Virulent Research Articles

Virulence perspective genomic research unlocks the secrets of Rhizoctonia solani associated with banded sheath blight in Barnyard Millet (Echinochloa frumentacea)

IntroductionBanded sheath blight (Bsb) disease, caused by Rhizoctonia solani, is an emerging problem in barnyard millet cultivation. One of the significant goals of pathogenomic research is to identify genes responsible for pathogenicity in the fungus.MethodsA virulence profiling-based approach was employed and six R. solani isolates were collected from various ecological zones of India. The morphological parameters and virulence of all of the six R. solani isolates were investigated. The most virulent strain was designated as RAP2 and its genome has been sequenced, assembled, and annotated.ResultsThe RAP2 genome is 43.63 megabases in size and comprises 10.95% repetitive DNA, within which 46% are retroelements, 8% are DNA transposons, and 46% are unidentified DNA. The Gene Ontology (GO) annotation of RAP2 proteins revealed that “phosphorylation”, “membrane”, and “ATP binding” have the highest gene enrichment in the “biological process”, “cellular component” and “molecular function” domains, respectively. The genome comprises a majority of secretory proteins in the pectin lyase fold/virulence factor superfamily, which break down plant cell wall polymers to extract saccharides. The RAP2 genome is comparable to R. solani, which infects maize and rice, but it diverges further from soybean in terms of nucleotide-level genetic similarity. Orthologous clustering of RAP2 protein sequences with R. solani infecting maize, rice, and soybean yields 5606 proteins shared across all genomes. GO analysis of 25 proteins specific to the RAP2 genome found enrichment in the ethylene response, which can cause spore germination and infection in host plants.DiscussionInterestingly, a 28-bp deletion in the RAP2 strain’s cutinase domain was discovered in the cutinase protein, which might be important in the infection process, perhaps rendering the enzyme inactive or allowing the pathogen to infect barnyard millet while avoiding host defense. This study sheds light on the genetic makeup of R. solani, allowing researchers to discover critical genes related with pathogenicity as well as potential targets for fungicide development.

Antibacterial effects of Kampo products against pneumonia causative bacteria.

Community-acquired pneumonia is caused primarily by bacterial infection. For years, antibiotic treatment has been the standard of care for patients with bacterial pneumonia, although the emergence of antimicrobial-resistant strains is recognized as a global health issue. The traditional herbal medicine Kampo has a long history of clinical use and is relatively safe in treating various diseases. However, the antimicrobial effects of Kampo products against pneumonia-causative bacteria remain largely uncharacterized. In this study, we investigated the bacteriological efficacy of 11 Kampo products against bacteria commonly associated with pneumonia. Sho-saiko-To (9), Sho-seiryu-To (19), Chikujo-untan-To (91) and Shin'i-seihai-To (104) inhibited the growth of S. pneumoniae serotype 3, a highly virulent strain that causes severe pneumonia. Also, the growth of S. pneumoniae serotype 1, another highly virulent strain, was suppressed by treatment with Sho-saiko-To (9), Chikujo-untan-To (91), and Shin'i-seihai-To (104). Minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) against these strains ranged from 6.25-50 mg/mL and 12.5-25 mg/mL, respectively. Furthermore, Sho-saiko-To (9), Chikujo-untan-To (91), and Shin'i-seihai-To (104) suppressed the growth of antibiotic-resistant S. pneumoniae isolates. Additionally, Sho-saiko-To (9) and Shin'i-seihai-To (104) showed growth inhibition activity against Staphylococcus aureus, another causative agent for pneumonia, with MIC ranging from 6.25-12.5 mg/mL. These results suggest that some Kampo products have antimicrobial effects against S. pneumoniae and S. aureus, and that Sho-saiko-To (9) and Shin'i-seihai-To (104) are promising medicines for treating pneumonia caused by S. pneumoniae and S. aureus infection.

