Wide Host Range Research Articles

First Report of Colletotrichum siamense causing Anthracnose on Ficus microcarpa in China.

Chinese banyan, Ficus microcarpaLinn. f. (Moraceae), is a native and popular landscape tree with highornamentalandeconomicvalue in South China. In May 2018, a foliar disease occurred on F. Microcarpa in Zhanjiang city (21˚17'51''N, 110˚18'16''E), Guangdong Province, China. Theincidenceof thediseasewas 10%andseveritywas 20% (n = 100 investigated plants). Symptoms first appeared on leaves as small black spots (up to 5 mm diam) with yellow haloes. The spots gradually enlarged in size and coalesced, resulting in necrosis and early shedding of the leaves. Ten symptomatic leaves from 10 plants were collected. The margins of the samples were cut into small pieces (5 × 5 mm), surface disinfected (75% ethanol 30 s, 0.1% HgCl2 45 s, rinsed 3 times with sterile distilled water), and placed on potato dextrose agar (PDA) at 28°C with a photoperiod of 12 h. After 5 days, a total of four isolates with 100% isolation frequency were obtained and three representative strains (T6, T6-1, and T6-2) were used for morphological and molecular characterization. Colonies on PDA were white to gray with cottony mycelia, a few bright orange conidial masses developed near the inoculum point. Conidia were single-celled, smooth-walled, straight, colorless, fusiform with obtuse to slightly rounded ends, and measured 13.2 to 17.5 (avg. 15.3) × 4.3 to 6.0 (avg. 5.2) μm in size (n = 50). Appressoria were oval to irregular in shape, dark brown, and ranged from 5.8 to 9.1 (avg. 7.5) × 4.8 to 6.5 (avg. 5.6) µm (n = 50). Morphological characteristics of the isolates agreed with the description of Colletotrichum siamense (Prihastuti et al. 2009). The ITS (Nos. MK225610, ON979519, ON979520), TUB2 (Nos. MK348533, OQ130408, OQ130409), ACT (Nos. MZ852755, OQ116933, OQ116934) andGAPDH (Nos. MZ852756, OQ130406, OQ130407) sequences were 99.35%, 98.76%, 98.92% and 97.60% identical to the type C. siamensestrain MFLU 090230 (accession nos. NR_144784, FJ907438, FJ907423 and FJ972575) through BLAST analysis, respectively. A phylogenetic tree was generated using the concatenated sequences of ITS, ACT, GAPDH and TUB2. The result showed that the 3 isolates were clustered with C. siamense strains including the type MFLU 090230. To perform pathogenicity tests, One leaf (wounded and/or unwounded) per seedling (n = 20, 2-year-old) was inoculated by dropping a 10 ul droplet of the conidial suspension (1 × 105) of isolate T6 or sterile distilled water (as control) at one point, respectively. These plants were wrapped in polyethylene bags for 2 days and incubated in a greenhouse at 28± 2°C with 80-90% relative humidity. Initial symptoms appeared within 5 days on all wounded and unwounded inoculated leaves, while the controls remained symptomless. Colletotrichum siamense was reisolated from the lesions in terms of morphology and molecular characterization, whereas no fungus was isolated from control leaves. The pathogenicity test was repeated three times under the same conditions. The diseases caused by C. siamense have been reported to cause anthracnose in a wide range of hosts (Weir et al. 2012), but not in F. microcarpa. In China, C. gloeosporioides has been reported to cause anthracnose on potted banyan F. microcarpa (Yao et al. 2016), but not C. siamense. This is the first report of C. siamense causing anthracnose on F. microcarpa in China.This study provides valuable information for the identification and control of the anthracnose on F. microcarpa.

