Classical Strain Research Articles

The immunity protection of intestine induced by pseudorabies virus del gI/gE/TK in piglets.

Compared to the classical strain of Pseudorabies virus (PRV), the PRV variant exhibits stronger transmissibility and pathogenicity, causing immense disasters for the global pig industry. Based on this variant, our laboratory has preliminarily constructed a modified pseudorabies virus with deletions in the gE/gI/TK genes. In this study, the protective efficacy of PRV XJ del gI/gE/TK against piglet intestinal damage was evaluated. The results demonstrated that piglets immunized with PRV XJ del gI/gE/TK exhibited alleviated intestinal damage caused by the PRV XJ variant strain. This included reduced viral load, suppressed inflammation, and maintenance of intestinal structure and function. Additionally, PRV XJ del gI/gE/TK also strongly activated the innate immune response in the intestines, increasing the expression of antiviral factor mRNA and the secretion of SIgA to counteract the attack of the PRV XJ variant strain. Our study indicates that PRV XJ del gI/gE/TK can inhibit intestinal damage caused by PRV XJ variant strain and activate the innate immune response in the intestines.

Advancing IBDV diagnostics: a one-step multiplex real-time qRT-PCR for discriminating between vvIBDV and non-vvIBDV viruses, including the newly emerged IBDV variant.

The very virulent infectious bursal disease virus (vvIBDV) induces an acute, highly contagious and immunosuppressive disease in younger chicken causing massive economic losses globally. A major challenge in the field's clinical diagnosis is distinguishing gross lesions caused by vvIBDV from those induced by classic IBDV (cIBDV), commonly used as live attenuated vaccines. This study introduces a one-step multiplex real-time PCR assay designed to distinguish between vvIBDV and non-vvIBDV viruses. Via simultaneously targeting the VP2 sequence for vvIBDV detection and the VP1 sequence for non-vvIBDV identification, including classic, American variant and the recently emerged novel variant IBDV (nvarIBDV), the assay's specificity was validated against common avian viral diseases and nonspecific IBDV strains without any observed cross-reactions. It effectively differentiated between vvIBDV and non-vvIBDV field samples, including nvarIBDV, as confirmed by genotyping based on VP2 sequencing. The assay demonstrated a limit of detection ranging from 1.9×1010 to 103 DNA copies for vvIBDV-VP2, 9.2×1010 to 103 DNA copies for classic strains, and 1.2×1011 to 104 DNA copies for nvarIBDV in VP1 detection of non-vvIBDV. In conclusion, this study presents a specific, sensitive, and straight forward multiplex real-time PCR assay.

Circulation of the reassorted very virulent genotype of infectious bursal disease virus isolated from vaccinated broiler chickens in Bangladesh

Objective: The methodology employed in this research was designed to identify and characterize the infectious bursal disease virus (IBDV) at the molecular level, originating from recent outbreaks in Bangladesh. Materials and Methods: The IBDV outbreak farm was investigated, and bursa of Fabricius (BF) specimens were acquired from infected chickens. Initially, viruses in the processed samples were detected in chicken embryo fibroblast (CEF) cells, and the RT-PCR method was used to confirm IBDV. The positive samples were injected through chorioallantoic membrane route into the embryo of a 10-day-old specific pathogen-free (SPF) egg for virus isolation and pathogenicity testing. Finally, we sequenced the VP2 gene to identify phylogenetic relationships and detect mutations. Results: From the 77 collected samples, 42.85% (33/77) were found positive for cytopathic effects in CEF cells, and IBDV was detected in 31.16% (24/77) of the samples by RT-PCR. IBDV was isolated in SPF chicken embryos. In the pathogenicity test, infectious bursal disease was evident in seronegative chickens with visible signs of disease. Sequence analysis shows that the broiler-isolated viruses clustered with genotype A3B2 and backyard chickens with genotype A1B1. The presence of amino acid motifs for virulence markers was revealed in the partially sequenced VP2 gene with a mutation at S254G in four IBDV isolates from broilers. However, amino acids for virulence markers were absent in two isolates from backyard chickens, which shows sequence homology with IBDV classic strains. Conclusion: In this study, we identified and characterized circulating reassorted IBDV from vaccinated broilers, which may be one of the major causes of vaccination failure in broilers.

