SARS-CoV-2 isolates of a given clade may contain low frequency genomes that encode amino acids or deletions which are typical of a different clade.
Here we use high resolution ultra-deep sequencing ...to analyze SARS-CoV-2 mutant spectra.
In 6 out of 11 SARS-CoV-2 isolates from COVID-19 patients, the mutant spectrum of the spike (S)-coding region included two or more amino acids or deletions, that correspond to discordant viral clades. A similar observation is reported for laboratory populations of SARS-CoV-2 USA-WA1/2020, following a cell culture infection in the presence of remdesivir, ribavirin or their combinations. Moreover, some of the clade-discordant genome residues are found in the same haplotype within an amplicon.
We evaluate possible interpretations of these findings, and reviewed precedents for rapid selection of genomes with multiple mutations in RNA viruses. These considerations suggest that intra-host evolution may be sufficient to generate minority sequences which are closely related to sequences typical of other clades. The results provide a model for the origin of variants of concern during epidemic spread─in particular Omicron lineages─that does not require prolonged infection, involvement of immunocompromised individuals, or participation of intermediate, non-human hosts.
Human Immunodeficiency Virus type 1 (HIV-1) because of high mutation rates, large population sizes, and rapid replication, exhibits complex evolutionary strategies. For the analysis of evolutionary ...processes, the graphical representation of fitness landscapes provides a significant advantage. The experimental determination of viral fitness remains, in general, difficult and consequently most published fitness landscapes have been artificial, theoretical or estimated. Self-Organizing Maps (SOM) are a class of Artificial Neural Network (ANN) for the generation of topological ordered maps. Here, three-dimensional (3D) data driven fitness landscapes, derived from a collection of sequences from HIV-1 viruses after "in vitro" passages and labelled with the corresponding experimental fitness values, were created by SOM. These maps were used for the visualization and study of the evolutionary process of HIV-1 "in vitro" fitness recovery, by directly relating fitness values with viral sequences. In addition to the representation of the sequence space search carried out by the viruses, these landscapes could also be applied for the analysis of related variants like members of viral quasiespecies. SOM maps permit the visualization of the complex evolutionary pathways in HIV-1 fitness recovery. SOM fitness landscapes have an enormous potential for the study of evolution in related viruses of "in vitro" works or from "in vivo" clinical studies with human, animal or plant viral infections.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Background
The continuing evolution of severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) variants with decreased susceptibility to neutralizing antibodies is of clinical importance. ...Several spike mutations associated with immune escape have evolved independently in association with different variants of concern (VOCs). How and when these mutations arise is still unclear. We hypothesized that such mutations might arise in the context of persistent viral replication in immunosuppressed hosts.
Methods
Nasopharyngeal specimens were collected longitudinally from two immunosuppressed patients with persistent SARS‐CoV‐2 infection. Plasma was collected from these same patients late in disease course. SARS‐CoV‐2 whole genome sequencing was performed to assess the emergence and frequency of mutations over time. Select Spike mutations were assessed for their impact on viral entry and antibody neutralization in vitro.
Results
Our sequencing results revealed the intrahost emergence of spike mutations that are associated with circulating VOCs in both immunosuppressed patients (del241‐243 and E484Q in one patient, and E484K in the other). These mutations decreased antibody‐mediated neutralization of pseudotyped virus particles in cell culture, but also decreased efficiency of spike‐mediated cell entry.
Conclusions
These observations demonstrate the de novo emergence of SARS‐CoV‐2 spike mutations with enhanced immune evasion in immunosuppressed patients with persistent infection. These data suggest one potential mechanism for the evolution of VOCs and emphasize the importance of continued efforts to develop antiviral drugs for suppression of viral replication in hospitalized settings.
Antiviral therapeutics to treat SARS‐CoV‐2 are needed to diminish the morbidity of the ongoing COVID‐19 pandemic. A well‐precedented drug target is the main viral protease (MPro), which is targeted ...by an approved drug and by several investigational drugs. Emerging viral resistance has made new inhibitor chemotypes more pressing. Adopting a structure‐based approach, we docked 1.2 billion non‐covalent lead‐like molecules and a new library of 6.5 million electrophiles against the enzyme structure. From these, 29 non‐covalent and 11 covalent inhibitors were identified in 37 series, the most potent having an IC50 of 29 and 20 μM, respectively. Several series were optimized, resulting in low micromolar inhibitors. Subsequent crystallography confirmed the docking predicted binding modes and may template further optimization. While the new chemotypes may aid further optimization of MPro inhibitors for SARS‐CoV‐2, the modest success rate also reveals weaknesses in our approach for challenging targets like MPro versus other targets where it has been more successful, and versus other structure‐based techniques against MPro itself.
