wall compensation in
A. fumigatus
.

IMPORTANCE

Aspergillus fumigatus
is a common and serious human fungal pathogen that causes a variety of diseases. Given the limited availability of antifungal drugs and increasing drug resistance, it is imperative to understand the fungus’ survival mechanisms for effective control of fungal infections. Our previous study highlighted the essential role of
A. fumigatus
PGI in maintaining cell wall integrity, phosphate sugar homeostasis, and virulence. The present study further illuminates the involvement of PGI in protein
N
-glycosylation. Furthermore, this research reveals that the nitrogen assimilation pathway, rather than the canonical MpkA-dependent CWI pathway, compensates for cell wall deficiencies in the mutant. These findings offer valuable insights into a novel adaptation mechanism of
A. fumigatus
to address cell wall defects, which could hold promise for the treatment of infections.
Practical Guidance for Clinical Microbiology Laboratories: Updated guidance for processing respiratory tract samples from people with cystic fibrosis
Authors: Saiman Lisa , Waters Valerie , LiPuma John J. , Hoffman Lucas R. , Alby Kevin , Zhang Sean X. , Yau Yvonne C. , Downey Damian G. , Sermet-Gaudelus Isabelle , Bouchara Jean-Philippe , Kidd Timothy J. , Bell Scott C. , Brown A. Whitney 
Published: August 2024

SUMMARY

This guidance presents recommendations for clinical microbiology laboratories for processing respiratory samples from people with cystic fibrosis (pwCF). Appropriate processing of respiratory samples is crucial to detect bacterial and fungal pathogens, guide treatment, monitor the epidemiology of cystic fibrosis (CF) pathogens, and assess therapeutic interventions. Thanks to CF transmembrane conductance regulator modulator therapy, the health of pwCF has improved, but as a result, fewer pwCF spontaneously expectorate sputum. Thus, the collection of sputum samples has decreased, while the collection of other types of respiratory samples such as oropharyngeal and bronchoalveolar lavage samples has increased. To optimize the detection of microorganisms, including
Pseudomonas aeruginosa
,
Staphylococcus aureus
,
Haemophilus influenzae
, and
Burkholderia cepacia
complex; other less common non-lactose fermenting Gram-negative bacilli, e.g.,
Stenotrophomonas maltophilia
,
Inquilinus
,
Achromobacter
,
Ralstonia
, and
Pandoraea
species; and yeasts and filamentous fungi, non-selective and selective culture media are recommended for all types of respiratory samples, including samples obtained from pwCF after lung transplantation. There are no consensus recommendations for laboratory practices to detect, characterize, and report small colony variants (SCVs) of
S. aureus
, although studies are ongoing to address the potential clinical impact of SCVs. Accurate identification of less common Gram-negative bacilli, e.g.,
S. maltophilia
,
Inquilinus
,
Achromobacter
,
Ralstonia
, and
Pandoraea
species, as well as yeasts and filamentous fungi, is recommended to understand their epidemiology and clinical importance in pwCF. However, conventional biochemical tests and automated platforms may not accurately identify CF pathogens. MALDI-TOF MS provides excellent genus-level identification, but databases may lack representation of CF pathogens to the species-level. Thus, DNA sequence analysis should be routinely available to laboratories for selected clinical circumstances. Antimicrobial susceptibility testing (AST) is not recommended for every routine surveillance culture obtained from pwCF, although selective AST may be helpful, e.g., for unusual pathogens or exacerbations unresponsive to initial therapy. While this guidance reflects current care paradigms for pwCF, recommendations will continue to evolve as CF research expands the evidence base for laboratory practices.
NLRP3 inflammasome inhibition decreases
Schistosomiasis japonica
-induced granulomatous inflammation and fibrosis in BALB/c mice
Authors: Lu Yaqi , Liu Jing , Tang Wangxian , Zhang Heng 
Published: August 2024

