Parental Isolates Research Articles

Adolescents hospitalisés dans les services de psychiatrie adulte : une étude descriptive à la lumière des problématiques relevant de la protection de l’enfance

BackgroundAdolescents hospitalized in adult mental health departments are many, and an important part of them benefit from a child welfare system. Many teenagers hospitalized at the adult psychiatric services have symptoms of auto- or hetero-aggressive behaviours. The aim of our study was to describe the population of adolescents supported by these services by analyzing their demographic and psychiatric characteristics and their links with the areas of child protection and disability. MethodsWe performed a retrospective descriptive study based on the analysis of hospital records of teenagers supported by the adult psychiatric services. Criteria for the analysis include sociodemographic, psychiatric morbidity and schooling data, data on the terrain, and those related to child protection or disability. Then subpopulations were analyzed in order to compare the different criteria whether or not within the child welfare system. ResultsSixty teenagers were included in our study. An analysis of the total population shows that these adolescents wer exposed to risk factors for psychiatric disorders: lower socioeconomic conditions, psychiatric family history and traumatic life events. Many were also school-leavers compared to the general population. Furthermore, a majority of the teenagers benefited from a child protection measure (n=33) and were institutionalized. The subpopulation analysis helped realize the particular vulnerability of adolescents under the care of child protection. Indeed, we significantly emphasized among them an increased prevalence of parental isolation (P=0.001), of psychiatric family history (P=0.001) and of having experienced traumatic events (P<0.0001). Concerning psychiatric disorders, we also found by the child welfare system that mild to moderate mental retardation was significantly more frequent among teens (P=0.003). In addition, our results show that these adolescents were significantly more often hospitalized (P=0.013). Finally, still in comparison with the other adolescents, these teens were significantly more school-leavers (P=0.032), mostly in specialized or adapted course of study (P<0.001), and more subject to disability (P<0.001), implying a double care. ConclusionThis study has allowed us to better know the youth population supported by adult psychiatric services. It has also enlightened the specific vulnerability of the teenagers under the child protection care who need psychiatric treatment. It offers interesting discussion topics to develop new modalities of care for these young people.

Characterizing the Pyrenophora teres f. maculata-Barley Interaction Using Pathogen Genetics.

Pyrenophora teres f. maculata is the cause of the foliar disease spot form net blotch (SFNB) on barley. To evaluate pathogen genetics underlying the P. teres f. maculata–barley interaction, we developed a 105-progeny population by crossing two globally diverse isolates, one from North Dakota and the other from Western Australia. Progeny were phenotyped on a set of four barley genotypes showing a differential reaction to the parental isolates, then genotyped using a restriction site-associated-genotype-by-sequencing (RAD-GBS) approach. Genetic maps were developed for use in quantitative trait locus (QTL) analysis to identify virulence-associated QTL. Six QTL were identified on five different linkage groups and individually accounted for 20–37% of the disease variation, with the number of significant QTL ranging from two to four for the barley genotypes evaluated. The data presented demonstrate the complexity of virulence involved in the P. teres f. maculata–barley pathosystem and begins to lay the foundation for understanding this important interaction.

Tracing Genetic Exchange and Biogeography of Cryptococcus neoformans var. grubii at the Global Population Level.

Cryptococcus neoformans var. grubii is the causative agent of cryptococcal meningitis, a significant source of mortality in immunocompromised individuals, typically human immunodeficiency virus/AIDS patients from developing countries. Despite the worldwide emergence of this ubiquitous infection, little is known about the global molecular epidemiology of this fungal pathogen. Here we sequence the genomes of 188 diverse isolates and characterize the major subdivisions, their relative diversity, and the level of genetic exchange between them. While most isolates of C. neoformans var. grubii belong to one of three major lineages (VNI, VNII, and VNB), some haploid isolates show hybrid ancestry including some that appear to have recently interbred, based on the detection of large blocks of each ancestry across each chromosome. Many isolates display evidence of aneuploidy, which was detected for all chromosomes. In diploid isolates of C. neoformans var. grubii (serotype AA) and of hybrids with C. neoformans var. neoformans (serotype AD) such aneuploidies have resulted in loss of heterozygosity, where a chromosomal region is represented by the genotype of only one parental isolate. Phylogenetic and population genomic analyses of isolates from Brazil reveal that the previously “African” VNB lineage occurs naturally in the South American environment. This suggests migration of the VNB lineage between Africa and South America prior to its diversification, supported by finding ancestral recombination events between isolates from different lineages and regions. The results provide evidence of substantial population structure, with all lineages showing multi-continental distributions; demonstrating the highly dispersive nature of this pathogen.