Differential Host Gene Expression in Response to Infection by Different Mycobacterium tuberculosis Strains—A Pilot Study

Tuberculosis (TB) represents a global public health threat and is a leading cause of morbidity and mortality worldwide. Effective control of TB is complicated with the emergence of multidrug resistance. Yet, there is a fundamental gap in understanding the complex and dynamic interactions between different Mycobacterium tuberculosis strains and the host. In this pilot study, we investigated the host immune response to different M. tuberculosis strains, including drug-sensitive avirulent or virulent, and rifampin-resistant or isoniazid-resistant virulent strains in human THP-1 cells. We identified major differences in the gene expression profiles in response to infection with these strains. The expression of IDO1 and IL-1β in the infected cells was stronger in all virulent M. tuberculosis strains. The most striking result was the overexpression of many interferon-stimulated genes (ISGs) in cells infected with the isoniazid-resistant strain, compared to the rifampin-resistant and the drug-sensitive strains. Our data indicate that infection with the isoniazid-resistant M. tuberculosis strain preferentially resulted in cGAS-STING/STAT1 activation, which induced a characteristic host immune response. These findings reveal complex gene signatures and a dynamic variation in the immune response to infection by different M. tuberculosis strains.

Outer membrane protein C is a protective and unique vaccine antigen against Shigella flexneri 3a

The anti-Shigella vaccine is one of the WHO’s top priorities. Every year the disease kills more than 200,000 people worldwide and poses a serious threat to children under 5 years of age and the elderly. Increasing antibiotic resistance and limitations in diagnostics emphasize the need to develop an effective vaccine. Recent research and clinical trials report multiple approaches used in Shigella-vaccine development. However, despite the efforts of researchers, pharmaceutical companies and health care organizations, there is no licensed vaccine against shigellosis available to the community. Here, we expressed, broadly characterized and demonstrated the protective properties of outer membrane protein C as an effective molecule serving as a universal antigen for Shigella vaccine. Most of the current approaches to the development of Shigella vaccine are based on the polysaccharide antigens, which are serotype specific and have always been challenging in terms of their high specificity, targeting the most exposed surface antigens identified for certain Shigella serotypes. Here, we confirm immunogenic and protective properties of the recombinant OmpC protein, which protects mice against a lethal dose of a virulent strain 2 weeks after active immunization.

Analysis of Powassan Virus Genome Sequences from Human Cases Reveals Substantial Genetic Diversity with Implications for Molecular Assay Development

Powassan virus (POWV) is an emerging tick-borne virus that causes severe meningoencephalitis in the United States, Canada, and Russia. Serology is generally the preferred diagnostic modality, but PCR on cerebrospinal fluid, blood, or urine has an important role, particularly in immunocompromised patients who are unable to mount a serologic response. Although the perceived poor sensitivity of PCR in the general population may be due to the biology of infection and health-seeking behavior (with short viremic periods that end before hospital presentation), limitations in assay design may also contribute. Genome sequences from clinical POWV cases are extremely scarce; PCR assay design has been informed by those available, but the numbers are limited. Larger numbers of genome sequences from tick-derived POWV are available, but it is not known if POWV genomes from human infections broadly mirror genomes from tick hosts, or if human infections are caused by a subset of more virulent strains. We obtained viral genomic data from 10 previously unpublished POWV human infections and showed that they broadly mirror the diversity of genome sequences seen in ticks, including all three major clades (lineage I, lineage II Northeast, and lineage II Midwest). These newly published clinical POWV genome sequences include the first confirmed lineage I infection in the United States, highlighting the relevance of all clades in human disease. An in silico analysis of published POWV PCR assays shows that many assays were optimized against a single clade and have mismatches that may affect their sensitivity when applied across clades. This analysis serves as a launching point for improved PCR design for clinical diagnostics and environmental surveillance.

Target antigen screening and development of a multi-component subunit vaccine against Mycoplasma synoviae in chickens

IntroductionMycoplasma synoviae (MS) is a globally important avian pathogen causing infectious synovitis and respiratory diseases in poultry, leading to significant economic losses. Despite advances in vaccine development, a commercially viable subunit vaccine against MS remains elusive.MethodsWe sequenced whole genomes of six clinical MS strains isolated from different Chinese provinces. Common genes were analyzed using Biopython software, identifying those with high copy numbers in virulent strains and shared among all strains. Vaxign2 and IEDB Antibody Epitope Prediction were used to analyze protein properties. We assessed immune protective effects of candidate proteins and developed a multivalent subunit vaccine.ResultsTen candidate vaccine proteins were initially selected. A multivalent subunit vaccine composed of MSPB, Ppht, Cfba, and EF-G displayed the best protective effect. The optimal immunization dosage was 20μg, with each protein accounting for 25%. The immune production period was determined to be 28 days post-first immunization, lasting 180 days. The immune protection rate against highly virulent strains reached 90%∼100%.DiscussionThis study provides a new approach for screening vaccine antigens and develops an effective candidate vaccine for MS prevention. The multivalent subunit vaccine shows promising results in protecting against MS infections, potentially offering a solution to reduce economic losses in the poultry industry.

