scholarly journals Viral Infection Spreading and Mutation in Cell Culture

Mathematics ◽  
2022 ◽  
Vol 10 (2) ◽  
pp. 256
Author(s):  
Latifa Ait Mahiout ◽  
Bogdan Kazmierczak ◽  
Vitaly Volpert

A new model of viral infection spreading in cell cultures is proposed taking into account virus mutation. This model represents a reaction-diffusion system of equations with time delay for the concentrations of uninfected cells, infected cells and viral load. Infection progression is characterized by the virus replication number Rv, which determines the total viral load. Analytical formulas for the speed of propagation and for the viral load are obtained and confirmed by numerical simulations. It is shown that virus mutation leads to the emergence of a new virus variant. Conditions of the coexistence of the two variants or competitive exclusion of one of them are found, and different stages of infection progression are identified.

2017 ◽  
Author(s):  
◽  
Obiaara Ukah

[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI AT AUTHOR'S REQUEST.] The Human Immunodeficiency Virus Type-1 (HIV-1) is the etiological agent of Acquired Immunodeficiency Syndrome, a disease that causes the host to succumb to secondary infections. There is currently no cure for HIV-1 infection, but Highly Active Anti-Retroviral Therapy (HAART) can bring the viral load in patients down to undetectable levels in the blood (less than 50 copies/mL). Furthermore, when the minimal limit of detection has been reached and the patient stops HAART, the viral load in the blood increases at an exponential rate due to the reactivation of latent HIV-1 infected cells that evaded HAART. Ongoing efforts focus on the eradication of HIV-1 by the development of potent latency reversing agents (LRAs) that can successfully reactivate latently infected cells, and of antivirals that can effectively inhibit re-establishment of infection post reactivation. This dissertation focuses on the evaluations of 2 classes of HIV-1 drugs, Non-Nucleoside Reverse Transcriptase Inhibitors (NNRTIs), and LRAs, to better understand the mechanisms by which each drug class inhibits and reactivates HIV-1 replication respectively, to aid in the effort towards the development of antivirals that will lead to HIV-1 eradication. Chapter II describes the inhibitory mechanisms of NNRTIs using biochemical methods, which may further explain the differences in potency among drugs of this class. In addition, we explain how changes in the position of HIV-1 RT in the DNA substrate sequence, and the nucleotide terminating the primer 3'-end have a significant effect on the polymerase properties of the enzyme. We demonstrate that there are NNRTI- and site-dependent differences in the potency of NNRTIs, which is demonstrated by the repositioning, or lack there of, of the primer 3'-end of DNA/DNA substrates from the polymerase active site. This is further supported by the efficiency of dNTP or NRTI incorporation in the presence of NNRTI with multiple DNA/DNA substrates, which are representative of different sites in the template sequence. We also show that there are site-dependent differences in the polymerase properties of RT, which is demonstrated by rate of dNTP incorporation and incorporation efficiency at different sites in the template sequence. Chapter III describes the various effects of different types of LRAs, such as histone deacetylase inhibitors and histone methyltransferase inhibitors, on the dynamics of HIV-1 latency reversal in latent cell lines. Here, we demonstrate the use of branched DNA in situ hybridization in combination with immunocytochemistry to study the kinetics and dynamics of latency reversal in various latent cell lines. This technique is augmented with the use of automated screening using microscopy and flow cytometry to quickly detect different populations of latent and reactivated proviruses in thousands of cells in a short amount of time. Understanding the mechanisms by which a drug affects a biological process is important for establishing drug efficacy. Such information can influence what modifications are added to, or removed from drugs, which can cause a change in drug potency. This dissertation outlines assays used to evaluate the mechanisms of various drugs, and the influence of these drugs on the dynamics of HIV-1 replication. It is our hope that the work presented here will help progress efforts to eradicate HIV-1 infection.


2009 ◽  
Vol 84 (2) ◽  
pp. 1057-1065 ◽  
Author(s):  
Yueh-Lung Wu ◽  
Carol P. Wu ◽  
Song-Tay Lee ◽  
Han Tang ◽  
Chi-Hua Chang ◽  
...  

