1
|
Amidei A, Dobrovolny HM. Estimation of virus-mediated cell fusion rate of SARS-CoV-2. Virology 2022; 575:91-100. [PMID: 36088794 PMCID: PMC9449781 DOI: 10.1016/j.virol.2022.08.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 08/27/2022] [Accepted: 08/28/2022] [Indexed: 12/22/2022]
Abstract
Several viruses have the ability to form large multinucleated cells known as syncytia. Many properties of syncytia and the role they play in the evolution of a viral infection are not well understood. One basic question that has not yet been answered is how quickly syncytia form. We use a novel mathematical model of cell-cell fusion assays and apply it to experimental data from SARS-CoV-2 fusion assays to provide the first estimates of virus-mediated cell fusion rate. We find that for SARS-CoV2, the fusion rate is in the range of 6 × 10−4–12×10−4/h. We also use our model to compare fusion rates when the protease TMPRSS2 is overexpressed (2–4 times larger fusion rate), when the protease furin is removed (one third the original fusion rate), and when the spike protein is altered (1/10th the original fusion rate). The use of mathematical models allows us to provide additional quantitative information about syncytia formation.
Collapse
Affiliation(s)
- Ava Amidei
- Department of Chemistry & Biochemistry, Texas Christian University, Fort Worth, TX, USA
| | - Hana M Dobrovolny
- Department of Physics & Astronomy, Texas Christian University, Fort Worth, TX, USA.
| |
Collapse
|
2
|
Neutrophil Extracellular Traps Do Not Induce Injury and Inflammation in Well-Differentiated RSV-Infected Airway Epithelium. Cells 2022; 11:cells11050785. [PMID: 35269407 PMCID: PMC8909397 DOI: 10.3390/cells11050785] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 02/15/2022] [Accepted: 02/22/2022] [Indexed: 02/01/2023] Open
Abstract
Respiratory syncytial virus (RSV) lower respiratory tract infection (LRTI) causes a major burden of disease. The host response in RSV-LRTI is characterized by airway epithelial injury, inflammation and neutrophil influx, with the formation of neutrophil extracellular traps (NETs). However, the precise role of NETs in the pathophysiology of RSV-LRTI remains to be elucidated. Here, we used well-differentiated human airway epithelial cultures (HAE) of a pediatric and adult donor to study whether NETs cause airway epithelial injury and inflammation in the setting of RSV infection. The exposure of uninfected and RSV-infected HAE cultures to NETs, as produced by stimulation of neutrophils by a low dose of phorbol 12-myristate 13-acetate (PMA), did not induce or aggravate cell injury or inflammation. RSV infection of HAE cultures caused release of pro-inflammatory cytokines such as IL-6 and RANTES in both adult and pediatric cultures, but the differential gene expression for regulated cell death differed between culture donors. In this in vitro airway epithelial model, NETs in the setting of RSV infection did not cause or aggravate epithelial injury or inflammation.
Collapse
|
3
|
Abstract
Respiratory syncytial virus (RSV) is a leading viral cause of pediatric respiratory infections and early infant mortality. Despite extensive development efforts currently underway, there remain no vaccines available for the prevention of RSV. RSV is an enveloped, negative-strand RNA virus that utilizes two different proteins (G and F) to mediate attachment and entry into host cells. These G and F proteins are the primary determinants of viral strain-specific differences and elicit protective neutralizing antibodies during natural infection in humans. Earlier studies have demonstrated that these proteins play an additional role in regulating the stability of RSV particles in response to temperature and pH. However, it remains unclear how much variability exists in the stability of RSV strains and what contribution changes in temperature and pH make to the clearance of virus during an active infection. In this study, we evaluated the impacts of changes in temperature and pH on the inactivation of four different chimeric recombinant RSV strains that differ exclusively in G and F protein expression. Using these data, we developed predictive mathematical models to examine the specific contributions and variations in susceptibility that exist between viral strains. Our data provide strain-specific clearance rates and temperature–pH landscapes that shed light on the optimal contributions of temperature and pH to viral clearance. These provide new insight into how much variation exists in the clearance of a major respiratory pathogen and may offer new guidance on optimization of viral strains for development of live-attenuated vaccine preparations.
