Genotype Strains Research Articles

Analysis of cross neutralizing activity of antibodies from sera of severe fever with thrombocytopenia syndrome patients to deal with different genotype strains.

Severe fever with thrombocytopenia syndrome bunyavirus (SFTSV) is a tick-borne virus that causes severe communicable fever with thrombocytopenia syndrome (SFTS) with an average case fatality rate of 10%. In the study, we aimed to identify the cross-neutralizing antibody (nAb) against different genotype strains from sera of SFTSV infected patients. Firstly the genotype of SFTSV was identified by constructing a phylogenetic tree based on the M segments epidemic in the Jiaodong area of Shandong province, then different sera of subjects cross reactive with recombinant Gn (rGn-Fc) or recombinant Gc (rGc-Fc) of 0921 strain were examined. The levels of polyclonal nAbs from sera of 25 convalescents were measured by a pseudovirus-based neutralizing experiment. We found local endemic strains were mainly C2 and C3 isolates of SFTSV. 14 of 15 sera from donors reacted with 0921 rGn-Fc, and 9 of 15 sera from donors reacted with 0921 rGc-Fc. Cross nAbs were produced by 10 of 25 sera from donors during the period of 2019-2021. Among these, five nAbs (A2, A4, A5, L9, and L10) neutralized the pseudoviruses of HB29, Gangwon, HN13, HN20, SPL030A, and SD4 strains. Our data suggested that epidemic strains showed relatively stable heredity. Some blood sources from patients produced cross nAbs that could neutralize all of the strains examined. These findings highlight the important role played by humoral immunity in combatting SFTSV.

Temperature-dependent Small RNA Expression Depends on Wild Genetic Backgrounds of Caenorhabditis briggsae.

Geographically distinct populations can adapt to the temperature conditions of their local environment, leading to temperature-dependent fitness differences between populations. Consistent with local adaptation, phylogeographically distinct Caenorhabditis briggsae nematodes show distinct fitness responses to temperature. The genetic mechanisms underlying local adaptation, however, remain unresolved. To investigate the potential role of small noncoding RNAs in genotype-specific responses to temperature, we quantified small RNA expression using high-throughput sequencing of C. briggsae nematodes from tropical and temperate strain genotypes reared under three temperature conditions (14 °C, 20 °C, and 30 C). Strains representing both tropical and temperate regions showed significantly lower expression of PIWI-interacting RNAs (piRNAs) at high temperatures, primarily mapping to a large ∼7 Mb long piRNA cluster on chromosome IV. We also documented decreased expression of 22G-RNAs antisense to protein-coding genes and other genomic features at high rearing temperatures for the thermally-intolerant temperate strain genotype, but not for the tropical strain genotype. Reduced 22G-RNA expression was widespread along chromosomes and among feature types, indicative of a genome-wide response. Targets of the EGO-1/CSR-1 22G-RNA pathway were most strongly impacted compared with other 22G-RNA pathways, implicating the CSR-1 Argonaute and its RNA-dependent RNA polymerase EGO-1 in the genotype-dependent modulation of C. briggsae 22G-RNAs under chronic thermal stress. Our work suggests that gene regulation via small RNAs may be an important contributor to the evolution of local adaptations.

Rare Wolbachia genotypes in laboratory Drosophila melanogaster strains.