ABSTRACT Heliothis zea nudivirus 1 (HzNV-1), previously known as Hz-1 virus, is an insect virus able to establish both productive and latent infections in several lepidopteran insect cells. Here, we have cloned and characterized one of the HzNV-1 early genes, hhi1, which maps to the HindIII-I fragment of the viral genome. During the productive viral infection, a 6.2-kb hhi1 transcript was detectable as early as 0.5 h postinfection (hpi). The level of transcript reached a maximum at 2 hpi and gradually decreased after 4 hpi. The transcript was not detectable during the latent phase of viral infection. Upon cycloheximide treatment, much higher levels of hhi1 transcript were detected throughout the productive viral infection cycle, suggesting that newly synthesized proteins are not needed for the expression of hhi1. Nevertheless, viral coinfection can further stimulate the expression of transfected hhi1 promoter in a plasmid. Transient hhi1 expression in latently infected cells resulted in a significant increase in virus titer and viral DNA propagation, suggesting that hhi1 plays a critical role in viral reactivation. Additional experiments showed that six early genes, which possibly function in transcription or DNA replication, were activated in the latent cells upon hhi1 transfection. Among these six genes, orf90 and orf121 expression could be induced by hhi1 alone without the need for other viral genes. Our discovery should be useful for future mechanistic study of the switches of latent/productive HzNV-1 viral infections.


2016 ◽  
Vol 90 (16) ◽  
pp. 7231-7247 ◽  
Author(s):  
Si C. Tran ◽  
Tu M. Pham ◽  
Lam N. Nguyen ◽  
Eun-Mee Park ◽  
Yun-Sook Lim ◽  
...  

ABSTRACTHepatitis C virus (HCV) infection often causes chronic hepatitis, liver cirrhosis, and ultimately hepatocellular carcinoma. However, the mechanisms underlying HCV-induced liver pathogenesis are still not fully understood. By transcriptome sequencing (RNA-Seq) analysis, we recently identified host genes that were significantly differentially expressed in cell culture-grown HCV (HCVcc)-infected cells. Of these, tribbles homolog 3 (TRIB3) was selected for further characterization. TRIB3 was initially identified as a binding partner of protein kinase B (also known as Akt). TRIB3 blocks the phosphorylation of Akt and induces apoptosis under endoplasmic reticulum (ER) stress conditions. HCV has been shown to enhance Akt phosphorylation for its own propagation. In the present study, we demonstrated that both mRNA and protein levels of TRIB3 were increased in the context of HCV replication. We further showed that promoter activity of TRIB3 was increased by HCV-induced ER stress. Silencing of TRIB3 resulted in increased RNA and protein levels of HCV, whereas overexpression of TRIB3 decreased HCV replication. By employing an HCV pseudoparticle entry assay, we further showed that TRIB3 was a negative host factor involved in HCV entry. Bothin vitrobinding and immunoprecipitation assays demonstrated that HCV NS3 specifically interacted with TRIB3. Consequently, the association of TRIB3 and Akt was disrupted by HCV NS3, and thus, TRIB3-Akt signaling was impaired in HCV-infected cells. Moreover, HCV modulated TRIB3 to promote extracellular signal-regulated kinase (ERK) phosphorylation, activator protein 1 (AP-1) activity, and cell migration. Collectively, these data indicate that HCV exploits the TRIB3-Akt signaling pathway to promote persistent viral infection and may contribute to HCV-mediated pathogenesis.IMPORTANCETRIB3 is a pseudokinase protein that acts as an adaptor in signaling pathways for important cellular processes. So far, the functional involvement of TRIB3 in virus-infected cells has not yet been demonstrated. We showed that both mRNA and protein expression levels of TRIB3 were increased in the context of HCV RNA replication. Gene silencing of TRIB3 increased HCV RNA and protein levels, and thus, overexpression of TRIB3 decreased HCV replication. TRIB3 is known to promote apoptosis by negatively regulating the Akt signaling pathway under ER stress conditions. Most importantly, we demonstrated that the TRIB3-Akt signaling pathway was disrupted by NS3 in HCV-infected cells. These data provide evidence that HCV modulates the TRIB3-Akt signaling pathway to establish persistent viral infection.


2019 ◽  
Author(s):  
Caroline Manet ◽  
Etienne Simon-Lorière ◽  
Grégory Jouvion ◽  
David Hardy ◽  
Matthieu Prot ◽  
...  

