To The Most Recent Common Ancestor Research Articles

The emergence and circulation of human immunodeficiency virus (HIV)-1 subtype C.

Introduction. Human immunodeficiency virus (HIV)-1 subtype C is the most prevalent globally and is thought to have originated in non-human primates in the Democratic Republic of Congo.Hypothesis/Gap Statement. Although the global dominance of HIV-1 subtype C is well established, a thorough understanding of its evolutionary history and transmission dynamics across various risk populations remains elusive. The current knowledge is insufficient to fully capture the global diversification and dissemination of this subtype.Aim. We for the first time sought to investigate the global evolutionary history and spatiotemporal dynamics of HIV-1 subtype C using a selection of maximum-likelihood-based phylodynamic approaches on a total of 1210 near full-length genomic sequences sampled from 32 countries, collected in 4 continents, with sampling dates between 1986-2019 among various risk groups were analysed.Methodology. We subsampled the HIV-1 subtype C genomic datasets based on continent and risk group traits, and performed nucleotide substitution model selection analysis, maximum likelihood (ML) phylogenetic reconstruction, phylogenetic tree topology similarity analysis, temporal signal analysis and traced the timings of viral spread both geographically and by risk group.Results. Based on the phylodynamic analyses of four datasets (full1210, locrisk626, loc562 and risk393), we inferred the time to the most recent common ancestor (TMRCA) in the 1930s and an evolutionary rate of 0.0023 substitutions per site per year. The total number of introduction events of HIV-1 subtype C between continents and between risk groups is estimated to be 71 and 115, respectively. The largest number of introductions occurred from Africa to Europe (n=32), from not-recorded to heterosexual (n=40) and from heterosexual to not-recorded (n=51) risk groups.Conclusion. Our results emphasize that HIV subtype C has mainly spread from Africa to Europe, likely through heterosexual transmission.

Evolutionary Analysis of a Parrot Bornavirus 2 Detected in a Sulphur-Crested Cockatoo (Cacatua galerita) Suggests a South American Ancestor.

Parrot bornavirus (PaBV) is an RNA virus that causes Proventricular Dilatation Disease (PDD), neurological disorders, and death in Psittaciformes. Its diversity in South America is poorly known. We examined a Cacatua galerita presenting neuropathies, PDD, and oculopathies as the main signs. We detected PaBV through reverse transcription polymerase chain reaction (RT-PCR) and partial sequencing of the nucleoprotein (N) and matrix (M) genes. Maximum likelihood and Bayesian phylogenetic inferences classified it as PaBV-2. The nucleotide identity of the sequenced strain ranged from 88.3% to 90.3% against genotype PaBV-2 and from 80.2% to 84.4% against other genotypes. Selective pressure analysis detected signs of episodic diversifying selection in both the N and M genes. No recombination events were detected. Phylodynamic analysis estimated the time to the most recent common ancestor (TMRCA) as the year 1758 for genotype PaBV-2 and the year 1049 for the Orthobornavirus alphapsittaciforme species. Substitution rates were estimated at 2.73 × 10-4 and 4.08 × 10-4 substitutions per year per site for N and M, respectively. The analysis of population dynamics showed a progressive decline in the effective population size during the last century. Timescale phylogeographic analysis revealed a potential South American ancestor as the origin of genotypes 1, 2, and 8. These results contribute to our knowledge of the evolutionary origin, diversity, and dynamics of PaBVs in South America and the world. Additionally, it highlights the importance of further studies in captive Psittaciformes and the potential impact on endangered wild birds.