Symbiotic bacteria of the genus Wolbachia are widespread in Drosophila melanogaster populations. Based on the polymorphism of the Wolbachia genome, the symbionts’ diversity in D. melanogaster is presented by two groups: MEL (wMel, wMel2, wMel3 and wMel4) and CS (wMelCS and wMelCS2). The wMel genotype is predominant in natural D. melanogaster populations and is distributed all over the world. The CS genotypes, on the other hand, are of particular interest because it is unclear how they are maintained in the fruit f ly populations since they should have been eliminated from them due to their low frequency and genetic drift or been replaced by the wMel genotype. However, this is not what is really observed, which means these genotypes are supported by selection. It is known that the wMelPlus strain of the wMelCS genotype can increase the lifespan of infected f lies at high temperatures. The same genotype also increases the intensity of dopamine metabolism in Drosophila compared to the MEL-group genotypes. In the present study, we searched for the rare Wolbachia wMelCS and wMelCS2 genotypes, as well as for new genotypes in wild-type D. melanogaster strains and in several mutant laboratory strains. The symbiont was found in all populations, in 200 out of 385 wild-type strains and in 83 out of 170 mutant strains. Wolbachia diversity in D. melanogaster wild-type strains was represented by the wMel, wMelCS and wMelCS2 genotypes. More than 90 % of the infected strains carried wMel; 9 %, wMelCS2; and only two strains were found to carry wMelCS. No new Wolbachia genotypes were found. The northernmost point reported for the wMelCS2 genotype was Izhevsk city (Udmurtia, Russia). For the f irst time the wMelCS2 genotype was detected in D. melanogaster from the Sakhalin Island, and wMelCS, in the f lies from Nalchik (the North Caucasus). A comparison of Wolbachia genetic diversity between the wild-type laboratory strains and previously obtained data on mutant laboratory strains demonstrated differences in the frequencies of rare CS genotypes, which were more prevalent in mutant strains, apparently due to the breeding history of these Drosophila strains

Carbapenem-Resistant Klebsiella pneumoniae: Diversity, Virulence, and Antimicrobial Resistance.

BackgroundKlebsiella pneumoniae (K. pneumoniae) is one of the most important pathogens in nosocomial infections. It has resistance to most antibiotics, even carbapenem, resulting in restricted therapeutic options.PurposeWe tried to assess the antimicrobial resistance and virulence fitness of carbapenem-resistant K. pneumoniae (CRKP) in addition to their phenotypic and genotypic diversity.Materials and MethodsThe conventional methods, automated Vitek-32 system, and antimicrobial susceptibility pattern were used to detect CRKP isolates. Virulence and resistance genes profiles were created by using PCR technique. The correlation analysis was done by using R-program.ResultsThe antimicrobial resistance profile for all our K. pneumoniae isolates was shocking as the MDR and CRKP were the most prominent phenotypes. Unfortunately, high degrees of heterogeneity among our CRKP isolates were recorded, as 97.5% of them were differentiated into different clusters. We found a negative correlation between the existence of virulence and antimicrobial resistance genes. In contrast to sputum and urine CRPK isolates, the blood isolates showed high antimicrobial resistance and low virulence fitness. Finally, K. pneumoniae creates several outbreaks and crises in Egypt owing to the highly heterogeneity and the wide spread of multidrug-resistant (MDR) and multi-virulent CRKP phenotypes.ConclusionOur results are significant and alarming to health organizations throughout the world for the severity and heterogeneity of K. pneumoniae infections. Therefore, the traditional method for treatment of CRKP infections must be renewed. Additionally, the treatment protocols must be well correlated with the site of infections, phenotypes, and genotypes of CRKP strains.

Recent Transmission and Prevalent Characterization of the Beijing Family Mycobacterium tuberculosis in Jiangxi, China.

The Beijing genotype is the most common type of tuberculosis in Jiangxi Province, China. The association of population characteristics and their prevalence in the development of recent transmission is still unclear. 1,433 isolates were subjected to drug-resistant tests and MIRU-VNTR analysis. We compared differences in demographic characteristics and drug resistance patterns between the Beijing and non-Beijing family strains. We also explored the association of the clustering rate with the Beijing genotype of Mycobacterium tuberculosis. The Beijing genotype was dominant (78.16%). The results of MIRU-VNTR showed that 775 of 1,433 strains have unique patterns, and the remaining gather into 103 clusters. A recent transmission rate was 31.54% (452/1,433). The Beijing genotype strains were more likely to spread among the recurrent population (p = 0.004), people less than 50 years of age (p = 0.02 or 0.003), and the personnel in the northern regions (p = 0.03). Drug resistance patterns did not show significant differences between Beijing and non-Beijing genotype isolates. Furthermore, we found that HIV-positive cases had a lower clustering rate (p = 0.001). Our results indicated that the recurrent population and people under 50 years of age were more likely to be infected with the Beijing genotype of M. tuberculosis. The strains from the Beijing family were easier to cluster compared to strains isolated from the non-Beijing family. Social activity and AIDS substantially impacted the clustering rate of the Beijing genotype of M. tuberculosis. Multidrug resistant M. tuberculosis affected Beijing genotype transmission.

