scholarly journals Physiological Differences in Cryptococcus neoformans Strains In Vitro versus In Vivo and Their Effects on Antifungal Susceptibility

2016 ◽  
Vol 61 (3) ◽  
Author(s):  
Nina T. Grossman ◽  
Arturo Casadevall
Keyword(s):  
Cryptococcus Neoformans ◽  
Cryptococcal Meningitis ◽  
Antifungal Susceptibility ◽  
Sub Saharan Africa ◽  
Content Type ◽  
Laboratory Conditions ◽  
Physiological Differences ◽  
Sub Saharan

ABSTRACT Cryptococcus neoformans is an environmentally ubiquitous fungal pathogen that primarily causes disease in people with compromised immune systems, particularly those with advanced AIDS. There are estimated to be almost 1 million cases per year of cryptococcal meningitis in patients infected with human immunodeficiency virus, leading to over 600,000 annual deaths, with a particular burden in sub-Saharan Africa. Amphotericin B (AMB) and fluconazole (FLC) are key components of cryptococcal meningitis treatment: AMB is used for induction, and FLC is for consolidation, maintenance and, for occasional individuals, prophylaxis. However, the results of standard antifungal susceptibility testing (AFST) for AMB and FLC do not correlate well with therapeutic outcomes and, consequently, no clinical breakpoints have been established. While a number of explanations for this absence of correlation have been proffered, one potential reason that has not been adequately explored is the possibility that the physiological differences between the in vivo infection environment and the in vitro AFST environment lead to disparate drug susceptibilities. These susceptibility-influencing factors include melanization, which does not occur during AFST, the size of the polysaccharide capsule, which is larger in infecting cells than in those grown under normal laboratory conditions, and the presence of large polyploid “titan cells,” which rarely occur under laboratory conditions. Understanding whether and how C. neoformans differentially expresses mechanisms of resistance to AMB and FLC in the AFST environment compared to the in vivo environment could enhance our ability to interpret AFST results and possibly lead to the development of more applicable testing methods.

scholarly journals In Vitro, Ex Vivo, and In Vivo Activities of Diamidines against Trypanosoma congolense and Trypanosoma vivax

2017 ◽  
Vol 61 (5) ◽  
Author(s):  
Kirsten Gillingwater ◽  
Christina Kunz ◽  
Christiane Braghiroli ◽  
David W. Boykin ◽  
Richard R. Tidwell ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Trypanosoma Congolense ◽  
Tsetse Fly ◽  
Sub Saharan Africa ◽  
Content Type ◽  
Lead Compounds ◽  
Single Bolus Dose ◽  
Sub Saharan

ABSTRACT African animal trypanosomosis (AAT) is caused by the tsetse fly-transmitted protozoans Trypanosoma congolense and T. vivax and leads to huge agricultural losses throughout sub-Saharan Africa. Three drugs are available to treat nagana in cattle (diminazene diaceturate, homidium chloride, and isometamidium chloride). With increasing reports of drug-resistant populations, new molecules should be investigated as potential candidates to combat nagana. Dicationic compounds have been demonstrated to have excellent efficacy against different kinetoplastid parasites. This study therefore evaluated the activities of 37 diamidines, using in vitro and ex vivo drug sensitivity assays. The 50% inhibitory concentrations obtained ranged from 0.007 to 0.562 μg/ml for T. congolense and from 0.019 to 0.607 μg/ml for T. vivax. On the basis of these promising results, 33 of these diamidines were further examined using in vivo mouse models of infection. Minimal curative doses of 1.25 mg/kg of body weight for both T. congolense- and T. vivax-infected mice were seen when the diamidines were administered intraperitoneally (i.p.) over 4 consecutive days. From these observations, 15 of these 33 diamidines were then further tested in vivo, using a single bolus dose for administration. The total cure of mice infected with T. congolense and T. vivax was seen with single i.p. doses of 5 and 2.5 mg/kg, respectively. This study identified a selection of diamidines which could be considered lead compounds for the treatment of nagana.

scholarly journals High Prevalence of HIV-Related Cryptococcosis and Increased Resistance to Fluconazole of the Cryptococcus neoformans Complex in Jiangxi Province, South Central China

2021 ◽  
Vol 11 ◽  
Author(s):  
Chunxi Yang ◽  
Zeyuan Bian ◽  
Oliver Blechert ◽  
Fengyi Deng ◽  
Hui Chen ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Mating Type ◽  
Severe Disease ◽  
Antifungal Susceptibility ◽  
Central China ◽  
Sub Saharan Africa ◽  
Jiangxi Province ◽  
South Central ◽  
Sub Saharan