Molecular epidemiology and phylodynamic analysis of enterovirus 71 in Beijing, China, 2009–2019

BackgroundEnterovirus 71(EV71)-associated hand, foot and mouth disease (HFMD) decreased dramatically in Beijing from 2009 to 2019. This study was to investigate the epidemiological characteristics, evolutionary dynamics, geographic diffusion pathway, and other features of EV71 in Beijing, China.MethodsWe conducted a retrospective study of EV71-associated HFMD and its causative agent in Beijing, China, from 2009 to 2019. Phylogenetic and phylogeographic methods based on the EV71 genome were used to determine the evolution features, origin, and spatiotemporal dynamics. Positive selection sites in the VP1 gene were identified and exhibited in the tertiary structure. Bayesian birth-death skyline model was used to estimate the effective reproductive number (Re).ResultsEV71-associated HFMD decreased greatly in Beijing. From 2009 to 2019, EV71 strains prevalent in Beijing shared high homology in each gene segment and evolved with a rate of 4.99*10− 3 substitutions per site per year. The genetic diversity of EV71 first increased and peaked in 2012 and then decreased with fluctuations. The time to the most recent common ancestor (TMRCA) of EV71 in Beijing was estimated around 2003 when the EV71 strains were transmitted to Beijing from east China. Beijing played a crucial role in seeding EV71 to central China as well. Two residues (E145Q/G, A293S) under positive selection were detected from both the VP1 dataset and the P1 dataset. They were embedded within the loop of the VP1 capsid and were exposed externally. Mean Re estimate of EV71 in Beijing was about 1.007.ConclusionIn recent years, EV71 was not the primary causative agent of HFMD in Beijing. The low Re estimate of EV71 in Beijing implied that strategies for preventing and controlling HFMD were performed effectively. Beijing and east China played a crucial role in disseminating EV71 to other regions in China.

Revealing an Iranian Isolate of Tomato Brown Rugose Fruit Virus: Complete Genome Analysis and Mechanical Transmission.

An analysis of the complete genome sequence of a novel isolate of tomato brown rugose fruit virus (ToBRFV) obtained from tomatoes in Iran and named ToBRFV-Ir is presented in this study. Comprehensive phylogenetic analysis utilizing key viral proteins, including 126 KDa, 183 KDa, movement protein (MP), and coat protein (CP), as well as the complete genome sequence, classified ToBRFV-Ir and 65 isolates from GenBank into three distinct clades. Notably, genetic diversity assessment revealed relatively low variability among the isolates, irrespective of their geographical or clade affiliation. Natural selection analysis based on the complete genome sequence showed that dN/dS values were consistently <1, indicating the prevailing role of negative selection across all populations. Analyses using the Recombination Detection Program and SplitsTree found no evidence of recombination events or signals in the complete genome sequence of the tested isolates. Thus, these results suggest that the genetic composition of ToBRFV remains stable without significant genetic exchange or recombination events occurring. A simple arithmetic comparison of the patristic distances and dates suggested that the time to the most recent common ancestor (TMRCA) of the ToBRFV populations is approximately 0.8 up to 2.7 with the closest tobamoviruses. An evolutionary study of the tested isolates from various countries based on the complete genome suggests Peruvian ancestry. The ToBRF-Ir isolate was successfully transmitted through mechanical inoculations to Solanum lycopersicum and Nicotiana rustica. These findings shed light on the genetic dynamics and transmission mechanisms of ToBRFV, providing valuable insights into its molecular characteristics and potential spread among susceptible plant species.

Inference of Coalescence Times and Variant Ages Using Convolutional Neural Networks.

Accurate inference of the time to the most recent common ancestor (TMRCA) between pairs of individuals and of the age of genomic variants is key in several population genetic analyses. We developed a likelihood-free approach, called CoalNN, which uses a convolutional neural network to predict pairwise TMRCAs and allele ages from sequencing or SNP array data. CoalNN is trained through simulation and can be adapted to varying parameters, such as demographic history, using transfer learning. Across several simulated scenarios, CoalNN matched or outperformed the accuracy of model-based approaches for pairwise TMRCA and allele age prediction. We applied CoalNN to settings for which model-based approaches are under-developed and performed analyses to gain insights into the set of features it uses to perform TMRCA prediction. We next used CoalNN to analyze 2,504 samples from 26 populations in the 1,000 Genome Project data set, inferring the age of ∼80 million variants. We observed substantial variation across populations and for variants predicted to be pathogenic, reflecting heterogeneous demographic histories and the action of negative selection. We used CoalNN's predicted allele ages to construct genome-wide annotations capturing the signature of past negative selection. We performed LD-score regression analysis of heritability using summary association statistics from 63 independent complex traits and diseases (average N=314k), observing increased annotation-specific effects on heritability compared to a previous allele age annotation. These results highlight the effectiveness of using likelihood-free, simulation-trained models to infer properties of gene genealogies in large genomic data sets.

