Lethal Pathogen Research Articles

Antimycotic effect of 3-phenyllactic acid produced by probiotic bacterial isolates against Covid-19 associated mucormycosis causing fungi.

The Covid-19 associated mucormycosis (CAM) is an emerging disease affecting immunocompromised patients. Prevention of such infections using probiotics and their metabolites persist as effective therapeutic agents. Therefore, the present study emphasizes on assessment of their efficacy and safety. Samples from different sources like human milk, honey bee intestine, toddy, and dairy milk were collected, screened and characterized for potential probiotic lactic acid bacteria (LAB) and their metabolites to be used as effective antimicrobial agents to curtail CAM. Three isolates were selected based on probiotic properties and characterized as Lactobacillus pentosus BMOBR013, Lactobacillus pentosus BMOBR061 and Pediococcus acidilactici BMOBR041 by 16S rRNA sequencing and MALDI TOF-MS. The antimicrobial activity against standard bacterial pathogens showed ˃9 mm zone of inhibition. Furthermore, the antifungal activity of three isolates was tested against Aspergillus flavus MTCC 2788, Fusarium oxysporum, Candida albicans and Candida tropicalis where the results showed significant inhibition of each fungal strain. Further studies were carried out on lethal fungal pathogens like Rhizopus sp. and two Mucor sp. which are associated with post Covid-19 infection in immunosuppressed diabetic patients. Our studies on CAM inhibitory effect of LAB revealed the efficient inhibition against Rhizopus sp. and two Mucor sp. The cell free supernatants of three LAB showed varied inhibitory activity against these fungi. Following the antimicrobial activity, the antagonistic metabolite 3-Phenyllactic acid (PLA) in culture supernatant was quantified and characterized by HPLC and LC-MS using standard PLA (Sigma Aldrich). The isolate L. pentosus BMOBR013 produced highest PLA (0.441 g/L), followed by P. acidilactici BMOBR041 (0.294 g/L) and L. pentosus BMOBR061 (0.165 g/L). The minimum inhibitory concentration of HPLC eluted PLA on the Rhizopus sp. and two Mucor sp. was found to be 180 mg/ml which was further confirmed by inhibition of total mycelia under live cell imaging microscope.

A single-dose F1-based mRNA-LNP vaccine provides protection against the lethal plague bacterium.

Messenger RNA (mRNA) lipid nanoparticle (LNP) vaccines have emerged as an effective vaccination strategy. Although currently applied toward viral pathogens, data concerning the platform's effectiveness against bacterial pathogens are limited. Here, we developed an effective mRNA-LNP vaccine against a lethal bacterial pathogen by optimizing mRNA payload guanine and cytosine content and antigen design. We designed a nucleoside-modified mRNA-LNP vaccine based on the bacterial F1 capsule antigen, a major protective component of Yersinia pestis, the etiological agent of plague. Plague is a rapidly deteriorating contagious disease that has killed millions of people during the history of humankind. Now, the disease is treated effectively with antibiotics; however, in the case of a multiple-antibiotic-resistant strain outbreak, alternative countermeasures are required. Our mRNA-LNP vaccine elicited humoral and cellular immunological responses in C57BL/6 mice and conferred rapid, full protection against lethal Y. pestis infection after a single dose. These data open avenues for urgently needed effective antibacterial vaccines.

Structure of the Newcastle Disease Virus L protein in complex with tetrameric phosphoprotein

Newcastle disease virus (NDV) belongs to Paramyxoviridae, which contains lethal human and animal pathogens. NDV RNA genome is replicated and transcribed by a multifunctional 250 kDa RNA-dependent RNA polymerase (L protein). To date, high-resolution structure of NDV L protein complexed with P protein remains to be elucidated, limiting our understanding of the molecular mechanisms of Paramyxoviridae replication/transcription. Here, we used cryo-EM and enzymatic assays to investigate the structure-function relationship of L-P complex. We found that C-terminal of CD-MTase-CTD module of the atomic-resolution L-P complex conformationally rearranges, and the priming/intrusion loops are likely in RNA elongation conformations different from previous structures. The P protein adopts a unique tetrameric organization and interacts with L protein. Our findings indicate that NDV L-P complex represents elongation state distinct from previous structures. Our work greatly advances the understanding of Paramyxoviridae RNA synthesis, revealing how initiation/elongation alternates, providing clues for identifying therapeutic targets against Paramyxoviridae.

