High Level Of Genetic Diversity Research Articles

Genetic diversity in a core collection of Iranian sour cherry.

The exploitation of plant genetic resources is an important and rapid strategy to release commercial cultivars. In this study, 234 sour cherry genotypes were collected from various locations of Iran and phenotypically assessed according to IPGRI and UPOV descriptors. The genotypes were grafted onto Mahaleb rootstock and were planted in Horticultural Science Research Institute (HSRI) core collection in Karaj, Iran. In this study, 22 different characteristics were measured in the sour cherry genotypes. The results showed that fruit and stone weights varied from 1.65 (G410) to 5.47 g (G125) and 0.13 (G428) to 0.59 g (G149), respectively. The fruit size index comprised average fruit length, width, and diameter, which varied from 10.57 to 19.13. The stalk length was less than 50 mm in 90.6% of the studied genotypes. Twelve of the 234 studied genotypes did not exhibit any symptoms of bacterial canker disease. Principle component analysis (PCA) and cluster analysis classified the studied genotypes into four main groups. Spearman's correlation analysis revealed that fruit size, stone shape, stone size, stalk thickness and weight, and fruit appearance correlated positively with stone and fruit weights. In contrast, fruit juice, fruit skin, and flesh color correlated negatively with the stone and fruit weights. The range of TSS varied between 12.66 (G251) and 26 (G427). Variations in pH value were between 3.66 (G236) and 5.63 (G352). In conclusion, a high level of genetic diversity was observed among the Iranian sour cherry genotypes. This diversity can be considered valuable and applicable for future breeding programs.

Analysis of 9 microsatellite markers in Kalmyk cattle

A genetic analysis of the Kalmyk cattle population for 9 microsatellite loci: BM1824, BM 2113, INRA023, SPS 115, TGLA 122, TGLA 126, TGLA 227ETH 10, ETH 225 was carried out on the basis of the youth scientific laboratory of molecular genetics of the Kalmyk State University. 60 animals of the Kalmyk breed of breeding reproducer “Plodovitoe” of the Republic of Kalmykia were subjected to genetic testing. The loci INRA 023, TGLA 122, and TGLA 227 turned out to be the most informative for the Kalmyk breed. A comparison of the observed and expected heterozygosity in the Kalmyk breed shows that all 9 microsatellite loci showed an excess of the expected heterozygosity value over the observed one. The number of possible genotypes (Ng) has the highest value at the TGLA 122 locus, the indicator is 171, a smaller number of possible genotypes is observed at the TGLA 126 locus. Thus, microsatellite analysis showed a high level of genetic diversity in the studied herd of Kalmyk cattle. The data obtained indicate the possibility of using microsatellite DNA analysis for genetic examination of breeding animals by origin and analysis of pedigrees in order to study the transmission of traits by inheritance.

Population Structure and Reproductive Biology of Monilinia vaccinii-corymbosi in Vaccinium angustifolium in Maine.

The fungus Monilinia vaccinii-corymbosi (Mvc) causes mummy berry disease in blueberries including lowbush blueberry, Vaccinium angustifolium, and is a significant pathogen of concern for Maine lowbush blueberry growers. This disease is typically managed with fungicides or by burning of plant debris containing overwintering pseudosclerotia. The population structure of Mvc in various fields in Maine was investigated using microsatellites and isolates collected from three stages in the Mvc lifecycle. The impacts of management strategies were also examined. A high level of genetic diversity was observed in Mvc from 12 lowbush blueberry fields with 199 unique multilocus haplotypes (MLHs) occurring in an original sample of 232 isolates. Twelve private alleles, including six private alleles with frequencies above 0.05, which indicated gene flow, were observed in six out of 12 fields. The population of Mvc in Maine as a whole is mostly a sexual, outcrossing population, as was seen in the diversity of MLHs and low amounts of linkage disequilibrium, although some apothecia appear to result from selfing. Three fields appear to have some clonal reproduction but were not strictly clonal, as multiple MLHs were noted in these fields. Management does not appear to affect population structure, and Mvc may be one large statewide population in Maine.