Probability Distribution of Tree Age for the Simple Birth-Death Process, with Applications to Distributions of Number of Ancestral Lineages and Divergence Times for Pairs of Taxa in a Yule Tree.

In this contribution, a general expression is derived for the probability density of the time to the most recent common ancestor (TMRCA) of a simple birth-death tree, a widely used stochastic null-model of biological speciation and extinction, conditioned on the constant birth and death rates and number of extant lineages. This density is contrasted with a previous result which was obtained using a uniform prior for the time of origin. The new distribution is applied to two problems of phylogenetic interest. First, that of the probability of the number of taxa existing at any time in the past in a tree of a known number of extant species, and given birth and death rates, and second, that of determining the TMRCA of two randomly selected taxa in an unobserved tree that is produced by a simple birth-only, or Yule, process. In the latter case, it is assumed that only the rate of bifurcation (speciation) and the size, or number of tips, are known. This is shown to lead to a closed-form analytical expression for the probability distribution of this parameter, which is arrived at based on the known mathematical form of the age distribution of Yule trees of a given size and branching rate, which is derived here de novo, and a similar distribution which additionally is conditioned on tree age. The new distribution is the exact Yule prior for divergence times of pairs of taxa under the stated conditions and is potentially useful in statistical (Bayesian) inference studies of phylogenies.

Predictions based on phylogeography and climatic niche modelling depict an uncertain future scenario for giant blister beetles (Berberomeloe, Meloidae) facing intensive greenhouse expansion and global warming

Abstract Large‐scale agricultural and tourism development are the main threats to biodiversity in south‐eastern Spain. Species with low dispersal abilities, such as some endemic insects from this region, are particularly vulnerable to fragmentation and loss of genetic and morphological diversity. Here, we studied the current and future threat of climate and land‐use change on the intraspecific diversity of one such group of endemics, the giant blister beetles of the Berberomeloe insignis species group. Using a phylogeographic approach and morphometrics, we identified intraspecific variation within the B. insignis species group. These data were coupled with ecological niche modelling (ENM) to determine the effect of agricultural and climate change on the connectivity across phylogroups. We identified a marked geographic structure within B. insignis, with the time to the most recent common ancestor (TMRCA) of the two main mtDNA clades dating back to 2.1 Ma. Cyto‐nuclear discordances found across parapatric populations suggest past events of genetic introgression. B. insignis presents a head pattern that is geographically structured and mostly congruent with the four mitochondrial lineages. In contrast, diversification within Berberomeloe tenebrosus is more recent, dating back to less than 1 Ma. Future ENMs highlight the role of mountains as potential refugia under a climate warming scenario but predict extinctions in the lowlands. Based on our analyses, two lineages of B. insignis are threatened and should be urgently considered as independent conservation units, and their current geographic distribution areas protected to conserve, at the very least, a portion of the species' evolutionary heritage.

Spatial and temporal diversity of positive selection on shared haplotypes at the PSCA locus among worldwide human populations.

Selection on standing genetic variation is important for rapid local genetic adaptation when the environment changes. We report that, for the prostate stem cell antigen (PSCA) gene, different populations have different target haplotypes, even though haplotypes are shared among populations. The C-C-A haplotype, whereby the first C is located at rs2294008 of PSCA and is a low risk allele for gastric cancer, has become a target of positive selection in Asia. Conversely, the C-A-G haplotype carrying the same C allele has become a selection target mainly in Africa. However, Asian and African share both haplotypes, consistent with the haplotype divergence time (170 kya) prior to the out-of-Africa dispersal. The frequency of C-C-A/C-A-G is 0.344/0.278 in Asia and 0.209/0.416 in Africa. Two-dimensional site frequency spectrum analysis revealed that the extent of intra-allelic variability of the target haplotype is extremely small in each local population, suggesting that C-C-A or C-A-G is under ongoing hard sweeps in local populations. From the time to the most recent common ancestor (TMRCA) of selected haplotypes, the onset times of positive selection were recent (3-55 kya), concurrently with population subdivision from a common ancestor. Additionally, estimated selection coefficients from ABC analysis were up to ~3%, similar to those at other loci under recent positive selection. Phylogeny of local populations and TMRCA of selected haplotypes revealed that spatial and temporal switching of positive selection targets is a unique and novel feature of ongoing selection at PSCA. This switching may reflect the potential of rapid adaptability to distinct environments.