Ferruginibacter albus sp. nov., isolated from a mountain soil, and Mucilaginibacter robiniae sp. nov., isolated from a black locust flower, Robinia pseudoacacia

Two bacterial strains, designated KIS38-8T and F39-2T, were isolated from a mountain soil sample and a black locust flower (Robinia pseudoacacia) in Republic of Korea, respectively. The phylogenetic tree based on 16S rRNA gene sequences showed that strain KIS38-8T was classified into the genus Ferruginibacter with the highest sequence similarity to Ferruginibacter lapsinanis HU1-HG42T (96.6 %), and strain F39-2T was grouped into the genus Mucilaginibacter with the highest sequence similarity to Mucilaginibacter daejeonensis Jip 10T (97.6 %). Orthologous average nucleotide identity and digital DNA-DNA hybridization values between strain KIS38-8T and closely related Ferruginibacter strains were less than 72 and 19 %, respectively, while those values between strain F39-2T and closely related Mucilaginibacter strains were less than 73 and 21 %, respectively. The DNA G+C contents of strain KIS38-8T and F39-2T were 36.4 and 41.4 mol%, respectively. On the basis of the phenotypic and genotypic evidence, strains KIS38-8T and F39-2T are considered to represent novel species of the genus Ferruginibacter and Mucilaginibacter, respectively, for which the names Ferruginibacter albus sp. nov. (type strain KIS38-8T=KACC 17328T=NBRC 113101T) and Mucilaginibacter robiniae sp. nov. (type strain F39-2T=KACC 19733T=JCM 33062T) have been proposed.

Duganella vulcania sp. nov., Rugamonas fusca sp. nov., Rugamonas brunnea sp. nov. and Rugamonas apoptosis sp. nov., isolated from subtropical streams, and phylogenomic analyses of the genera Janthinobacterium, Duganella, Rugamonas, Pseudoduganella and Massilia.

