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PLoS Pathogens Apr 2024As a type of parasitic agent, satellite RNAs (satRNAs) rely on cognate helper viruses to achieve their replication and transmission. During the infection of satRNAs,...
As a type of parasitic agent, satellite RNAs (satRNAs) rely on cognate helper viruses to achieve their replication and transmission. During the infection of satRNAs, helper virus RNAs serve as templates for synthesizing viral proteins, including the replication proteins essential for satRNA replication. However, the role of non-template functions of helper virus RNAs in satRNA replication remains unexploited. Here we employed the well-studied model that is composed of cucumber mosaic virus (CMV) and its associated satRNA. In the experiments employing the CMV trans-replication system, we observed an unexpected phenomenon the replication proteins of the mild strain LS-CMV exhibited defective in supporting satRNA replication, unlike those of the severe strain Fny-CMV. Independent of translation products, all CMV genomic RNAs could enhance satRNA replication, when combined with the replication proteins of CMV. This enhancement is contingent upon the recruitment and complete replication of helper virus RNAs. Using the method developed for analyzing the satRNA recruitment, we observed a markedly distinct ability of the replication proteins from both CMV strains to recruit the positive-sense satRNA-harboring RNA3 mutant for replication. This is in agreement with the differential ability of both 1a proteins in binding satRNAs in plants. The discrepancies provide a convincing explanation for the variation of the replication proteins of both CMV strains in replicating satRNAs. Taken together, our work provides compelling evidence that the non-template functions of helper virus RNAs create an optimal replication environment to enhance satRNA proliferation.
Topics: Virus Replication; Helper Viruses; Cucumovirus; RNA, Satellite; RNA, Viral; Plant Diseases; Nicotiana; Viral Proteins
PubMed: 38630801
DOI: 10.1371/journal.ppat.1012174 -
Proceedings of the National Academy of... Apr 2024Global control of infectious diseases depends on the continuous development and deployment of diverse vaccination strategies. Currently available live-attenuated and...
Global control of infectious diseases depends on the continuous development and deployment of diverse vaccination strategies. Currently available live-attenuated and killed virus vaccines typically take a week or longer to activate specific protection by the adaptive immunity. The mosquito-transmitted Nodamura virus (NoV) is attenuated in mice by mutations that prevent expression of the B2 viral suppressor of RNA interference (VSR) and consequently, drastically enhance in vivo production of the virus-targeting small-interfering RNAs. We reported recently that 2 d after immunization with live-attenuated VSR-disabled NoV (NoVΔB2), neonatal mice become fully protected against lethal NoV challenge and develop no detectable infection. Using mice that produce no mature B and T lymphocytes as a model, here we examined the hypothesis that adaptive immunity is dispensable for the RNAi-based protective immunity activated by NoVΔB2 immunization. We show that immunization of both neonatal and adult mice with live but not killed NoVΔB2 induces full protection against NoV challenge at 2 or 14 d postimmunization. Moreover, NoVΔB2-induced protective antiviral immunity is virus-specific and remains effective in adult mice 42 and 90 d after a single-shot immunization. We conclude that immunization with the live-attenuated VSR-disabled RNA virus vaccine activates rapid and long-lasting protective immunity against lethal challenges by a distinct mechanism independent of the adaptive immunity mediated by B and T cells. Future studies are warranted to determine whether additional animal and human viruses attenuated by VSR inactivation induce similar protective immunity in healthy and adaptive immunity-compromised individuals.
Topics: Animals; Humans; Mice; T-Lymphocytes; RNA Interference; Vaccines, Attenuated; Viral Vaccines; Viruses; Homeodomain Proteins; Influenza Vaccines; Antibodies, Viral
PubMed: 38630724
DOI: 10.1073/pnas.2321170121 -
American Journal of Veterinary Research Jun 2024The aim of this study was to assess the efficacy and safety of a third-generation lentivirus-based vector encoding the feline erythropoietin (EPO) (feEPO) gene in vitro...
A lentivirus-vectored feline erythropoietin gene therapy strategy in tissue culture and rodent models for the potential treatment of chronic renal disease-associated anemia.