Mutual antagonism of mouse-adaptation mutations in HA and PA proteins on H9N2 virus replication

Avian H9N2 viruses have wide host range among the influenza A viruses. However, knowledge of H9N2 mammalian adaptation is limited. To explore the molecular basis of the adaptation to mammals, we performed serial lung passaging of the H9N2 strain A/chicken/Hunan/8.27 YYGK3W3-OC/2018 (3W3) in mice and identified six mutations in the hemagglutinin (HA) and polymerase acidic (PA) proteins. Mutations L226Q, T511I, and A528V of HA were responsible for enhanced pathogenicity and viral replication in mice; notably, HA-L226Q was the key determinant. Mutations T97I, I545V, and S594G of PA contributed to enhanced polymerase activity in mammalian cells and increased viral replication levels in vitro and in vivo. PA-T97I increased viral polymerase activity by accelerating the viral polymerase complex assembly. Our findings revealed that the viral replication was affected by the presence of PA-97I and/or PA-545V in combination with a triple-point HA mutation. Furthermore, the double- and triple-point PA mutations demonstrated antagonistic effect on viral replication when combined with HA-226Q. Notably, any combination of PA mutations, along with double-point HA mutations, resulted in antagonistic effect on viral replication. We also observed antagonism in viral replication between PA-545V and PA-97I, as well as between HA-528V and PA-545V. Our findings demonstrated that several antagonistic mutations in HA and PA proteins affect viral replication, which may contribute to the H9N2 virus adaptation to mice and mammalian cells. These findings can potentially contribute to the monitoring of H9N2 field strains for assessing their potential risk in mammals.

First Record of Meloidogyne javanica (Treub, 1885) (Chitwood, 1949) in Lettuce (Lactuca sativa L.) Growing Areas in the Southern Marmara Region

First Record of Meloidogyne javanica (Treub, 1885) (Chitwood, 1949) in Lettuce (Lactuca sativa L.) Growing Areas in the Southern Marmara Region
 ABSTRACT
 The estimated loss of the annual agricultural production due to plant parasitic nematodes, which are among the important soil-borne pathogens, is estimated to be approximately 118 billion US dollars. Root-knot nematodes are the most important plant parasitic nematode group due to their wide host range and difficulties in control and cause significant quality and yield losses in vegetables including lettuce plant. Root-knot nematodes are causing symptoms such as yellowing, wilting and stunting on lettuce plant. For monitoring lettuce fields for detecting nematode infected areas, surveys were made to the lettuce growing areas of Çanakkale province in the winter months of 2021-2022 and the plants infected with root-knot nematodes were examined and pure nematode cultures were obtained in the laboratory. Species identification was made using morphological methods and morphometric measurements from second-stage infective juvenile and female individuals obtained from pure cultures. As a result, the first record of M. javanica in lettuce growing areas in the Southern Marmara Region was made in this study.
 Keywords: Lettuce, Southern Marmara Region, Root-knot nematode

A new Salmonella enterica serovar that was isolated from a wild sparrow presents a distinct genetic, metabolic and virulence profile

Salmonella enterica is a ubiquitous and clinically-important bacterial pathogen, able to infect and cause different diseases in a wide range of hosts. Here, we report the isolation and characterization of a new S. enterica serovar (13,23:i:-; S. Tirat-Zvi), belonging to the Havana supper-lineage that was isolated from a wild house sparrow (Passer domesticus) in Israel. Whole genome sequencing and complete assembly of its genome indicated a plasmid-free, 4.7 Mb genome that carries the Salmonella pathogenicity islands 1–6, 9, 19 and an integrative and conjugative element (ICE), encoding arsenic resistance genes. Phenotypically, S. Tirat-Zvi isolate TZ282 was motile, readily formed biofilm, more versatile in carbon source utilization than S. Typhimurium and highly tolerant to arsenic, but impaired in host cell invasion. In-vivo infection studies indicated that while S. Tirat-Zvi was able to infect and cause an acute inflammatory enterocolitis in young chicks, it was compromised in mice colonization and did not cause an inflammatory colitis in mice compared to S. Typhimurium. We suggest that these phenotypes reflect the distinctive ecological niche of this new serovar and its evolutionary adaptation to passerine birds, as a permissive host. Moreover, these results further illuminate the genetic, phenotypic and ecological diversity of S. enterica pathovars.