Six Gram-stain-negative, catalase- and oxidase-positive, rod-shaped and motile strains (FT81WT, FT82W, FT107W, FT3ST, LX20WT and LX47WT) sharing high 16S rRNA gene sequence similarities with species of the genera Janthinobacterium (97.0–98.3 %), Duganella (96.3–98.8 %), Rugamonas (97.8–98.6 %), Pseudoduganella (96.8–97.5 %) and Massilia (94.5–98.6 %) were isolated from subtropical streams in PR China. The phylogenetic trees reconstructed using the 16S rRNA gene sequences indicated that the species of above five genera often mix together, indicating that the taxonomic statuses of some species were questionable. Phylogenomic reconstruction based on 369 single-copy orthologous clusters indicated that the species of the genus Janthinobacterium form a distinct cluster, strains FT81WT, FT82W and FT107W form a tight cluster with the species of the genus Duganella , and strains FT3ST, LX20WT and LX47WT form a tight cluster with the species of genus Rugamonas , and the species of genus Pseudoduganella form a tight cluster with Massilia guangdongensis , Massilia ginsengisoli , Massilia rivuli , Massilia namucuonensis , Massilia aquatica sensu Lu et al., Massilia buxea , Massilia armeniaca , Massilia plicata , Massilia flava , Massilia lurida , Massilia dura , Massilia lutea , Massilia umbonata , Massilia albidiflava and Massilia violacea . It should be noted that Massilia aquatica Lu et al. 2020 non Massilia aquatica Holochová et al. 2020 is a later homonym and an illegitimate name. The GTDB Release 202 also supported the proposal that M. guangdongensis , M. ginsengisoli , M. rivuli , M. namucuonensis , M. aquatica sensu Lu et al., M. buxea , M. armeniaca , M. plicata , M. flava , M. lurida , M. dura , M. lutea , M. umbonata , M. albidiflava and M. violacea should be transferred into the genus Pseudoduganella . The calculated pairwise orthologous average nucleotide identity by usearch (OrthoANIu) values were between 95.0 % and 95.6 % among strains FT81WT, FT82W and FT107W, but were less than 91.5 % among strains FT3ST, LX20WT, LX47WT and other related strains. Combining the results of phylogenomic analyses, phenotypic, biochemical and genotypic characteristics, strains FT81WT, FT82W and FT107W should represent a novel species of the genus Duganella , and strains FT3ST, LX20WT and LX47WT should represent three novel species of the genus Rugamonas , for which the names Duganella vulcania sp. nov. (type strain FT81WT=GDMCC 1.1679T =KACC 21471T), Rugamonas fusca sp. nov. (type strain FT3ST=GDMCC 1.1907T =KACC 21952T), Rugamonas brunnea sp. nov. (type strain LX20WT=GDMCC 1.1911T =KACC 21956T) and Rugamonas apoptosis sp. nov. (type strain LX47WT=GDMCC 1.1914T =KACC 21959T) are proposed.

Antibiotic resistance and genomic features of Clostridioides difficile in southwest China.

BackgroundClostridioides difficile infection (CDI) caused by toxigenic strains leads to antibiotic-related diarrhea, colitis, or even fatal pseudomembranous enteritis. Previously, we conducted a cross-sectional study on prevalence of CDI in southwest China. However, the antibiotics resistance and characteristics of genomes of these isolates are still unknown.MethodsAntibiotic susceptibility testing with E-test strips and whole genome sequence analysis were used to characterize the features of these C. difficile isolates.ResultsForty-nine strains of C. difficile were used in this study. Five isolates were non-toxigenic and the rest carried toxigenic genes. We have previously reported that ST35/RT046, ST3/RT001 and ST3/RT009 were the mostly distributed genotypes of strains in the children group. In this study, all the C. difficile isolates were sensitive to metronidazole, meropenem, amoxicillin/clavulanic acid and vancomycin. Most of the strains were resistant to erythromycin, gentamicin and clindamycin. The annotated resistant genes, such as macB, vanRA, vanRG, vanRM, arlR, and efrB were mostly identified related to macrolide, glycopeptide, and fluoroquinolone resistance. Interestingly, 77.55% of the strains were considered as multi-drug resistant (MDR). Phylogenetic analysis based on core genome of bacteria revealed all the strains were divided into clade 1 and clade 4. The characteristics of genome diversity for clade 1 could be found. None of the isolates showed 18-bp deletion of tcdC as RT027 strain as described before, and polymorphism of tcdB showed a high degree of conservation than tcdA gene.ConclusionsMost of the C. difficile isolates in this study were resistant to macrolide and aminoglycoside antibiotics. Moreover, the MDR strains were commonly found. All the isolates belonged to clade 1 and clade 4 according to phylogenetic analysis of bacterial genome, and highly genomic diversity of clade 1 was identified for these strains.

Rhizobium leguminosarum symbiovar viciae strains are natural wheat endophytes that can stimulate root development.