OBJECTIVE
The aim of this study was to assess the efficacy and safety of a third-generation lentivirus-based vector encoding the feline erythropoietin (EPO) (feEPO) gene in vitro and in rodent models in vivo. This vector incorporates a genetic mechanism to facilitate the termination of the therapeutic effect in the event of supraphysiologic polycythemia, the herpes simplex virus thymidine kinase (HSV-TK) "suicide gene."
ANIMALS
CFRK cells and replication-defective lentiviral vectors encoding feEPO were used for in vitro experiments. Eight Fischer rats were enrolled in the pilot in vivo study, 24 EPO-deficient mice were used in the initial mouse study, and 15 EPO-deficient mice were enrolled in the final mouse study.
METHODS
Efficacy of a third-generation lentivirus encoding feEPO was determined in vitro using western blot assays. Subsequently, in a series of rodent experiments, animals were administered the viral vector in progressively increasing inoculation doses with serial measurements of blood packed cell volume (PCV) over time.
RESULTS
We documented production of feEPO protein in transduced CRFK cells with subsequent cessation of production when treated with the HSV-TK substrate ganciclovir. In vivo, we demonstrated variably persistent elevated PCV values in treated rats and mice with eventual return to baseline values over time.
CLINICAL RELEVANCE
These results provide justification for a lentiviral gene therapy approach to the treatment of nonregenerative anemia associated with chronic renal disease in cats.
Topics: Animals; Erythropoietin; Genetic Therapy; Lentivirus; Mice; Anemia; Cats; Genetic Vectors; Rats; Rats, Inbred F344; Renal Insufficiency, Chronic; Male; Female; Cell Line
PubMed: 38626794
DOI: 10.2460/ajvr.23.12.0280 -
PLoS Pathogens Apr 2024Kaposi's sarcoma-associated herpesvirus (KSHV) is a double-stranded DNA virus etiologically associated with multiple malignancies. Both latency and sporadic lytic...
Kaposi's sarcoma-associated herpesvirus (KSHV) is a double-stranded DNA virus etiologically associated with multiple malignancies. Both latency and sporadic lytic reactivation contribute to KSHV-associated malignancies, however, the specific roles of many KSHV lytic gene products in KSHV replication remain elusive. In this study, we report that ablation of ORF55, a late gene encoding a tegument protein, does not impact KSHV lytic reactivation but significantly reduces the production of progeny virions. We found that cysteine 10 and 11 (C10 and C11) of pORF55 are palmitoylated, and the palmytoilation is essential for its Golgi localization and secondary envelope formation. Palmitoylation-defective pORF55 mutants are unstable and undergo proteasomal degradation. Notably, introduction of a putative Golgi localization sequence to these palmitoylation-defective pORF55 mutants restores Golgi localization and fully reinstates KSHV progeny virion production. Together, our study provides new insight into the critical role of pORF55 palmitoylation in KSHV progeny virion production and offers potential therapeutic targets for the treatment of related malignancies.
Topics: Herpesvirus 8, Human; Golgi Apparatus; Humans; Lipoylation; Virion; Viral Proteins; Virus Replication; HEK293 Cells
PubMed: 38626263
DOI: 10.1371/journal.ppat.1012141 -
Hepatology Communications May 2024The low prevalence of HDV infection in the United States could be attributed to insufficient testing rate, which can result in an underestimation of the true burden of...
BACKGROUND
The low prevalence of HDV infection in the United States could be attributed to insufficient testing rate, which can result in an underestimation of the true burden of HDV. The primary objective of this study is to quantify the prevalence of and factors associated with HDV antibody (anti-HDV) or RNA testing, among participants with positive HBsAg in the Veterans Health Administration (VHA).
METHODS
We conducted a retrospective cohort study of participants who tested positive for HBsAg between January 2000 and December 2022 within the VHA. We identified those who were tested for HDV, and patient and provider-level factors associated with HDV testing.