Dynamics of Serological and Mucosal Antibody Responses against African Swine Fever Viruses in Experimentally Infected Pigs

African swine fever virus (ASFV) is a lethal swine pathogen, and there is no effective vaccine or treatment available for ASFV infection. Recently, the occurrence of ASFV genotype I and genotype II natural mutants that manifest as subacute, longer-incubation, or persistent infections poses threats to preventing ASFV infection. The dynamics of antibody responses to ASFV are still completely unrevealed, especially the secretion of mucosal antibodies in oral fluid. Here, a systematic analysis was performed of serological and mucosal antibody secretion against 6 ASFV antigens after direct or indirect infection with four different ASFV strains or genotypes, namely, the field virulent genotype II isolate ASFV HLJ/18, the artificially attenuated genotype II strain HLJ/18-7GD, the naturally attenuated genotype II isolate HLJ/HRB1/20, and genotype I isolate SD/DY-I/21. Severe clinical signs of HLJ/18 infection were observed in pigs from 4 days postinoculation. However, no clinical signs were observed in HLJ/18-7GD-infected pigs. The contact pigs cohoused with the pigs intramuscularly infected with the isolate SD/DY-I/21 or HLJ/HRB1/20 only showed chronic clinical signs. Interestingly, the oral fluid sIgA responses to all the selected antigens were significantly stronger and earlier than the serum IgG responses in both HLJ/18- and HLJ/18-7GD-challenged pigs. Although significant fluctuations and individual differences appeared in oral swab sIgA responses in the contact transmission group, they were earlier than the corresponding serological IgG responses. Moreover, according to the comparative analysis of the three infection groups, P54 was proposed to be a dominant target for serological IgG diagnosis, while P30, CD2v, P54, P22, and P10 were more advantageous as mucosal sIgA diagnosis targets. These results highlight the important role of mucosal antibodies in the early diagnosis of ASFV infection and can provide references to screen appropriate targets for ASFV detection.

Ebola virus disease: In vivo protection provided by the PAMP restricted TLR3 agonist rintatolimod and its mechanism of action

Ebola virus (EBOV) is a highly infectious and lethal pathogen responsible for sporadic self-limiting clusters of Ebola virus disease (EVD) in Central Africa capable of reaching epidemic status. 100% protection from lethal EBOV-Zaire in Balb/c mice was achieved by rintatolimod (Ampligen) at the well tolerated human clinical dose of 6 mg/kg. The data indicate that the mechanism of action is rintatolimod's dual ability to act as both a competitive decoy for the IID domain of VP35 blocking viral dsRNA sequestration and as a pathogen-associated molecular pattern (PAMP) restricted agonist for direct TLR3 activation but lacking RIG-1-like cytosolic helicase agonist properties. These data show promise for rintatolimod as a prophylactic therapy against human Ebola outbreaks.

Surfactants alter mosquito’s flight and physical condition

Mosquitoes carry lethal pathogens for humans and hundreds of thousands of people are killed by mosquito-borne diseases every year. Therefore, controlling mosquitoes is essential to protect the lives of people around the world. Insecticides are highly effective in controlling mosquitoes and have been used extensively worldwide. However, they have potentially harmful effects on biodiversity and environment, and some mosquitoes are resistant to insecticide ingredients and survive upon their application. Therefore, there is a demand for a method to control mosquitoes without using conventional insecticide ingredients. Here, we used Aedes albopictus to test whether solutions with low surface tension, particularly surfactant solutions can alter mosquito behavior by spreading over the hydrophobic cuticle of mosquitoes. We found that solutions with low surface tension indeed attached to mosquitoes flying or resting on the wall, and made them fall. In addition, solutions with yet lower surface tension covered the mosquito surface more quickly and widely, knocking down or killing mosquitoes. These results suggest that surfactants such as sodium dioctyl sulfosuccinate can be used to alter mosquito behavior without relying on conventional insecticides.