Multiplex Genome Editing by Natural Transformation (MuGENT) for Synthetic Biology in Vibrio natriegens.

Vibrio natriegens has recently emerged as an alternative to Escherichia coli for molecular biology and biotechnology, but low-efficiency genetic tools hamper its development. Here, we uncover how to induce natural competence in V.natriegens and describe methods for multiplex genome editing by natural transformation (MuGENT). MuGENT promotes integration of multiple genome edits at high-efficiency on unprecedented time scales. Also, this method allows for generating highly complex mutant populations, which can be exploited for metabolic engineering efforts. As a proof-of-concept, we attempted to enhance production of the value added chemical poly-β-hydroxybutyrate (PHB) in V.natriegens by targeting the expression of nine genes involved in PHB biosynthesis via MuGENT. Within 1 week, we isolated edited strains that produced ∼100 times more PHB than the parent isolate and ∼3.3 times more than a rationally designed strain. Thus, the methods described here should extend the utility of this species for diverse academic and industrial applications.

Recombination analysis of 51 Plum pox virus (PPV) isolates, including 10 genomes of PPV-M Istanbul

Plum pox virus strain M (PPV-M) isolates were previously detected in different districts of Turkey, and they grouped together with European M isolates in phylogenetic trees. However, PPV-M isolates from Istanbul formed a separate group adjacent to European PPV-M isolates. Here, we have obtained full genomes of 10 PPV-M isolates from Istanbul derived from apricot and peach trees. The Recombination Detection Program version 4.16 (RDP4) was used for recombination analysis of 51 genomes of PPV, including the 10 full genomes of PPV-M Istanbul and six Turkish PPV-D isolates. Genome sequences were selected from GenBank to represent global PPV variation. Recombination events, likely parental isolates of recombinants and recombination break points were analysed using nine independent recombination detection methods (RDP, Bootscan, Geneconv, Maxchi, Chimaera, Siscan, 3seq, Lard and Phlopro) implemented in the RDP4 program with default settings. The program identified 19 recombination events. Of the total events, 13 recombination events included Turkish PPV-M and PPV-D isolates. Seven of the recombination detection methods showed that isolates from the PPV-Rec strain (AF357541, GU461889, EU117116, GU474956 and JX013532) included in the 51 genomes are likely to contain recombinant fragments from the one of the Turkish PPV-D isolates and a PPV-M isolate from Istanbul. Recombination events among the 10 PPV-M isolates were also detected at the intrastrain level. This is possible because all PPV-M Istanbul isolates were collected from a narrow district in Istanbul. Genome nucleotide comparisons revealed that PPV-M isolates from Istanbul had identity with European PPV-M, PPV-T, PPV-An, PPV-Rec, PPV-D, PPV-EA, PPV-CR, PPV-W and PPV-C of 97, 94, 92, 89, 88, 076, 74, 74 and 73%, respectively. The average intragroup diversity was found to be 0.014 for the Turkish PPV-M group (10 isolates) and 0.019 for the European PPV-M isolates (four isolates).

Resistance risk assessment for fludioxonil in Bipolaris maydis

Bipolaris maydis (anamorph: Cochliobolus heterostrophus) is the causal agent of Southern Corn Leaf Blight (SCLB), leading to huge annually losses worldwide. Although fludioxonil, a phenylpyrrole fungicide with a broad spectrum of activity, was introduced in the 1990s, no baseline sensitivity has been established for B. maydis. One hundred field isolates were used to establish a baseline sensitivity of B. maydis against fludioxonil during 2015–2016. The results showed that the baseline sensitivity was distributed as a unimodal curve with a mean EC50 value of 0.044±0.022μgmL−1. With repeated exposure to fludioxonil, a total of five fludioxonil-resistant mutants (RF>100, RF=Resistance factor) were obtained in the laboratory. Compared with the parental isolates, the five fludioxonil-resistant mutants showed decreased fitness in sporulation and virulence, and exhibited different features of sensitivity to various stresses (oxidation and osmotic pressure, cell membrane and cell wall inhibitors), but not in mycelial growth on PDA without stress amendation. The five fludioxonil-resistant mutants showed a positive cross-resistance between fludioxonil and the dicarboximide fungicide procymidone, but not between fludioxonil and boscalid or fluazinam. All mutants exhibited stable resistance to fludioxonil after 10 transfers, as indicated by resistance factor values that ranged from 116.82 to 445.59. When treated with 1.0 M NaCl, all the fludioxonil-resistant mutants showed greater mycelial glycerol content than corresponding parental isolates. Sequencing alignment results of Bmos1 indicated that mutant R27-5 had a single point mutation (Z1125K), while the mutant R104 had a 34-bp deletion fragment between the codons of amino acid residues 1125 to 1236 and encodes a putative attenuated 1133-AA protein. The 34-bp deletion fragment led to not only a 11-AA deletion(DNAVNQKLAVR), but also the resulting frameshift mutation and early stop. The mutations of R27-5 and R104 were located in the Rec domain of the Bmos1 gene. No mutations at the Bmos1 were detected in the other three resistant mutants R27-1, R27-2 and R32.