Molecular Detection and Distribution of Giardia duodenalis and Cryptosporidium spp. Infections in Wild and Domestic Animals in Portugal

Enteric protozoan parasites Giardia duodenalis, Cryptosporidium spp., and, to a lesser extent, the ciliate Balantioides coli are responsible for severe human and animal intestinal disorders globally. However, limited information is available on the occurrence and epidemiology of these parasites in domestic, but especially wild species in Portugal. To fill this gap of knowledge, we have investigated G. duodenalis, Cryptosporidium spp., and B. coli occurrence, distribution, genetic diversity, and zoonotic potential by analyzing 756 fecal samples from several wild carnivores (n = 288), wild ungulates (n = 242), and domestic species (n = 226) collected across different areas of mainland Portugal. Overall, infection rates were 16.1% (122/756; 95% CI: 13.59–18.96) for G. duodenalis and 2.7% (20/756; CI: 1.62–4.06) for Cryptosporidium spp., while no ungulate sample analyzed yielded positive results for B. coli. Giardia duodenalis was found across a wide range of hosts and sampling areas, being most prevalent in the Iberian lynx (26.7%), the Iberian wolf (24.0%), and the domestic dog (23.9%). Cryptosporidium spp. was only identified in wild boar (8.4%), red fox (3.4%), Iberian lynx (3.3%), red deer (3.1%), and Iberian wolf (2.5%). Sequence analysis of G. duodenalis determined zoonotic assemblage A (subassemblage AI) in one roe deer sample, canine-specific assemblages C and D in Iberian wolf, red fox, and domestic dog, and ungulate-specific assemblage E in wild boar, sheep, cattle, and horse. Six Cryptosporidium species were identified: C. scrofarum in wild boar, C. canis in the Iberian wolf and red fox, C. ubiquitum in red deer and wild boar, C. felis in the Iberian lynx, and both C. ryanae and C. occultus in red deer. Giardia duodenalis and Cryptosporidium spp. coinfections were observed in 0.7% (5/756) of the samples. This is the first, most comprehensive, and largest molecular-based epidemiology study of its kind carried out in Portugal, covering a wide range of wild and domestic hosts and sampling areas. The detection of zoonotic Cryptosporidium spp. and G. duodenalis subassemblage AI demonstrates the role of wild and domestic host species in the transmission of these agents while representing a potential source of environmental contamination for other animals and humans.

From Primate Myth to Global Concern

This analysis delves into the enigmatic nature of the Human Mpox Virus (formerly Monkeypox), a pathogenic virus that affects humans and has recently garnered attention due to its wide range of hosts and a global pandemic in 2022. Despite its misleading name, which implies primate transmission, the true origins and hosts of Mpox remain unknown, sparking debates about its classification and concerns about stigmatization. Through a thorough examination of the virus's historical emergence, clinical manifestations, evolving epidemiology, and transmission patterns, this analysis aims to provide valuable insights into this infectious disease. By understanding its complexities, effective control and prevention strategies can be developed. Mpox, belonging to the Orthopoxvirus species, shares genetic similarities with other poxviruses such as smallpox and cowpox. Early recognition of symptoms is vital for prompt diagnosis and isolation, as there is no permanent cure for Mpox. Preventive measures involve surveillance, early detection, isolation, and vaccination. By further exploring Mpox’s complexities, advancements can be made in controlling and preventing this infectious disease.

Five families of diverse DNA viruses comprehensively restructure the nucleus.

Many viruses have evolved ways to restructure their host cell's nucleus profoundly and unexpectedly upon infection. In particular, DNA viruses that need to commandeer their host's cellular synthetic functions to produce their progeny can induce the condensation and margination of host chromatin during productive infection, a phenomenon known as virus-induced reorganization of cellular chromatin (ROCC). These ROCC-inducing DNA viruses belong to 5 families (herpesviruses, baculoviruses, adenoviruses, parvoviruses, and geminiviruses) that infect a wide range of hosts and are important for human and ecosystem health, as well as for biotechnology. Although the study of virus-induced ROCC is in its infancy, investigations are already raising important questions, such as why only some DNA viruses that replicate their genomes in the nucleus elicit ROCC. Studying the shared and distinct properties of ROCC-inducing viruses will provide valuable insights into viral reorganization of host chromatin that could have implications for future therapies that target the viral life cycle.