Genetic evaluation of the breeding strategy effectiveness for horses of the New Altai breed

The purpose of the study was to study the dynamics of the main selected traits in horses of the New Altai breed and the genetic characteristics of the breed. In this paper, the indicators of the main measurements of the body and live weight of horses, depending on gender and region of birth, are analyzed. The main genetic and population parameters of the breed were calculated based on microsatellite DNA loci: the total number of alleles at 17 loci (Na), the average number of alleles per locus (Nv), the level of polymorphism (Ae), observed (Ho) and expected (He) heterozygosity, coefficients of intrapopulation inbreeding (Fis), genetic similarity (RXY) and genetic distances (DXY). It has been established that the horses of the New Altai breed are characterized by a relatively high level of polymorphism and genetic diversity, both in the breed as a whole and in the context of breeding regions. The high genetic similarity of the New Altai breed with the Russian Heavy Draft and Altai breeds has been revealed. The study of the genetic structure of the breed, the levels of its intra- and inter-population diversity in combination with classical zootechnical assessment methods showed the consistency of the chosen cultivation strategy of the New Altai breed.

A comprehensive review of HVS-I mitochondrial DNA variation of 19 Iranian populations.

Iran is located along the Central Asian corridor, a natural artery that has served as a cross-continental route since the first anatomically modern human populations migrated out of Africa. We compiled and reanalyzed the HVS-I (hypervariable segment-I) of 3840 mitochondrial DNA (mtDNA) sequences from 19 Iranian populations and from 26 groups from adjacent countries to give a comprehensive review of the maternal genetic variation and investigate the impact of historical events and cultural factors on the maternal genetic structure of modern Iranians. We conclude that Iranians have a high level of genetic diversity. Thirty-six haplogroups were observed in Iran's populations, and most of them belong to widespread West-Eurasian haplogroups, such as H, HV, J, N, T, and U. In contrast, the predominant haplogroups observed in most of the adjacent countries studied here are H, M, D, R, U, and C haplogroups. Using principal component analysis, clustering, and genetic distance-based calculations, we estimated moderate genetic relationships between Iranian and other Eurasian groups. Further, analyses of molecular variance and comparing geographic and genetic structures indicate that mtDNA HVS-I sequence diversity does not exhibit any sharp geographic structure in the country. Barring a few from some culturally distinct and naturally separated minorities, most Iranian populations have a homogenous maternal genetic structure.

Genetic diversity and population differentiation in Earliella scabrosa, a pantropical species of Polyporales

Earliella scabrosa is a pantropical species of Polyporales (Basidiomycota) and well-studied concerning its morphology and taxonomy. However, its pantropical intraspecific genetic diversity and population differentiation is unknown. We initiated this study to better understand the genetic variation within E. scabrosa and to test if cryptic species are present. Sequences of three DNA regions, the nuclear ribosomal internal transcribed spacer (ITS), the large subunit ribosomal DNA (LSU), and the translation elongation factor (EF1α) were analysed for 66 samples from 15 geographical locations. We found a high level of genetic diversity (haplotype diversity, Hd = 0.88) and low nucleotide diversity (π = 0.006) across the known geographical range of E. scabrosa based on ITS sequences. The analysis of molecular variance (AMOVA) indicates that the genetic variability is mainly found among geographical populations. The results of Mantel tests confirmed that the genetic distance among populations of E. scabrosa is positively correlated with the geographical distance, which indicates that geographical isolation is an important factor for the observed genetic differentiation. Based on phylogenetic analyses of combined dataset ITS-LSU-EF1α, the low intraspecific divergences (0–0.3%), and the Automated Barcode Gap Discovery (ABGD) analysis, E. scabrosa can be considered as a single species with five different geographical populations. Each population might be in the process of allopatric divergence and in the long-term they may evolve and become distinct species.

Anthropogenic and natural disturbances increase local genetic diversity in an early spring geophyte (Ficaria verna Huds)