Detection of hypervirulent and classical type of Klebsiella pneumoniae and screening their resistant properties in Erbil city

Background and objective: Klebsiella pneumoniaei s an opportunistic pathogenic bacterium and is considered one of the main causes of nosocomial infection. Hypervirulent K. pneumoniae (hvKp) has emerged as a pathogen of global importance. The current study aimed to determine Extended-spectrum beta-lactamase, carbapenem resistance, and serum bactericidal effect among the clinical isolates and to find the relationship of the above features with antimicrobial resistance. Methods: A total of 90 K. pneumoniae isolates were collected from different clinical specimens. Isolates were diagnosed using routine bacteriological methods and VITEK 2 compact system. Several phenotypic tests including string test, serum resistant, ESBL test, and Modified Carbapenem inactivation method were performed. The antibiotic resistance pattern was compared among ESBL-positive, carbapenem-resistant in both Hypervirulent (hvKp) and classical K. pneumoniae (cKp) isolates. Results: The results revealed that among 90 isolates, 56.7% of the isolates were of classical K. pneumoniae (cKp) type within which 70.6% of them were ESBL positive, 37.3% of them were resistant to carbapenem, and 51% were resistant to serum bactericidal activity. On the other hand, 43.3% were of hvKp type within which 61.5% of them were ESBL positive, 30.8% were carbapenem-resistant and all of the hvKp were resistant to human serum. The rate of antibiotic-resistant among cKp was higher than hvKp isolates. Conclusion: In this study, classical strains were more resistant to antibiotics and the rates of ESBL and Carbapenem resistance were higher compared to hvKp strains. but they were killed by serum bactericidal activities more rapidly.

Antigenic similarities and clinical cross-protection between variant and classic non-viscous strains of Moritella viscosa in Atlantic salmon in Norway

Moritella viscosa (M. viscosa) is one of the major etiological agents of winter-ulcers in Atlantic salmon (Salmo salar) in Norway. Outbreaks of ulcerative disease in farmed fish occur across the North Atlantic region, causing reduced animal welfare and economical challenges, and are of hindrance for sustainable growth within the industry. Commercially available multivalent core vaccines containing inactivated bacterin of M. viscosa reduce mortality and clinical signs related to winter ulcer disease. It has previously been described two major genetic clades within M. viscosa, typical (hereafter referred to as classic) and variant, based on gyrB sequencing. In addition, there are phenotypical traits such as viscosity that may differ between different types of isolates. Western blot using salmon plasma showed that classic non-viscous strains are antigenically different from the classic viscous type included in core vaccines. Further, Western blot also showed that there are similarities in binding patterns between Norwegian variant and classic non-viscous isolates, indicating they may be antigenically related. Vaccination-challenge trials using Norwegian gyrB-classic non-viscous isolates of M. viscosa, demonstrate that the isolates from the classic clade that are included in current commercial multivalent core vaccines, provide limited cross protection against the emerging non-viscous strains. However, a vaccine recently approved for marketing authorization in Norway, containing inactivated antigen of a variant M. viscosa strain, demonstrates reduced mortality as well as clinical signs caused by infections with the classic non-viscous M. viscosa isolated from outbreaks in Norwegian salmon farms. The study shows that there are antigenic similarities between variant and classic non-viscous types of M. viscosa, and these similarities are mirrored in the observed cross-protection in vaccination-challenge trials.

Industrial Production of Antibiotics in Fungi: Current State, Deciphering the Molecular Basis of Classical Strain Improvement and Increasing the Production of High-Yielding Strains by the Addition of Low-Molecular Weight Inducers

The natural fermentation of antibiotics, along with semi-synthetic and synthetic approaches, is one of the most important methods for their production. The majority of the antibiotic market comes from the fermentation of high-yielding (HY) fungal strains. These strains have been obtained since the 1950s from wild-type (WT) isolates as a result of classical strain improvement (CSI) programs primarily involving multi-round random mutagenesis and screening. However, the molecular basis leading to high-yield production was unknown. In recent years, due to the application of multiomic approaches, key changes that occur in CSI programs, with WT strains that become HY industrial producers of a particular antibiotic, have begun to be understood. It becomes obvious that, during CSI, certain universal events are selected, which lead both to a direct increase in the production of the target metabolite and affect other vital processes of the cell (side mutations). These key events include: the upregulation of the target biosynthetic gene cluster (BGC), changes in the system of global regulation, disruption of alternative BGCs, the rearrangement of energy fluxes in favor of the target SM (secondary metabolite), changes in the regulation of the response to stress, and the redirection of primary metabolic pathways to obtain more precursors for target production. This knowledge opens up the possibility of both introducing targeted changes using genetic engineering methods when creating new producers and increasing the production of CSI strains as a result of fermentation with low-molecular compounds, targeted to compensate for the effects of side mutations.