Taxonomic and Phylogenetic Updates on Apiospora: Introducing Four New Species from Wurfbainia villosa and Grasses in China.

Apiospora, an ascomycetous genus in Apiosporaceae, comprises saprobes, endophytes, and pathogens of humans and plants. They have a cosmopolitan distribution with a wide range of hosts reported from Asia. In the present study, we collected and isolated Apiospora species from Wurfbainia villosa and grasses in Guangdong and Yunnan provinces in China. Multi-locus phylogeny based on the internal transcribed spacer, the large subunit nuclear rDNA, the partial translation elongation factor 1-α, and β-tubulin was performed to clarify the phylogenetic affinities of the Apiospora species. Based on the distinctive morphological characteristics and molecular evidence, Ap. endophytica, Ap. guangdongensis, Ap. wurfbainiae, and Ap. yunnanensis are proposed. Descriptions, illustrations, and notes for the newly discovered species are provided and compared with closely related Apiospora species. An updated phylogeny of Apiospora is presented, along with a discussion on the phylogenetic affinities of ambiguous taxa.

Evaluation of local movement of Bemisia tabaci MEAM1 and tomato severe rugose virus transmission to tomato plants using marked and unmarked whiteflies

AbstractTomato golden mosaic disease, caused by the tomato severe rugose virus (ToSRV), is one of the most serious tomato diseases. ToSRV is transmitted by the whitefly Bemisia tabaci MEAM1, from a wide range of hosts. Introducing ToSRV in commercial fields probably can occur by transporting the virus from distant locations. However, our hypothesis is that the inoculum causing epidemic development might be related to nearby sources. This study evaluated the short‐range flight distance of B. tabaci MEAM1 (marked with detectable proteins and powder dye), through recaptures in yellow sticky traps, and the transmission of ToSRV by viruliferous B. tabaci MEAM1 to tomato plants placed at increasing distances from a release point. Evaluated whiteflies reached a maximum of 30 m from the release point, and no ToSRV‐infected tomato plants were detected at greater distances. These findings reinforce the suspicion that the epidemic‐supporting source of ToSRV inoculum must be close to commercial cultivation areas. About the efficacy of the type of markers used, of the two protein sources tested (pasteurized chicken egg‐white albumin and commercial soy‐based extracts as sources of albumin and lecithin, respectively), albumin was considered easier to detect. Marking with these proteins or with two dyes (blue or pink) did not affect B. tabaci MEAM1 mortality, although field tests showed that fewer marked than unmarked insects were recaptured. Dye marking was considered more practical because of the ease of detection. The study validates a new tool to understand the movement of B. tabaci MEAM1, based on different marking methods.

Seroprevalence and risk factors of Toxoplasma gondii infection in slaughtered chickens in Tripoli, Lebanon.

Toxoplasma gondii is a cosmopolitan protozoan parasite that has a wide range of intermediate hosts. It infects all warm-blooded animals, including humans and birds. The latter typically pick up the infection by ground feeding, and people can contract the parasite from eating undercooked chicken meat. In recent years, investigations into T. gondii infection in poultry have been reported worldwide. However, there is no epidemiological data regarding the seroprevalence of anti-T. gondii antibodies in chicken in Lebanon. Thus, the current investigation was carried out to determine the seroprevalence and associated risk factors of T. gondii infection in chicken destined for human consumption in the Tripoli district of Lebanon. For this, a cross-sectional study was carried out between April 2021 and February 2022. Blood samples were collected from 400 chickens in four poultry abattoirs in Tripoli. The modified agglutination test (MAT) was used to test sera for T. gondii antibodies. The association of T. gondii seroprevalence with potential risk factors was assessed using the Chi-square test. Multivariate analysis was used to confirm the association. The seroprevalence of T. gondii antibodies reported in this study was 13% (52/400); it was higher in the free-range chicken group (19.3%, 29/150) than in the caged group (9.2%, 23/250) (OR=2.365; 95% CI: 1.311-4.267) (P=0.004). The wet season and the presence of cats in the poultry farms were significantly associated with an increased seropositivity to T. gondii infection (P≤0.0001). Given the occurrence of T. gondii antibodies in slaughtered chicken in this area, the consumption of raw or undercooked chicken meats may pose a serious threat to public health and highlight the need to implement appropriate precautionary strategies to halt the spread of T. gondii to humans.