ABSTRACT

To research the role of the NLRP3 inflammasome in
Schistosoma japonicum
-induced granuloma formation and liver fibrosis. In
in vivo
tests, BALB/c mice were used. shNLRP3 plasmid based on adeno-associated virus serotype 8 (AAV8-shNLRP3) was injected to block NLRP3 inflammasome via tail vein. Serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were detected to assess liver injury. H&E staining was used for routine histopathological assessment; Masson’s trichrome staining was used to detect fibrous tissues and collagen fibers. Hepatic expression of NLRP3, procaspase-1, bioactive caspase-1, collagen-1, tissue inhibitor of metalloproteinases-1 (TIMP-1), and α-smooth muscle actin (α-SMA) were detected by western blot. Serum levels of IL-1β were detected by enzyme-linked immunosorbent assay (ELISA). The inflammatory cell infiltration and hepatic expression of IL-1β around the granuloma were detected by immunohistochemistry staining. Treatment of
S. japonicum
infected mice with AAV8-shNLRP3 significantly reduced the hepatic levels of bioactive caspase-1 and IL-1β, as well as circulating IL-1β concentrations, while reducing the amounts of myeloperoxidase (MPO) and F4/80 positive cells around the granuloma. Moreover, collagen deposition, TIMP-1, and α-SMA, which are markers of hepatic stellate cell (HSC) activation, were reduced around the liver granuloma. These findings highlight a therapeutic potential of AAV8-shNLRP3 in schistosomiasis cirrhosis.
The CpxAR signaling system confers a fitness advantage for flea gut colonization by the plague bacillus
Authors: Robin Brandon , Dewitte Amélie , Alaimo Véronique , Lecoeur Cecile , Pierre François , Billon Gabriel , Sebbane Florent , Bontemps-Gallo Sébastien 
Published: August 2024

ABSTRACT

The adaptation of
Yersinia pestis
, the flea-borne plague agent, to fluctuating environmental conditions is essential for the successful colonization of the flea vector. A previous comparative transcriptomic analysis showed that the Cpx pathway of
Y. pestis
is up-regulated in infected fleas. The CpxAR two-component system is a component of the envelope stress response and is critical for maintaining the integrity of the cell. Here, a phenotypic screening revealed a survival defect of the
cpxAR
mutant to oxidative stress and copper. The measured copper concentration in the digestive tract contents of fed fleas increased fourfold during the digestive process. By direct analysis of phosphorylation of CpxR by a Phos-Tag gel approach, we demonstrated that biologically relevant concentrations of copper triggered the system. Then, a competitive challenge highlighted the role of the CpxAR system in bacterial fitness during flea infection. Lastly, an
in vitro
sequential exposure to copper and then H
2
O
2
to mimic the flea suggests a model in which, within the insect digestive tract, the CpxAR system would be triggered by copper, establishing an oxidative stress response.

IMPORTANCE

The bacterium
Yersinia pestis
is the agent of flea-borne plague. Our knowledge of the mechanisms used by the plague bacillus to infect the flea vector is limited. The up-regulation of the envelope stress response under the control of the Cpx signaling pathway was previously shown in a transcriptomic study. Here, our
in vivo
and
in vitro
approaches suggest a model in which
Y. pestis
uses the CpxAR phosphorelay system to sense and respond to the copper present in the flea gut, thereby optimizing the flea gut colonization. In other words, the system is essential for bacterial fitness in the flea.
A spike-based mRNA vaccine that induces durable and broad protection against porcine deltacoronavirus in piglets
Authors: Li Jizong , Xiao Li , Chen Zhuoqi , Fan Liyuan , Wang Wei , Guo Rongli , He Zhaoming , Hu Hongpeng , Jiang Jianhao , Zhao Lixiang , Zhong Tianyi , Fan Baochao , Zhu Xing , Li Bin 
Published: August 2024

ABSTRACT

Coronaviruses (CoVs) are important pathogens for humans and other vertebrates, causing severe respiratory and intestinal infections that have become a threat to public health because of the potential for interspecies transmission between animals and humans. Therefore, the development of safe, effective vaccines remains a top priority for the control of CoV infection. The unique immunological characteristics of vaccines featuring messenger RNA (mRNA) present an advantageous tool for coronavirus vaccine development. Here, we designed two lipid nanoparticle (LNP)-encapsulated mRNA (mRNA-LNP) vaccines: one encoding full-length spike (S) protein and the other encoding the spike ectodomain (Se) from porcine deltacoronavirus (PDCoV). Fourteen days after primary immunization, both mRNA vaccines induced high levels of immunoglobulin G and neutralizing antibodies in mice, with the S vaccine showing better performance than the Se vaccine. Passive immune protection of the S mRNA vaccine in suckling piglets was confirmed by the induction of robust PDCoV-specific humoral and cellular immune responses. The S mRNA vaccine also showed better protective effects than the inactivated vaccine. Our results suggest that the novel PDCoV-S mRNA-LNP vaccine may have the potential to combat PDCoV infection.