Phenotypic and genotypic characteristics of Escherichia coli strains isolated during a longitudinal follow-up study of chronic urinary tract infections.

Worldwide, Urinary Tract Infections (UTIs) are an important health problem with many cases reported annually, women being the most affected. UTIs are relevant because they can become a recurrent condition, associated with different factors that contribute to the chronicity of the disease (cUTI). cUTI can be classified as persistent (peUTI) when the causative agent is the same each time the infection occurs or as reinfection (reUTI) when the associated microorganism is different. The purpose of this work was to characterize Escherichia coli isolates obtained in two prospective studies of patients with cUTI, to define which of them corresponded to peUTI and which to reUTI. A total of 394 isolates of E. coli were analyzed by agglutination with specific sera, antimicrobial susceptibility by diffusion disc test, and the phylogroups and presence of genes associated with virulence by PCR assays. Additionally, in some characterized strains adherence, invasiveness, and biofilm formation were analyzed by in vitro assays. The results showed that the peUTI strains belonged mainly to the classical UPEC serogroups (O25, O75, O6), were included in the B2 phylogroup, carried a great number of virulence genes, and were adherent, invasive, and biofilm-forming. Meanwhile, reUTI strains showed great diversity of serogroups, belonged mainly in the A phylogroup, and carried fewer virulence genes. Both peUTI and reUTI strains showed extensively drug-resistant (XDR) and multidrug-resistant (MDR) profiles in the antimicrobial susceptibility test. In conclusion, it appears that peUTIs are caused principally by classical UPEC strains, while reUTIs are caused by strains that appear to be a part of the common E. coli intestinal biota. Moreover, although both peUTI and reUTI strains presented different serotypes and phylogroups, their antimicrobial resistance profile (XDR and MDR) was similar, confirming the importance of regulating prophylactic treatments and seeking alternatives for the treatment and control of cUTI. Finally, it was possible to establish the features of the E. coli strains responsible for peUTI and reUTI which could be helpful to develop a fast diagnostic methodology.

Failure to experimentally infect 10 days-old piglets with a cell culture-propagated infectious stock of a classical genotype 1a porcine epidemic diarrhea virus.

Porcine epidemic diarrhea virus (PEDV) causes enteric disease in pigs of all ages. PEDV can be grouped into G1 (classical strains) and G2 (variant strains) based on sequence differences in the spike gene. Although several pathogenesis studies using contemporary strains of PEDV have been conducted to date, there is limited information on the pathogenesis of historical PEDV strains in contemporary pigs. This study aimed to investigate the clinical disease course of 10 days-old pigs infected with a classical European G1a PEDV strain from the 1980s which was last passaged in pigs in 1994. Sequencing results confirmed that the virus inoculum was a PEDV strain closely related to the prototype CV777 strain. The PEDV stock was serially passaged three times in Vero cells, and the P3 infectious virus stock was used to inoculate the pigs. A total of 40 pigs were inoculated using the oral route. Pigs showed no enteric disease signs, and PEDV shedding was not detected for 44 days post-inoculation (dpi). At necropsy at 3 (5 pigs) or 7 dpi (5 pigs), no lesions were observed in intestinal sections, which were negative for PEDV antigen by immunohistochemistry. In addition, no IgG or IgA PEDV-specific antibodies in serum or fecal samples for 35 dpi further indicates a lack of infection. Titration of the leftover thawed and refrozen PEDV virus stock inoculum showed that the virus stock retained its infectivity in Vero cell culture and the porcine small intestine enterocytes cell line IPEC-J2. The reasons for the loss of infectivity in pigs are unknown. In conclusion, we showed that a classical G1a PEDV strain successfully propagated in cell cultures could not orally infect 40 piglets.

Molecular epidemiological and genetic characterization of pseudorabies virus in Guangxi, China.