Comparative investigation of different chemicals on the germination of two aquatic microsporidia

Microsporidia are eukaryotic obligatory intracellular parasites that infect a wide range of vertebrates and invertebrate hosts. Spores infect target cells of the host by transferring their sporoplasm through a distinctive polar tube. This study investigated how selected chemicals influence the germination of two newly discovered microsporidia species from central-western Iran. Spores of Parathelohania iranica were extracted from infected larvae of Anopheles superpictus s.l. and purified by the Percoll discontinuous density gradient method. Because of the small number of spores per copepod, extraction and purification were not performed for spores of the microsporidium infecting Paracyclops chiltoni. Both spores were exposed to KCl, NaCl, KI, NaI, and H2O2 and the effects of concentration (0.5, 1.5, and 2.5 M), pH (7.0, 9.0, and 11.0), temperature (4 °C and 25 °C), and duration of exposure (10 and 30 min) on spore germination were investigated and compared. This study indicated that the type of the ionic nature of the surrounding environment of spores plays an important role in the release of polar tubes of both microsporidia. Additionally, anions played a more significant role than cations. This effect was directly related to concentration, temperature, and time. However, no specific pattern was recognized at different alkaline pH levels. Hydrogen peroxide was not effective in releasing the polar tubes of the spores of these microsporidia. This study demonstrated the comparative role of some chemicals and the associated factors in the release of the polar tube of two aquatic microsporidia. Future research should examine the practical value of these findings in the mass production of candidate microsporidia for the biological control of pest invertebrate hosts.

Detection and Practical Differentiation of Phytoplasmas from Several Host Plants Using PCR-RFLP

Phytoplasma as a phytopathogenic prokaryote with a wide host range is a pathogen that needs more attention in Indonesia. This pathogen is relatively difficult to detect and identify due to its complicated biological properties. This study involved detection of phytoplasmas by polymerase chain reaction (PCR) technique with P1/P7 primers from seven symptomatic plants, i.e. Bermuda grass white leaf, bamboo yellows, witches’ broom of peanut, soybean, yard long bean, and cactus, and sweet potato little leaf. The phytoplasma DNA of the 16S rRNA gene resulting from PCR amplification was examined by digestion reaction using three endonuclease enzymes AluI, RSaI, and MSeI to generate restriction fragment length polymorphism (RFLP) profile. The seven diseased plants were confirmed positive to be associated with phytoplasma as indicated by the PCR product of 1800 bp. Based on the RFLP profiles of the three enzymes, the phytoplasmas were divided into two groups, namely group I (Bermuda grass and bamboo) and group II (peanuts, soybeans, yard long beans, cactus, and sweet potatoes). Cactus phytoplasma is a sub-group (strain) because it has a slightly different fragment of MSeI RFLP profile.