Bioactivity of Citral and Its Nanoparticle in Attenuating Pathogenicity of Pseudomonas aeruginosa and Controlling Drosophila melanogaster

Plant-based essential oils are hydrophobic, volatile concentrate extracted from aromatic plants. They are the upcoming alternative and appealing source of antimicrobial compounds, citral (major constituent of lemongrass oil) being one of them, whose antiquorum sensing, in vivo delivery, and insecticidal potential need further exploration. Pseudomonas aeruginosa is one of the most prevalent, clinically lethal pathogens, which is resistible toward various treatments because of the inherent resistance acquired by the organism to many classes of drugs (multidrug resistant (MDR)). Moreover, fruit flies have been considered as the vectors of potentially lethal and opportunistic pathogens, including multiantibiotic-resistant microbes. As a result, controlling both the pathogen and its host vector are of utmost importance. The present study focused on the efficacy of essential oil of citral (EOC) and its nanoencapsulated form on quorum sensing inhibition (QSI) of P. aeruginosa PAO1 and its insecticidal activity against Drosophila melanogaster. Chitosan-based citral nanoparticles were synthesized and characterized using hydrodynamic size, zeta potential, polydispersity index, and field-emission scanning electron microscopy (FE-SEM). Citral nanoparticles at sub-minimum inhibitory concentration (MIC) exhibited QSI potential by attenuating biofilm formation (p-value < 0.05), while insecticidal activity of citral tested against D. melanogaster demonstrated toxicity of the EOC at a concentration of 3%–5%. Hence, the results elucidated the prospects of citral nanoparticles in the delivery of citral, which can be applied as a strategy to specifically target clinically lethal pathogens, major insect pests, and associated microbes.

Infection behavior of Listeria monocytogenes on iceberg lettuce (Lactuca sativa var. capitata)

Iceberg lettuce among leafy vegetables is susceptible to contamination with foodborne pathogens, posing a risk of food microbial safety. Listeria monocytogenes (L. monocytogenes) is a highly lethal pathogen that can survive and proliferate on leafy vegetables. In this paper, the contamination stage, attachment site, internalization pathway, proliferation process, extracellular substance secretion and virulence factors expression of L. monocytogenes on iceberg lettuce were researched. Results showed that the contamination stage of L. monocytogenes on iceberg lettuce was 0–20 min, the proliferation stage was after 20 min. The attachment tissues were stomata and winkles. The internalization distance of L. monocytogenes in the midrib was farther than that in the leaf blade. They enhanced the movement ability of cells by up-regulating the expression of flaA and motA genes, and enhanced the adhesion ability of cells by up-regulating the expression of actA and inla genes, which was beneficial to the proliferation. During proliferation, cells gradually secreted extracellular substances to promote the biofilm formation on iceberg lettuce. The formation of biofilms experienced: individual bacteria, cell aggregation and biofilm maturation. Biofilms were more likely to form on the leaf blade of iceberg lettuce.

Viral transmission and infection prevalence in a cannibalistic host–pathogen system

Cannibalism, while prevalent in the natural world, is often viewed as detrimental to a cannibal's health, especially when they consume pathogen-infected conspecifics. The argument stems from the idea that cannibalizing infected individuals increases the chance of coming into contact with a pathogen and subsequently becoming infected. Using an insect pest, the fall armyworm (Spodoptera frugiperda), that readily cannibalizes at the larval stage and its lethal pathogen, we experimentally examined how cannibalism affects viral transmission at both an individual and population level. Prior to death, the pathogen in the system stops the larval host from growing, resulting in infected individuals being smaller than healthy individuals. This leads to size-structured cannibalism of infected individuals with the larger healthy larvae consuming the smaller infected larvae, which is commonly observed. At the individual level, we show that the probability of cannibalism is relatively high for both infected and uninfected individuals especially when the cannibal is larger than the victim. However, the probability of the cannibal becoming infected given that a pathogen-infected individual has been cannibalized is relatively low. On a population level, when cannibalism is allowed to occur transmission rates decline. Additionally, by cannibalizing infected larvae, cannibals lower the infection risk for non-cannibals. Thus, cannibalism can decrease infection prevalence and, therefore, may not be as deleterious as once thought. Under certain circumstances, cannibalizing infected individuals, from the uninfected host's perspective, may even be advantageous, as one obtains a meal and decreases competition for resources with little chance of becoming infected.