IMPORTANCE
As an emerging porcine enteropathogenic coronavirus, porcine deltacoronavirus (PDCoV) has the potential for cross-species transmission, attracting extensive attention. Messenger RNA (mRNA) vaccines are a promising option for combating emerging and re-emerging infectious diseases, as evidenced by the demonstrated efficacy of the COVID-19 mRNA vaccine. Here, we first demonstrated that PDCoV-S mRNA-lipid nanoparticle (LNP) vaccines could induce potent humoral and cellular immune responses in mice. An evaluation of passive immune protection of S mRNA vaccines in suckling piglets confirmed that the protective effect of mRNA vaccine was better than that of inactivated vaccine. This study suggests that the PDCoV-S mRNA-LNP vaccine may serve as a potential and novel vaccine candidate for combating PDCoV infection.
Phenotypic and genomic analysis of the hypervirulent methicillin-resistant
Staphylococcus aureus
ST630 clone in China
Authors: Shi Junhong , Xiao Yanghua , Shen Li , Wan Cailing , Wang Bingjie , Zhou Peiyao , Zhang Jiao , Han Weihua , Yu Fangyou 
Published: August 2024

ABSTRACT

Methicillin-resistant
Staphylococcus aureus
(MRSA) sequence type 630 (ST630) is a rarely reported lineage worldwide. This study aimed to trace the dissemination of the emerging MRSA ST630 clones in China and investigate their virulence potential. We collected 22 ST630-MRSA isolates from across China and performed whole-genome sequencing analysis and virulence characterization on these isolates. Epidemiological results showed that MRSA ST630 isolates were primarily isolated from pus/wound secretions, mainly originating from Jiangxi province, and carried diverse virulence and drug resistance genes. Staphylococcal cassette chromosome mec type V (SCCmec V) predominated (11/22, 50.0%) among the MRSA ST630 isolates. Interestingly, nearly half (45.5%) of the 22 ST630-MRSA isolates tested lacked intact SCCmec elements. Phylogenetic analysis demonstrated that ST630-MRSA could be divided into two distinct clades, with widespread dissemination mainly in Chinese regions. Five representative isolates were selected for phenotypic assays, including hemolysin activity, real-time fluorescence quantitative PCR, western blot analysis, hydrogen peroxide killing assay, blood killing assay, cell adhesion and invasion assay, and mouse skin abscess model. The results showed that, compared to the USA300-LAC strain, ST630 isolates exhibited particularly strong invasiveness and virulence in the aforementioned phenotypic assays. This study described the emergence of a highly virulent ST630-MRSA lineage and improved our insight into the molecular epidemiology of ST630 clones in China.

IMPORTANCE

Methicillin-resistant
Staphylococcus aureus
(MRSA) sequence type 630 (ST630) is an emerging clone with an increasing isolation rate in China. This study raises awareness of the hypervirulent MRSA ST630 clones in China and alerts people to their widespread dissemination. ST630-staphylococcal cassette chromosome mec V is a noteworthy clone in China, and we present the first comprehensive genetic and phenotypic analysis of this lineage. Our findings provide valuable insights for the prevention and control of infections caused by this emerging MRSA clone.
Molecular detection using hybridization capture and next-generation sequencing reveals cross-species transmission of feline coronavirus type-1 between a domestic cat and a captive wild felid
Authors: Olarte-Castillo Ximena A. , Goodman Laura B. , Whittaker Gary R. 
Published: August 2024

ABSTRACT

Feline coronavirus (FCoV) infection normally causes mild or subclinical signs and is common in domestic cats. However, in some cats, FCoV infection can also lead to the development of feline infectious peritonitis (FIP)—a typically lethal disease. FCoV has two serotypes or genotypes, FCoV-1 and FCoV-2, both of which can cause FIP. The main difference between the genotypes is the viral spike (S) protein that determines tropism and pathogenicity, crucial mechanisms in the development of FIP. Subclinical infection and FIP have both been reported in wild felids, including in threatened species. Due to the high genetic variability of the S gene and the technical challenges to sequencing it, detection and characterization of FCoV in wild felids have mainly centered on other more conserved genes. Therefore, the genotype causing FIP in most wild felids remains unknown. Here, we report a retrospective molecular epidemiological investigation of FCoV in a zoological institution in the U.Ss. In 2008, a domestic cat (
Felis catus
) and a Pallas’ cat (
Otocolobus manul
) sharing the same room succumbed to FIP. Using
in situ
hybridization, we detected FCoV RNA in different tissues of both felids. Using hybridization capture and next-generation sequencing, we detected, sequenced, and characterized the whole genome of the FCoV infecting both felids. Our data show for the first time that FCoV-1 can be transmitted between domestic and wild felids and extends the known host range of FCoV-1. Our findings highlight the importance of identifying the genotype causing FIP, to develop effective control measures.