Occurrence of wilt disease caused by Fusarium proliferatum on carnation in Türkiye

AbstractDuring the survey in greenhouse‐cut flower carnation (Dianthus caryophyllus L.) areas in Izmir, wilted carnation samples were collected from 92 greenhouses. A total of 95 Fusarium spp. isolates were obtained from carnation greenhouses, 80 had been identified as Fusarium oxysporum f.sp. dianthi and published earlier, while the remaining 15 were identified as Fusarium proliferatum (Fp) based on morphological and molecular analysis using TEF1‐α gene sequences in this study. The prevalence of wilting disease of carnation caused by Fp was estimated to be 16.3% of the total area. Pathogenicity tests were conducted by dipping the carnation roots (cv. Turbo) in a spore suspension of monoconidial isolates and transplanting them into pots. Pathogenicity studies confirmed the ability of all Fp to cause symptoms of wilting, leaves and stems shriving. Phylogenetic analysis of sequences from the translation elongation factor 1α (TEF‐1 α) region of the 15 Fp isolates obtained from carnation formed a large clade of isolates originating from carnation and a wide range of other hosts in different geographical locations worldwide. To our knowledge, this is the first report of F. proliferatum causing wilt disease of carnation based on molecular identification in Türkiye.

Phylogenetic diversity and functional potential of large and cell-associated viruses in the Bay of Bengal.

The BoB, the world's largest bay, is of significant economic importance to surrounding countries, particularly Bangladesh, which heavily relies on its coastal resources. Concurrently, the BoB holds substantial ecological relevance due to the region's high vulnerability to climate change-induced impacts. Yet, our understanding of the BoB's microbiome in relation to marine food web and biogeochemical cycling remains limited. Particularly, there are little or no data on the viral diversity and host association in the BoB. We examined the viral community in two distinct BoB coastal regions to reveal a multitude of viral species interacting with a wide range of microbial hosts, some of which play key roles in coastal biogeochemical cycling or potential pathogens. Furthermore, we demonstrate that the BoB coast harbors a diverse community of large and giant viruses, underscoring the importance of investigating understudied environments to discover novel viral lineages with complex metabolic capacities.

Loop-Mediated Isothermal Amplification Assays for Rapid Detection of Ralstonia solanacearum Species Complex and Phylotype I in Solanaceous Crops

The Ralstonia solanacearum species complex (RSSC) causes bacterial wilt diseases, which affect a wide range of plant hosts, including Solanaceae, and is of major economic importance. Point-of-care (POC) techniques such as loop-mediated isothermal amplification (LAMP) enable the rapid and sensitive detection of plant pathogens and can be deployed directly in the field. For fast and reliable diagnosis on site, we optimized an RSSC-LAMP assay and developed a real-time LAMP assay targeting the phylotype I. Both LAMPs were highly specific, yielding negative results for a wide collection of nontarget strains and positive results for all target strains, except for two particular mulberry strains for the phylotype I assay. These results were supported by an extensive in silico analysis performed on 6,105 genomes of Burkholderiaceae. The two LAMP assays displayed high sensitivity on pure suspensions, with a detection limit at 103 and 104 CFU/ml for phylotype I and the RSSC, respectively. These thresholds correspond to theoretical quantities of as low as 5 and 50 CFU per reaction. Two simplified extraction methods were successfully used to detect the pathogen from different Solanaceae samples. We demonstrated that LAMP assays were operable on solanaceous crops during field surveys and varietal evaluation trials as rapid POC diagnostics tools, which can improve the disease management and control of the RSSC. [Formula: see text] Copyright © 2023 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Egg hatching success is influenced by the time of thermal stress in four hard tick species.

Ticks are blood-feeding arthropods responsible for the transmission of disease-causing pathogens to a wide range of vertebrate hosts, including livestock and humans. Tick-borne diseases have been implicated in significant economic losses to livestock production, and this threat will increase as these obligate parasites widen their geographical ranges. Similar to other ectotherms, thermal stress due to changing global temperatures has been shown to influence tick survival and distribution. However, studies on the influence of extreme temperatures in ticks have focused on advanced, mobile stages, ignoring immobile stages that cannot move to more favorable microhabitats. In this study, low- and high-temperature regimens were assessed in relation to egg viability for hard tick species-Amblyomma maculatum (Gulf Coast tick), Ixodes scapularis (black-legged tick), Dermacentor variabilis (American dog tick), and Rhipicephalus sanguineus (Brown dog tick). Tick eggs exposed early in development (freshly laid during early embryo development) were significantly more susceptible to thermal stress when compared with those exposed later in development (late embryo development denoted by a fecal spot). Based on our studies, differences in egg hatching success among treatments were greater than in hatching success when comparing species. Lastly, there was evidence of extreme thermal exposure significantly altering the hatching times of tick eggs for specific treatments. These results provide insights into the critical period for tick egg viability in relation to thermal exposure and tick survival associated with stress and climate change.