AbstractThe tetraploid Ficaria verna is a common spring geophyte in central Europe and is considered invasive in the USA and Canada. It is considered an almost seed‐sterile taxon, relying on vegetative reproduction by underground tubers and aerial bulbils. Recent studies have revealed high levels of population genetic diversity in F. verna, raising the question of how genetic diversity is maintained and which factors may be responsible for the observed patterns. Polymorphic nuclear microsatellite markers were established to define multi‐locus genotypes (MLGs), to analyze fine‐scale spatial genetic structure (SGS) using grid and cross‐sampling schemes, and to quantify genetic diversity within and between nine populations with different disturbance regimes in central Germany. In total, 115 MLGs were identified among a total of 347 samples. The G/N ratio varied between 0.16 and 0.70 among populations, and in each population several unique MLGs occurred. Genotypes were highly intermingled within populations, suggesting a “guerrilla” dispersal strategy. Significant SGS (negative regression slope of kinship coefficients against inter‐individual distances) was found in four out of nine populations in fine‐scale cross‐sampling (up to 4 m) and in only one population in grid sampling (up to 14.6 m). No single MLG was found in more than one population, while many alleles were shared between populations. Within‐population clonal and allelic diversity increased with greater exposure to both anthropogenic and natural disturbances. Regular gap openings, facilitated propagule establishment, and propagule dispersal by water and mowing machines are likely important factors explaining the positive effects of disturbance on local genetic diversity of F. verna.

Assessment of genetic diversity, population structure and wolf-dog hybridisation in the Eastern Romanian Carpathian wolf population

The Carpathian Mountains have been constantly inhabited by grey wolves and present one of the largest distribution areas in Europe, comprising between 2300 and 2700 individuals in Romania. To date, however, relatively little is known about the Romanian wolf population. We aimed to provide a first assessment of genetic diversity, population structure and wolf-dog hybridisation based on 444 mostly non-invasively collected samples in the Eastern Romanian Carpathians. Pack reconstruction and analysis of population genetic parameters were performed with mitochondrial DNA control-region sequencing and microsatellite genotyping. We found relatively high levels of genetic diversity, which is similar to values found in previous studies on Carpathian wolves from Poland and Slovakia, as well as to the long-lasting Dinaric-Balkan wolf population. We found no significant population structure in our study region, suggesting effective dispersal and admixture. Analysis of wolf-dog hybridisation using a Single Nucleotide Polymorphism panel optimised for hybrid detection revealed low rates of admixture between wolves and domestic dogs. Our results provide evidence for the existence of a genetically viable wolf population in the Romanian Carpathians. The genetic data obtained in this study may serve as valuable baseline information for the elaboration of monitoring standards and management plans for wolves in Romania.

Филогенетика и географическое распространение скальных ящериц (Lacertidae, Reptilia) на горной системе Эльбурс

Rock lizards of the genus Darevskia have long been an important model object for study of reptile evolution. To understand the overall picture, it is important to know how bisexual and parthenogenetic species are distributed within this genus. The ranges of Caucasian species of rock lizards have been studied for a long time and in detail. However, recent attention to the species inhabiting the territory of Iran has been attracted after the description of several new species in 2013. As part of the continuation of these studies, we studied the distribution and genetic diversity of five species of lizards of the Darevskia genus along the Alborz mountain range in Iran: D. chlorogaster, D. caspica, D. defilippii, D. schaekeli and D. raddei. In the course of this, we discovered new localities of D. defilippii that are outside their known range. We assessed the phylogenetic relationships between the studied species according to the ND4 – Leu tRNA region of mitochondrial DNA and found a relatively high level of genetic variability in D. defilippii and D. chlorogaster, while D. raddei, despite its wide distribution, has low variability. In general, the phylogenetic position of the studied species is somewhat different from that described by Ahmadzadeh et al. (2013).

Genetic characterization of domestic pigs in the core zone of swine production of Argentina.

Argentina is a small player in the global pork market, contributing only 0.7% of the total production. With increasing global demand for meat, there is an opportunity for countries with an agricultural profile to grow their pork production. However, there is a need to understand the current state of the pork production sector in all aspects to inform decision-making. The aim of this study was to genetically characterize pig herds from different production strata in the primary region for pork production in the country. For this purpose, phylogenetic and genetic variability analyses were performed using the mitochondrial control region marker (n=95 pig samples). Moreover, genotyping of ryr1 and PRKAG3 genes (n=108 pig samples) were performed to evaluate the frequency of deleterious alleles for meat quality traits in the region. The results showed high levels of genetic variability in the pig herds (Hd= 0.840 ± 0.031 and π= 0.010 ± 0.001), with a creole sow and Iberian lineage standing out in the phylogeny. The genotyping of the ryr1 marker revealed the presence of the deleterious t allele in all analyzed strata. However, the RN-allele of the PRKAG3 gene was detected only in the two lower strata. This study represents the first analysis of the phylogenetic relationships among domestic pigs from Argentina and provides an initial assessment of genetic variability in the region. Additionally, the results present, for the first time, the frequency of deleterious alleles for pig production in the productive core area, demonstrating their prevalence.