Lymphoid tissue is a key reservoir established by HIV-1 during acute infection. It is a site associated with viral production, storage of viral particles in immune complexes, and viral persistence. ...Although combinations of antiretroviral drugs usually suppress viral replication and reduce viral RNA to undetectable levels in blood, it is unclear whether treatment fully suppresses viral replication in lymphoid tissue reservoirs. Here we show that virus evolution and trafficking between tissue compartments continues in patients with undetectable levels of virus in their bloodstream. We present a spatial and dynamic model of persistent viral replication and spread that indicates why the development of drug resistance is not a foregone conclusion under conditions in which drug concentrations are insufficient to completely block virus replication. These data provide new insights into the evolutionary and infection dynamics of the virus population within the host, revealing that HIV-1 can continue to replicate and replenish the viral reservoir despite potent antiretroviral therapy.
Vertical transmission of human immunodeficiency virus (HIV) can occur in utero, during delivery, and through breastfeeding. We utilized Positron Emission Tomography (PET) imaging coupled with ...fluorescent microscopy of 64Cu-labeled photoactivatable-GFP-HIV (PA-GFP-BaL) to determine how HIV virions distribute and localize in neonatal rhesus macaques two and four hours after oral viral challenge. Our results show that by four hours after oral viral exposure, HIV virions localize to and penetrate the rectal mucosa. We also used a dual viral challenge with a non-replicative viral vector and a replication competent SHIV-1157ipd3N4 to examine viral transduction and dissemination at 96 hours. Our data show that while SHIV-1157ipd3N4 infection can be found in the oral cavity and upper gastrointestinal (GI) tract, the small and large intestine contained the largest number of infected cells. Moreover, we found that T cells were the biggest population of infected immune cells. Thus, thanks to these novel technologies, we are able to visualize and delineate of viral distribution and infection throughout the entire neonatal GI tract during acute viral infection.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract Lethal mutagenesis, a new antiviral strategy to extinguish virus through elevated mutation rates, was explored in H61-D cells an HIV-1 persistently infected lymphoid cell line. Three ...mutagenic agents: 5-hydroxy-2′ -deoxycytidine (5-OHdC), 5-fluorouracil (5-FU) and 2,2′ -difluoro-2′ -deoxycytidine (gemcitabine) were used. After 54 passages, treatments with 5-FU and gemcitabine reduced virus infectivity, p24 and RT activity. Treatment with the pyrimidine analog 5-OHdC resulted in increases of p24 production, RT activity and infectivity. Rise in viral replication by 5-OHdC during HIV-1 persistence is in contrast with its inhibitory effect in acute infections. Viral replication enhancement by 5-OHdC was associated with an increase in intracellular HIV-1 RNA mutations. Mechanisms of HIV-1 replication enhancement by 5-OHdC are unknown but some potential factors are discussed. Increase of HIV-1 replication by 5-OHdC cautions against the use, without previous analyses, of mutagenic nucleoside analogs for AIDS treatment.
Elite controllers (EC) represent a small subset of HIV-1-infected people that spontaneously control viral replication. However, natural virological suppression and absence of immune dysfunction are ...not always long-term sustained. We define exceptional EC (EEC) as HIV-1 subjects who maintain the EC characteristics without disease progression for more than 25 years. We analyzed three EEC, diagnosed between 1988 and 1992, who never showed signs of clinical disease progression in absence of any antiretroviral treatment. A comprehensive clinical, virological, and immunological study was performed. The individuals simultaneously exhibited ≥3 described host protective alleles, low levels of total HIV-1 DNA (<20 copies/10
CD4
T-cells) without evidence of replication-competent viruses (<0.025 IUPM), consistent with high levels of defective genomes, strong cellular HIV-1-specific immune response, and a high poly-functionality index (>0.50). Inflammation levels of EEC were similar to HIV-1 negative donors. Remarkably, they showed an exceptional lack of viral evolution and 8-fold lower genetic diversity (<0.01 s/n) in env gene than other EC. We postulate that these EEC represent cases of spontaneous functional HIV-1 cure. A non-functional and non-genetically evolving viral reservoir along with an HIV-1-specific immune response seems to be key for the spontaneous functional cure.
Respiratory Syncytial Virus (RSV) is a leading cause of acute respiratory tract infection, with the greatest impact on infants, immunocompromised individuals, and older adults. RSV prevalence ...decreased substantially in the United States (US) following the implementation of COVID-19-related non-pharmaceutical interventions but later rebounded with abnormal seasonality. The biological and epidemiological factors underlying this altered behavior remain poorly defined. In this retrospective cohort study from 2009 to 2023 in Chicago, Illinois, US, we examined RSV epidemiology, clinical severity, and genetic diversity. We found that changes in RSV diagnostic platforms drove increased detections in outpatient settings post-2020 and that hospitalized adults infected with RSV-A were at higher risk of intensive care admission than those with RSV-B. While population structures of RSV-A remained unchanged, RSV-B exhibited a genetic shift into geographically distinct clusters. Mutations in the antigenic regions of the fusion protein suggest convergent evolution with potential implications for vaccine and therapeutic development.
PDF