BackgroundCryptococcosis is caused by a fungi of the Cryptococcus neoformans/Cryptococcus gattii complex and is a severe concern for public health worldwide. C. neoformans species are globally distributed, and C. gattii species are mostly found in America, Australia, and Sub-Saharan Africa. Cryptococcus usually infects an immunocompromised population; however, the majority of cryptococcosis in China has been reported in patients without any recognizable immunosuppression, i.e., HIV infection. To date, very few studies investigated this disease in South Central China.MethodsThe present study recruited 230 clinically suspected cryptococcosis cases in the last 5 years at two hospitals in Jiangxi Province, South Central China. All isolated strains were subjected to multilocus sequence typing (MLST) and phylogenetic analysis. Serotype and mating type were assessed by PCR, in vitro antifungal susceptibility was assessed by the CLSI-M27-A3 protocol.ResultsA total of 230 patients were identified as infected by C. neoformans, including 12 cases with Talaromyces marneffei coinfection. All seven MLST markers were successfully amplified and used to identify the ST genotype in 199 strains. C. gattii strains were not detected. In contrast to previous studies, 59.3% of the patients had an immunocompromised status, and 61.9% of these patients were infected with HIV. All isolates manifested serotype A and mating type α. The ST5 genotype was common (89.5%) in the Jiangxi region, and three novel genotypes (ST656, ST657, and ST658 in six isolates) were detected in the present study. A total of 86 of the isolates (43.2%) were not sensitive to fluconazole at a MIC50 ≥ 8 μg/ml, most of the isolates were resistant to amphotericin B, and nearly all isolates were resistant to itraconazole and posaconazole. Resistances to 5-Flucytosine and voriconazole were very rare.ConclusionsThe results of the present study indicated that C. neoformans is the predominant species for cryptococcosis in Jiangxi Province, and a large proportion of the strains were not sensitive to fluconazole, which may be related to treatment failure and relapse. A high percentage of HIV-related C. neoformans infections was reported in Jiangxi, supporting a previous hypothesis that cryptococcosis is more frequent among the HIV-infected population in China. Continuous monitoring of species distribution and antifungal sensitivity is important for the investigation of this severe disease in the Jiangxi region.

scholarly journals Schistosoma mansoni eggs induce Wnt/β-catenin signaling and activate the protooncogene c-Jun in human and hamster colon

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Jakob Weglage ◽  
Friederike Wolters ◽  
Laura Hehr ◽  
Jakob Lichtenberger ◽  
Celina Wulz ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Colorectal Carcinogenesis ◽  
Sub Saharan Africa ◽  
Interleukin 4 ◽  
Health Burden ◽  
Sub Saharan ◽  
Considerable Morbidity ◽  
First Time

AbstractSchistosomiasis (bilharzia) is a neglected tropical disease caused by parasitic flatworms of the genus Schistosoma, with considerable morbidity in parts of the Middle East, South America, Southeast Asia, in sub-Saharan Africa, and particularly also in Europe. The WHO describes an increasing global health burden with more than 290 million people threatened by the disease and a potential to spread into regions with temperate climates like Corsica, France. The aim of our study was to investigate the influence of S. mansoni infection on colorectal carcinogenic signaling pathways in vivo and in vitro. S. mansoni infection, soluble egg antigens (SEA) and the Interleukin-4-inducing principle from S. mansoni eggs induce Wnt/β-catenin signaling and the protooncogene c-Jun as well as downstream factor Cyclin D1 and markers for DNA-damage, such as Parp1 and γH2a.x in enterocytes. The presence of these characteristic hallmarks of colorectal carcinogenesis was confirmed in colon biopsies from S. mansoni-infected patients demonstrating the clinical relevance of our findings. For the first time it was shown that S. mansoni SEA may be involved in the induction of colorectal carcinoma-associated signaling pathways.

scholarly journals Sulfamethoxazole Susceptibility of Mycobacterium tuberculosis Isolates from HIV-Infected Ugandan Adults with Tuberculosis Taking Trimethoprim-Sulfamethoxazole Prophylaxis

2015 ◽  
Vol 59 (9) ◽  
pp. 5844-5846 ◽  
Author(s):  
Sam Ogwang ◽  
Caryn E. Good ◽  
Brenda Okware ◽  
Mary Nsereko ◽  
Michael R. Jacobs ◽  
...  
Keyword(s):  
Mycobacterium Tuberculosis ◽  
Multidrug Resistant ◽  
Sub Saharan Africa ◽  
Content Type ◽  
Pulmonary Tb ◽  
Resistant Tuberculosis ◽  
Multidrug Resistant Tuberculosis ◽  
Sub Saharan