Assessment the Kalmyk cattle breed genetic diversity in the Kalmykia republic based on genome-wide analysis

In the article results of the biodiversity evaluation of the indigenous breed resources of cattle of the Republic of Kalmykia by whole-genome genotyping are presented. The objects of research were samples of biomaterial obtained from two herds of Kalmyk cattle raised in the Republic of Kalmykia (n = 20). Other samples for population-genetic studies were taken from L.K. Ernst FRC (Podolsk, Russia). Modern molecular-genetics and bioinformatics methods were used in this research. As a result, DNA was isolated and comparative study was carried out. The obtained DNA samples are suitable for carrying out whole-genome SNP studies using Bovine SNP HD BeadChip according to their qualitative and quantitative characteristics. The concentration of double-stranded DNA in the studied samples varied up 16 to 80 ng/µl, the ratio of OD260/OD280 varied up 1.77 to 2.12. The efficiency of genotyping (call rate) varied up 99.72 to 99.84%. The novelty of this research is the genetic diversity of two populations of Kalmyk cattle raised in the Republic of Kalmykia was established at the first time using high-density DNA chips and population-genetic estimation was also carried out for comparison with three breeds of Turano-Mongolian origin. Kalmyk breed have shown the highest level of genetic diversity compared to other breeds of Turano-Mongolian origin. This fact may be a consequence of the use of free mating in the breeding , as well as a relatively high number of Kalmyk cattle compared to other breeds. The minimum level of genetic diversity established in the Yakut breed is a consequence of the small number of livestock. The results obtained will be useful in the development of breeding and conservation programs of the Kalmyk cattle.

Amplicon deep sequencing of five highlypolymorphic markers of Plasmodium falciparum reveals high parasite genetic diversity and moderate populationstructure in Ethiopia

BackgroundPlasmodium falciparum genetic diversity can add information on transmission intensity and can be used to track control and elimination interventions.MethodsDried blood spots (DBS) were collected from patients who were recruited for a P. falciparum malaria therapeutic efficacy trial in three malaria endemic sites in Ethiopia from October to December 2015, and November to December 2019. qPCR-confirmed infections were subject to amplicon sequencing of polymorphic markers ama1-D3, csp, cpp, cpmp, msp7. Genetic diversity, the proportion of multiclonal infections, multiplicity of infection, and population structure were analysed.ResultsAmong 198 samples selected for sequencing, data was obtained for 181 samples. Mean MOI was 1.38 (95% CI 1.24–1.53) and 17% (31/181) of infections were polyclonal. Mean He across all markers was 0.730. Population structure was moderate; populations from Metema and Metehara 2015 were very similar to each other, but distinct from Wondogent 2015 and Metehara 2019.ConclusionThe high level of parasite genetic diversity and moderate population structure in this study suggests frequent gene flow of parasites among sites. The results obtained can be used as a baseline for additional parasite genetic diversity and structure studies, aiding in the formulation of appropriate control strategies in Ethiopia.

Genetic diversity of Toxoplasma gondii in goats and sheep from the Northeast Region of Brazil destined for human consumption

This study aimed to genotype isolates of Toxoplasma gondii obtained from samples of brain, diaphragm and heart of goats and sheep intended for human consumption in the State of Paraíba, Brazil. Tissue samples from 14 animals, goats (n = 5) and lambs (n = 9), were sourced from public slaughterhouses in seven cities and bio-assayed in mice. The brains of the mice were utilized for DNA extraction. Genotyping was carried out by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) using 10 markers (SAG1, SAG2, SAG3, BTUB, c22-8, PK1, GRA6, L358, c-29-2 and Apico). A total of 10 isolates were fully genotyped (i.e. at all loci), three from goats and seven from sheep, revealing five distinct genotypes: #13 (n = 4); #48 (n = 3); #57 (n = 1); #273 (n = 1); and one new genotype that had not been previously described. Genotype #13 is frequently found in the Northeast of Brazil and represents a clonal lineage circulating in this region and was the most prevalent genotype identified (n = 4). Moreover, in the present study genotypes #13, #48, #57, and #273 were documented for the first time in sheep from Brazil, and the novel genotype was isolated from a goat. Our findings align with previous studies on T. gondii from Brazil, where new genotypes are continuously being identified, highlighting a high level of genetic diversity of T. gondii isolates in the country.