A phylogenetic study of dengue virus in urban Vietnam shows long-term persistence of endemic strains.

Dengue virus (DENV) causes repeated outbreaks of disease in endemic areas, with patterns of local transmission strongly influenced by seasonality, importation via human movement, immunity, and vector control efforts. An understanding of how each of these interacts to enable endemic transmission (continual circulation of local virus strains) is largely unknown. There are times of the year when no cases are reported, often for extended periods of time, perhaps wrongly implying the successful eradication of a local strain from that area. Individuals who presented at a clinic or hospital in four communes in Nha Trang, Vietnam, were initially tested for DENV antigen presence. Enrolled positive individuals then had their corresponding household members invited to participate, and those who enrolled were tested for DENV. The presence of viral nucleic acid in all samples was confirmed using quantitative polymerase chain reaction, and positive samples were then whole-genome sequenced using an amplicon and target enrichment library preparation techniques and Illumina MiSeq sequencing technology. Generated consensus genome sequences were then analysed using phylogenetic tree reconstruction to categorise sequences into clades with a common ancestor, enabling investigations of both viral clade persistence and introductions. Hypothetical introduction dates were additionally assessed using a molecular clock model that calculated the time to the most recent common ancestor (TMRCA). We obtained 511 DENV whole-genome sequences covering four serotypes and more than ten distinct viral clades. For five of these clades, we had sufficient data to show that the same viral lineage persisted for at least several months. We noted that some clades persisted longer than others during the sampling time, and by comparison with other published sequences from elsewhere in Vietnam and around the world, we saw that at least two different viral lineages were introduced into the population during the study period (April 2017-2019). Next, by inferring the TMRCA from the construction of molecular clock phylogenies, we predicted that two of the viral lineages had been present in the study population for over a decade. We observed five viral lineages co-circulating in Nha Trang from three DENV serotypes, with two likely to have remained as uninterrupted transmission chains for a decade. This suggests clade cryptic persistence in the area, even during periods of low reported incidence.

THE YAKUT BRANCH OF Y-CHROMOSOME AS A PART OF THE HAPLOGROUP N-M2016

Based on the massive parallel sequencing, phylogenetic tree of the Y-chromosomal haplogroup N-M2016 was built. The branch N-M1982 of Yakut-Sakha men majority is located on the tree. The ages of tree branching nodes are estimated. Time to the most recent common ancestor (TMRCA) 970 ± 210 years BP (“present” defined as AD 1950) of one of the main Yakut male lineages N-M1991 is confirmed by accelerator mass spectrometry dating of a sample of the ancient man Yana Young [1] who died about 766 yBP. A sharp increase in the number of Yakut-Sakha ancestors observed on the Yakut branch N-M1982, began from 1320 ± 100 AD. Age of the population explosion is consistent with the radiocarbon dating of the Kulun-Atakh archaeological culture sites.