Genetic diversity within and among aecia of the wheat rust fungus Puccinia striiformis on the alternate host Berberis vulgaris

An isolate of the fungus Puccinia striiformis, causing yellow (stripe) rust on cereals and grasses, was selfed on the alternate (sexual) host, Berberis vulgaris. This enabled us to investigate genetic variability of progeny isolates within and among aecia. Nine aecial clusters each consisting of an aecium (single aecial cup) and nine clusters containing multiple aecial cups were selected from 18 B. vulgaris leaves. Aeciospores from each cluster were inoculated on susceptible wheat seedlings and 64 progeny isolates were recovered. Molecular genotyping using 37 simple sequence repeat markers confirmed the parental origin of all progeny isolates. Thirteen molecular markers, which were heterozygous in the parental isolate, were used to analyse genetic diversity within and among aecial cups. The 64 progeny isolates resulted in 22 unique recombinant multilocus genotypes and none of them were resampled in different aecial clusters. Isolates derived from a single cup were always of the same genotype whereas isolates originating from clusters containing up to nine aecial cups revealed one to three genotypes per cluster. These results implied that each aecium was the result of a successful fertilization in a corresponding pycnium and that an aecium consisted of genetically identical aeciospores probably multiplied via repetitive mitotic divisions. Furthermore, the results suggested that aecia within a cluster were the result of independent fertilization events often involving genetically different pycniospores. The application of molecular markers represented a major advance in comparison to previous studies depending on phenotypic responses on host plants. The study allowed significant conclusions about fundamental aspects of the biology and genetics of an important cereal rust fungus.

Disruption of rcsB by a duplicated sequence in a curli-producing Escherichia coli O157:H7 results in differential gene expression in relation to biofilm formation, stress responses and metabolism

BackgroundEscherichia coli O157:H7 (O157) strain 86–24, linked to a 1986 disease outbreak, displays curli- and biofilm-negative phenotypes that are correlated with the lack of Congo red (CR) binding and formation of white colonies (CR−) on a CR-containing medium. However, on a CR medium this strain produces red isolates (CR+) capable of producing curli fimbriae and biofilms.ResultsTo identify genes controlling differential expression of curli fimbriae and biofilm formation, the RNA-Seq profile of a CR+ isolate was compared to the CR− parental isolate. Of the 242 genes expressed differentially in the CR+ isolate, 201 genes encoded proteins of known functions while the remaining 41 encoded hypothetical proteins. Among the genes with known functions, 149 were down- and 52 were up-regulated. Some of the upregulated genes were linked to biofilm formation through biosynthesis of curli fimbriae and flagella. The genes encoding transcriptional regulators, such as CsgD, QseB, YkgK, YdeH, Bdm, CspD, BssR and FlhDC, which modulate biofilm formation, were significantly altered in their expression. Several genes of the envelope stress (cpxP), heat shock (rpoH, htpX, degP), oxidative stress (ahpC, katE), nutrient limitation stress (phoB-phoR and pst) response pathways, and amino acid metabolism were downregulated in the CR+ isolate. Many genes mediating acid resistance and colanic acid biosynthesis, which influence biofilm formation directly or indirectly, were also down-regulated. Comparative genomics of CR+ and CR− isolates revealed the presence of a short duplicated sequence in the rcsB gene of the CR+ isolate. The alignment of the amino acid sequences of RcsB of the two isolates showed truncation of RcsB in the CR+ isolate at the insertion site of the duplicated sequence. Complementation of CR+ isolate with rcsB of the CR− parent restored parental phenotypes to the CR+ isolate.ConclusionsThe results of this study indicate that RcsB is a global regulator affecting bacterial survival in growth-restrictive environments through upregulation of genes promoting biofilm formation while downregulating certain metabolic functions. Understanding whether rcsB inactivation enhances persistence and survival of O157 in carrier animals and the environment would be important in developing strategies for controlling this bacterial pathogen in these niches.