Molecular Characterization of Local Walnut (Juglans regia) Genotypes in the North-East Parnon Mountain Region of Greece.

Walnut is one of the most important nuts regarding their production and consumption. The available but uncharacterized genetic resources of walnut are important for the development and breeding of local varieties. Greece holds an important number of genetically uncharacterized walnut landraces, especially within the area of Parnon, which is considered to play a significant role as an in situ gene bank, due to its unique location traits. However, the genetic characterization and further use of these resources has been insufficient, due to the absence of genetic studies. In this study, we implemented SSR molecular markers, both to genetically characterize the walnut tree genetic diversity of the Parnon area and to identify its unique genetic structure, which will form the starting material for subsequent breeding programs. Overall, high levels of genetic variation were found among the individual walnut accessions that were collected in the Parnon mountain region.

Resistance to aminoglycoside and quinolone drugs among Klebsiella pneumoniae clinical isolates from northern Jordan

This study aimed to identify phenotypic and genotypic aminoglycoside and quinolone non-susceptibility and the prevalence of aminoglycoside-modifying enzymes and plasmid-mediated quinolone resistance genes among K. pneumoniae clinical isolates from northern Jordan. K. pneumoniae isolates (n = 183) were tested for antimicrobial susceptibility using the Kirby-Bauer disk diffusion method. The double-disk synergy test was used for the detection of the extended-spectrum beta-lactamase phenotype. Polymerase chain reaction was used to detect genes encoding aminoglycoside-modifying enzyme (aac (3′)-II, aac (6′)-II, aac (6′)-Ib, ant (3″)-I, aph (3′)-VI, armA, and rmtB), and plasmid-mediated quinolone resistance (qnrA, qnrB, qnrC, qnrD, qnrS, acc(6′)-Ib–cr, qepA, and oqxAB) genes. Multi-locus sequence typing was used to elucidate the genetic diversity of selected isolates. The non-susceptibility percentages to aminoglycosides and quinolones were 65.0 % and 61.7 %, respectively. The most frequent aminoglycoside-modifying enzyme gene was ant (3″)-I at 73.8 %, followed by aac (6′)-Ib at 25.1 %, aac (3′)-II at 17.5 %, aph (3′)-VI at 12.0 %, armA at 9.8 %, and rmtB at 0.5 %. Aac (6′)-II was not detected among the isolates. The most frequent plasmid-mediated quinolone resistance gene was oqxAB at 31.7 %, followed by qnrS at 26.2 %, qnrB at 25.7 %, and aac(6′)-Ib–cr at 25.7 %. QnrA, qnrD, qebA, and qnrC were not detected among the isolates. Aac (3′)-II, aac (6′)-Ib, aph (3′)-VI, armA, qnrB, qnrS, and acc(6′)-Ib–cr were significantly associated with non-susceptibility to aminoglycosides, quinolones, and beta-lactams. Among 27 randomly selected K. pneumoniae isolates, the most common sequence type was ST2096, followed by ST348 and ST1207. Overall, 19 sequence types were observed, confirming a high level of genetic diversity among the isolates. High percentages of non-susceptibility to the studied antimicrobials were found and were associated with the presence of several resistance genes. Similar studies should be periodically carried out to monitor changes in the prevalence of resistance phenotypes and genotypes of isolates.

Wild and cultivated olive tree genetic diversity in Greece: a diverse resource in danger of erosion.