Pre COVID-19 molecular epidemiology of respiratory syncytial virus (RSV) among children in Bangladesh

Epidemiological data of specific respiratory pathogens from the pre-COVID-19 period are essential to determine the effects of the COVID-19 pandemic on other respiratory infections. In this study, we revealed the pre-COVID-19 molecular epidemiology of respiratory syncytial virus (RSV) among children in Bangladesh. We tested 3170 samples collected from 2008 to 2012 for a panel of respiratory viruses; RSV, human metapneumovirus (hMPV), human parainfluenza viruses (hPIV) 1, 2, 3, and adenovirus. Five hundred fifty-five samples (17.5 %) were positive for RSV, including 2.5% having co-infections with other viruses. Genotypic characterization of RSV showed that RSV-A (82%) contributed more acute respiratory infections than RSV-B (18%). Clinical features were similar with RSV-A and RSV-B infections. However, children with RSV-B were more likely to have upper respiratory infections (URI) (10% vs. 29%, p = 0.03). Among RSV-A cases, hospitalization was higher for ON1 cases (25%, ON1 vs. 8%, NA1, p = 0.04), whereas the recovery without a disability was higher among the NA1 cases (56%, ON1 vs. 88%, NA1, p = 0.02). The time to the most recent common ancestor (TMRCA) for RSV in Bangladesh was 1949 for RSV-A and 1944 for RSV-B. This study revealed the genotypic diversity and evolutionary relatedness of RSV strains in Bangladesh and provided pre-COVID molecular epidemiology data to understand better the COVID-19 impact on upcoming RSV epidemiology in Bangladesh.

The phylogeographical pattern of the Amur minnow Rhynchocypris lagowskii (Cypriniformes: Cyprinidae) in the Qinling Mountains.

In this study, the phylogeographical pattern of the Amur minnow (Rhynchocypris lagowskii) widely distributed in the cold freshwaters of the Qinling Mountains was examined. A total of 464 specimens from 48 localities were sequenced at a 540‐bp region of the mitochondrial cytochrome b (Cytb) gene, and 69 haplotypes were obtained. The mean ratio of the number of synonymous and nonsynonymous substitutions per site (dN/dS) was 0.028 and indicated purifying selection. Haplotype diversity (h) and nucleotide diversity (π) of natural populations of R. lagowskii varied widely between distinct localities. Phylogenetic trees based on Bayesian inference (BI), maximum likelihood (ML), and maximum parsimony (MP) methods, and network analysis showed five well‐differentiated lineages, but these did not completely correspond to localities and geographic distribution. Meanwhile, analysis of molecular variances (AMOVA) indicated the highest proportion of genetic variation was attributed to the differentiation between populations rather than by our defined lineages. In addition, there was no significant correlation between the pairwise Fst values and geographic distance (p > .05). Based on the molecular clock calibration, the time to the most recent common ancestor (TMRCA) was estimated to have emerged from the Late Miocene to the Early Pleistocene. Finally, the results of demographic history based on the neutrality test, mismatch distribution, and Bayesian skyline plot (BSP) analyses showed that collectively, the populations were stable during the Pleistocene while one lineage (lineage E) probably underwent a slight contraction during the Middle Pleistocene and a rapid expansion from the Middle to the Late Pleistocene. Therefore, the study suggests the current phylogeographical pattern of R. lagowskii was likely shaped by geological events that led to vicariance followed by dispersal and secondary contact, river capture, and climatic oscillation during the Late Miocene to the Early Pleistocene in the Qinling Mountains.

Carnivore protoparvovirus 1 in Peruvian dogs: Temporal/geographical and evolutionary dynamics of virus.

Canine parvovirus (CPV) has been recognized all around the world as the causal agent of a contagious and highly mortal disease in domestic dogs. In Peru, the infection is endemic and unvaccinated animals and puppies are the most at risk. In order to analyze viral diversity and determine the evolutionary genetic relationships and transmission dynamic of Peruvian CPV-2, were collected during the period of 2016-2017 rectal swabs from puppies with parvovirosis compatible symptoms. Viral DNA was amplified by PCR using primers that flanked the ends of the viral genome and sequenced by Illumina Miseq platform. Twenty-six genomic sequences (NSP1-VP1) of CPV from several districts in Lima Metropolitan area were obtained. The VP2 gene analysis demonstrated the presence of the New CPV-2a, New CPV-2b and 2c variants. The phylodynamic analysis of the viral genomes determined that all Peruvian sequences were clustered into a big clade named South American clade that emerged from the west region of Europe (Italy). The Time to the Most Recent Common Ancestor (TMRCA) of the South American clade was dated to 1993. Peruvian sequences were distributed into three subclades, and the 92% of these sequences were related to Ecuadorian CPV-2. The results suggests that three independent introduction events of virus from other countries could have occurred, in two of these events, CPV-2 from Ecuador were introduced in Peru in 2003 and 2009, and another introduction event, in 2000, from Europe. Overall, these results indicate a viral genetic relationship between Peruvian with Ecuadorian and European virus, and the circulation of several viral subpopulations in Lima Metropolitan.