Construction of Potent Recombinant Strain Through Intergeneric Protoplast Fusion in Endophytic Fungi for Anticancerous Enzymes Production Using Rice Straw.

Among all fungal endophytes isolates derived from different ethno-medical plants, the hyper-yield L-asparaginase and L-glutaminase wild strains Trichoderma sp. Gen 9 and Cladosporium sp. Gen 20 using rice straw under solid-state fermentation (SSF) were selected. The selected strains were used as parents for the intergeneric protoplast fusion program to construct recombinant strain for prompt improvement production of these enzymes in one recombinant strain. Among 21 fusants obtained, the recombinant strain AYA 20-1, with 2.11-fold and 2.58-fold increase in L-asparaginase and L-glutaminase activities more than the parental isolates Trichoderma sp. Gen 9 and Cladosporium sp. Gen 20, respectively, was achieved using rice straw under SSF. Both therapeutic enzymes L-asparaginase and L-glutaminase were purified and characterized from the culture supernatant of the recombinant AYA 20-1 strain with molecular weights of 50.6 and 83.2kDa, respectively. Both enzymes were not metalloenzymes. Whereas thiol group blocking reagents such as p-chloromercurybenzoate and iodoacetamide totally inhibited L-asparaginase activity, which refer to sulfhydryl groups and cysteine residues involved in its catalytic activity, they have no effect toward L-glutaminase activity. Interestingly, potent anticancer, antioxidant, and antimicrobial activities were detected for both enzymes.

Virulence and Molecular Characterization of Experimental Isolates of the Stripe Rust Pathogen (Puccinia striiformis) Indicate Somatic Recombination.

Puccinia striiformis causes stripe rust on wheat, barley, and grasses. Natural population studies have indicated that somatic recombination plays a possible role in P. striiformis variation. To determine whether somatic recombination can occur, susceptible wheat or barley plants were inoculated with mixed urediniospores of paired isolates of P. striiformis. Progeny isolates were selected by passing through a series of inoculations of wheat or barley genotypes. Potential recombinant isolates were compared with the parental isolates on the set of 18 wheat or 12 barley genotypes that are used to differentiate races of P. striiformis f. sp. tritici (the wheat stripe rust pathogen) and P. striiformis f. sp. hordei (the barley stripe rust pathogen), respectively, for virulence changes. They were also tested with 51 simple-sequence repeat and 90 single-nucleotide polymorphism markers for genotype changes. From 68 possible recombinant isolates obtained from nine combinations of isolates based on virulence tests, 66 were proven to be recombinant isolates by molecular markers. Various types of recombinants were determined, including lost virulence from both virulent parental isolates, gained virulence from both avirulent isolates, combined virulences from both parents, and inherited virulence from one parent and avirulence from another. Marker data indicate that most of the recombinants were produced through chromosome reassortment and crossover after the hybridization of two parental isolates. The results demonstrate that somatic recombination is a mechanism by which new variants can be generated in P. striiformis.

Sensitivity to Fludioxonil of Botrytis cinerea Isolates from Tomato in Henan Province of China and Characterizations of Fludioxonil‐resistant Mutants

AbstractGrey mould, caused by Botrytis cinerea Pers ex Fr., is one of the most common diseases of tomato worldwide. Fludioxonil belongs to the phenylpyrrole fungicides, which have high activity against B. cinerea. The sensitivity of fludioxonil was evaluated on the basis of the level of inhibition of mycelium growth in 274 B. cinerea isolates collected from different locations (untreated with this fungicide) in Henan Province, China. The EC50 values for fludioxonil ranged from 0.0033 to 0.0415 mg/l, and the average EC50 values were 0.0156 ± 0.0078 mg/l. Three fludioxonil‐resistant mutants were obtained by subculturing fludioxonil‐sensitive wild‐type isolates on continuously increasing fludioxonil concentrations. For the cross‐resistance assay, fludioxonil revealed positive cross‐resistance with procymidone but did not reveal cross‐resistance with pyrimethanil, boscalid and trifloxystrobin. Mycelial growth, conidial production, hyphal dry weight and pathogenicity were diminished significantly between the fludioxonil‐resistant mutants and their sensitive wild‐type parental isolates. This study shows for the first time that fludioxonil‐resistant isolates of B. cinerea are still not present in Henan Province because this fungicide is an attractive and effective fungicide for chemical control. Recommendations can be made to growers to use fludioxonil to control grey mould and to consider the potential moderate resistance risk of using this fungicide.