Molecular characterization of reassortant infectious bursal disease virus (IBDV) strains of genogroup A3B1 detected in some areas of Britain between 2020 and 2021

Infectious bursal disease virus (IBDV) causes a major immunosuppressive disease of chickens. As part of ongoing epidemiological surveillance for IBDV, the hypervariable region (HVR) of the VP2 capsid gene encoded by segment A, and a region of the VP1 polymerase gene, encoded by segment B, were sequenced from 20 IBDV-positive bursal samples obtained in 2020 and 2021, from 16 commercial British broiler farms. Birds had received a live IBDV vaccine at 17–22 days of age, and samples were obtained at 25–55 days of age. Of the 16 farms, none contained very virulent (vv) strains, one contained a classical virulent strain, two contained vaccine strains, and five contained sequences of reassortant strains with a vv segment A and a non-vv segment B belonging to genogroup A3B1. In eight of the farms, we identified the sequences of both genogroup A3B1 reassortant strains and vaccine strains in the same samples. Therefore, the majority of the farms (13/16 (81%)) contained genogroup A3B1 reassortant viruses. Of the flocks containing reassortant strains, 5/13 (38%) had HVR mutations Q219L, G254D, D279N, and N280T, consistent with a recently described Western European clade, but the rest had other mutations or no mutations, demonstrating that multiple clades were present in the samples. Taken together, vv strains were not detected, but reassortant strains predominated in the farms, which belonged to different clades, and were frequently found together with vaccine strains.

Host combats porcine reproductive and respiratory syndrome virus infection at non-coding RNAs level.

Porcine reproductive and respiratory syndrome virus (PRRSV) poses a significant threat to the global swine industry. The emergence of new, highly virulent strains has precipitated recurrent outbreaks worldwide, underscoring the ongoing battle between host and virus. Thus, there is an imperative to formulate a more comprehensive and effective disease control strategy. Studies have shown that host non-coding RNA (ncRNA) is an important regulator of host - virus interactions in PRRSV infection. Hence, a thorough comprehension of the roles played by ncRNAs in PRRSV infection can augment our understanding of the pathogenic mechanisms underlying PRRSV infection. This review focuses on elucidating contemporary insights into the roles of host microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs) in PRRSV infection, providing both theoretical foundations and fresh perspectives for ongoing research into the mechanisms driving PRRSV infection and its pathogenesis.

Mucosal sugars delineate pyrazine vs pyrazinone autoinducer signaling in Klebsiella oxytoca

Virulent Klebsiella oxytoca strains are associated with gut and lung pathologies, yet our understanding of the molecular signals governing pathogenesis remains limited. Here, we characterized a family of K. oxytoca pyrazine and pyrazinone autoinducers and explored their roles in microbial and host signaling. We identified the human mucin capping sugar Neu5Ac as a selective elicitor of leupeptin, a protease inhibitor prevalent in clinical lung isolates of K. oxytoca, and leupeptin-derived pyrazinone biosynthesis. Additionally, we uncovered a separate pyrazine pathway, regulated by general carbohydrate metabolism, derived from a broadly conserved PLP-dependent enzyme. While both pyrazine and pyrazinone signaling induce iron acquisition responses, including enterobactin biosynthesis, pyrazinone signaling enhances yersiniabactin virulence factor production and selectively activates the proinflammatory human histamine receptor H4 (HRH4). Our findings suggest that the availability of specific carbohydrates delineates distinct autoinducer pathways in K. oxytoca that may have differential effects on bacterial virulence and host immune responses.