Outcomes and management of pregnancy and puerperal group A streptococcal infections: A systematic review.

Group A streptococcus (Streptococcus pyogenes) is one of the most lethal bacterial pathogens of humans, with increased risk of progression to septic shock and multiorgan failure in the pregnant population. The objective of this study is to systematically review the outcomes and management strategies for pregnancy and puerperal group A streptococcus infections in an effort to provide further guidance for prevention and treatment of a rare but lethal infection worldwide. A comprehensive search using puerperium and streptococcus pyogenes terms was completed across several registered databases. A total of 902 articles investigating pregnancy and puerperal group A streptococcus infection were identified, with 40 studies fulfilling inclusion criteria of original research articles in humans published from 1990 onwards reporting four or more unique cases of group A streptococcus in pregnancy or postpartum. This study was registered in PROSPERO: CRD42020198983. A total of 1160 patients with pregnancy and puerperal group A streptococcus infection were identified. Most infections occurred postpartum (91.9%), with 4.7% reported antepartum and 0.6% intrapartum. Bacteremia was present in 49.0% of patients and endometritis in 45.9%. Puerperal sepsis was described in 28.2% of cases and progressed to streptococcal toxic shock syndrome in one-third of such cases. Overall, the case fatality ratio was 2.0%, with one-third of the deaths from antenatal cases including 3/22 (13.6%) cases of septic abortion and 10/46 (21.7%) antenatal cases of group A streptococcus infection. Group A streptococcus infection remains an important contributor to pregnancy and puerperal morbidity and mortality. Early recognition, diagnosis and aggressive management are important for favorable outcomes given the serious risk of sepsis and streptococcal toxic shock syndrome.

Comparison of five commercial kits for isolation of total RNA in samples of WSSV-infected shrimp.

Viral diseases are the most serious threat to the expansion and development of shrimp aquaculture. Rapid diagnosis of the white spot syndrome virus (WSSV), a lethal shrimp pathogen, is essential to restrict its spread and reduce the mortality of infected shrimp. This virus has globally affected the shrimp farming industry, with a devastating economic impact. Several studies have focused on the expression of WSSV transcripts to understand the molecular mechanisms governing the pathological development of the disease. Since gene expression studies and molecular diagnostics at the early stages of infection depend on the efficient isolation of high-quality RNA, the extraction methods should be carefully selected. However, previous comparisons of the performance of RNA isolation kits have yet to be systematically investigated. In this study, 5 commercial RNA extraction methods were compared in WSSV-infected shrimp. The highest total RNA yield (ng mg-1 tissue) was obtained using TRIzol. Even though the 260/280 nm absorption ratios showed significant differences, the methods showed good purity values (>2.0). RNA integrity was evaluated in a denaturing agarose gel electrophoresis, and degradation was observed after the total RNA samples were treated with DNase I. Finally, the method that allowed the earlier detection of WSSV transcripts by qRT-PCR was the Zymo Direct-zol RNA MiniPrep kit. This study shows that the amount of observed (or estimated) WSSV transcripts might be affected because of the RNA isolation method. In addition, these results may contribute to improve the accuracy of the results obtained in gene expression studies, for more sensitive and robust detection of WSSV.

Vibrio vulnificus, an Underestimated Zoonotic Pathogen.

V. vulnificus, continues being an underestimated yet lethal zoonotic pathogen. In this chapter, we provide a comprehensive review of numerous aspects of the biology, epidemiology, and virulence mechanisms of this poorly understood pathogen. We will emphasize the widespread role of horizontal gene transfer in V. vulnificus specifically virulence plasmids and draw parallels from aquaculture farms to human health. By placing current findings in the context of climate change, we will also contend that fish farms act as evolutionary drivers that accelerate species evolution and the emergence of new virulent groups. Overall, we suggest that on-farm control measures should be adopted both to protect animals from Vibriosis, and also as a public health measure to prevent the emergence of new zoonotic groups.

Quantifying resistance to myxomatosis in wild rabbits produces novel evolutionary insights.