The genetic relationships between Greek wild olive tree populations and cultivars were investigated. A total of 219 wild genotypes and 67 cultivar genotypes were analyzed by employing 10 SSR markers. Data evidenced that the wild populations exhibited high levels of genetic diversity and exclusively host 40% of the total number of alleles detected. Inbreeding was observed within populations, probably as a consequence of their fragmented spatial distribution. The genetic differentiation between cultivars and wild individuals, as well as within wild populations, was low. Nevertheless, three gene pools of wild trees were detected, corresponding to the geographical areas of Northeastern Greece, Peloponnese-Crete and Epirus. Most cultivars clustered in a separate group, while the rest of them formed a heterogenous group with membership coefficients akin to the three wild olive clusters. Regarding the history of olive cultivation in Greece, bidirectional gene flow was detected between populations of Peloponnese-Crete and the gene pool that composes some of Greece's most important cultivars, such as "Koroneiki" and "Mastoidis", which is inferred as an indication of a minor domestication event in the area. A strategy for the protection of Greek-oriented olive genetic resources is proposed, along with suggestions for the utilization of the genetically diverse wild resources with regard to the introgression of traits of agronomical interest to cultivars.

Genetic Diversity and Genetic Structure of Three Sympatric Oak Species in Serbian Landscape of Outstanding Features "Kosmaj" Assessed by Nuclear Microsatellites

Quercus petraea (Matt.) Liebl., Q. pubescens Willd., and Q. frainetto Ten. grow naturally in sympatry in the Landscape of Outstanding Features "Kosmaj" (Mt. Kosmaj) in Serbia, in the Western Balkans. The levels of genetic diversity and genetic structure in populations of these species (160 trees in total) was assessed by means of 14 nuclear microsatellites. The number of alleles detected in overall sample was 314, with the locus QrZAG90 being the most informative one in all three species (31, 35 and 36 alleles in Q. frainetto, Q. pubescens and Q. petraea, respectively). The levels of genetic diversity of all three species were relatively high (HE = 0.824, 0.834, and 0.794 in Q. petraea, Q. pubescens and Q. frainetto, respectively). Low but statistically significant inbreeding was detected in all three species (F = 0.100, 0.131 and 0.065 in Q. petraea, Q. pubescens and Q. frainetto, respectively), which, however, most likely reflects population substructure, which was observed in the STRUCTURE analysis. The optimal number of genetic groups revealed by Bayesian clustering analysis did not coincide with the number of analyzed species as it amounted to four (one gene pool was observed in each of the two species, Q. petraea and Q. pubescens, while two gene pools were observed in Q. pubescens). Furthermore, a higher level of hierarchical genetic structure, with six gene pools was found, with Q. frainetto being the only oak species in which population substructure was not observed. Genetic differentiation of three sympatric oak species was relatively low but statistically significant, with the highest FST value found among Q. petraea and Q. frainetto (FST = 0.047, P = 0.001), and the lowest between Q. petraea and Q. pubescens (FST = 0.032, P = 0.001). Our results reveal rather high levels of genetic diversity in all three studied oak species, which retained their genetic integrity despite sympatric distribution, indicating low levels of interspecific hybridization, and pronounced genetic structure of Q. pubescens and Q. petraea.

Genetic diversity and population differentiation of wild and domesticated banana shrimp Fenneropenaeus merguiensis: Applications for development of its breeding program

The basic information on genetic diversity is important for the construction of a breeding scheme leading to the sustainable farming activity of banana shrimp Fenneropenaeus merguiensis. Here, its genetic variability was examined (N = 584). Species authentication was performed by cytochrome oxidase subunit I (COI) polymorphism (N = 77). Microsatellite analysis revealed limited genetic diversity (average no. of alleles per locus, NA = 4.857-5.571) in the previous domesticated stocks. Subsequently, specimens from different geographic locations including Trat, Rayong, Chonburi, Pattani and Nakhon Si Thammarat on the Gulf of Thailand (east) and Trang and Krabi on the Andaman Sea (west) were genetically analyzed. Relatively high levels of genetic diversity (NA = 7.857–23.429) and heterozygosity (Ho = 0.500–0.733) were observed. Genetic differentiation was found between all pairwise comparisons (P < 0.001) except Trat-Nakhon Si Thammarat (P > 0.0071). Phylogenetic analysis allocated wild F. merguiensis to three groups, A (Gulf of Thailand), B (Trang) and C (Krabi). Admixture analysis did not reveal large mixing between different lineages of genotypes in each population. However, the Krabi population (west) mainly showed the eastern genetic lineage. A new domestication program was established by selecting shrimp from different genetic groups. High genetic diversity was found in founders (NA = 27.714 and AR = 14.137) and brooders of the second generation (NA = 24.571 and AR = 12.835). Currently, genome-wide association study (GWAS) of G2 shrimp exhibiting large and small sizes from four families is being carried out to analyze growth-related SNPs in this species.