Although rhizobia that establish a nitrogen-fixing symbiosis with legumes are also known to promote growth in non-legumes, studies on rhizobial associations with wheat roots are scarce. We searched for Rhizobium leguminosarum symbiovar viciae (Rlv) strains naturally competent to endophytically colonize wheat roots. We isolated 20 strains from surface-sterilized wheat roots and found a low diversity of Rlv compared to that observed in the Rlv species complex. We tested the ability of a subset of these Rlv for wheat root colonization when co-inoculated with other Rlv. Only a few strains, including those isolated from wheat roots, and one strain isolated from pea nodules, were efficient in colonizing roots in co-inoculation conditions, while all the strains tested in single strain inoculation conditions were found to colonize the surface and interior of roots. Furthermore, Rlv strains isolated from wheat roots were able to stimulate root development and early arbuscular mycorrhizal fungi colonization. These responses were strain and host genotype dependent. Our results suggest that wheat can be an alternative host for Rlv; nevertheless, there is a strong competition between Rlv strains for wheat root colonization. In addition, we showed that Rlv are endophytic wheat root bacteria with potential ability to modify wheat development.

Phylogenetic analysis of the viral proteins VP4/VP7 of circulating human rotavirus strains in China from 2016 to 2019 and comparison of their antigenic epitopes with those of vaccine strains.

Group A rotaviruses (RVAs) are the most common etiological agents of severe acute diarrhea among children under 5 years old worldwide. At present, two live-attenuated RVA vaccines, LLR (G10P[15]) and RotaTeq (G1–G4, G6 P[8], P[5]), have been introduced to mainland China. Although RVA vaccines can provide homotypic and partially heterotypic protection against several strains, it is necessary to explore the genetic and antigenic variations between circulating RVAs and vaccine strains. In this study, we sequenced viral protein VP7 and VP4 outer capsid proteins of 50 RVA strains circulating in China from 2016 to 2019. The VP7 and VP4 sequences of almost all strains showed high homology to those of previously reported human strains and vaccine strains of the same genotype. However, in the presumed antigenic epitopes of the VP7 and VP4, multiple amino acid variations were found, regardless of the G and P genotypes of these strains. Moreover, all circulating G3 RVA strains in China potentially possess an extra N-linked glycosylation site compared with the G3 strain of RotaTeq. The potential N-linked glycosylation site at residues 69–71 was found in all G9 strains in China but not in the G9 strain of the Rotavac or Rotasill vaccine. These variations in antigenic sites might result in the selection of strains that escape the RVA neutralizing-antibody pressure imposed by vaccines. Furthermore, the G4 and P[6] genotypes in this study showed high homology to those of porcine strains, indicating the transmission of G4 and P[6] genotypes from pigs to humans in China. More genetic surveillance with antigenic evaluation in prevalent RVAs is necessary for developing and implementing rotavirus vaccines in China.

Group a Rotavirus Detection in Calves and Piglets from Honduras and Panama

The epidemiology of animal rotaviruses infection and their association with illnesses in humans remains unknown in Central America and the world. In this study, we performed a genotyping of rotavirus strains by RT-PCR for-G (VP7) and P (VP4), in samples of diarrhea in calves and piglets, in Honduras and Panama. Mixed infections and combinations of genotypes G (VP7) and P (VP4) were identified in calves in Honduras: 3 (4%) G2P [6], 2 (2%) G2P [4], in piglets: 4 (5%) G4P [6], and in calves in Panama: 63 (72%) G10 P [2], 12 (13%) G8 P [11], 9 (10%) G6 P [11] and 3 (3%) G10 P [1].This investigation represents the first report of bovine and porcine rotavirus strains in Honduras and Panama.

Basic Bacteriological Routines.