RESULTS
Of 41,658 participants with positive HBsAg who had follow-up, 4438 (10.7%) were tested at least once for HDV, of which 135 (3.0%) were positive. Participants in the Northeast (adjusted odds ratio [aOR]: 1.30, 95% CI: 1.17-1.44, p<0.001), and receiving hepatology care (aOR: 1.38, 95% CI: 1.24-1.54, p<0.001) were more likely, while those in the Midwest (aOR: 0.69, 95% CI: 0.60-0.79, p<0.001), under the care of a primary care provider (aOR: 0.61, 95% CI: 0.50-0.74, p<0.001), Blacks (aOR: 0.85, 95% CI: 0.77-0.94, p=0.001), participants who were HCV antibody-positive (aOR: 0.89, 95% CI: 0.81-0.99, p=0.03), and participants who were HIV-positive (aOR: 0.80, 95% CI: 0.71-0.90, p<0.001) were less likely to be tested for HDV.
CONCLUSIONS
HDV screening rates in the VHA remain low overall. Participants who are Black, living in the Midwest, patients who are HIV-positive, and patients who are HCV-positive are less likely to be tested for HDV. These results suggest that risk-based screening strategies are ineffective in the VHA and highlight the need for refining testing strategies to increase HDV screening rates.
Topics: Humans; Hepatitis Delta Virus; Hepatitis B Surface Antigens; Retrospective Studies; Hepatitis D; HIV Infections; Hepatitis C
PubMed: 38619425
DOI: 10.1097/HC9.0000000000000401 -
Biological Procedures Online Apr 2024MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), original found in synthetic heroin, causes Parkinson's disease (PD) in human through its metabolite MPP by...
BACKGROUND
MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine), original found in synthetic heroin, causes Parkinson's disease (PD) in human through its metabolite MPP by inhibiting complex I of mitochondrial respiratory chain in dopaminergic neurons. This study explored whether yeast internal NADH-quinone oxidoreductase (NDI1) has therapeutic effects in MPTP- induced PD models by functionally compensating for the impaired complex I. MPP-treated SH-SY5Y cells and MPTP-treated mice were used as the PD cell culture and mouse models respectively. The recombinant NDI1 lentivirus was transduced into SH-SY5Y cells, or the recombinant NDI1 adeno-associated virus (rAAV5-NDI1) was injected into substantia nigra pars compacta (SNpc) of mice.
RESULTS
The study in vitro showed NDI1 prevented MPP-induced change in cell morphology and decreased cell viability, mitochondrial coupling efficiency, complex I-dependent oxygen consumption, and mitochondria-derived ATP. The study in vivo revealed that rAAV-NDI1 injection significantly improved the motor ability and exploration behavior of MPTP-induced PD mice. Accordingly, NDI1 notably improved dopaminergic neuron survival, reduced the inflammatory response, and significantly increased the dopamine content in striatum and complex I activity in substantia nigra.
CONCLUSIONS
NDI1 compensates for the defective complex I in MPP/MPTP-induced models, and vastly alleviates MPTP-induced toxic effect on dopaminergic neurons. Our study may provide a basis for gene therapy of sporadic PD with defective complex I caused by MPTP-like substance.
PubMed: 38594619
DOI: 10.1186/s12575-024-00236-3 -
MicroPublication Biology 2024animals with a compromised pharynx accumulate bacteria in their intestinal lumen and activate a transcriptional response that includes anti-bacterial response genes....
animals with a compromised pharynx accumulate bacteria in their intestinal lumen and activate a transcriptional response that includes anti-bacterial response genes. In this study, we demonstrate that animals with defective pharynxes are resistant to Orsay virus (OrV) infection. This resistance is observed for animals grown on OP50 and on BIGb0172, a bacterium naturally associated with . The viral resistance observed in defective-pharynx mutants does not seem to result from constitutive transcriptional immune responses against viruses. OrV resistance is also observed in mutants with defective defecation, which share with the pharynx-defective perturbations in the regulation of their intestinal contents and altered lipid metabolism. The underlying mechanisms of viral resistance in pharynx- and defecation-defective mutants remain elusive.
PubMed: 38590801
DOI: 10.17912/micropub.biology.001166 -
MedRxiv : the Preprint Server For... Mar 2024Antiretroviral therapy (ART) is not a cure. Upon ART cessation, virus rapidly rebounds from latently-infected cells ("the HIV reservoir"). The reservoir is largely...
