Biology subjects

Joy, J. B.

Publications and source records attributed to Joy, J. B..

9 recordsLinked to original sources

bioRxiv2026

The emergence and molecular evolution of H5N1 influenza viruses in United States dairy cattle

Prior to 2024, highly pathogenic avian influenza H5N1 clade 2.3.4.4b viruses circulated predominantly in wild birds and poultry. In 2024 and 2025, 2.3.4.4b genotypes B3.13 and D1.1 were detected in United States dairy cattle. Using whole-genome and segment-specific phylodynamic inference, we estimate that B3.13 and D1.1 spilled over from wild birds into dairy cattle in late 2023 and late 2024, respectively. Spillover occurred shortly after the formation of the reassortant genotypes and was followed by months of cryptic transmission prior to detection. We found that both B3.13 and D1.1 evolved at higher rates in cattle relative to birds, primarily due to relaxed purifying selection. Site-specific analyses identified genomic sites under positive selection in cattle relative to birds, indicating adaptation and likely contributing to improved viral fitness after spillover. Intensified genomic surveillance in dairy cattle is essential as population immunity introduces additional selection pressures, with ever-changing risk for human emergence.

evolutionary biology↗

bioRxiv2026

Functional genomic analysis reveals mechanisms of epigenetic interference in SARS-CoV-1 and SARS-CoV-2

Small viral RNAs (svRNA) are key factors in host adaptation and virulence and are previously identified in SARS-CoV-2 and SARS-CoV-1. Little is known about svRNA conservation among high-risk coronaviruses (subgenus Sarbecovirus) or how svRNAs might contribute to COVID-19. Here, using functional genomics we identify six novel svRNA-triplex-forming oligonucleotides (svRNA-TFOs) in SARS-CoV-2, and through comparative analyses with SARS-CoV-1, delineate evolutionary pathways for svRNA-TFOs in Sarbecovirus. In addition to significant enrichment of the svRNA-TFO enhancer-associated gene targets among differentially expressed gene sets collected during SARS-CoV-2 infection, we find statistical support for non-random associations with >25 % of recombination breakpoints and hotspots in the Wuhan-Hu-1 genome. Small RNA-sequencing reveals highly abundant svRNA-TFO-N derived from the nucleocapsid of SARS-CoV-2. Using synonymous site conservation analysis, we find svRNA-TFO-N, and other svRNA-TFOs are conserved among both SARS-CoV-2- and SARS-CoV-1-related lineages. Furthermore, BLASTn reveals svRNA-TFO-N, svRNA-TFO-S.1 and svRNA-TFO-E share sequence homology against various mammalian genomes supporting a potential mechanism of host adaptation. Finally, we identify potential links between the putative svRNA-TFO-S.1 and svRNA-TFO-N RNA progenitor structures with variant of concern-associated S:D614G and N:D377Y mutations, respectively. Collectively these findings support a role for epigenetic interference with potential to reveal critical insights into the evolution of SARS-CoV-2 and SARS-CoV-1.

genetics↗

bioRxiv2023

HIV reservoirs are dominated by genetically younger and clonally enriched proviruses