Synergistic role of Mycobacterium indicus pranii and human beta Defensin-2 as adjunctive therapy against Mycobacterium tuberculosis

Host-directed therapies (HDT) via modulation of specific host responses like inflammation can limit mycobacterial infection. HDTs could be included in current TB therapy as an adjunct to increase bacterial clearance and limit tissue damage to control spread. Individually, Mycobacterium indicus pranii (MIP) and human beta defensin-2 (hBD-2) are promising therapies for tuberculosis (TB). They can directly target the TB bacilli and enhance cell-mediated immune responses, which is limiting with conventional drugs. Therefore, our study investigated the combined application of MIP and hBD-2 to evaluate their efficacy in clearing infections caused by Mycobacterium smegmatis (M.smeg) and Mycobacterium tuberculosis (M.tb) (both avirulent; H37Ra and virulent strain; H37Rv) in THP-1 cells and human monocyte-derived macrophages (MDMs). A strong pro-inflammatory response was observed against the combination of MIP and hBD-2 which also correlated with a significant reduction in the bacterial load. This combination further showed protection against M.tb by enhancing pyroptosis in the infected cells. The study suggests the combined use of these potent immunomodulators, which could be employed as an effective mode of therapy as adjuvants against mycobacterial infections after validation in a suitable animal model.

Pathogenesis of Klebsiella Pneumoniae Induced Proteinopathy is Amyloid Strain Dependent

Abstract Introduction/Objective The World Health Organization has labeled Klebsiella pneumoniae (KP), a Gram-negative bacterium, as a ‘Critical Priority’ pathogen due to its increasing prevalence in serious conditions like pneumonia and sepsis, along with its growing resistance to multiple drugs. Infections with KP have been linked to the collapse of microtubules and the release of harmful proteins called amyloid-beta (Aβ) and tau from lung endothelial cells. These infection-induced lung endothelial amyloids can spread like prions and are stable under heat. Methods/Case Report However, the mechanisms behind these effects and whether the infection-generated proteinopathy depends on tau and/or Aβ were not well understood. This study hypothesized that KP infection triggers tau dysfunction, breakdown of microtubules, increased lung barrier permeability, and the production and release of toxic amyloids. To test this, researchers used CRISPR/Cas9 technology to create lung endothelial cells without tau and/or amyloid precursor protein (APP). They confirmed gene deletion through various methods and exposed these cells, along with regular cells, to a highly virulent KP strain. Results (if a Case Study enter NA) The results showed that the KP strain (Kp 1-008) caused disruption of cellular structures, increased permeability, and bacterial spread within hours of infection. Supernatants containing proteins from infected cells, when applied to healthy cells, led to barrier disruption, permeability, and cell death. Interestingly, different pathologies were induced by supernatants from cells lacking tau or APP, indicating that either tau or Aβ alone could propagate damage in a strain- specific manner. The most severe damage required both tau and Aβ together. Conclusion In conclusion, KP infection disturbs cellular structures, promoting barrier breakdown and bacterial dissemination. It also generates toxic tau and Aβ proteins. Either of these proteins can spread harm from cell to cell, but together, they enhance the severity and potency of the resulting lung endothelial protein damage caused by the infection. The study sheds light on the complex mechanisms of KP-related infections and their impact on cellular structures and protein pathways.

Assessing the Pathogenicity of Berkeleyomyces rouxiae and Fusarium oxysporum f. sp. vasinfectum on Cotton (Gossypium hirsutum) Using a Rapid and Robust Seedling Screening Method.

Cotton (Gossypium spp.) is the most important fibre crop worldwide. Black root rot and Fusarium wilt are two major diseases of cotton caused by soil-borne Berkeleyomyces rouxiae and Fusarium oxysporum f. sp. vasinfectum (Fov), respectively. Phenotyping plant symptoms caused by soil-borne pathogens has always been a challenge. To increase the uniformity of infection, we adapted a seedling screening method that directly uses liquid cultures to inoculate the plant roots and the soil. Four isolates, each of B. rouxiae and Fov, were collected from cotton fields in Australia and were characterised for virulence on cotton under controlled plant growth conditions. While the identities of all four B. rouxiae isolates were confirmed by multilocus sequencing, only two of them were found to be pathogenic on cotton, suggesting variability in the ability of isolates of this species to cause disease. The four Fov isolates were phylogenetically clustered together with the other Australian Fov isolates and displayed both external and internal symptoms characteristic of Fusarium wilt on cotton plants. Furthermore, the isolates appeared to induce varied levels of plant disease severity indicating differences in their virulence on cotton. To contrast the virulence of the Fov isolates, four putatively non-pathogenic Fusarium oxysporum (Fo) isolates collected from cotton seedlings exhibiting atypical wilt symptoms were assessed for their ability to colonise cotton host. Despite the absence of Secreted in Xylem genes (SIX6, SIX11, SIX13 and SIX14) characteristic of Fov, all four Fo isolates retained the ability to colonise cotton and induce wilt symptoms. This suggests that slightly virulent strains of Fo may contribute to the overall occurrence of Fusarium wilt in cotton fields. Findings from this study will allow better distinction to be made between plant pathogens and endophytes and allow fungal effectors underpinning pathogenicity to be explored.