Simultaneous Deletion of the 9GL and UK Genes from the African Swine Fever Virus Georgia 2007 Isolate Offers Increased Safety and Protection against Homologous Challenge.

Currently, there is no commercially available vaccine against African swine fever. Outbreaks of the disease are devastating to the swine industry and are caused by circulating strains of African swine fever virus. Here, we report a putative vaccine derived from a currently circulating strain but containing two deletions in two separate areas of the virus, allowing increased safety. Using this genetically modified virus, we were able to vaccinate swine and protect them from developing ASF. We were able to achieve protection from disease as early as 2 weeks after vaccination, even when the pigs were exposed to a higher than normal concentration of ASFV.

Characterization of a pathogenic full-length cDNA clone of a virulent porcine epidemic diarrhea virus strain AH2012/12 in China

Since 2010, outbreaks of variant porcine epidemic diarrhea virus (PEDV) have swept across the world causing substantial economic losses. The development of new, more effective vaccines has been hampered by difficulties in isolating strains and viral genome manipulation. In the present study, we successfully isolated a highly pathogenic field strain AH2012/12, from a pig farm reporting severe diarrhea in China. Phylogenetic analysis revealed that the new isolate belongs to group G2, which represents epidemic and pandemic field strains. Furthermore, we constructed an infectious cDNA clone of the newly isolated strain, rAH2012/12, and the rescued virus displayed phenotypic properties identical to the parental virus in vitro. In vivo experiments demonstrated that the rescued virus displayed similar pathogenicity to the parental isolate, causing high mortality rates in suckling pigs. This study provided a strong basis for the development of live attenuated vaccines and for research into the pathogenic mechanisms of this virus.

Homozygous and heterozygous point mutations in succinate dehydrogenase subunits b, c and d of Rhizoctonia cerealis conferring resistance to thifluzamide.

Thifluzamide, a succinate dehydrogenase inhibitor (SDHI) fungicide, is a promising fungicide for controlling wheat sharp eyespot (WSE). WSE is caused by Rhizoctonia cerealis. Information on the resistance mechanism of this pathogen to thifluzamide remains unavailable. We used selective reculturing and UV mutagenesis to generate thifluzamide-resistant mutants. Thifluzamide-resistant mutants were only generated through UV mutagenesis. Sequence analysis of succinate dehydrogenase (Sdh) genes revealed that two mutants had no mutation in RCSdhB, RCSdhC and RCSdhD, and the other 18 mutants all had at least one mutation in RCSdhB, RCSdhC or RCSdhD, either in a homozygous or heterozygous state. The majority of mutants included either RCSdhD-H116Y or RCSdhC-H139Y. They showed slight resistance to boscalid, bixafen and penflufen. Only one mutant possessed RCSdhB-H246Y, and it showed medium resistance to boscalid and penflufen and a slight resistance to bixafen. All the thifluzamide mutants were sensitive to flutolanil. Compared with their parental isolates, these mutants present no or minor fitness penalties. Homozygous and heterozygous point mutations in the succinate dehydrogenase subunits b, c and d of R. cerealis may be involved in thifluzamide resistance. © 2016 Society of Chemical Industry.