In experimental bacteriology, bacteria are generally manipulated, stored, and shipped in the form of cultures. Depending on various factors, including strain genotype, storage and shipping methods, and manipulator skills, the culture may contain genetic variants or simply contaminants. It is therefore important to begin an experiment by streaking the culture on an agar plate. Streaking, a technique to disperse bacterial cells on the surface of the agar, serves the purpose of isolating individual colonies. A colony originates from a single cell and is a nearly pure culture. On rich LB medium after 24 h of incubation at 37°C, a colony of Salmonella contains ∼5 × 108 cells (about 29 generations). Streaking is also required in experiments that themselves generate single colonies as a result of selection (e.g., when constructing strains or introducing plasmids). Except in the few instances in which the selection efficiently kills all counter-selected bacteria, colonies growing on the selective plates are contaminated, sometimes heavily, with cells from the bacterial lawn. "Purifying" the colonies arising in such experiments by streaking on selective plates is therefore a mandatory step. Here, we show how this can be conveniently done using simple toothpicks. We also briefly describe the steps involved in inoculating liquid cultures, spreading plates, and replica plating.

Genotyping and antibiotic resistance of methicillin-resistant staphylococcus aureus strains isolated from raw and frozen meat samples and assessment of the antimicrobial effects of origanum vulgare against MRSA isolates

Background: Methicillin-resistant Staphylococcus aureus is a resistant bacterium responsible for food poisoning. The present survey was done to assess the genotyping and antibiotic resistance of MRSA strains isolated from raw and frozen meat samples and assessment of the antimicrobial effects of Origanum vulgare against MRSA isolates. Methods: Two-hundred raw and frozen meat samples were collected and presence of MRSA was assessed using the culture. Disk diffusion was used to assess the antibiotic resistance of isolates. Isolates were subjected to PCR to obtain the virulence characters. Gas chromatography was used to determine chemical components of O. vulgare. Minimum Inhibitory Concentration and Minimum Bacterial Concentration of O. vulgare essential oil was also assessed. Results: Thirty two out of 200 meat samples (16%) were positive for MRSA. MRSA isolates had the highest resistance toward penicillin (100%), ceftaroline (100%), tetracycline (87.50%), and erythromycin (68.75%). Distribution of seA and eta genes amongst the raw and frozen meat samples were 75% and 58.33% and 50% and 33.33%, respectively. Β-Caryophyllene (31.10%), 1-Octen-3-ol (18.41%), 1,8-Cineole (15.19%), and Thujopsene (8.20%) were the most commonly identified chemical components.

Changes of gut microbiota structure in rats infected with Toxoplasma gondii.

Toxoplasma gondii (T. gondii) infection can cause intestinal inflammation in rodents and significantly alters the structure of gut microbiota. However, the effects of different T. gondii genotypes on the gut microbiota of rats remain unclear. In this study, acute and chronic T. gondii infection in Fischer 344 rats was induced artificially by intraperitoneal injection of tachyzoites PYS (Chinese 1 ToxoDB#9) and PRU (Type II). Fecal 16S rRNA gene amplicon sequencing was employed to analyze the gut microbiota structure at different stages of infection, and to compare the effects of infection by two T. gondii genotypes. Our results suggested that the infection led to structural changes of gut microbiota in rats. At the acute infection stage, the microbiota diversity increased, while both diversity and abundance of beneficial bacteria decreased at the chronic infection stage. The differences of microbiota structure were caused by strains of different genotypes. However, the diversity changes were consistent. This study demonstrates that the gut microbiota plays an important role in T. gondii infection in rats. The data will improve our understanding of the association between T. gondii infection and gut microbiota in rodents.

Immunobiological Characteristics of the Attenuated African Swine Fever Virus Strain Katanga-350.

The African swine fever virus (ASFV) is the cause of a recent pandemic that is threatening the global pig industry. The virus infects domestic and wild pigs and manifests with a variety of clinical symptoms, depending on the strain. No commercial vaccine is currently available to protect animals from this virus, but some attenuated and recombinant live vaccine candidates might be effective against the disease. This article describes the immunobiological characteristics of one such candidate—the laboratory-attenuated ASFV strain, Katanga-350—which belongs to genotype I. In this study, we assessed clinical signs and post-mortem changes, the levels of viremia and the presence of viral DNA caused by injection of ASF virus strains Katanga-350, Lisbon-57, and Stavropol 08/01. Intramuscular injection of this strain protected 80% of pigs from a virulent strain of the same genotype and seroimmunotype (Lisbon-57). At least 50% of the surviving pigs received protection from subsequent intramuscular infection with a heterologous (genotype II, seroimmunotype VIII) virulent strain (Stavropol 08/01). Virus-specific antibodies were detectable in serum and saliva samples between 8–78 days after the first inoculation of the Katanga-350 strain (the observational period). The results suggested that this strain could serve as a basis for the development of a recombinant vaccine against ASF viruses belonging to seroimmunotype I.