Evaluation of a Low-Temperature Immersion Immunization Strategy for the Infectious Spleen and Kidney Necrosis Virus orf037l Gene-Deleted Attenuated Vaccine

Background: Infectious spleen and kidney necrosis virus (ISKNV) poses a significant threat to aquaculture sustainability, particularly affecting mandarin fish (Siniperca chuatsi) and causing significant economic losses. Methods: To address this challenge, this study developed an ISKNV Δorf037l vaccine strain, where the orf037l gene was knocked out. Infection assays conducted at 28 °C showed that the knocking out the orf037l gene decreased the virulence of ISKNV and reduced lethality against mandarin fish by 26.7% compared to wild-type ISKNV. To further diminish residual virulence, the effect of low-temperature (22 °C) immersion immunization was evaluated. Results: The results indicate that low temperature significantly diminished the virulence of the Δorf037l vaccine strain, elevating the survival rate of mandarin fish to 90%. Furthermore, the vaccine strain effectively triggered the expression of crucial immune-related genes, such as IFN-h, IL-1, IκB, Mx, TNF-α, and Viperin, while inducing the production of specific neutralizing antibodies. Low-temperature immersion with Δorf037l achieved a high relative percentage of survival of 92.6% (n = 30) in mandarin fish, suggesting the potential of Δorf037l as a promising immersion vaccine candidate. Conclusions: These findings contribute to advancing fish immersion vaccine development and demonstrate the importance and broad applicability of temperature optimization strategies in vaccine development. Our work carries profound implications for both the theoretical understanding and practical application in aquaculture disease control.

Whole genome sequences of Yersinia pestis strains of ancient phylogenetic branch 0.ANT5 isolated in the 21st century in the Tien-Shan in Kyrgyzstan.

We announce the whole genome hybrid sequences of 11 highly virulent Yersinia pestis strains of the ancient phylogenetic branch 0.ANT5, one of the closest to the strains of the First Plague Pandemic. Nine strains were isolated in 2013-2023 and two in 1953 and 1971 in the Tien Shan plague focus in Kyrgyzstan.

Pathogenicity of psychrotolerant strains of Antarctic Pseudogmynoascus fungi reveals potential opportunistic profiles

Recent studies have demonstrated the presence of fungal taxa in the extreme ecosystems of Antarctica that are known to opportunistically infect humans and animals. Among these are members of the genus Pseudogymnoascus, including some that are genetically similar to P. destructans, known to be pathogenic to bats. We evaluated the in vitro and in vivo pathogenic potential of 11 Pseudogymnoascus spp. strains recovered from Antarctica. All strains were able to grow at temperatures up to 28 °C and displayed in vitro pathogenicity through hemolytic activity, growth at different pH levels, production of hydrolytic enzymes, spore diameters, tolerance to oxidative stress, hypoxia, and halotolerance. Among them, Pseudogymnoascus sp. UFMG 8532 exhibited strong in vitro pathogenicity and in preliminary in vivo assay killed 100 % of Tenebrio molitor larvae within one day. The pathogenicity of the same strain was also tested using immunosuppressed BALB/c mouse models. Survival of BALB/c mice was affected, with oscillations between weight gain and loss, and impacts on sensory function, reflexes and autonomic function. Histopathological data from the organs of infected mice showed evidence of inflammatory processes, with numerous neutrophils, a small number of macrophages, fluid accumulation inside the lungs and intense hyperemia. Our results indicate that Antarctic Pseudogymnoascus spp. strains obtained from various substrates/habitats in maritime Antarctica may possess intrinsic virulence factors and pathogenic potential for immunosuppressed animals and humans in the region. Given that the Antarctic environment is an important reservoir for Pseudogymnoascus species, which display growth performance across a range of temperatures, it is possible that increasing temperatures in the maritime Antarctic could activate dormant genes or biochemical pathways, select virulent species and/or strains, and facilitate their spread within and beyond the region. The ability of Pseudogymnoascus species to grow slowly even at 28°C, coupled with their potential in vitro and in vivo virulence factors, suggests that these fungi might be undergoing an opportunistic transition due to the effects of climate change on the Antarctic Peninsula.