Identification of a newly emerging HIV-1 CRF111_01C comprising CRF01_AE and C in Yunnan, China: Genetic characterization and recombinant history.

New human immunodeficiency virus (HIV)-1 circulating recombinant forms (CRFs) have recently emerged and disseminated rapidly in China; in total 38 CRFs have been identified thus far. Yunnan province shares its border with Myanmar, and is regarded as a "hotspot" for the occurrence of new HIV-1 recombinations; more than half of novel CRFs reported in China have been first documented in Yunnan province. In the present study, based on the information available on four existing near-full-length genome (NFLG) sequences, combined with data on four other closely related sequences obtained via Basic Local Alignment Search Tool (BLAST) analysis, NFLG/subregion phylogenetic, bootscanning, and time to the most recent common ancestor (TMRCA) analyses were performed. Phylogenetic analysis revealed that the eight strains demonstrated the formation of a distinct monophyletic branch with a bootstrap value of 100%. Strains in this branch were distantly related to all known HIV-1 CRFs; it was temporarily named CRF111_01C. Bootscanning analysis revealed that CRF111_01C consisted of a CRF01_AE backbone and four inserted subtype C segments. Remarkably, CRF111_01C shared six mosaic fragment identities with the previously identified CRF100_01C. Furthermore, CRF111_01C may be deemed a potential second-generation CRF consisting of CRF100_01C and C. Coalescent Bayesian analyses revealed that the TMRCA of CRF111_01C was approximately the period 1999-2002. The emergence of such second-generation recombinants highlights that continuous molecular screening is necessary to carefully monitor the evolutionary dynamics of HIV-1 epidemics.

The Algerian Chapter of SARS-CoV-2 Pandemic: An Evolutionary, Genetic, and Epidemiological Prospect.

To explore the SARS-CoV-2 pandemic in Algeria, a dataset comprising ninety-five genomes originating from SARS-CoV-2 sampled from Algeria and other countries worldwide, from 24 December 2019, through 4 March 2021, was thoroughly examined. While performing a multi-component analysis regarding the Algerian outbreak, the toolkit of phylogenetic, phylogeographic, haplotype, and genomic analysis were effectively implemented. We estimated the Time to the Most Recent Common Ancestor (TMRCA) in reference to the Algerian pandemic and highlighted the multiple introductions of the disease and the missing data depicted in the transmission loop. In addition, we emphasized the significant role played by local and international travels in disease dissemination. Most importantly, we unveiled mutational patterns, the effect of unique mutations on corresponding proteins, and the relatedness regarding the Algerian sequences to other sequences worldwide. Our results revealed individual amino-acid replacements such as the deleterious replacement A23T in the orf3a gene in Algeria_EPI_ISL_418241. Additionally, a connection between Algeria_EPI_ISL_420037 and sequences originating from the USA was observed through a USA characteristic amino-acid replacement T1004I in the nsp3 gene, found in the aforementioned Algerian sequence. Similarly, successful tracing could be established, such as Algeria/G37318-8849/2020|EPI_ISL_766863, which was imported from Saudi Arabia during the pilgrimage. Lastly, we assessed the Algerian mitigation measures regarding disease containment using statistical analyses.

Genomic Epidemiology of SARS-CoV-2 From Mainland China With Newly Obtained Genomes From Henan Province.