Genome-wide epitope mapping across multiple host species reveals significant diversity in antibody responses to Coxiella burnetii vaccination and infection.

Coxiella burnetii is an important zoonotic bacterial pathogen of global importance, causing the disease Q fever in a wide range of animal hosts. Ruminant livestock, in particular sheep and goats, are considered the main reservoir of human infection. Vaccination is a key control measure, and two commercial vaccines based on formalin-inactivated C. burnetii bacterins are currently available for use in livestock and humans. However, their deployment is limited due to significant reactogenicity in individuals previously sensitized to C. burnetii antigens. Furthermore, these vaccines interfere with available serodiagnostic tests which are also based on C. burnetii bacterin antigens. Defined subunit antigen vaccines offer significant advantages, as they can be engineered to reduce reactogenicity and co-designed with serodiagnostic tests to allow discrimination between vaccinated and infected individuals. This study aimed to investigate the diversity of antibody responses to C. burnetii vaccination and/or infection in cattle, goats, humans, and sheep through genome-wide linear epitope mapping to identify candidate vaccine and diagnostic antigens within the predicted bacterial proteome. Using high-density peptide microarrays, we analyzed the seroreactivity in 156 serum samples from vaccinated and infected individuals to peptides derived from 2,092 open-reading frames in the C. burnetii genome. We found significant diversity in the antibody responses within and between species and across different types of C. burnetii exposure. Through the implementation of three different vaccine candidate selection methods, we identified 493 candidate protein antigens for protein subunit vaccine design or serodiagnostic evaluation, of which 65 have been previously described. This is the first study to investigate multi-species seroreactivity against the entire C. burnetii proteome presented as overlapping linear peptides and provides the basis for the selection of antigen targets for next-generation Q fever vaccines and diagnostic tests.

First report of Perkinsus olseni infections in blood cockles Tegillarca granosa on the south coast of Korea

The protozoan parasite Perkinsus olseni has become a focus of attention since it has been responsible for mass mortalities and economic losses in a wide range of bivalve hosts globally. The P. olseni host range along the south coast of Korea may extend beyond what was previously understood, and blood cockles in the Family Arcidae are also suggested to be potential hosts of P. olseni. In the present study, we applied histology and molecular techniques to identify Perkinsus sp. infections in the blood cockles Tegillarca granosa, which have been commercially exploited on the south coast of Korea for several decades. Histology and molecular techniques, including genus-specific immunofluorescence assay, species-specific fluorescence in situ hybridization, and phylogeny based on the ribosomal DNA internal transcribed spacer region revealed that T. granosa is infected by P. olseni, although the prevalence was low (0.5%). Histology revealed massive hemocyte infiltrations in the mantle, gill, and digestive gland connective tissues, indicating that the infection exerts negative impacts on the host cockles.

Polyamine signaling communications play a key role in regulating the pathogenicity of Dickeya fangzhongdai.