ABSTRACTThe explosive spread of Zika virus (ZIKV) has been associated with major variations in severe disease and congenital afflictions among infected populations, suggesting an influence of host genes. We investigated how genome-wide variants could impact susceptibility to ZIKV infection in mice. We first describe that the susceptibility of Ifnar1 knockout mice is largely influenced by their genetic background. We then show that the broad genetic diversity of Collaborative Cross mice, which receptor to type I interferon (IFNAR) was blocked by anti-IFNAR antibody, expressed phenotypes ranging from complete resistance to severe symptoms and death with large variations in the peak and rate of decrease of plasma viral load, in brain viral load, in brain histopathology and in viral replication rate in infected cells. Differences of susceptibility between CC strains were correlated between Zika, Dengue and West Nile viruses. We identified highly susceptible and resistant mouse strains as new models to investigate the mechanisms of human ZIKV disease and other flavivirus infections. Genetic analyses revealed that phenotypic variations are driven by multiple genes with small effects, reflecting the complexity of ZIKV disease susceptibility in human population. Notably, our results rule out a role of the Oas1b gene in the susceptibility to ZIKV. Altogether, this study emphasizes the role of host genes in the pathogeny of ZIKV infection and lays the foundation for further genetic and mechanistic studies.IMPORTANCEIn recent outbreaks, ZIKV has infected millions of people and induced rare but potentially severe complications, including Guillain-Barré syndrome and encephalitis in adults. While several viral sequence variants were proposed to enhance the pathogenicity of ZIKV, the influence of host genetic variants in the clinical heterogeneity remains mostly unexplored. We have addressed this question using a mouse panel which models the genetic diversity of human population and a ZIKV strain from a recent clinical isolate. Through a combination of in vitro and in vivo approaches, we demonstrate that multiple host genetic variants determine viral replication in infected cells, and clinical severity, kinetics of blood viral load and brain pathology in mice. We describe new mouse models expressing high susceptibility or resistance to ZIKV and to other flaviviruses. These models will facilitate the identification and mechanistic characterization of host genes that influence ZIKV pathogenesis.


2016 ◽  
Vol 21 (4) ◽  
pp. 196-205
Author(s):  
Thomas Aschacher ◽  
Artem Krokhin ◽  
Irina Kuznetsova ◽  
Johannes Langle ◽  
Vladimir Nebolsin ◽  
...  

Ingavirin® (imidazolyl ethanamide pentandioic acid) is an original antiviral drug, which is used in Russia for treatment and profilaxis of influenza and other acute viral infections. We confirmed that imidazolyl ethanamide pentandioic acid (IEPA), not being interferon inducer itself, enhances synthesis of both interferon-a/fi receptors (IFNAR) to interferone and cell sensitivity to interferone signalling, which was suppressed by NS1 protein - pathogen factor of influenza virus. IEPA is able to promote antiviral effector proteins PKR and MxA in infected cells, in opposition to interferon system suppression by influenza virus. Theoretical ground of clinical efficacy of Ingavirine® could be confirmed by obtained data of influence to innate immune system during viral infection.


2021 ◽  
Vol 10 (36) ◽  
pp. 167-169
Author(s):  
Camila Siqueira ◽  
Diogo Kuczera ◽  
Eneida Da Lozzo ◽  
Dorly Buchi ◽  
José Nelson Couceiro ◽  
...  

Introduction: Strains of macrophages, such as murine J774.G8 macrophages, are susceptible to influenza A infection [1]. One of the responses to viral infection involves the production of various types of immunostimulatory cytokines by infected cells [2]. Methods: In the present study, the macrophage strain J774.G8, maintained in RPMI medium, was submitted to treatment with 10% V/V of two different biotherapics prepared from influenza H3N2, both at 30x. Additionally, two control groups were analyzed: macrophages stimulated with water 30x and macrophages without any treatment. Biotherapics were prepared from intact H3N2 influenza virus and H3N2 inactivated by alcohol 70%. The compounding of both biotherapics followed this procedure: one part of viral particles was diluted in 9 parts of sterile distilled water. The 1:10 sample was submitted to 100 mechanical succussions using Autic® Brazilian machine, originating the first dilution, named decimal (1x). 1 ml of this solution was diluted in 9 ml of solvent and was submitted to 100 succussions, generating biotherapic 2x. This procedure was successively repeated, according to Brazilian Homeopathic Pharmacopoeia, to obtain the biotherapic 30x. By the same technique, water vehicle was prepared in the potency of 30x to be used as control. All samples were prepared under sterile and aseptic conditions, using laminar flow cabinet, class II, and were stored in the refrigerator (8ºC), to avoid microbiological contamination. J774.G8 macrophages were stimulated for 2 days, in a total of six stimuli. Immediately before infection with 25 µl of H3N2 influenza virus, the supernatants were collected and frozen at -20 ºC for later analysis. Next, 24 hours after the virus infection, the supernatants were aliquoted and frozen under the same conditions. Three independent experiments were done in triplicate. Analysis of supernatants was performed by flow cytometry using the Mouse Inflammation Kit. The cytokines detected in this experiment were IL-10, IL 12, TNF-α and MCP1. Results: In all cases, there were no significant differences compared to control groups. However, the production of TNF-α detected in macrophages treated by intact and inactivated biotherapics presented a tendency to increase after infection. In fact, similar results were previously detected in other experiments conducted only with the intact biotherapic [3]. The release of the cytokine MCP1 in all experimental situations presented a tendency to decrease after the viral infection when compared to untreated macrophages. No statistically significant difference was detected in the production of IL 12 and IL 10. These experiments will be repeated to confirm the data obtained.