Maltreatment in Infancy

Burgeoning research has documented high rates of maltreatment during the first 3 years of life. Early exposure to maltreatment is related to a host of negative physical, developmental, and mental health outcomes in childhood and adulthood. Scientists have documented the “biological embedding” of maltreatment, including alterations in the structures and processes of the young brain. Maltreatment is a complex phenomenon, which manifests in contexts of family poverty, inadequate parental knowledge and skill regarding child development and caregiving, social isolation of parents, disruptions in parent–child relationships, compromised parental psychological functioning, and concrete issues that affect parenting. Capitalizing on research on young child maltreatment, interventions have been designed to ameliorate infant/toddler maltreatment, buffer young children against the effects of maltreatment, and promote the well-being of maltreated young children. There is a growing empirical base on interventions to address early maltreatment within the context of a public health prevention framework. Primary prevention programs aim to reduce the incidence of maltreatment and related outcomes for infants, toddlers, and their families through the implementation of population-based programs, such as home visiting and early care and education programs. Secondary prevention models target families with specific risk factors associated with maltreatment, such as maternal depression. Tertiary programs generally entail involuntary services, designed to prevent maltreatment recurrence and to improve parenting skills through therapeutic approaches targeting the parent–child dyad. Empirical knowledge about maltreated young children and their families and interventions to support them can inform the design and delivery of child welfare services.

Antibiotic Resistance Induction by Benzalkonium Chloride Exposure in Nosocomial Pathogens

Background: Biocides (disinfectants) are crucial for controlling various infections and are widely used in environments for the control of microorganisms. Exposure of bacteria to biocides can select for mutants with decreased biocide susceptibility that often display a decrease in susceptibility to antibiotics. Objectives: The present work was done during 14 months from February 2015, at the microbiology laboratory of the Veterinary college of Shahrekord university with the aim of investigating the impact of benzalkonium chloride exposure on antibiotic resistance in some common nosocomial pathogens. Methods: Standard strains of Pseudomonas aeruginosa, Acinetobacter baumannii, Escherichia coli and Staphylococcus aureus were used, and in parallel to each standard strain four hospital isolates collected from Shahrekord and Esfahan hospitals were examined. Tube double serial dilution method was used for determination of minimum inhibitory concentration (MIC) of antibiotics and Benzalkonium Chloride (BKC). Spontaneous mutants were developed by exposure of examined species to BKC, and their mean MICs to examined drugs were evaluated. Results: The mean MICs of the BKC and antibiotics used in this study were not similar between the parent and mutant strains of the examined isolates. In E. coli, A. baumannii and S. aureus isolates, differences between the mean MICs of BZK and ciprofloxacin had a similar pattern and were statistically significant (P < 0.05). In isolates of P. aeruginosa, differences between parent and mutant isolates for all of the tested drugs were significant. Conclusions: Vast use of BKC in various environments and their accumulation represents a potential risk for selective pressure towards selection of bacteria with decreased antibiotic susceptibility.

A Full-Length Infectious cDNA Clone of Zika Virus from the 2015 Epidemic in Brazil as a Genetic Platform for Studies of Virus-Host Interactions and Vaccine Development

ABSTRACTAn arthropod-borne virus, Zika virus (ZIKV), has recently emerged as a major human pathogen. Associated with complications during perinatal development and Guillain-Barré syndrome in adults, ZIKV raises new challenges for understanding the molecular determinants of flavivirus pathogenesis. This underscores the necessity for the development of a reverse genetic system based on an epidemic ZIKV strain. Here, we describe the generation and characterization in cell cultures of an infectious cDNA clone of ZIKV isolated from the 2015 epidemic in Brazil. The cDNA-derived ZIKV replicated efficiently in a variety of cell lines, including those of both neuronal and placental origin. We observed that the growth of cDNA-derived virus was attenuated compared to the growth of the parental isolate in most cell lines, which correlates with substantial differences in sequence heterogeneity between these viruses that were determined by deep-sequencing analysis. Our findings support the role of genetic diversity in maintaining the replicative fitness of viral populations under changing conditions. Moreover, these results indicate that caution should be exercised when interpreting the results of reverse-genetics experiments in attempts to accurately predict the biology of natural viruses. Finally, a Vero cell-adapted cDNA clone of ZIKV was generated that can be used as a convenient platform for studies aimed at the development of ZIKV vaccines and therapeutics.