In order to cure HIV, we need to better understand the within-host evolutionary origins of the small reservoir of genome-intact proviruses that persists within infected cells during antiretroviral therapy (ART). Most prior studies on reservoir evolutionary dynamics however did not discriminate genome-intact proviruses from the vast background of defective ones. We reconstructed within-host pre-ART HIV evolutionary histories in six individuals and leveraged this information to infer the ages of intact and defective proviruses sampled after an average >9 years on ART, along with the ages of rebound and low-level/isolated viremia occurring during this time. We observed that the longest-lived proviruses persisting on ART were exclusively defective, usually due to large deletions. In contrast, intact proviruses and rebound HIV exclusively dated to the years immediately preceding ART. These observations are consistent with genome-intact proviruses having shorter lifespans, likely due to the cumulative risk of elimination following viral reactivation and protein production. Consistent with this, intact proviruses (and those with packaging signal defects) were three times more likely to be genetically identical compared to other proviral types, highlighting clonal expansion as particularly important in ensuring their survival. By contrast, low-level/isolated viremia sequences were genetically heterogeneous and sometimes ancestral, where viremia may have originated from defective proviruses. Results reveal that the HIV reservoir is dominated by clonally-enriched and genetically younger sequences that date to the untreated infection period when viral populations had been under within-host selection pressures for the longest duration. Knowledge of these qualities may help focus strategies for reservoir elimination. ImportanceCharacterizing the HIV reservoir that endures despite antiretroviral therapy (ART) is critical to cure efforts. Our observation that the oldest proviruses persisting during ART were exclusively defective, while intact proviruses (and rebound HIV) all dated to the years immediately pre- ART, explains why prior studies that sampled sub-genomic proviruses on-ART (which are largely defective) routinely found sequences dating to early infection, whereas those that sampled viral outgrowth sequences found essentially none. Together with our findings that intact proviruses were also more likely to be clonal, and that on-ART low-level/isolated viremia originated from proviruses of varying ages (including possibly defective ones), our observations indicate that: 1) on-ART and rebound viremia can have distinct within-host origins, 2) intact proviruses have shorter lifespans than grossly-defective ones, and therefore depend on clonal expansion for persistence, and 3) the HIV reservoir, being overall genetically younger, will be substantially adapted to within-host pressures, complicating immune-based cure strategies.

genetics↗

bioRxiv2022

HIV proviral genetic diversity, compartmentalization and inferred dynamics in lung and blood during long-term suppressive antiretroviral therapy

The lung is an understudied site of HIV persistence. We isolated 882 subgenomic proviral sequences by single-genome approaches from blood and lung from nine individuals on long-term suppressive antiretroviral therapy (ART), and characterized genetic diversity and compartmentalization using formal tests. Consistent with clonal expansion as a driver of HIV persistence, identical sequences comprised between 9% to 86% of within-host datasets, though their location (blood vs. lung) followed no consistent pattern. The majority (77%) of participants harbored at least one sequence shared across blood and lung, supporting the migration of clonally-expanded cells between sites. No participant exhibited genetic compartmentalization so obvious that it was visually apparent in a phylogeny. When formal tests were applied however, two (22%) participants showed modest yet significant support for compartmentalization when analysis was restricted to distinct proviruses per site. This increased to four participants (44%) when considering all within-host sequences. Thus, while a minority of individuals harbor somewhat distinctive proviral populations in blood and lung, these can simply be due to unequal distributions of clonally-expanded sequences. Importantly, the extent of lung proviral diversity on ART strongly reflected that in blood (Spearman {rho} = 0.98, p < 0.0001), confirming blood as a strong indicator of total body proviral diversity. Analysis of on-ART proviral diversity in context of pre-therapy viral diversity in two participants revealed marked differences in proviral longevity and dynamics. Whereas one participants proviral pool was rich in ancestral sequences that recapitulated more of HIVs within-host evolutionary history, the others largely comprised more contemporary sequences, including ones that re-seeded the reservoir during a three-year treatment interruption. Results highlight the genetic complexity of proviruses persisting in lung and blood during ART, and the uniqueness of each individuals proviral composition. Individualized HIV remission and cure strategies may be needed to overcome these challenges. Author SummaryHIV persists in the body despite long-term suppressive antiretroviral therapy. Much of our knowledge about the HIV reservoir comes from studying proviruses in blood, but a fundamental question is whether these are distinct from those in tissues. The lung could theoretically engender genetically distinctive HIV populations, but this remains understudied. Our analysis of nearly 900 proviral sequences from blood and lung of nine individuals with HIV receiving long-term therapy revealed substantial within-host heterogeneity, yet some common patterns. Identical sequences (consistent with clonal expansion of infected cells) were observed in everyone, though at different (9-86%) frequencies. Recovery of shared sequences across blood and lung was common (77% of participants). Fewer than half of participants exhibited blood-lung genetic compartmentalization, and only modestly so. Moreover, when present, compartmentalization was often attributable to differential distribution of identical sequences, not the presence of genetically distinctive populations, across sites. Results also revealed marked inter-individual differences in proviral dynamics, as evidenced by the proportion of persisting proviruses that represented ancestral versus more recently-circulating viral sequences. Critically, the extent of within-host proviral diversity in blood correlated strongly with that in lung, indicating that despite inter-individual heterogeneity, blood is a strong indicator of proviral diversity elsewhere in the body.