Phenotypic drug-susceptibility profiles and genetic analysis based on whole-genome sequencing of Mycobacterium avium complex isolates in Thailand.

Mycobacterium avium complex (MAC) infections are a significant clinical challenge. Determining drug-susceptibility profiles and the genetic basis of drug resistance is crucial for guiding effective treatment strategies. This study aimed to determine the drug-susceptibility profiles of MAC clinical isolates and to investigate the genetic basis conferring drug resistance using whole-genome sequencing (WGS) analysis. Drug-susceptibility profiles based on minimum inhibitory concentration (MIC) assays were determined for 38 MAC clinical isolates (12 Mycobacterium avium and 26 Mycobacterium intracellulare). Mutations associated with drug resistance were identified through genome analysis of these isolates, and their phylogenetic relationships were also examined. Drug resistance, based on MIC values, was most commonly observed for moxifloxacin (81.6%), followed by linezolid (78.9%), clarithromycin (44.7%) and amikacin (36.8%). We identified specific mutations associated with resistance to amikacin. These include the rrs mutation at C464T in amikacin intermediate-resistance M. avium, and two mutations at T250A and G1453T in amikacin non-susceptible M. intracellulare. Mutations in rrl at A2058G, A2059C and A2059G were potentially linked to clarithromycin resistance. MAC clinical isolates not susceptible to linezolid exhibited mutations in rplC at G237C and C459T, as well as two rplD mutations at G443A and A489G. GyrB substitution Thr521Ala (T521A) was identified in moxifloxacin non-susceptible isolates, which may contribute to this resistance. A phylogeny of our MAC isolates revealed high levels of genetic diversity. Our findings suggest that the standard treatment regimen for MAC infections using moxifloxacin, linezolid, clarithromycin and amikacin may be driving development of resistance, potentially due to specific mutations. The combination of phenotypic and genotypic susceptibility testing can be valuable in guiding the clinical use of drugs for the treatment of MAC infections.

Determination of Seasonal Influenza Intrahost Viral Diversity as a Function of Host Immune Status

Abstract Background Seasonal influenza viruses evolve predominately via antigenic drift, the slow accumulations of genetic mutations leading to changes in key antigenic sites. Due to the accumulation of antigenic changes, influenza vaccines must be updated each year and, even then, can suffer from limited efficacy due to strain mismatch. Despite high levels of genetic diversity seen across the population, most studies show that intrahost viral diversity in humans following natural infection is limited. It is unclear where the population-level diversity in influenza virus originates. Previous studies have shown that host characteristics, such as pre-existing immunity, may affect the intrahost viral evolution during a single infection. As very young children have limited immunologic memory, we hypothesize these infections may serve as a source of viral diversity. Methods In this study, we characterize influenza genetic diversity in the pediatric population as a function of age and vaccine status. We use next generation sequencing to assess intrahost influenza virus diversity in 200 clinical isolates generated during the 2017-2018 flu season from children between 6 months and 18 years of age. We quantify intrahost diversity as the number and frequency of mutations of influenza virus present within each clinical isolate. The clinical samples were obtained from left over influenza-positive nasopharyngeal swabs from the Children's Hospital of Philadelphia Infectious Disease Diagnostics Laboratory. We stratify these isolates by host subject age and vaccine status (with respect to that season's influenza vaccine). Results The isolates sequenced thus far fall within the 6B.1A, 6B.1A.1, and 6B.1A.5b clades for H1N1 and 3C.2a.1, 3C.2a2, and 3C.3a1 clades for H3N2, as expected. Thus far, there does not appear to be a significant relationship between the number of variants detected and either the age or vaccine status of the subject for either H3N2 or H1N1, though this may change as additional isolates are sequenced. Conclusions Through ongoing studies, we evaluate how host age and vaccination status influences intrahost viral diversity. Using clinical metadata, we investigate the association between viral diversity and the duration of symptoms and disease severity. By identifying a reservoir of influenza diversity, we will be better able to evaluate influenza strains for inclusion in the seasonal vaccine.