2018 ◽  
Vol 2018 ◽  
pp. 1-12
Author(s):  
Adnane Boukhouima ◽  
Khalid Hattaf ◽  
Noura Yousfi

In this paper, we study the dynamics of a viral infection model formulated by five fractional differential equations (FDEs) to describe the interactions between host cells, virus, and humoral immunity presented by antibodies. The infection transmission process is modeled by Hattaf-Yousfi functional response which covers several forms of incidence rate existing in the literature. We first show that the model is mathematically and biologically well-posed. By constructing suitable Lyapunov functionals, the global stability of equilibria is established and characterized by two threshold parameters. Finally, some numerical simulations are presented to illustrate our theoretical analysis.


2019 ◽  
Vol 5 (10) ◽  
pp. eaax4761 ◽  
Author(s):  
Wu Liu ◽  
Mehmet U. Caglar ◽  
Zhangming Mao ◽  
Andrew Woodman ◽  
Jamie J. Arnold ◽  
...  

Because many aspects of viral infection dynamics and inhibition are governed by stochastic processes, single-cell analysis should provide more information than approaches using population averaging. We have developed a microfluidic device composed of ~6000 wells, with each well containing a microstructure to capture single, infected cells replicating an enterovirus expressing a fluorescent reporter protein. We have used this system to characterize enterovirus inhibitors with distinct mechanisms of action. Single-cell analysis reveals that each class of inhibitor interferes with the viral infection cycle in a manner that can be distinguished by principal component analysis. Single-cell analysis of antiviral candidates not only reveals efficacy but also facilitates clustering of drugs with the same mechanism of action and provides some indication of the ease with which resistance will develop.


2006 ◽  
Vol 72 (12) ◽  
pp. 7829-7834 ◽  
Author(s):  
Janice E. Lawrence ◽  
Corina P. D. Brussaard ◽  
Curtis A. Suttle

ABSTRACT We used flow cytometry to examine the process of cell death in the bloom-forming alga Heterosigma akashiwo during infection by a double-stranded DNA virus (OIs1) and a single-stranded RNA virus (H. akashiwo RNA virus [HaRNAV]). These viruses were isolated from the same geographic area and infect the same strain of H. akashiwo. By use of the live/dead stains fluorescein diacetate and SYTOX green as indicators of cellular physiology, cells infected with OIs1 showed signs of infection earlier than HaRNAV-infected cultures (6 to 17 h versus 23 to 29 h). Intracellular esterase activity was lost prior to increased membrane permeability during infection with OIs1, while the opposite was seen with HaRNAV-infected cultures. In addition, OIs1-infected cells accumulated in the cultures while HaRNAV-infected cells rapidly disintegrated. Progeny OIs1 viruses consisted of large and small morphotypes with estimated latent periods of 11 and 17 h, respectively, and about 1,100 and 16,000 viruses produced per cell, respectively. In contrast, HaRNAV produced about 21,000 viruses per cell and had a latent period of 29 h. This study reveals that the characteristics of viral infection in algae are virus dependent and therefore are variable among viruses infecting the same species. This is an important consideration for ecosystem modeling exercises; calculations based on in situ measurements of algal physiology must be sensitive to the diverse responses of algae to viral infection.


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