molecular biology↗

bioRxiv2021

HIV proviral burden, genetic diversity and dynamics in viremic controllers who subsequently initiated suppressive antiretroviral therapy

Curing HIV will require eliminating the reservoir of integrated, replication-competent proviruses that persist despite antiretroviral therapy (ART). Understanding the burden, genetic diversity and longevity of persisting proviruses in diverse individuals with HIV is critical to this goal, but these characteristics remain understudied in some groups. Among them are viremic controllers, individuals who naturally suppress HIV to low levels but for whom therapy is nevertheless recommended. We reconstructed within-host HIV evolutionary histories from longitudinal single-genome amplified viral sequences in four viremic controllers who eventually initiated ART, and used this information to characterize the age and diversity of proviruses persisting on therapy. We further leveraged these within-host proviral age distributions to estimate rates of proviral turnover prior to ART. This is an important yet understudied metric, since pre-ART proviral turnover dictates reservoir composition at ART initiation (and thereafter), which is when curative interventions, once developed, would be administered. Despite natural viremic control, all participants displayed significant within-host HIV evolution pre-therapy, where overall on-ART proviral burden and diversity broadly reflected the extent of viral replication and diversity pre-ART. Consistent with recent studies of non-controllers, the proviral pools of two participants were skewed towards sequences that integrated near ART initiation, suggesting dynamic proviral turnover during untreated infection. In contrast, proviruses recovered from the two other participants dated to time-points that were more evenly spread throughout infection, suggesting slow or negligible proviral decay following deposition. HIV cure strategies will need to overcome within-host proviral diversity, even in individuals who naturally controlled HIV replication before therapy. ImportanceHIV therapy is life-long because integrated, replication-competent viral copies persist within long-lived cells. To cure HIV, we need to understand when these viral reservoirs form, how large and genetically diverse they are, and how long they endure. Elite controllers, individuals who naturally suppress HIV to undetectable levels, are being intensely studied as models of HIV remission, but viremic controllers, individuals who naturally suppress HIV to low levels, remain understudied even though they too may hold valuable insights. We combined phylogenetics and mathematical modeling to reconstruct proviral seeding and decay from infection to therapy-mediated suppression in four viremic controllers. We recovered diverse proviruses persisting during therapy that broadly reflected HIVs within-host evolutionary history, where the estimated half-lives of the persistent proviral pool during untreated infection ranged from <1 year to negligible. Cure strategies will need to contend with proviral diversity and between-host heterogeneity, even in individuals who naturally control HIV.

microbiology↗

bioRxiv2021

Fundamental identifiability limits in molecular epidemiology

Viral phylogenies provide crucial information on the spread of infectious diseases, and many studies fit mathematical models to phylogenetic data to estimate epidemiological parameters such as the effective reproduction ratio (Re) over time. Such phylodynamic inferences often complement or even substitute for conventional surveillance data, particularly when sampling is poor or delayed. It remains generally unknown, however, how robust phylodynamic epidemiological inferences are, especially when there is uncertainty regarding pathogen prevalence and sampling intensity. Here we use recently developed mathematical techniques to fully characterize the information that can possibly be extracted from serially collected viral phylogenetic data, in the context of the commonly used birth-death-sampling model. We show that for any candidate epidemiological scenario, there exist a myriad of alternative, markedly different and yet plausible "congruent" scenarios that cannot be distinguished using phylogenetic data alone, no matter how large the dataset. In the absence of strong constraints or rate priors across the entire study period, neither maximum-likelihood fitting nor Bayesian inference can reliably reconstruct the true epidemiological dynamics from phylogenetic data alone; rather, estimators can only converge to the "congruence class" of the true dynamics. We propose concrete and feasible strategies for making more robust epidemiological inferences from viral phylogenetic data.