Collapse
|
4
|
Rodriguez T, Dobrovolny HM. Estimation of viral kinetics model parameters in young and aged SARS-CoV-2 infected macaques. ROYAL SOCIETY OPEN SCIENCE 2021; 8:202345. [PMID: 34804559 PMCID: PMC8595996 DOI: 10.1098/rsos.202345] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Accepted: 10/25/2021] [Indexed: 06/13/2023]
Abstract
The SARS-CoV-2 virus disproportionately causes serious illness and death in older individuals. In order to have the greatest impact in decreasing the human toll caused by the virus, antiviral treatment should be targeted to older patients. For this, we need a better understanding of the differences in viral dynamics between SARS-CoV-2 infection in younger and older adults. In this study, we use previously published averaged viral titre measurements from the nose and throat of SARS-CoV-2 infection in young and aged cynomolgus macaques to parametrize a viral kinetics model. We find that all viral kinetics parameters differ between young and aged macaques in the nasal passages, but that there are fewer differences in parameter estimates from the throat. We further use our parametrized model to study the antiviral treatment of young and aged animals, finding that early antiviral treatment is more likely to lead to a lengthening of the infection in aged animals, but not in young animals.
Collapse
Affiliation(s)
- Thalia Rodriguez
- Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX, USA
| | - Hana M. Dobrovolny
- Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX, USA
| |
Collapse
|
5
|
Khan S, Dobrovolny HM. A study of the effects of age on the dynamics of RSV in animal models. Virus Res 2021; 304:198524. [PMID: 34329697 DOI: 10.1016/j.virusres.2021.198524] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Revised: 06/24/2021] [Accepted: 07/17/2021] [Indexed: 01/18/2023]
Abstract
Respiratory syncytial virus can cause severe illness and even death, particularly in infants. The increased severity of disease in young children is thought to be due to a lack of previous exposure to the virus as well as the limited immune response in infants. While studies have examined the clinical differences in disease between infants and adults, there has been limited examination of how the viral dynamics differ as infants develop. In this study, we apply a mathematical model to data from cotton rats and ferrets of different ages to assess how viral kinetics parameters change as the animals age. We find no clear trend in the viral decay rate, infecting time, and basic reproduction number as the animals age. We discuss possible reasons for the null result including the limited data, lack of detail of the mathematical model, and the limitations of animal models.
Collapse
Affiliation(s)
- Shaheer Khan
- Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX USA
| | - Hana M Dobrovolny
- Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX USA.
| |
Collapse
|
6
|
The role of syncytia during viral infections. J Theor Biol 2021; 525:110749. [PMID: 33964289 DOI: 10.1016/j.jtbi.2021.110749] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Revised: 03/25/2021] [Accepted: 04/29/2021] [Indexed: 12/16/2022]
Abstract
Respiratory syncytial virus (RSV) is a common, contagious infection of the lungs and the respiratory tract. RSV is characterized by syncytia, which are multinuclear cells created by cells that have fused together. We use a mathematical model to study how different assumptions about the viral production and lifespan of syncytia change the resulting infection time course. We find that the effect of syncytia on viral titer is only apparent when the basic reproduction number for infection via syncytia formation is similar to the reproduction number for cell free viral transmission. When syncytia fusion rate is high, we find the presence of syncytia can lead to slowly growing infections if viral production is suppressed in syncytia. Our model provides insight into how the presence of syncytia can affect the time course of a viral infection.
Collapse
|
7
|
Rodriguez T, Dobrovolny HM. Quantifying the effect of trypsin and elastase on in vitro SARS-CoV infections. Virus Res 2021; 299:198423. [PMID: 33845063 PMCID: PMC8043718 DOI: 10.1016/j.virusres.2021.198423] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2021] [Revised: 03/29/2021] [Accepted: 04/01/2021] [Indexed: 11/24/2022]
Abstract
The SARS coronavirus (SARS-CoV) has the potential to cause serious disease that can spread rapidly around the world. Much of our understanding of SARS-CoV pathogenesis comes from in vitro experiments. Unfortunately, in vitro experiments cannot replicate all the complexity of the in vivo infection. For example, proteases in the respiratory tract cleave the SARS-CoV surface protein to facilitate viral entry, but these proteases are not present in vitro. Unfortunately, proteases might also have an effect on other parts of the replication cycle. Here, we use mathematical modeling to estimate parameters characterizing viral replication for SARS-CoV in the presence of trypsin or elastase, and in the absence of either. In addition to increasing the infection rate, the addition of trypsin and elastase causes lengthening of the eclipse phase duration and the infectious cell lifespan.
Collapse
Affiliation(s)
- Thalia Rodriguez
- Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX, United States
| | - Hana M Dobrovolny
- Department of Physics and Astronomy, Texas Christian University, Fort Worth, TX, United States.