Wild rabbits in Australia developed genetic resistance to the myxoma virus, which was introduced as a biological control agent. However, little is known about the rate at which this evolutionary change occurred. We collated data from challenge trials that estimated rabbit resistance to myxomatosis in Australia and expressed resistance on a continuous scale, enabling trends in its development to be assessed over 45 years up to 1995. Resistance initially increased rapidly, followed by a plateau lasting ten years, before a second rapid increase occurred associated with the introduction of European rabbit fleas as myxoma virus vectors. By contrast, in the United Kingdom, where rabbit flea vectors were already present when the myxoma virus initially spread, resistance developed more slowly. No estimates of rabbit resistance to myxomatosis have been made for almost 30 years, despite other highly lethal rabbit pathogens becoming established worldwide. Continued testing of wild-caught rabbits in Australia to determine current levels of resistance to myxomatosis is recommended to assess its current effectiveness for managing pest rabbits. Given the economic and environmental significance of invasive rabbits, it would be remiss to manage such biological resources and ecosystem services poorly.

Detection, Identification and Molecular Characterization of Tomato Mosaic Virus (ToMV) Isolates from Pakistan.

Tomato mosaic virus (ToMV) is one of the lethal tomato pathogens. In this study, we collected tomato leaves exhibiting interveinal chlorosis from farmer’s fields in district Lahore, Pakistan. The presence of tobamoviruses was confirmed through extracting RNA, cDNA synthesis, PCR amplification and subsequent sequencing of capsid protein (CP) gene of ToMV that contained 480 nucleotides (encoded for 160 amino acids making ~17 kDa protein) located at 5703rd to 6182nd nucleotide position in ToMV genome. In sequence analysis, Pakistani isolates shared 98.9-99.5% and 97.3-99.3% nucleotide and amino acid homologies with each other and 96-99% and 90-98.6% with other isolates respectively. In phylogenetic analysis the Pakistani isolates grouped with Iranian and Chines isolates, exhibiting higher nucleotides and amino acids identities as well. This research reveals a geographical association among Pakistani, Chines and Iranian ToMV isolates. The study suggests extensive surveys of tobamoviruses infecting field crops for their detailed genetic information.

1225. The Perfect Storm: A Hardy and Lethal Pathogen and a Unit Filled with Immunocompromised Patients with Large Open Wounds. Troubles with Candida Auris in a Burn Intensive Care Unit

Abstract Background C auris is an emerging often multidrug resistant pathogen capable of causing severe morbidity and mortality. C auris has been increasingly isolated from patients in skilled nursing facilities and hospitals, and has been associated with facility outbreaks. A resilient pathogen, C. auris survives harsh disinfectants, desiccation and readily colonizes the environment posing an especially great risk to immunocompromised patients with large open wounds and long lengths of stay. Methods From 7/1/21 - 8/30/21 we noted a cluster of 4 patients with C auris in clinical cultures from the Burn ICU (BICU). A multidisciplinary team involving infection prevention, nursing/medical directors, health and safety, engineering, environmental services, and hospital leadership investigated the cluster as a potential outbreak. Mitigation measures involved a multi-modal response of C auris admission screening, weekly point prevalence testing of all BICU patients, environmental surface cultures, enhanced room cleaning, staff education, hand hygiene and personal protective equipment usage audits. Results 11 cases of C auris were identified on our BICU from 7/1/21 - 2/28/22. 5 (45.5%) cases from clinical isolates, 1 (9.1%) from a BICU point prevalence screen on 12/15/21, 5 (45.5%) as a part of weekly point prevalence screens started on 1/1/22. 6 (54.5%) patients were admitted for burn related injuries, 2 (18.2%) for Steven Johnson Syndrome, 2 (18.2%) for necrotizing wounds, and 1 (9.1%) for COVID-19 pneumonia. Cases occurred in 6/10 rooms in the Burn ICU. One (9.1%) patient expired during this outbreak (not deemed to be from C auris infection). Conclusion Resilient infections like C auris pose a risk of nosocomial transmission and potential high morbidity and mortality to burn patients with impaired immune defense and large open wounds. A multidisciplinary team using targeted interventions including screening, education, enhanced cleaning eradicated the outbreak in our BICU. As of 5/1/22, we went 13 + weeks without identifying a new case. The last patient with C auris was discharged 3/16/22. To prevent future outbreaks, we created a standardized response plan and instituted a universal screening protocol for C auris targeting all patient admissions from skilled nursing facilities and admissions to all ICUs. Disclosures Jorge Paiva Parada, MD MPH, Shionogi: Honoraria.