Even though the COVID-19 epidemic in China has been successfully put under control within a few months, it is still very important to infer the origin time and genetic diversity from the perspective of the whole genome sequence of its agent, SARS-CoV-2. Yet, the sequence of the entire virus genome from China in the current public database is very unevenly distributed with reference to time and place of collection. In particular, only one sequence was obtained in Henan province, adjacent to China's worst-case province, Hubei Province. Herein, we used high-throughput sequencing techniques to get 19 whole-genome sequences of SARS-CoV-2 from 18 severe patients admitted to the First Affiliated Hospital of Zhengzhou University, a provincial designated hospital for the treatment of severe COVID-19 cases in Henan province. The demographic, baseline, and clinical characteristics of these patients were described. To investigate the molecular epidemiology of SARS-CoV-2 of the current COVID-19 outbreak in China, 729 genome sequences (including 19 sequences from this study) sampled from Mainland China were analyzed with state-of-the-art comprehensive methods, including likelihood-mapping, split network, ML phylogenetic, and Bayesian time-scaled phylogenetic analyses. We estimated that the evolutionary rate and the time to the most recent common ancestor (TMRCA) of SARS-CoV-2 from Mainland China were 9.25 × 10−4 substitutions per site per year (95% BCI: 6.75 × 10−4 to 1.28 × 10−3) and October 1, 2019 (95% BCI: August 22, 2019 to November 6, 2019), respectively. Our results contribute to studying the molecular epidemiology and genetic diversity of SARS-CoV-2 over time in Mainland China.

The effect of consanguinity on coalescence times on the X chromosome

Consanguineous unions increase the frequency at which identical genomic segments are inherited along separate paths of descent, decreasing coalescence times for pairs of alleles drawn from an individual who is the offspring of a consanguineous pair. For an autosomal locus, it has recently been shown that the mean time to the most recent common ancestor (TMRCA) for two alleles in the same individual and the mean TMRCA for two alleles in two separate individuals both decrease with increasing consanguinity in a population. Here, we extend this analysis to the X chromosome, considering X-chromosomal coalescence times under a coalescent model with diploid, male–female mating pairs. We examine four possible first-cousin mating schemes that are equivalent in their effects on autosomes, but that have differing effects on the X chromosome: patrilateral-parallel, patrilateral-cross, matrilateral-parallel, and matrilateral-cross. In each mating model, we calculate mean TMRCA for X-chromosomal alleles sampled either within or between individuals. We describe a consanguinity effect on X-chromosomal TMRCA that differs from the autosomal pattern under matrilateral but not under patrilateral first-cousin mating. For matrilateral first cousins, the effect of consanguinity in reducing TMRCA is stronger on the X chromosome than on the autosomes, with an increased effect of parallel-cousin mating compared to cross-cousin mating. The theoretical computations support the utility of the model in understanding patterns of genomic sharing on the X chromosome.

Y-LineageTracker: a high-throughput analysis framework for Y-chromosomal next-generation sequencing data

BackgroundY-chromosome DNA (Y-DNA) has been used for tracing paternal lineages and offers a clear path from an individual to a known, or likely, direct paternal ancestor. The advance of next-generation sequencing (NGS) technologies increasingly improves the resolution of the non-recombining region of the Y-chromosome (NRY). However, a lack of suitable computer tools prevents the use of NGS data from the Y-DNA studies.ResultsWe developed Y-LineageTracker, a high-throughput analysis framework that not only utilizes state-of-the-art methodologies to automatically determine NRY haplogroups and identify microsatellite variants of Y-chromosome on a fine scale, but also optimizes comprehensive Y-DNA analysis methods for NGS data. Notably, Y-LineageTracker integrates the NRY haplogroup and Y-STR analysis modules with recognized strategies to robustly suggest an interpretation for paternal genetics and evolution. NRY haplogroup module mainly covers haplogroup classification, clustering analysis, phylogeny construction, and divergence time estimation of NRY haplogroups, and Y-STR module mainly includes Y-STR genotyping, statistical calculation, network analysis, and estimation of time to the most recent common ancestor (TMRCA) based on Y-STR haplotypes. Performance comparison indicated that Y-LineageTracker outperformed existing Y-DNA analysis tools for the high performance and satisfactory visualization effect.ConclusionsY-LineageTracker is an open-source and user-friendly command-line tool that provide multiple functions to efficiently analyze Y-DNA from NGS data at both Y-SNP and Y-STR level. Additionally, Y-LineageTracker supports various formats of input data and produces high-quality figures suitable for publication. Y-LineageTracker is coded with Python3 and supports Windows, Linux, and macOS platforms, and can be installed manually or via the Python Package Index (PyPI). The source code, examples, and manual of Y-LineageTracker are freely available at https://www.picb.ac.cn/PGG/resource.php or CodeOcean (https://codeocean.com/capsule/7424381/tree).