ABSTRACTAdditional drugs are needed for the treatment of multidrug-resistant tuberculosis (TB). Sulfamethoxazole has been shown to havein vitroactivity againstMycobacterium tuberculosis; however, there is concern about resistance given the widespread use of trimethoprim-sulfamethoxazole prophylaxis among HIV-infected patients in sub-Saharan Africa. Thirty-eight of 40Mycobacterium tuberculosisisolates (95%) from pretreatment sputum samples from Ugandan adults with pulmonary TB, including HIV-infected patients taking trimethoprim-sulfamethoxazole prophylaxis, were susceptible with MICs of ≤38.4 μg/ml.

scholarly journals New Triazole NT-a9 Has Potent Antifungal Efficacy against Cryptococcus neoformans In Vitro and In Vivo

2019 ◽  
Vol 64 (2) ◽  
Author(s):  
Ren-Yi Lu ◽  
Ting-Jun-Hong Ni ◽  
Jing Wu ◽  
Lan Yan ◽  
Quan-Zhen Lv ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Amphotericin B ◽  
Pathogenic Fungi ◽  
Control Group ◽  
Survival Times ◽  
Content Type ◽  
Fungal Burden ◽  
Wide Range

ABSTRACT In the past decades, the incidence of cryptococcosis has increased dramatically, which poses a new threat to human health. However, only a few drugs are available for the treatment of cryptococcosis. Here, we described a leading compound, NT-a9, an analogue of isavuconazole, that showed strong antifungal activities in vitro and in vivo. NT-a9 showed a wide range of activities against several pathogenic fungi in vitro, including Cryptococcus neoformans, Cryptococcus gattii, Candida albicans, Candida krusei, Candida tropicalis, Candida glabrata, and Candida parapsilosis, with MICs ranging from 0.002 to 1 μg/ml. In particular, NT-a9 exhibited excellent efficacy against C. neoformans, with a MIC as low as 0.002 μg/ml. NT-a9 treatment resulted in changes in the sterol contents in C. neoformans, similarly to fluconazole. In addition, NT-a9 possessed relatively low cytotoxicity and a high selectivity index. The in vivo efficacy of NT-a9 was assessed using a murine disseminated-cryptococcosis model. Mice were infected intravenously with 1.8 × 106 CFU of C. neoformans strain H99. In the survival study, NT-a9 significantly prolonged the survival times of mice compared with the survival times of the control group or the isavuconazole-, fluconazole-, or amphotericin B-treated groups. Of note, 4 and 8 mg/kg of body weight of NT-a9 rescued all the mice, with a survival rate of 100%. In the fungal-burden study, NT-a9 also significantly reduced the fungal burdens in brains and lungs, while fluconazole and amphotericin B only reduced the fungal burden in lungs. Taken together, these data suggested that NT-a9 is a promising antifungal candidate for the treatment of cryptococcosis infection.

scholarly journals Identification of Pathogen Genomic Differences That Impact Human Immune Response and Disease during Cryptococcus neoformans Infection

mBio ◽  
2019 ◽  
Vol 10 (4) ◽  
Author(s):  
Aleeza C. Gerstein ◽  
Katrina M. Jackson ◽  
Tami R. McDonald ◽  
Yina Wang ◽  
Benjamin D. Lueck ◽  
...  
Keyword(s):  
Immune Response ◽  
Cryptococcus Neoformans ◽  
Candidate Genes ◽  
Cryptococcal Meningitis ◽  
Human Disease ◽  
Whole Genome ◽  
Content Type ◽  
Future Studies ◽  
Human Survival