Dickeya fangzhongdai is a devastating bacterial pathogen infecting a wide range of crops and ornamental plants worldwide. As a newly identified bacterial species in 2016, the regulatory mechanisms that govern its virulence are still a mystery. In this study, we explored the potential roles of polyamine-mediated cell-to-cell communication in regulation of D. fangzhongdai virulence. Null mutation of speA and speC in D. fangzhongdai strain ZXC1, which encodes polyamine biosynthesis through arginine and ornithine pathways, respectively, dramatically reduced bacterial motility, decreased production of plant cell wall degradation (PCWD) enzymes, and attenuated the bacterial virulence on taro and potato. We then tested the effect of various polyamine molecules in the restoration of the mutant phenotypes and showed that putrescine was the most potent signal in the regulation of virulence traits in strain ZXC1. In addition, we found that taro extract contained active signals to rescue putrescine-deficient phenotypes. High-performance liquid chromatography mass spectrometry analysis validated the speA was essential for production of putrescine in D. fangzhongdai ZXC1. We further showed that the putrescine transporters PotF and PlaP are required for putrescine-mediated cell-to-cell communication and virulence against taro and potato tubers. quantitative reverse transcription-PCR analysis demonstrated that putrescine influences the pathogenicity of D. fangzhongdai ZXC1 by regulating the expression of PCWD enzymes, bacterial chemotaxis, and flagellar-related genes. The findings from this study shed a new light for elucidating the pathogenic mechanisms of D. fangzhongdai and present useful clues for developing relevant disease control strategies. IMPORTANCE Dickeya fangzhongdai is a newly identified plant bacterial pathogen with a wide host range. A clear understanding of the cell-to-cell communication systems that modulate the bacterial virulence is of key importance for elucidating its pathogenic mechanisms and for disease control. In this study, we present evidence that putrescine molecules from the pathogen and host plants play an essential role in regulating the bacterial virulence. The significance of this study is in (i) demonstrating that putrescine signaling system regulates D. fangzhongdai virulence mainly through modulating the bacterial motility and production of PCWD enzymes, (ii) outlining the signaling and regulatory mechanisms with which putrescine signaling system modulates the above virulence traits, and (iii) validating that D. fangzhongdai could use both arginine and ornithine pathways to synthesize putrescine signals. To our knowledge, this is the first report to show that putrescine signaling system plays a key role in modulating the pathogenicity of D. fangzhongdai.

Сравнително изпитване устойчивостта на образци фасул към склеротинийно гниене (Sclerotinia sclerotiorum) чрез директен и индиректен метод

White mold, caused by Sclerotinia sclerotiorum, is a key disease of common beans in temperate and subtropical climates. For the climatic conditions of Bulgaria, the infection occurs mainly as a result of mycelogenic development of the sclerotia, which is why the disease is observed mostly in varieties with a prostrate type of the habitus. Due to the wide range of hosts of the pathogen and long-term preservation of sclerotia in the soil, agrotechnical measures have little effect in controlling the fungus. Therefore, breeding resistant varieties are the most effective measure to prevent the disease. The selection of appropriate and verified methods for testing the source and breeding materials is of primary importance for the success of breeding programs to increase resistance to the pathogen. The present study aimed to compare the response of bean accessions to S. sclerotiorum, by applying a direct and indirect evaluation method with a view to their parallel use in the breeding process. The studies were conducted under greenhouse conditions, and 29 bean accessions were included in them. The accessions were grown in pots (45x30x10 cm) with a soil-sand mixture. In the first trifoliate leaf, the stem was cut at 3 cm from the node of the primary leaves (STAW test). A single-sided closed plastic straw containing an agar disc from the periphery of 3-day-old cultures of four isolates cultivated on PDA medium (five plants per isolate), was placed on the cut. The reaction of the accessions was recorded 7 days after inoculation on a 9-point scale. The cut plant parts (stem and trifoliate leaf) were immersed in oxalic acid solution (20 mM brought to pH=4.0 with 1N NaOH), five plants per sample. The cut plant parts immersed in sterile water adjusted to pH=4.0 with 1N HCl were used for the control. The reaction of the accessions was recorded after 19h on a 9-point scale. The data were processed with the SPSS stat. ver. 19 software. Significant differences were observed in the response of the accessions concerning the isolates used. Weak positive or negative correlations were found between the oxalate test and the STRAW test, and the direction was related to the aggressiveness of the isolates. It was established that for accessions A195, ‘GTB Scythia’, ‘Izabel’, ‘Rhodopeia’ and ‘Pirina’ the results of the oxalic test are comparable to those of the STRW-test. The obtained results give us reason to recommend the application of the oxalate test in the initial generations of the breeding materials, after a preliminary comparative analysis of the parental forms by both methods.