Pseudorabies virus (PRV) is an important pathogen that can cause harm to the pig population. Since 2011, there have been a number of large-scale outbreaks of pseudorabies on Chinese farms where animals had been vaccinated with the Bartha-K61 vaccine. In order to understand the epidemiological trend and genetic variations of PRV in Guangxi province, China, 819 tissue samples were collected from swine farms where PRV infection was suspected from 2013 to 2019, and these were tested for infectious wild strains of PRV. The results showed a positive rate of PRV in Guangxi province of 28.21% (231/819). Thirty-six wild-type PRV strains were successfully isolated from PRV-positive tissue samples, and a genetic evolutionary analysis was performed based on the gB, gC, gD, gE, and TK genes. Thirty of the PRV strains were found to be closely related to the Chinese variant strains HeN1-China-2012 and HLJ8-China-2013. In addition, five PRV strains were genetically related to Chinese classical strains, and one isolate was a recombinant of the PRV variant and the vaccine strain Bartha-K61. Amino acid sequence analysis showed that all 36 PRV strains had characteristic variant sites in the amino acid sequences of the gB, gC, gD, and gE proteins. Pathogenicity analysis showed that, compared to classical PRV strains, the PRV variant strains were more pathogenic in mice and had a lower LD50. Taken together, our results show that wild-type PRV infections are common on pig farms in Guangxi province of China and that the dominant prevalent strains were those of the PRV variants. The PRV variant strains also had increased pathogenicity in mice. Our data will provide a useful reference for understanding the prevalence and genetic evolution of PRV in China.

Quantitative analysis of local plasticity accompanying hydrogen-related fracture in low-carbon martensitic steel

In this study, the local plasticity accompanying hydrogen-related fracture in a low-carbon martensitic steel was quantitatively investigated by correlative microscopy analysis combining digital image correlation technique and electron backscatter diffraction. The results revealed that strain localization occurred mainly in the bulk of martensite blocks and at prior austenite grain boundaries, both with and without the presence of hydrogen. Moreover, hydrogen enhanced strain localization during deformation and facilitated crack nucleation and propagation. The quantitative analysis showed that the hydrogen-related quasi-cleavage cracking was closely related to the local plastic deformation, and increasing hydrogen content decreased the local strain level required for quasi-cleavage cracking. It was found that strain localization also occurred around the intergranular cracks, suggesting that hydrogen-induced intergranular cracking was not a classical simple decohesion process and strain localization was involved in the sequence of hydrogen-induced intergranular cracking. These findings shed light on the understanding of the intrinsic nature of hydrogen embrittlement.

Relationship between bullying victimization and suicide ideation among Chinese adolescents: A moderated chain mediation model

Previous studies have highlighted a strong association between bullying victimization and suicide ideation. However, little is known about the mediating and moderating mechanisms underlying this relationship. Building on the classic General Strain Theory, the current study investigated the chained mediating roles of school adaptation and stress response and the moderating role of gender on the relationship between bullying victimization and suicide ideation among Chinese adolescents. A total of 7159 junior high school students (46.9% female, mean age = 13.91 years) were recruited to participate in this study and completed measures of demographic information, bullying victimization, school adaptation, stress response, and suicide ideation. The results found that: (1) There were significant correlations between bullying victimization, school adaptation, stress response, gender, and suicide ideation. (2) Bullying victimization positively predicted suicide ideation. (3) Suicide ideation related to bullying victimization via school adaptation, via stress response, and serially via school adaptation and stress response. (4) Gender moderated the relationship between school adaptation and stress response. This negative relationship was stronger for females. These findings expand the understanding of the theoretical mechanism underlying the relationship between bullying victimization and suicide ideation. It also highlights the crucial roles of school adaptation, stress response, and gender in designing bullying-related and suicide-related interventions among Chinese adolescents.

Genome-wide screens reveal shared and strain-specific genes that facilitate enteric colonization by Klebsiella pneumoniae.

Klebsiella pneumoniae is a common cause of difficult-to-treat infections due to its propensity to express resistance to many antibiotics. For example, carbapenem-resistant K. pneumoniae has been named an urgent threat by the United States Centers for Disease Control and Prevention. Gastrointestinal colonization in patients with K. pneumoniae has been linked to subsequent infection, making it a key process to control in the prevention of multidrug-resistant infections. However, the bacterial factors which contribute to K. pneumoniae colonization are not well understood. Additionally, individual strains exhibit large amounts of genetic diversity, begging the question of whether some colonization factors are strain dependent. This study identifies the enteric colonization factors of three classical strains using transposon mutant screens to define a core colonization program for K. pneumoniae as well as detecting strain-to-strain differences in colonization strategies.