Fast and Economic Microarray-Based Detection of Species-, Resistance-, and Virulence-Associated Genes in Clinical Strains of Vancomycin-Resistant Enterococci (VRE)

Today, there is a continuous worldwide battle against antimicrobial resistance (AMR) and that includes vancomycin-resistant enterococci (VRE). Methods that can adequately and quickly detect transmission chains in outbreaks are needed to trace and manage this problem fast and cost-effectively. In this study, DNA-microarray-based technology was developed for this purpose. It commenced with the bioinformatic design of specific oligonucleotide sequences to obtain amplification primers and hybridization probes. Microarrays were manufactured using these synthesized oligonucleotides. A highly parallel and stringent labeling and hybridization protocol was developed and employed using isolated genomic DNA from previously sequenced (referenced) clinical VRE strains for optimal sensitivity and specificity. Microarray results showed the detection of virulence, resistance, and species-specific genes in the VRE strains. Theoretical predictions of the microarray results were also derived from the sequences of the same VRE strain and were compared to array results while optimizing protocols until the microarray result and theoretical predictions were a match. The study concludes that DNA microarray technology can be used to quickly, accurately, and economically detect specifically and massively parallel target genes in enterococci.

Construction and Immunogenicity of a Recombinant Porcine Pseudorabies Virus (PRV) Expressing the Major Neutralizing Epitope Regions of S1 Protein of Variant PEDV

Porcine epidemic diarrhea virus (PEDV) infection causes severe diarrhea and high mortality in neonatal piglets. Pseudorabies causes acute and often fatal infections in young piglets, respiratory disorders in growing pigs, and reproductive failure in sows. In late 2011, pseudorabies virus (PRV) variants occurred in Bartha-K61-vaccine-immunized swine herds, resulting in economic losses to the global pig industry. Therefore, it is essential to develop a safe and effective vaccine against both PEDV and PRV infections. In this study, we constructed a recombinant virus rPRV-PEDV S1 expressing the major neutralizing epitope region (COE, SS2, and SS6) of the PEDV S1 protein by homologous recombination technology and CRISPR/Cas9 gene editing technology, and then evaluated its biological characteristics in vitro and immunogenicity in pigs. The recombinant virus rPRV-PEDV S1 had similar growth kinetics in vitro to the parental rPRV NY-gE−/gI−/TK− strain, and was proven genetically stable in swine testicle (ST) cells and safe for piglets. PEDV S1-specific antibodies were detected in piglets immunized with rPRV-PEDV S1 on the 7th day post-immunization (dpi), and the antibody level increased rapidly at 14–21 dpi. Moreover, the immunized piglets receiving the recombinant virus exhibited alleviated clinical signs and reduced viral load compared to the unvaccinated group following a virulent PEDV HN2021 strain challenge. Also, piglets immunized with rPRV-PEDV S1 developed a PRV-specific humoral immune response and elicited complete protection against a lethal PRV NY challenge. These data indicate that the recombinant rPRV-PEDV S1 is a promising vaccine candidate strain for the prevention and control of PEDV and PRV infections.

Attenuated African swine fever viruses and the live vaccine candidates: a comprehensive review.

The African swine fever virus (ASFV) is spreading worldwide and causing huge economic losses to the global pig industry. The ASFV genome is 170-193 kb in length, contains approximately 150 open reading frames, and encodes more than 200 proteins, most of which have unknown functions. Owing to the unique viral structure, replication strategy, large number of genes of unknown function, and complicated pathogenesis, vaccine development research is challenging. Several naturally attenuated ASFV isolates have been extensively investigated and many genetically manipulated, gene-deleted, and cell-adapted ASFVs have been reported. Currently, live attenuated viruses prepared from weakly virulent strains are an efficient method to provide effective protection in vaccinated pigs; however, these have seldom been widely approved for vaccine use, except in Vietnam. Herein, we summarize the attenuated isolates or vaccine candidates for live vaccines derived from different sources, including naturally mutated, attenuated, cell-adapted, and genetically modified recombinant ASFVs. This will help to understand the gene function and immunogenicity of attenuated live ASFV, as well as the shortcomings of these viruses as vaccine candidates, and provide clues to prepare live, efficient, and safe vaccines for African swine fever.IMPORTANCEOutbreaks of African swine fever (ASF) have caused devastating losses to the global pig industry. Pigs immunized with ASFV attenuated virus can resist the lethal challenge of a strongly virulent virus. Here, we summarize the virulence of naturally mutated, cell-adapted, and genetically recombinant ASFV for pigs, and the protective effect after facing an attack challenge. We also analyze the advantages and disadvantages of ASFV attenuated viruses as vaccine candidates to provide clues for the preparation of efficient and safe live African swine fever vaccines.