| |
Collapse
|
8
|
Bianchini S, Silvestri E, Argentiero A, Fainardi V, Pisi G, Esposito S. Role of Respiratory Syncytial Virus in Pediatric Pneumonia. Microorganisms 2020; 8:microorganisms8122048. [PMID: 33371276 PMCID: PMC7766387 DOI: 10.3390/microorganisms8122048] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 12/15/2020] [Accepted: 12/17/2020] [Indexed: 12/12/2022] Open
Abstract
Respiratory viral infections represent the leading cause of hospitalization in infants and young children worldwide and the second leading cause of infant mortality. Among these, Respiratory Syncytial Virus (RSV) represents the main cause of lower respiratory tract infections (LRTIs) in young children worldwide. RSV manifestation can range widely from mild upper respiratory infections to severe respiratory infections, mainly bronchiolitis and pneumonia, leading to hospitalization, serious complications (such as respiratory failure), and relevant sequalae in childhood and adulthood (wheezing, asthma, and hyperreactive airways). There are no specific clinical signs or symptoms that can distinguish RSV infection from other respiratory pathogens. New multiplex platforms offer the possibility to simultaneously identify different pathogens, including RSV, with an accuracy similar to that of single polymerase chain reaction (PCR) in the majority of cases. At present, the treatment of RSV infection relies on supportive therapy, mainly consisting of oxygen and hydration. Palivizumab is the only prophylactic method available for RSV infection. Advances in technology and scientific knowledge have led to the creation of different kinds of vaccines and drugs to treat RSV infection. Despite the good level of these studies, there are currently few registered strategies to prevent or treat RSV due to difficulties related to the unpredictable nature of the disease and to the specific target population.
Collapse
Affiliation(s)
- Sonia Bianchini
- Department of Medicine and Surgery, University of Perugia, 06123 Perugia, Italy; (S.B.); (E.S.)
- Pediatric Unit, ASST Santi Carlo e Paolo, 20142 Milan, Italy
| | - Ettore Silvestri
- Department of Medicine and Surgery, University of Perugia, 06123 Perugia, Italy; (S.B.); (E.S.)
| | - Alberto Argentiero
- Pediatric Clinic, Pietro Barilla Children’s Hospital, Department of Medicine and Surgery, University of Parma, 43126 Parma, Italy; (A.A.); (V.F.); (G.P.)
| | - Valentina Fainardi
- Pediatric Clinic, Pietro Barilla Children’s Hospital, Department of Medicine and Surgery, University of Parma, 43126 Parma, Italy; (A.A.); (V.F.); (G.P.)
| | - Giovanna Pisi
- Pediatric Clinic, Pietro Barilla Children’s Hospital, Department of Medicine and Surgery, University of Parma, 43126 Parma, Italy; (A.A.); (V.F.); (G.P.)
| | - Susanna Esposito
- Pediatric Clinic, Pietro Barilla Children’s Hospital, Department of Medicine and Surgery, University of Parma, 43126 Parma, Italy; (A.A.); (V.F.); (G.P.)
- Correspondence: ; Tel.: +39-0521-704790
| |
Collapse
|
9
|
Schmid H, Dobrovolny HM. An approximate solution of the interferon-dependent viral kinetics model of influenza. J Theor Biol 2020; 498:110266. [PMID: 32339545 DOI: 10.1016/j.jtbi.2020.110266] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 01/10/2020] [Accepted: 04/01/2020] [Indexed: 11/25/2022]
Abstract
The analysis of viral kinetics models is mostly achieved by numerical methods. We present an approach via a Magnus expansion that allows us to give an approximate solution to the interferon-dependent viral infection model of influenza which is compared with numerical results. The time of peak viral load is calculated from the approximation and stays within 10% in the studied range of interferon (IFN) efficacy ϵ ∈ [0, 1000]. We utilize our solution to interpret the effect of varying IFN efficacy, suggesting a competition between virions and interferon that can cause an additional peak in the usually exponential increase in the viral load.
Collapse
Affiliation(s)
- Harald Schmid
- Department of Physics & Astronomy, Texas Christian University, Fort Worth, TX, USA
| | - Hana M Dobrovolny
- Department of Physics & Astronomy, Texas Christian University, Fort Worth, TX, USA.
| |
Collapse
|
10
|
González-Parra G, Dobrovolny HM. The rate of viral transfer between upper and lower respiratory tracts determines RSV illness duration. J Math Biol 2019; 79:467-483. [PMID: 31011792 DOI: 10.1007/s00285-019-01364-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Revised: 04/11/2019] [Indexed: 12/26/2022]
Abstract
Respiratory syncytial virus can lead to serious lower respiratory infection (LRI), particularly in children and the elderly. LRI can cause longer infections, lingering respiratory problems, and higher incidence of hospitalization. In this paper, we use a simplified ordinary differential equation model of viral dynamics to study the role of transport mechanisms in the occurrence of LRI. Our model uses two compartments to simulate the upper respiratory tract and the lower respiratory tract (LRT) and assumes two distinct types of viral transfer between the two compartments: diffusion and advection. We find that a range of diffusion and advection values lead to long-lasting infections in the LRT, elucidating a possible mechanism for the severe LRI infections observed in humans.
Collapse
|