Biological Properties and Antibiotic Resistance of <i>Klebsiella pneumoniae</i> and Its Role in the Etiological Structure of Community-Acquired Pneumonia Pathogens

Background. In a novel coronavirus pandemic, the most common complications of viral pneumonia are secondary infections of bacterial and fungal etiology. At the same time, the spread of multidrug-resistant bacteria remains a global threat to public health. One of such microorganisms of the Enterobacteriaceae family is Klebsiella pneumoniae, which belongs to dangerous resistant pathogens of the ESKAPE group.The aim of the study was the comparative analysis of the biological properties of classical and hypermucoid strains of K.pneumoniae isolated from patients with community-acquired pneumonia (CAP): characterization of their sensitivity to antibacterial drugs, Klebsiella bacteriophage, and a disinfectant (polyhexamethylene guanidine hydrochloride), as well as assessment of the strains’ virulence in the model of experimental infection in white mice.Material and methods. 56 strains of Klebsiella isolated in diagnostic quantities from patients’ sputum samples were studied. Species identification of cultures was carried out using bacteriological and mass spectrometric methods. The sensitivity of bacteria to antibiotics, bacteriophage, and the disinfectant was determined in accordance with regulatory documents.Results. In the course of the study, 243 gram-negative cultures were isolated, of which 30% were bacteria of the genus Klebsiella spp. An analysis of their species composition showed that K.pneumoniae occupied a dominant place in the structure. Based on colony morphology, Burri-Gins smear staining, and a positive string test, 14 strains with a hypermucoid phenotype were identified. These strains differed from the classic K.pneumoniae strain by the presence of a thicker capsule in smears, virulence in white mice (DCL≤103 mc), and increased resistance to commercial Klebsiella bacteriophage. At the same time, they were characterized by a wider spectrum of sensitivity to antibiotics. There were no significant differences in sensitivity to the disinfectant in strains of both morphotypes.Conclusion. The results obtained demonstrated the important role of K.pneumoniae in the etiological structure of CAP pathogens.

Isolation and Characterization of a Novel Recombinant Classical Pseudorabies Virus in the Context of the Variant Strains Pandemic in China.

Pseudorabies virus (PRV) variants were discovered in immunized pigs in Northern China and have become the dominant strains since 2011, which caused huge economic losses. In this study, a classical PRV strain was successfully isolated in a PRV gE positive swine farm. The complete genome sequence was obtained using a high-throughput sequencing method and the virus was named JS-2020. The nucleotide homology analysis and phylogenetic tree based on complete genome sequences or gC gene showed that the JS-2020 strain was relatively close to the classical Ea strain in genotype II clade. However, a large number of amino acid variations occurred in the JS-2020 strain compared with the Ea strain, including multiple immunogenic and virulence-related genes. In particular, the gE protein of JS-2020 was similar to earlier Chinese PRV strains without Aspartate insertion. However, the amino acid variations analysis based on major immunogenic and virulence-related genes showed that the JS-2020 strain was not only homologous with earlier PRV strains, but also with strains isolated in recent years. Moreover, the JS-2020 strain was identified as a recombinant between the GXGG-2016 and HLJ-2013 strains. The pathogenicity analysis proved that the PRV JS-2020 strain has typical neurogenic infections and a strong pathogenicity in mice. Together, a novel recombinant classical strain was isolated and characterized in the context of the PRV variant pandemic in China. This study provided some valuable information for the study of the evolution of PRV in China.

CD4+TGFβ+ cells infiltrated the bursa of Fabricius following IBDV infection, and correlated with a delayed viral clearance, but did not correlate with disease severity, or immunosuppression.