A rapid and reliable method for early Legionella pneumophila identification and characterization in support of the epidemiology study.

Legionnaires' disease is a severe pneumonia predominantly caused by Legionella pneumophila (Lp), whose major reservoirs are artificial water systems. As most human infections are caused by L. pneumophila serogroup 1 (Lp1), a reliable method for Lp distinction can be crucial for bacterial spread prevention. As the ability to withstand in environments and to cause the waterborne disease is strongly related to specific genes, the identification of virulent strains can be of great relevance to implement water environmental monitoring and to contain harmful outbreaks to public health. We aimed to test an assay for Lp identification among different Legionella species, and to determine the serogroups. Additionally, we investigated the carriage of virulence and antimicrobial resistance genes. A total of 90 Legionella spp. isolates identified by phenotypic tests were subjected to the designed quantitative PCR assay targeting specific mip for Lp, wzm for Lp1, pvcA and ahpD for biofilm production. Eleven serogroups were investigated in all our isolates tested positive for mip gene, subsequently analyzed for 12 virulence and 8 antimicrobial resistance genes. Only the 70 Lp isolates were positive for mip. Out of 27 Lp isolates belonging to serogroup 1 based on agglutination test, 23 (85.2%) carried wzm. The presence of ahpD and pvcA was found in 94.3 and 98.6% of Lp isolates, respectively. By multiplex PCR, all 23 wzm-positive strains were confirmed as serogroup 1 that was the most predominant (33%). At least one virulence gene was detected in all Lp isolates. The most frequent gene was ispE (100%), followed by issD (96%), icmK and enhC (93%), cpxA (91%), rtxA2 (74%), lvhB8-B9 (61%), and prpA (54%). The other genes were less diffused in Lp strains (rtxA1, 44%; lvhB3-B4, 47%; pvcB, 27%; lvrE, 24%). Of the macrolide resistance genes, the ereA was found in 84% of Lp strains, while only 14 (20%) harbored the lpeAB among the efflux pump genes. The assays validated in this study enable the simultaneous Lp and Lp1 detection. The differentiation of Lp strains according to their virulence properties could be useful to predict the bacterial ability to survive and to cause the disease.

Characterizing virulence differences in a parasitoid wasp through comparative transcriptomic and proteomic

BackgroundTwo strains of the endoparasitoid Cotesia typhae (Hymenoptera: Braconidae) present a differential parasitism success on the host, Sesamia nonagrioides (Lepidoptera: Noctuidae). One is virulent on both permissive and resistant host populations, and the other only on the permissive host. This interaction provides a very interesting frame for studying virulence factors. Here, we used a combination of comparative transcriptomic and proteomic analyses to unravel the molecular basis underlying virulence differences between the strains.ResultsFirst, we report that virulence genes are mostly expressed during the pupal stage 24 h before adult emergence of the parasitoid. Especially, 55 proviral genes are up-regulated at this stage, while their expression is only expected in the host. Parasitoid gene expression in the host increases from 24 to 96 h post-parasitism, revealing the expression of 54 proviral genes at early parasitism stage and the active participation of teratocytes to the parasitism success at the late stage. Secondly, comparison between strains reveals differences in venom composition, with 12 proteins showing differential abundance. Proviral expression in the host displays a strong temporal variability, along with differential patterns between strains. Notably, a subset of proviral genes including protein-tyrosine phosphatases is specifically over-expressed in the resistant host parasitized by the less virulent strain, 24 h after parasitism. This result particularly hints at host modulation of proviral expression. Combining proteomic and transcriptomic data at various stages, we identified 8 candidate genes to support the difference in reproductive success of the two strains, one proviral and 7 venom genes, one of them being also produced within the host by the teratocytes.ConclusionsThis study sheds light on the temporal expression of virulence factors of Cotesia typhae, both in the host and in the parasitoid. It also identifies potential molecular candidates driving differences in parasitism success between two strains. Together, those findings provide a path for further exploration of virulence mechanisms in parasitoid wasps, and offer insights into host-parasitoid coevolution.