Attempts to use breeding approaches in Aedes aegypti to create lines with distinct and stable relative Wolbachia densities

Wolbachia is an insect endosymbiont being used for biological control in the mosquito Aedes aegypti because it causes cytoplasmic incompatibility (CI) and limits viral replication of dengue, chikungunya, and Zika viruses. While the genetic mechanism of pathogen blocking (PB) is not fully understood, the strength of both CI and PB are positively correlated with Wolbachia densities in the host. Wolbachia densities are determined by a combination of Wolbachia strain and insect genotype, as well as interactions with the environment. We employed both artificial selection and inbreeding with the goal of creating lines of Ae. aegypti with heritable and distinct Wolbachia densities so that we might better dissect the mechanism underlying PB. We were unable to shift the mean relative Wolbachia density in Ae. aegypti lines by either strategy, with relative densities instead tending to cycle over a narrow range. In lieu of this, we used Wolbachia densities in mosquito legs as predictors of relative densities in the remaining individual’s carcass. Because we worked with outbred mosquitoes, our findings indicate either a lack of genetic variation in the mosquito for controlling relative density, natural selection against extreme densities, or a predominance of environmental factors affecting densities. Our study reveals that there are moderating forces acting on relative Wolbachia densities that may help to stabilize density phenotypes post field release. We also show a means to accurately bin vector carcasses into high and low categories for non-DNA omics-based studies of Wolbachia-mediated traits.

Comparative Genomic Analysis Discloses Differential Distribution of Antibiotic Resistance Determinants between Worldwide Strains of the Emergent ST213 Genotype of Salmonella Typhimurium.

Salmonella enterica constitutes a global public health concern as one of the main etiological agents of human gastroenteritis. The Typhimurium serotype is frequently isolated from human, animal, food, and environmental samples, with its sequence type 19 (ST19) being the most widely distributed around the world as well as the founder genotype. The replacement of the ST19 genotype with the ST213 genotype that has multiple antibiotic resistance (MAR) in human and food samples was first observed in Mexico. The number of available genomes of ST213 strains in public databases indicates its fast worldwide dispersion, but its public health relevance is unknown. A comparative genomic analysis conducted as part of this research identified the presence of 44 genes, 34 plasmids, and five point mutations associated with antibiotic resistance, distributed across 220 genomes of ST213 strains, indicating the MAR phenotype. In general, the grouping pattern in correspondence to the presence/absence of genes/plasmids that confer antibiotic resistance cluster the genomes according to the geographical origin where the strain was isolated. Genetic determinants of antibiotic resistance group the genomes of North America (Canada, Mexico, USA) strains, and suggest a dispersion route to reach the United Kingdom and, from there, the rest of Europe, then Asia and Oceania. The results obtained here highlight the worldwide public health relevance of the ST213 genotype, which contains a great diversity of genetic elements associated with MAR.

Molecular genotypic analysis of porcine circovirus type 2 reveals the predominance of PCV2d in Vietnam (2018-2020) and the association between PCV2h, the recombinant forms, and Vietnamese vaccines.