African Swine Fever Virus Circulation between Tanzania and Neighboring Countries: A Systematic Review and Meta-Analysis.

For over 100 years after the description of the first case of African swine fever (ASF) in Kenya, ASF virus (ASFV) cross-border spread in eastern and southern Africa has not been fully investigated. In this manuscript, we reviewed systematically the available literature on molecular epidemiology of ASF in Tanzania and its eight neighboring countries in order to establish the transmission dynamics of ASFV between these countries. Data were retrieved from World Animal Health Information System (WAHIS), Google Scholar, PubMed, Scopus, and CrossRef databases, using the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines and reviewed to document ASF outbreaks and ASFV genotypes distribution. Using phylogeographic approach applied to ASFV p72 sequence dataset, the evolutionary history and the dispersal pattern of the ASFV strains were assessed. From 2005 to 2019, a total of 1588 ASF outbreaks affecting 341,742 cases that led to 302,739 domestic pig deaths were reported. The case fatality rates (CFR) varied from 15.41% to 98.95% with an overall CFR of 88.58%. Fifteen different p72 ASFV genotypes were reported and the time to the most recent common ancestor (TMRCA) for ASFV strains dated back to 1652.233 (1626.473, 1667.735) with an evolutionary rate of 4.805 × 10−5 (2.5857 × 10−5, 9.7789 × 10−5). Phylogeographic dispersal analysis revealed several transboundary spread events of ASFV strains between these countries. These results suggest persistent circulation of ASFV in these countries and advocate for more research to improve our understanding of the transmission dynamics of the virus and for a regional approach to mitigate the spread of ASFV.

Evolutionary analysis of rabies virus using the partial Nucleoprotein and Glycoprotein gene in Mumbai region of India.

Nearly 1.7 million cases of dog bites are reported every year in India and many cases of animal rabies are left unattended and undiagnosed. Therefore, a mere diagnosis of rabies is not sufficient to understand the epidemiology and the spread of the rabies virus (RV) in animals. There is a paucity of information about the evolutionary dynamics of RV in dogs and its biodiversity patterns in India. In total, 50 dog-brain samples suspected of rabies were screened by the nucleoprotein- (N) and glycoprotein- (G) gene PCR. The N and G genes were subsequently sequenced to understand the molecular evolution in these genes. The phylogenetic analysis of the N gene revealed that six isolates in the Mumbai region belonged to a single Arctic lineage. Time-scaled phylogeny by Bayesian coalescent analysis of the partial N gene revealed that the time to the most recent common ancestor (TMRCA) for the sequences belonged to the cluster from 2006.68 with a highest posterior density of 95 % betweeen 2005-2008, which is assigned to Indian lineage I. Migration pattern revealed a strong Bayes factor between Mumbai to Delhi, Panji to Hyderabad, Delhi to Chennai, and Chennai to Chandigarh. Phylogenetic analysis of the G gene revealed that the RVs circulating in the Mumbai region are divided into three lineages. Time-scaled phylogeny by the Bayesian coalescent analysis method estimated that the TMRCA for sequences under study was from 1993 and Indian clusters was from 1962. In conclusion, the phylogenetic analysis of the N gene revealed that six isolates belonged to single Arctic lineages along with other Indian isolates and they were clustered into a single lineage but divided into three clades based on the G-gene sequences. The present study highlights and enhances the current molecular epidemiology and evolution of RV and revealed strong location bias and geographical clustering within Indian isolates on the basis of N and G genes.