ABSTRACT Patient outcomes during infection are due to a complex interplay between the quality of medical care, host immunity factors, and the infecting pathogen’s characteristics. To probe the influence of pathogen genotype on human survival, immune response, and other parameters of disease, we examined Cryptococcus neoformans isolates collected during the Cryptococcal Optimal Antiretroviral Therapy (ART) Timing (COAT) Trial in Uganda. We measured human participants’ survival, meningitis disease parameters, immunologic phenotypes, and pathogen in vitro growth characteristics. We compared those clinical data to whole-genome sequences from 38 C. neoformans isolates of the most frequently observed sequence type (ST), ST93, in our Ugandan participant population and to sequences from an additional 18 strains of 9 other sequence types representing the known genetic diversity within the Ugandan Cryptococcus clinical isolates. We focused our analyses on 652 polymorphisms that were variable among the ST93 genomes, were not in centromeres or extreme telomeres, and were predicted to have a fitness effect. Logistic regression and principal component analysis identified 40 candidate Cryptococcus genes and 3 hypothetical RNAs associated with human survival, immunologic response, or clinical parameters. We infected mice with 17 available KN99α gene deletion strains for these candidate genes and found that 35% (6/17) directly influenced murine survival. Four of the six gene deletions that impacted murine survival were novel. Such bedside-to-bench translational research identifies important candidate genes for future studies on virulence-associated traits in human Cryptococcus infections. IMPORTANCE Even with the best available care, mortality rates in cryptococcal meningitis range from 20% to 60%. Disease is often due to infection by the fungus Cryptococcus neoformans and involves a complex interaction between the human host and the fungal pathogen. Although previous studies have suggested genetic differences in the pathogen impact human disease, it has proven quite difficult to identify the specific C. neoformans genes that impact the outcome of the human infection. Here, we take advantage of a Ugandan patient cohort infected with closely related C. neoformans strains to examine the role of pathogen genetic variants on several human disease characteristics. Using a pathogen whole-genome sequencing approach, we showed that 40 C. neoformans genes are associated with human disease. Surprisingly, many of these genes are specific to Cryptococcus and have unknown functions. We also show deletion of some of these genes alters disease in a mouse model of infection, confirming their role in disease. These findings are particularly important because they are the first to identify C. neoformans genes associated with human cryptococcal meningitis and lay the foundation for future studies that may lead to new treatment strategies aimed at reducing patient mortality.

scholarly journals Serum Bactericidal Assays To Evaluate Typhoidal and Nontyphoidal Salmonella Vaccines

2014 ◽  
Vol 21 (5) ◽  
pp. 712-721 ◽  
Author(s):  
Mary Adetinuke Boyd ◽  
Sharon M. Tennant ◽  
Venant A. Saague ◽  
Raphael Simon ◽  
Khitam Muhsen ◽  
...  
Keyword(s):  
Sub Saharan Africa ◽  
Content Type ◽  
Vaccine Candidates ◽  
Live Attenuated Vaccines ◽  
Bactericidal Antibody ◽  
Paratyphi B ◽  
Sub Saharan ◽  
Functional Antibodies ◽  
New Vaccines

ABSTRACTInvasiveSalmonellainfections for which improved or new vaccines are being developed include enteric fever caused bySalmonella entericaserovars Typhi, Paratyphi A, and Paratyphi B and sepsis and meningitis in young children in sub-Saharan Africa caused by nontyphoidalSalmonella(NTS) serovars, particularlyS. entericaserovars Typhimurium and Enteritidis. Assays are needed to measure functional antibodies elicited by the new vaccines to assess their immunogenicities and potential protective capacities. We developedin vitroassays to quantify serum bactericidal antibody (SBA) activity induced byS. Typhi,S. Paratyphi A,S. Typhimurium, andS. Enteritidis vaccines in preclinical studies. Complement from various sources was tested in assays designed to measure antibody-dependent complement-mediated killing. Serum from rabbits 3 to 4 weeks of age provided the best complement source compared to serum from pigs, goats, horses, bovine calves, or rabbits 8 to 12 weeks of age. ForS. Enteritidis,S. Typhimurium, andS. Typhi SBA assays to be effective, bacteria had to be harvested at log phase. In contrast,S. Paratyphi A was equally susceptible to killing whether it was grown to the stationary or log phase. The typhoidal serovars were more susceptible to complement-mediated killing than were the nontyphoidal serovars. Lastly, the SBA endpoint titers correlated with serum IgG anti-lipopolysaccharide (LPS) titers in mice immunized with mucosally administeredS. Typhimurium,S. Enteritidis, andS. Paratyphi A but notS. Typhi live attenuated vaccines. The SBA assay described here is a useful tool for measuring functional antibodies elicited bySalmonellavaccine candidates.

scholarly journals Cryptococcus neoformans Dual GDP-Mannose Transporters and Their Role in Biology and Virulence

2014 ◽  
Vol 13 (6) ◽  
pp. 832-842 ◽  
Author(s):  
Zhuo A. Wang ◽  
Cara L. Griffith ◽  
Michael L. Skowyra ◽  
Nichole Salinas ◽  
Matthew Williams ◽  
...  
Keyword(s):  
Cryptococcus Neoformans ◽  
Protein Glycosylation ◽  
Content Type ◽  
Phenotypic Differences ◽  
Major Virulence Factor ◽  
Transmembrane Transporters ◽  
Mutant Cells ◽  
Made In