We conducted nucleotide and amino acid sequence alignment and phylogenetic analysis of porcine circovirus ORF2 (Cap protein) from 17 PCV2-positive clinical samples from nine different northern Vietnamese provinces (Mar 2018-Nov 2020), four local vaccines, and 77 reference strains. We identified one PCV2a (1/17 = 5.9%), five PCV2b (5/17 = 29.9%), and 11 PCV2d (11/17 = 64.7%) isolates, while only PCV2d was detected in 2020. Timeline analysis indicated an increasing predominance of PCV2d nationwide (2018-2020). With strong nodal support (98% for nucleotides and 74% for amino acids), the phylogenetic tree topology revealed a distinct PCV2h clade including recombinant/intermediate strains and local vaccines. The Cap protein sequences from 11 PCV2d field strains had the 2d-genotype-typical motif 86SNPLSV91 in loop CD, the motif TGID in loop GH-HI, and the motif 230PLNPK234 in loop CT. The PCV2h isolates (and vaccines) had the 86SNPLSV91, SAID, and 230L(N/H)PK234 motifs. Selection pressure analysis indicated positive selection at seven sites: A68N in immunoreactive region (IRR)-A; 119G and 130V in IRR-B; and 167L, T190(A/S), 194D and 202F in IRR-C. We identified PCV2h as the genotype of the recombinant strains, which resulted from intergenotype recombination of PCV2a, PCV2b, and PCV2d. The current data provide new information about the diversity, distribution, and dominance of the PCV2 genotype in Vietnam.

Comparative virulence of the worldwide ST19 and emergent ST213 genotypes of Salmonella enterica serotype Typhimurium strains isolated from food

Salmonella enterica Typhimurium represents one of the most frequent causal agents of food contamination associated to gastroenteritis. The sequence type ST19 is the founder and worldwide prevalent genotype within this serotype, but its replacement by emerging genotypes has been recently reported. Particularly, the ST213 genotype has replaced it as the most prevalent in clinical and contaminated food samples in Mexico and has been recently reported in several countries. In this study, the in vitro and in vivo virulence of ST213 and ST19 strains isolated from food samples in Mexico was evaluated. Three out of the five analyzed ST213 strains, showed a greater internalization capacity and increased secretion of interleukins IL-8 and IL-6 of Caco-2 cells than the ST19 strains. Microbiological counts in feces and tissues showed the ability of all strains tested to establish infection in the rat model. The ST213 strains also caused histopathological damage, characteristic of gastroenteritis in Wistar rats. In contrast to the in vitro result, one of the ST19 strains showed marked damage in the test animals. The ST213 genotype strains showed in vitro and in vivo virulence variability, but significantly higher than the observed in the ST19 genotype strains, thus such emergent genotype represents a public health concern.

Comparative analysis of CpG islands in two genotypes of African swine fever virus.

African swine fever (ASF) is an acute, hemorrhagic, and devastating viral infectious disease that causes important economic losses to the swine industry. Currently, there are no effective vaccines or drugs available. Epigenetic mechanisms, especially cytosine methylation of cytosine- -phosphate-guanine (CpG) islands, have a significant impact on the life cycle of several viruses. Hence, drugs targeting DNA methylation may potentially be used for the treatment of ASF. Here, we selected the inner core, core shell, inner membrane, capsid, and external envelope membrane, to analyze the characteristics of CpG islands in the ASF virus (ASFV) genomes. Furthermore, we analyzed the promoters and CpG islands in the upstream regions of these genes. Results showed that the CpG islands of seven genes were conserved in the genomes of two genotype of ASFV strains, whereas the CpG islands of other genes were relatively conserved (ASFV strains differed mainly in the quantity of CpG islands). The different distribution of CpG islands in the genomes of different ASFV strains may affect their methylation status, which may in turn affect the regulation of viral gene expression, leading to different clinical outcomes. In addition, the predicted promoter regions based on the upstream sequences of most genes overlapped with CpG island positions. Methylation of the binding sites of the promoter regions inhibits the binding of the transcription factors to the promoters, thus inhibiting the activation of the promoters and limiting the synthesis of viral proteins. The results of this study provide a basis for exploring new antiviral therapeutic strategies from an epigenetic perspective.