evolutionary biology↗

bioRxiv2020

A General Birth-Death-Sampling Model for Epidemiology and Macroevolution

Birth-death stochastic processes are the foundation of many phylogenetic models and are widely used to make inferences about epidemiological and macroevolutionary dynamics. There are a large number of birth-death model variants that have been developed; these impose different assumptions about the temporal dynamics of the parameters and about the sampling process. As each of these variants was individually derived, it has been difficult to understand the relationships between them as well as their precise biological and mathematical assumptions. Without a common mathematical foundation, deriving new models is non-trivial. Here we unify these models into a single framework, prove that many previously developed epidemiological and macroevolutionary models are all special cases of a more general model, and illustrate the connections between these variants. This framework centers around a technique for deriving likelihood functions for arbitrarily complex birth-death(-sampling) models that will allow researchers to explore a wider array of scenarios than was previously possible. We then use this frame-work to derive general model likelihoods for both the "single-type" case in which all lineages diversify according to the same process and the "multi-type" case, where there is variation in the process among lineages. By re-deriving existing single-type birth-death sampling models we clarify and synthesize the range of explicit and implicit assumptions made by these models.

evolutionary biology↗

bioRxiv2020

Assessing in vivo mutation frequencies and creating a high-resolution genome-wide map of fitness costs of Hepatitis C virus

Like many viruses, Hepatitis C Virus (HCV) has a high nutation rate, which helps the virus adapt quickly, but mutations come with fitness costs. Fitness costs can be studied by different approaches, such as experimental or frequency-based approaches. The frequency-based approach is particularly useful to estimate in vivo fitness costs, but this approach works best with deep sequencing data from many hosts, are. In this study, we applied the frequency-based approach to a large dataset of 195 patients and estimated the fitness costs of mutations at 7957 sites along the HCV genome. We used beta regression and random forest models to better understand how different factors influenced fitness costs. Our results revealed that costs of nonsynonymous mutations were three times higher than those of synonymous mutations, and mutations at nucleotides A or T had higher costs than those at C or G. Genome location had a modest effect, with lower costs for mutations in HVR1 and higher costs for mutations in Core and NS5B. Resistance mutations were, on average, costlier than other mutations. Our results show that in vivo fitness costs of mutations can be virus specific, reinforcing the utility of constructing in vivo fitness cost maps of viral genomes. Author SummaryUnderstanding how viruses evolve within patients is important for combatting viral diseases, yet studying viruses within patients is difficult. Laboratory experiments are often used to understand the evolution of viruses, in place of assessing the evolution in natural populations (patients), but the dynamics will be different. In this study, we aimed to understand the within-patient evolution of Hepatitis C virus, which is an RNA virus that replicates and mutates extremely quickly, by taking advantage of high-throughput next generation sequencing. Here, we describe the evolutionary patterns of Hepatitis C virus from 195 patients: We analyzed mutation frequencies and estimated how costly each mutation was. We also assessed what factors made a mutation more costly, including the costs associated with drug resistance mutations. We were able to create a genome-wide fitness map of within-patient mutations in Hepatitis C virus which proves that, with technological advances, we can deepen our understanding of within-patient viral evolution, which can contribute to develop better treatments and vaccines.

evolutionary biology↗

bioRxiv2020

The emergence of SARS-CoV-2 in Europe and the US

Accurate understanding of the global spread of emerging viruses is critically important for public health response and for anticipating and preventing future outbreaks. Here, we elucidate when, where and how the earliest sustained SARS-CoV-2 transmission networks became established in Europe and the United States (US). Our results refute prior findings erroneously linking cases in January 2020 with outbreaks that occurred weeks later. Instead, rapid interventions successfully prevented onward transmission of those early cases in Germany and Washington State. Other, later introductions of the virus from China to both Italy and Washington State founded the earliest sustained European and US transmission networks. Our analyses reveal an extended period of missed opportunity when intensive testing and contact tracing could have prevented SARS-CoV-2 from becoming established in the US and Europe.

genetics↗