Three Amino Acid Substitutions in the Spike Protein Enable the Coronavirus Porcine Epidemic Diarrhea Virus To Infect Vero Cells.

Porcine epidemic diarrhea virus (PEDV), a continuously evolving pathogen, causes severe diarrhea in piglets, with high mortality rates. To prevent or mitigate the disease, it is common practice to develop live or inactivated PEDV vaccines based on cell-adapted viral variants. Propagating wild-type PEDV in cultured cells is, however, often challenging due to the lack of knowledge about the requirements for the cell adaptation of PEDV. In the present study, by using the RNA-targeted reverse genetic system for PEDV to apply S protein swapping followed by the rescue of the recombinant viruses, three key amino acid mutations in the S protein, A605E, E633Q, and R891G, were identified, which enable attenuated PEDV strain DR13 (DR13att) to efficiently and productively infect Vero cells, in contrast to the parental DR13 strain (DR13par). The former two key mutations reside inside and in the vicinity of the receptor binding domain (RBD), respectively, while the latter occurs at the N-terminal end of the fusion peptide (FP). Besides the three key mutations, other mutations in the S protein further enhanced the infection efficiency of the recombinant viruses. We hypothesize that the three mutations changed PEDV tropism by altering the S2' cleavage site and the RBD structure. This study provides basic molecular insight into cell adaptation by PEDV, which is also relevant for vaccine design. IMPORTANCE Porcine epidemic diarrhea virus (PEDV) is a lethal pathogen for newborn piglets, and an efficient vaccine is needed urgently. However, propagating wild-type PEDV in cultured cells for vaccine development is still challenging due to the lack of knowledge about the mechanism of the cell adaptation of PEDV. In this study, we found that three amino acid mutations, A605E, E633Q, and R891G, in the spike protein of the Vero cell-adapted PEDV strain DR13att were critical for its cell adaptation. After analyzing the mutation sites in the spike protein, we hypothesize that the cell adaptation of DR13att was achieved by altering the S2' cleavage site and the RBD structure. This study provides new molecular insight into the mechanism of PEDV culture adaptation and new strategies for PEDV vaccine design.

Population genetic analyses unveiled genetic stratification and differential natural selection signatures across the G-gene of viral hemorrhagic septicemia virus.

Introduction: Viral hemorrhagic septicemia virus (VHSV) is the most lethal pathogen in aquaculture, infecting more than 140 fish species in marine, estuarine, and freshwater environments. Viral hemorrhagic septicemia virus is an enveloped RNA virus that belongs to the family Rhabdoviridae and the genus Novirhabdovirus. The current study is designed to infer the worldwide Viral hemorrhagic septicemia virus isolates' genetic diversity and evolutionary dynamics based on G-gene sequences. Methods: The complete G-gene sequences of viral hemorrhagic septicemia virus were retrieved from the public repositories with known timing and geography details. Pairwise statistical analysis was performed using Arlequin. The Bayesian model-based approach implemented in STRUCTURE software was used to investigate the population genetic structure, and the phylogenetic tree was constructed using MEGA X and IQ-TREE. The natural selection analysis was assessed using different statistical approaches, including IFEL, MEME, and SLAC. Results and Discussion: The global Viral hemorrhagic septicemia virus samples are stratified into five genetically distinct subpopulations. The STRUCTURE analysis unveiled spatial clustering of genotype Ia into two distinct clusters at K = 3. However, at K = 5, the genotype Ia samples, deposited from Denmark, showed temporal distribution into two groups. The analyses unveiled that the genotype Ia samples stratified into subpopulations possibly based on spatiotemporal distribution. Several viral hemorrhagic septicemia virus samples are characterized as genetically admixed or recombinant. In addition, differential or subpopulation cluster-specific natural selection signatures were identified across the G-gene codon sites among the viral hemorrhagic septicemia virus isolates. Evidence of low recombination events elucidates that genetic mutations and positive selection events have possibly driven the observed genetic stratification of viral hemorrhagic septicemia virus samples.