Infectious Bursal Disease Virus (IBDV) causes immunosuppression in chickens. While B-cell destruction is the main cause of humoral immunosuppression, bursal T cells from IBDV-infected birds have been reported to inhibit the mitogenic response of splenocytes, indicating that some T cell subsets in the infected bursa have immunomodulatory activities. CD4+CD25+TGFβ+ cells have been recently described in chickens that have immunoregulatory properties and play a role in the pathogenesis of Marek's Disease Virus. To evaluate if CD4+CD25+TGFβ+ cells infiltrated the bursa of Fabricius (BF) following IBDV infection, and influenced the outcome of infection, birds were inoculated at either 2 days or 2 weeks of age with vaccine strain (228E), classic field strain (F52/70), or PBS (mock), and bursal cell populations were quantified by flow cytometry. Both 228E and F52/70 led to atrophy of the BF, a significant reduction of Bu1+-B cells, and a significant increase in CD4+ and CD8α+ T cells in the BF, but only F52/70 caused suppression of immune responses to a test antigen in younger birds, and clinical signs in older birds. Virus was cleared from the BF more rapidly in younger birds than older birds. An infiltration of CD4+CD25+T cells into the BF, and elevated expression of bursal TGFβ-1+ mRNA was observed at all time points following infection, irrespective of the strain or age of the birds, but CD4+TGFβ+cells and CD4+CD25+TGFβ+ cells only appeared in the BF at 28 dpi in younger birds. In older birds, CD4+TGFβ+ cells and CD4+CD25+TGFβ+ cells were present at earlier time points, from 7dpi following 228E infection, and from 14 and 28 dpi following F52/70 infection, respectively. Our data suggest that an earlier infiltration of CD4+TGFβ+ cells into the BF correlated with a delayed clearance of virus. However, the influx of CD4+TGFβ+ cells and CD4+CD25+TGFβ+ into the BF did not correlate with increased pathogenicity, or immunosuppression.

Comparison of Gross Pathology between Classical and Recombinant Lumpy Skin Disease Viruses.

The pathology caused by three different isolates of lumpy skin disease virus, classical field cluster 1.2 strain Dagestan/2015, recombinant vaccine-like cluster 2.1 strain Saratov/2017, and cluster 2.2 strain Udmurtiya/2019, in cattle was compared from experimental infections. The infection of cattle was performed using intravenous administration of 2 mL of 105 TCID50/mL of each specific LSDV. Both classical and recombinant forms of LSDV cause pathological changes in the skin and lymph nodes, as well as the trachea and lungs. Due to circulatory disorders in the affected organs, multiple areas of tissue necrosis were observed, which, with the resurgence of secondary microflora, led to the development of purulent inflammation. Observed pathological changes caused by the recombinant vaccine-like strain Udmurtiya/2019 were characterized by a more pronounced manifestation of the pathoanatomical picture compared to the classical field strains Dagestan/2015 and Saratov/2017. Interestingly, Dagestan/2015 and Udmurtiya/2019 caused damage to the lymph nodes, characterized by serous inflammation and focal purulent lymphadenitis caused by purulent microflora. "Saratov/2017" did not cause pathology in the lymph nodes. All LSDVs were virulent and caused pathology, which was not distinguishable between viruses. This data set will serve as the experimentally validated basis for the comparative examination of novel LSDV strains in gross pathology.

Pathological assessment and tissue tropism of two different Egyptian infectious bronchitis strains.

Avian infectious bronchitis is one of the most common viral infections in chickens affecting all ages. The tropism of infectious bronchitis virus (IBV) strains became broader and more variable posing major implications for the effective control of IBV infection. In this study, two IBV viruses representing classic and variant strains were inoculated intranasally into day-old SPF chicks (105 EID50/0.2ml/bird). Clinical signs were observed for 15 days post-infection (DPI). Five chicks from each group were euthanized at 2, 4, 6, 8, 10, 12, and 15 DPI for histopathology and virus antigen detection by IHC and quantitative rRT-PCR. Results revealed that both classic and variant IBV strains induced mild clinical signs with no mortalities and fewer various histopathological lesions in infected SPF chickens. Although the viruses were detected by rRT-PCR up to 12DPI, the affected tissues showed regeneration after 10DPI with IHC revealing no IBV antigen. In summary, no differences were found in the behaviour of both IBV isolates in chickens. The broad tissue tropism for both IBV strains as indicated by viral antigen detection in various organs with no clinical or gross lesion suggest that the main cause of death in IBV infection under field conditions occurs as a result of complication with secondary infections rather single IBV infection. Due to positive immunostaining in the bursa, it is thought that IBV infection has immunosuppressive consequences, hence further study is required to validate this impact.

Metavirome Analysis and Identification of Midge-Borne Viruses from Yunnan Province, China, in 2021.