ABSTRACTCryptococcus neoformansis an opportunistic yeast responsible for lethal meningoencephalitis in humans. This pathogen elaborates a polysaccharide capsule, which is its major virulence factor. Mannose constitutes over one-half of the capsule mass and is also extensively utilized in cell wall synthesis and in glycosylation of proteins and lipids. The activated mannose donor for most biosynthetic reactions, GDP-mannose, is made in the cytosol, although it is primarily consumed in secretory organelles. This compartmentalization necessitates specific transmembrane transporters to make the donor available for glycan synthesis. We previously identified two cryptococcal GDP-mannose transporters, Gmt1 and Gmt2. Biochemical studies of each protein expressed inSaccharomyces cerevisiaeshowed that both are functional, with similar kinetics and substrate specificitiesin vitro. We have now examined these proteinsin vivoand demonstrate that cells lacking Gmt1 show significant phenotypic differences from those lacking Gmt2 in terms of growth, colony morphology, protein glycosylation, and capsule phenotypes. Some of these observations may be explained by differential expression of the two genes, but others suggest that the two proteins play overlapping but nonidentical roles in cryptococcal biology. Furthermore,gmt1 gmt2double mutant cells, which are unexpectedly viable, exhibit severe defects in capsule synthesis and protein glycosylation and are avirulent in mouse models of cryptococcosis.

In Vitro and In Vivo Efficacy of the Triazole TAK-187 against Cryptococcus neoformans

1998 ◽  
Vol 42 (10) ◽  
pp. 2630-2632 ◽  
Author(s):  
Wiley A. Schell ◽  
Gisele Madeira Duboc De Almeida ◽  
Richard K. Dodge ◽  
Kenji Okonogi ◽  
John R. Perfect
Keyword(s):  
Cerebrospinal Fluid ◽  
Cryptococcus Neoformans ◽  
Cryptococcal Meningitis ◽  
Rabbit Model ◽  
Intermittent Therapy ◽  
In Vitro Activity ◽  
Fluconazole Resistance ◽  
In Vivo Efficacy

ABSTRACT Multiple isolates of Cryptococcus neoformans, including those with fluconazole resistance, were tested to assess the in vitro activity of the new triazole TAK-187. MICs of TAK-187 were at least eightfold lower than those of fluconazole, and fungicidal concentrations for most isolates were 4 μg/ml or less. TAK-187 also was evaluated as intermittent therapy using two dosages in a rabbit model of experimental cryptococcal meningitis. Compared to daily treatment with fluconazole, as little as two doses of TAK-187 given 7 days apart were found to be effective. Plasma and cerebrospinal fluid TAK-187 concentrations were many times higher than MICs and fungicidal concentrations. Based upon its therapeutic efficacy and long half-life in the rabbit model, TAK-187 should be investigated for intermittent dosing in treatment or suppression of cryptococcal infections in humans.

scholarly journals Solution structure, glycan specificity and of phenol oxidase inhibitory activity of Anopheles C-type lectins CTL4 and CTLMA2

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Ritika Bishnoi ◽  
Gregory L. Sousa ◽  
Alicia Contet ◽  
Christopher J. Day ◽  
Chun-Feng David Hou ◽  
...  
Keyword(s):  
Malaria Vector ◽  
Solution Structure ◽  
Biochemical Characterization ◽  
Phenol Oxidase ◽  
Sub Saharan Africa ◽  
Scattering Data ◽  
Molecular Features ◽  
Sub Saharan

Abstract Malaria, the world’s most devastating parasitic disease, is transmitted between humans by mosquitoes of the Anopheles genus. An. gambiae is the principal malaria vector in Sub-Saharan Africa. The C-type lectins CTL4 and CTLMA2 cooperatively influence Plasmodium infection in the malaria vector Anopheles. Here we report the purification and biochemical characterization of CTL4 and CTLMA2 from An. gambiae and An. albimanus. CTL4 and CTLMA2 are known to form a disulfide-bridged heterodimer via an N-terminal tri-cysteine CXCXC motif. We demonstrate in vitro that CTL4 and CTLMA2 intermolecular disulfide formation is promiscuous within this motif. Furthermore, CTL4 and CTLMA2 form higher oligomeric states at physiological pH. Both lectins bind specific sugars, including glycosaminoglycan motifs with β1-3/β1-4 linkages between glucose, galactose and their respective hexosamines. Small-angle x-ray scattering data supports a compact heterodimer between the CTL domains. Recombinant CTL4/CTLMA2 is found to function in vivo, reversing the enhancement of phenol oxidase activity in dsCTL4-treated mosquitoes. We propose these molecular features underline a common function for CTL4/CTLMA2 in mosquitoes, with species and strain-specific variation in degrees of activity in response to Plasmodium infection.

Sign in / Sign up

Export Citation Format

Share Document