Epidemiological investigation of canine coronavirus infection in Chinese domestic dogs: A systematic review and data synthesis

Canine enteric coronavirus (CCoV) is a pathogenic virus that infects dogs worldwide, causing enteric issues and causing harm to the dog industry and dogs. Although CCoV is not recognized as a highly lethal canine intestinal pathogen, it has been reported that CCoV is significantly associated with canine diarrhea in dogs. CCoV is a common health problem in dogs, attracting major concern from veterinarians and dog owners across China. In this study, we summarized the prevalence and epidemiological characteristics of CCoV in dogs in mainland China. The study revealed that the pooled prevalence of CCoV infection was 33%, and which associated with age, but not with sex, season and immunization status. In addition, the study also further suggested that CCoV-II was the predominant CCoV subtype in Chinese dogs. This study will provide valuable information for CCoV infections across China and other countries. Furthermore, this study also suggested that continuous surveillance and epidemiological studies of CCoV are necessary.

Epidemiological Analysis and Genetic Characterization of Parvovirus in Ducks in Northern Vietnam Reveal Evidence of Recombination.

Simple SummaryWaterfowl parvoviruses are highly contagious lethal pathogens that cause economic loss in the duck production industry. In Vietnam, information is limited on epidemiological and genetic characterization of the viral genome. This study investigated epidemiological characteristics and the further genetic characterization of the viral genome in ducks farmed in northern Vietnam. The results revealed that waterfowl parvovirus was circulating among ducks at a moderately positive rate. The viral strains were clustered with another novel goose parvovirus from China.In total, 130 tissue-pooled samples collected from ducks in some provinces/cities in north Vietnam were examined for waterfowl parvovirus genome identification. Twenty-six (20%) samples were positive for the parvovirus infection, based on polymerase chain reaction analysis. Of the 38 farms tested, 14 (36.84%) were positive for the waterfowl parvovirus genome. The rate of the parvovirus genome detection in ducks aged 2–4 weeks (37.04%) was significantly (p < 0.05) higher than that at ages <2 weeks (9.09%) and >4 weeks (16.30%). The positive rate on medium-scale farms (9.36%) was significantly (p < 0.05) lower than for small-scale (31.03%) and large-scale (29.73%) farms. The lengths of the four Vietnamese waterfowl parvovirus genomes identified were 4750 nucleotides. Among the four Vietnamese parvovirus genomes, nucleotide identities were from 99.29% to 99.87%. Phylogenetic analysis of the near-complete genomes indicated that the waterfowl circulating in northern Vietnam belonged to the novel goose parvovirus (NGPV) group. The Vietnamese NGPV group was closely related to the Chinese group. Recombination analysis suggested that the Vietnam/VNUA-26/2021 strain was generated by a recombination event. One positive selection site of the capsid protein was detected.

Toxicity of Bacillus thuringiensis Strains to Six Lepidopteran Pests of Brazilian Agricultural Landscape.

The first step for biological insecticide production is the evaluating of the pathogenicity and strains virulence of entomopathogens against the target pests. Bacillus thuringiensis (Bt) is widespread in nature, lethal pathogen of a range of orders and the most widely used entomopathogenic biological control agent. Therefore, our objective was to study the susceptibility of six important lepidopteran pests in Brazilian agricultural production systems, Anticarsia gemmatalis(Hübner),Chrysodeixis includens(Walker)Helicoverpa armigera(Hübner), Spodoptera cosmioides(Walker), S. eridania(Cramer), and S. frugiperda(Smith), to Bt strains. In vitro bioassays were conducted with neonate larvae exposed to two Bt strains, 1680A and 775E, in seven concentrations of spores and protein crystals. After 7days, the mortality was evaluated and indicated that lethal concentration (LC50) for 775E strain ranged from 7.72 × 104 to 2.45 × 106 spores mL-1 and for 1608A strain from 5.63 × 103 to 1.21 × 106 spores mL-1. The strain 1608A was more toxic for A. gemmatalis and H. armigera than 775E strain, and then was further evaluated in greenhouse bioassays with maize and soybean plants infested separately with target insects. The strain 1608A showed an efficient control for most insect species studied in the greenhouse bioassays, promoting considerable reduction in leaf injury and demonstrating a high potential in biological control of important lepidopteran species in crop production systems in Brazil.