IMPORTANCE
Feline coronavirus (FCoV) is highly prevalent in domestic cats worldwide and has also been reported in wild felids, including endangered species, in which it has caused substantial population declines. Characterizing the genetic diversity of FCoV is crucial due to recent reports of novel pathogenic recombinant variants causing high mortality in feral cats in Cyprus. In this retrospective molecular epidemiology study, we used archived samples collected in a zoological institution in the U.S. in which a domestic and a wild felid succumbed to FCoV. Using hybridization capture (HC) and next-generation sequencing, we show for the first time that FCoV can be naturally transmitted between domestic and wild felids. We demonstrate the efficacy of HC for detecting and sequencing the whole genome of FCoV, which is essential to characterize its different genotypes.
Reattachment rate with pneumatic retinopexy versus pars plana vitrectomy for single break rhegmatogenous retinal detachment
Authors: Pecaku Aurora , Martins Melo Isabela , Shor Reut , Francisconi Carolina L M , Marafon Samara Barbara , Chaudhary Varun , Hillier Roxane Jo , Muni Rajeev H 
Published: August 2024

Aim
To assess the primary reattachment rate (PARR) in pneumatic retinopexy (PnR) versus pars plana vitrectomy (PPV) for rhegmatogenous retinal detachment (RRD) meeting the Pneumatic Retinopexy versus Vitrectomy for the Management of Primary Rhegmatogenous Retinal Detachment Outcomes Randomised Trial (PIVOT) criteria with a single break in detached retina.

Methods
A post hoc analysis of two clinical trials. To be included, patients with primary RRD had to meet PIVOT criteria but could have only one break in the detached retina. Patients with additional pathology in the attached retina were included in a secondary analysis. The primary outcome was PARR following PnR versus PPV at 1-year postoperatively.

Results
162 patients were included. 53% (86/162) underwent PnR and 47% (76/162) had a PPV. 99% (85/86) and 86.8% (66/76) completed the 1-year follow-up visits in the PnR and PPV groups, respectively. PARR was 88.2% (75/85) in the PnR group and 90.9% (60/66) in the PPV group (p=0.6) with a mean postoperative logMAR best-corrected visual acuity of 0.19±0.25 versus 0.34±0.37 (Snellen 20/30 vs 20/44) (p=0.01) each in the PnR and PPV groups, respectively.
In an additional analysis of patients who were also allowed to have any pathology in the attached retina, the PARR was 85% (91/107) and 91.6% (66/72) in the PnR and PPV groups, respectively (p=0.18).

Conclusions
PnR and PPV provide similar long-term PARR in a substantial proportion of patients meeting PIVOT criteria with only a single break in the detached retina. Therefore, in patients meeting these specific criteria, PnR is an appropriate first-line therapy as it offers superior functional outcomes without compromising PARR.
Digital training for self-injectable contraceptives: a feasibility and acceptability pilot study
Authors: Mills Rhiana , Krong Rapha , Kithinji Fiona , Baraitser Paula 
Published: August 2024

BackgroundSelf-injectable contraceptives, namely subcutaneous depot medroxyprogesterone acetate 104 mg micronised formulation delivered via uniject system, reduce the need to travel to a facility for contraceptive access, but the initial, in-person, training may be a barrier to starting this method. This article reports on a small, exploratory pilot in Kenya to test the feasibility and acceptability of digital self-injection training.MethodsParticipants (n=11) who were currently using injectable contraceptives, intramuscular depot medroxyprogesterone acetate 150 mg injected by a healthcare worker, received digital self-injection training from a trained clinician via a WhatsApp video call. Participants administered a simulated self-injection on a model and an actual self-injection (under supervision) on themselves. The participants’ self-injection proficiency, a measure of the feasibility of remote training, was documented using a checklist, and participants were administered a questionnaire about their training experience. The training was observed, and content analysis was used to understand the functionality of training.ResultsAll participants were proficient when performing the self-injection on themselves after receiving the remote training and reported that the training was acceptable. A barrier to training via a video call was lack of access to quality digital devices. Eight training ‘lessons learnt’ emerged from the training observations.ConclusionsTraining participants to administer self-injectable contraceptives via WhatsApp video call was feasible and acceptable. Training lessons learnt offer pragmatic adaptations for communicating about a practical skill via a digital channel. Further research is needed to ascertain the efficacy of digital training for self-injection and feasibility and acceptability for wider groups.