Midges are widely distributed globally and can transmit various human and animal diseases through blood-sucking. As part of this study, 259,300 midges were collected from four districts in Yunnan province, China, to detect the viral richness and diversity using metavirome analysis techniques. As many as 26 virus families were detected, and the partial sequences of bluetongue virus (BTV), dengue virus (DENV), and Getah virus (GETV) were identified by phylogenetic analysis and PCR amplification. Two BTV gene fragments, 866 bps for the VP2 gene of BTV type 16 and 655 bps for the VP5 gene of BTV type 21, were amplified. The nucleotide sequence identities of the two amplified BTV fragments were 94.46% and 98.81%, respectively, with two classical BTV-16 (GenBank: JN671907) and BTV-21 strains (GenBank: MK250961) isolated in Yunnan province. Furthermore, the BTV-16 DH2021 strain was successfully isolated in C6/36 cells, and the peak value of the copy number reached 3.13 × 107 copies/μL after five consecutive BHK-21 cell passages. Moreover, two 2054 bps fragments including the E gene of DENV genotype Asia II were amplified and shared the highest identity with the DENV strain isolated in New Guinea in 1944. A length of 656 bps GETV gene sequence encoded the partial capsid protein, and it shared the highest identity of 99.68% with the GETV isolated from Shandong province, China, in 2017. Overall, this study emphasizes the importance of implementing prevention and control strategies for viral diseases transmitted by midges in China.

Development of highly efficient electrocompetent cells for electroporation of Geobacillus thermoglucosidasius NCIMB 11955

Geobacillus thermoglucosidasius is a kind of Gram-positive facultative anaerobic bacteria. The fast growth rate under high temperature and less susceptibility to microbial contamination enable G. thermoglucosidasius to be a desirable producer of biofuels and high-value-added chemicals for the next-generation industrial biotechnology. However, compared with the classical model strain Escherichia coli, the applications of G. thermoglucosidasius are hampered by its low transformation efficiency. This study aimed at obtaining competent cells with high transformation efficiency through inactivating restriction enzymes, adding cell membrane inhibitors and cell wall weakening agents. The results showed that the electro-transformation efficiency achieved 1.2×104 CFU/(μg DNA) by knocking out four genes encoding restriction enzymes. Adding a certain amount of tween 80, dl-threonine and glycine further increased the competent efficiency about 22.5, 44, and 334 times, respectively. The electro-transformation efficiency was enhanced to 4.6×106 CFU/(μg DNA) under the optimized conditions, laying a foundation for genetic manipulation and metabolic engineering of G. thermoglucosidasius.

Температурна характеристика електричного опору тензометра при вимірюванні статичних та термічних напружень деталей при температурі до 700 °С

An overview of the existing methods of measuring static stresses at elevated temperatures, at which it is problematic to use classical strain gauges, and methods of compensating the imaginary temperature deformation was performed. Namely: the use of multi-component alloys, the manufacture of active and compensatory sensitive elements from different alloys, which should theoretically compensate for each other's shortcomings. In practice, this can be sufficiently achieved only in a narrow temperature range. The described primary transducer is a rectangular strain-gauge rosette for measuring static and thermal stresses in structural parts operating under extreme conditions at temperatures up to 700°C. This sensor is a two-layer rosette consisting of two sensitive elements (SE), the main axes of which are rotated relative to each other by 90°. The lower SE perceives the main deformation of the part, and the upper one, located above the lower one, plays the role of a temperature-compensating electrical resistance of the element and simultaneously registers the transverse deformation of the part. SE rosettes were made of a wire with a diameter of 30 microns of the Х20Н80 alloy and fixed to each other and to the part using Ц-165-32А cement. The experimental study consisted in determining the temperature characteristics of the resistance of both the lower and the upper SE of the studied strain gauge associated with the temperature expansion of the part-strain gauge system as well as with the shunting of the insulator-connector and the change in the specific resistance of the SE material. Experimental determination of apparent strain gauge deformation at different temperatures was performed. To determine the influence of the coefficient of linear expansion of the material of the part on the change in the resistance of the SE, strain gauges were attached to samples of various materials. The change in the apparent deformation of the strain gauge in the temperature range from room temperature to 700 °C is shown. Its maximum value for the ceramic sample was less than 350 µm/m, for the 30ХГСА steel sample it was less than 1000 µm/m, and for the ВЖЛ14Н-ВІ alloy sample it was less than 750 µm/m. Dependencies were obtained that allow corrections to be made in the result of a real study of the stressed state of the part to achieve the maximum accuracy of measurements.