African swine fever virus Georgia isolate harboring deletions of 9GL and MGF360/505 genes is highly attenuated in swine but does not confer protection against parental virus challenge

African swine fever virus (ASFV) produces a contagious disease of domestic pigs that results in severe economic consequences to the swine industry. Control of the disease has been hampered by the unavailability of vaccines. We recently reported the development of two experimental vaccine strains (ASFV-G-Δ9GL and ASFV-G-ΔMGF) based on the attenuation of the highly virulent and epidemiologically relevant Georgia2007 isolate. Deletion of the 9GL gene or six genes of the MGF360/505 group produced two attenuated ASFV strains which were able to confer protection to animals when challenged with the virulent parental virus. Both viruses, although efficient in inducing protection, present concerns regarding their safety. In an attempt to solve this problem we developed a novel virus strain, ASFV-G-Δ9GL/ΔMGF, based on the deletion of all genes deleted in ASFV-G-Δ9GL and ASFV-G-ΔMGF. ASFV-G-Δ9GL/ΔMGF is the first derivative of a highly virulent ASFV field strain subjected to a double round of recombination events seeking to sequentially delete specific genes. ASFV-G-Δ9GL/ΔMGF showed a decreased ability to replicate in primary swine macrophage cultures relative to that of ASFV-G and ASFV-G-ΔMGF but similar to that of ASFV-G-Δ9GL. ASFV-G-Δ9GL/ΔMGF was attenuated when intramuscularly inoculated into swine, even at doses as high as 106 HAD50. Animals infected with doses ranging from 102 to 106 HAD50 did not present detectable levels of virus in blood at any time post-infection and they did not develop detectable levels of anti-ASFV antibodies. Importantly, ASFV-G-Δ9GL/ΔMGF does not induce protection against challenge with the virulent parental ASFV-G isolate. Results presented here suggest caution towards approaches involving genomic manipulations when developing rationally designed ASFV vaccine strains.

Fashionably late partners have more fruitful encounters: Impact of the timing of co-infection and pathogenicity on sexual reproduction in Zymoseptoria tritici

The wheat pathogen Zymoseptoria tritici is a relevant fungal model organism for investigations of the epidemiological determinants of sexual reproduction. The objective of this experimental study was to determine which intrinsic factors, including parental fitness and timing conditions of infection, affect the numbers of ascospores produced. We first performed 28 crosses on adult wheat plants in semi-controlled conditions, with 10 isolates characterized for their fitness traits. We validated the efficiency of the crossing method, opening up new perspectives for epidemiological studies. We found that the ability to reproduce sexually was determined, at least partly, by the parental genotypes. We also found that the number of ascospores released was correlated with the mean size of the sporulating lesions of the parental isolates on the one hand, and the absolute difference in the latent periods of these isolates on the other. No functional trade-off between the two modes of reproduction in Z. tritici was revealed: there was no adaptive compromise between pathogenicity (asexual multiplication on leaves) and transmission (intensity of sexual reproduction on wheat debris). Moreover, a few days’ difference in the latent periods of the two parental isolates, such that one progressed more rapidly in the host tissue than the other, seemed to be slightly beneficial to ascosporogenesis. This may be because the first parental isolate breaks down host defenses, thereby facilitating infection for the other parental isolate. However, a larger difference (a few weeks), generated by leaving two to three weeks between the inoculations of the plant with the parental isolates, was clearly detrimental to ascosporogenesis. In this case, the host tissues were likely colonized by the first isolate, leaving less host resources available for the second, consistent with a competition effect during the asexual stage.

Resistance Assessment for Oxathiapiprolin in Phytophthora capsici and the Detection of a Point Mutation (G769W) in PcORP1 that Confers Resistance.

The potential for oxathiapiprolin resistance in Phytophthora capsici was evaluated. The baseline sensitivities of 175 isolates to oxathiapiprolin were initially determinated and found to conform to a unimodal curve with a mean EC50 value of 5.61 × 10-4 μg/ml. Twelve stable oxathiapiprolin-resistant mutants were generated by fungicide adaptation in two sensitive isolates, LP3 and HNJZ10. The fitness of the LP3-mutants was found to be similar to or better than that of the parental isolate LP3, while the HNJZ10-mutants were found to have lost the capacity to produce zoospores. Taken together these results suggest that the risk of P. capsici developing resistance to oxathiapiprolin is moderate. Comparison of the PcORP1 genes in the LP3-mutants and wild-type parental isolate, which encode the target protein of oxathiapiprolin, revealed that a heterozygous mutation caused the amino acid substitution G769W. Transformation and expression of the mutated PcORP1-769W allele in the sensitive wild-type isolate BYA5 confirmed that the mutation in PcORP1 was responsible for the observed oxathiapiprolin resistance. Finally diagnostic tests including As-PCR and CAPs were developed to detect the oxathiapiprolin resistance resulting from the G769W point mutation in field populations of P. capsici.