Antiretroviral therapy (ART) is not a cure. Upon ART cessation, virus rapidly rebounds from latently-infected cells ("the HIV reservoir"). The reservoir is largely stabilized at the time of ART initiation and then decays slowly. Here, leveraging >500 longitudinal samples from 67 people with HIV (PWH) treated during acute infection, we developed a novel mathematical model to predict reservoir decay using the intact proviral DNA assay (IPDA) from peripheral CD4+ T cells. Nonlinear generalized additive models adjusted for initial CD4+ T count, pre-ART viral load, and timing of ART initiation demonstrated rapid biphasic decay of intact DNA (week 0-5: t ~0.71 months; week 5-24: t ~3.9 months) that extended out to 1 year of ART, with similar trends for defective DNA. Predicted reservoir decay were faster for participants individuals with earlier timing of ART initiation, higher initial CD4+ T cell count, and lower pre-ART viral load. These estimates are ~5-fold faster than prior reservoir decay estimates among chronic-treated PWH. Thus, these data add to our limited understanding of host viral control at the earliest stages of HIV reservoir stabilization, potentially informing future HIV cure efforts aimed at diverse, global population of PWH initiating ART at varying stages of disease.
PubMed: 38585951
DOI: 10.1101/2024.03.27.24304867 -
PLoS Pathogens Apr 2024RNA viruses and viroids exist and evolve as quasispecies due to error-prone replication. Quasispecies consist of a few dominant master sequences alongside numerous...
RNA viruses and viroids exist and evolve as quasispecies due to error-prone replication. Quasispecies consist of a few dominant master sequences alongside numerous variants that contribute to genetic diversity. Upon environmental changes, certain variants within quasispecies have the potential to become the dominant sequences, leading to the emergence of novel infectious strains. However, the emergence of new infectious variants remains unpredictable. Using mutant pools prepared by saturation mutagenesis of selected stem and loop regions, our study of potato spindle tuber viroid (PSTVd) demonstrates that mutants forming local three-dimensional (3D) structures similar to the wild type (WT) are more likely to accumulate in PSTVd quasispecies. The selection mechanisms underlying this biased accumulation are likely associated with cell-to-cell movement and long-distance trafficking. Moreover, certain trafficking-defective PSTVd mutants can be spread by functional sister genomes in the quasispecies. Our study reveals that the RNA 3D structure of stems and loops constrains the evolution of viroid quasispecies. Mutants with a structure similar to WT have a higher likelihood of being maintained within the quasispecies and can potentially give rise to novel infectious variants. These findings emphasize the potential of targeting RNA 3D structure as a more robust approach to defend against viroid infections.
Topics: Viroids; Solanum tuberosum; RNA, Viral; Quasispecies; Mutagenesis; Plant Diseases; Plant Viruses
PubMed: 38574111
DOI: 10.1371/journal.ppat.1012142 -
MBio May 2024Defective viral genomes (DVGs) are truncated derivatives of their parental viral genomes generated during an aberrant round of viral genomic replication. Distinct... (Review)
Review
Defective viral genomes (DVGs) are truncated derivatives of their parental viral genomes generated during an aberrant round of viral genomic replication. Distinct classes of DVGs have been identified in most families of both positive- and negative-sense RNA viruses. Importantly, DVGs have been detected in clinical samples from virally infected individuals and an emerging body of association studies implicates DVGs in shaping the severity of disease caused by viral infections in humans. Consequently, there is growing interest in understanding the molecular mechanisms of DVG generation, how DVGs interact with the innate immune system, and harnessing DVGs as novel therapeutics and vaccine adjuvants to attenuate viral pathogenesis. This minireview focuses on single-stranded RNA viruses (excluding retroviridae), and summarizes the current knowledge of DVG generation, the functions and diversity of DVG species, the roles DVGs play in influencing disease progression, and their application as antivirals and vaccine adjuvants.
Topics: Humans; Genome, Viral; Defective Viruses; Virus Replication; Animals; RNA Viruses; Immunity, Innate; Virus Diseases
PubMed: 38567955
DOI: 10.1128/mbio.00692-24