Limits...
Effect of in vitro syncytium formation on the severity of human metapneumovirus disease in a murine model.

Aerts L, Cavanagh MH, Dubois J, Carbonneau J, Rhéaume C, Lavigne S, Couture C, Hamelin MÈ, Boivin G - PLoS ONE (2015)

Bottom Line: Human metapneumovirus (HMPV) is an important cause of acute respiratory tract infections (ARTI) in children, elderly individuals and immunocompromised patients.In vitro, different HMPV strains can induce variable cytopathic effects ranging from large multinucleated syncytia to focal cell rounding.In vivo, however, the virulence and replicative capacity of the different HMPV strains did not appear to be solely dependent on the F gene but also on the viral background, with the strains containing the C-85473 background inducing more weight loss as well as increased lung viral titers, pro-inflammatory cytokines and inflammation than strains containing the CAN98-75 background.

View Article: PubMed Central - PubMed

Affiliation: Centre de Recherche en Infectiologie of the Centre Hospitalier Universitaire de Québec and Université Laval, Quebec, Canada.

ABSTRACT
Human metapneumovirus (HMPV) is an important cause of acute respiratory tract infections (ARTI) in children, elderly individuals and immunocompromised patients. In vitro, different HMPV strains can induce variable cytopathic effects ranging from large multinucleated syncytia to focal cell rounding. In this study, we investigated the impact of different in vitro phenotypes of two HMPV strains on viral replication and disease severity in a BALB/c mouse model. We first generated two recombinant GFP-expressing HMPV viruses: C-85473, a syncytium-inducing strain (rC-85473) belonging to the A1 subtype and CAN98-75, a focal cell rounding-inducing strain (rCAN98-75) of the B2 subtype. We subsequently exchanged the F genes of both strains to create the chimeric viruses rC-85473_F and rCAN98-75_F. We demonstrated that the F protein was the sole protein responsible for the syncytium phenotype and that viruses carrying a syncytium-inducing F protein replicated to significantly higher titers in vitro. In vivo, however, the virulence and replicative capacity of the different HMPV strains did not appear to be solely dependent on the F gene but also on the viral background, with the strains containing the C-85473 background inducing more weight loss as well as increased lung viral titers, pro-inflammatory cytokines and inflammation than strains containing the CAN98-75 background. In conclusion, the F protein is the main determinant of syncytium formation and replication kinetics in vitro, although it is not the only factor implicated in HMPV disease severity in mice.

No MeSH data available.


Related in: MedlinePlus

Pulmonary cytokine levels of BALB/c mice infected with recombinant HMPV strains.BALB/c mice were infected with 6x105 TCID50 of rHMPV (as determined by back-titration). On days 3 through 6, four mice per group were euthanized to determine pro-inflammatory cytokine/chemokine levels in the lungs of infected mice. Mock-infected mice are representad as day 0. ***, p < 0.001; **, p < 0.01; * p < 0.05 comparing all other strains to rC-85473.°°°, p < 0.001; °°, p < 0.01; °, p < 0.05 comparing all other strains to rCAN98–75 using Repeated Measures Two-way ANOVA.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4372586&req=5

pone.0120283.g007: Pulmonary cytokine levels of BALB/c mice infected with recombinant HMPV strains.BALB/c mice were infected with 6x105 TCID50 of rHMPV (as determined by back-titration). On days 3 through 6, four mice per group were euthanized to determine pro-inflammatory cytokine/chemokine levels in the lungs of infected mice. Mock-infected mice are representad as day 0. ***, p < 0.001; **, p < 0.01; * p < 0.05 comparing all other strains to rC-85473.°°°, p < 0.001; °°, p < 0.01; °, p < 0.05 comparing all other strains to rCAN98–75 using Repeated Measures Two-way ANOVA.

Mentions: On days 3 through 6 pi of the previously described experiment, an aliquot of lung homogenates was used to determine pulmonary cytokine/chemokine levels using a multiplexed bead assay (Fig. 7).


Effect of in vitro syncytium formation on the severity of human metapneumovirus disease in a murine model.

Aerts L, Cavanagh MH, Dubois J, Carbonneau J, Rhéaume C, Lavigne S, Couture C, Hamelin MÈ, Boivin G - PLoS ONE (2015)

Pulmonary cytokine levels of BALB/c mice infected with recombinant HMPV strains.BALB/c mice were infected with 6x105 TCID50 of rHMPV (as determined by back-titration). On days 3 through 6, four mice per group were euthanized to determine pro-inflammatory cytokine/chemokine levels in the lungs of infected mice. Mock-infected mice are representad as day 0. ***, p < 0.001; **, p < 0.01; * p < 0.05 comparing all other strains to rC-85473.°°°, p < 0.001; °°, p < 0.01; °, p < 0.05 comparing all other strains to rCAN98–75 using Repeated Measures Two-way ANOVA.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4372586&req=5

pone.0120283.g007: Pulmonary cytokine levels of BALB/c mice infected with recombinant HMPV strains.BALB/c mice were infected with 6x105 TCID50 of rHMPV (as determined by back-titration). On days 3 through 6, four mice per group were euthanized to determine pro-inflammatory cytokine/chemokine levels in the lungs of infected mice. Mock-infected mice are representad as day 0. ***, p < 0.001; **, p < 0.01; * p < 0.05 comparing all other strains to rC-85473.°°°, p < 0.001; °°, p < 0.01; °, p < 0.05 comparing all other strains to rCAN98–75 using Repeated Measures Two-way ANOVA.
Mentions: On days 3 through 6 pi of the previously described experiment, an aliquot of lung homogenates was used to determine pulmonary cytokine/chemokine levels using a multiplexed bead assay (Fig. 7).

Bottom Line: Human metapneumovirus (HMPV) is an important cause of acute respiratory tract infections (ARTI) in children, elderly individuals and immunocompromised patients.In vitro, different HMPV strains can induce variable cytopathic effects ranging from large multinucleated syncytia to focal cell rounding.In vivo, however, the virulence and replicative capacity of the different HMPV strains did not appear to be solely dependent on the F gene but also on the viral background, with the strains containing the C-85473 background inducing more weight loss as well as increased lung viral titers, pro-inflammatory cytokines and inflammation than strains containing the CAN98-75 background.

View Article: PubMed Central - PubMed

Affiliation: Centre de Recherche en Infectiologie of the Centre Hospitalier Universitaire de Québec and Université Laval, Quebec, Canada.

ABSTRACT
Human metapneumovirus (HMPV) is an important cause of acute respiratory tract infections (ARTI) in children, elderly individuals and immunocompromised patients. In vitro, different HMPV strains can induce variable cytopathic effects ranging from large multinucleated syncytia to focal cell rounding. In this study, we investigated the impact of different in vitro phenotypes of two HMPV strains on viral replication and disease severity in a BALB/c mouse model. We first generated two recombinant GFP-expressing HMPV viruses: C-85473, a syncytium-inducing strain (rC-85473) belonging to the A1 subtype and CAN98-75, a focal cell rounding-inducing strain (rCAN98-75) of the B2 subtype. We subsequently exchanged the F genes of both strains to create the chimeric viruses rC-85473_F and rCAN98-75_F. We demonstrated that the F protein was the sole protein responsible for the syncytium phenotype and that viruses carrying a syncytium-inducing F protein replicated to significantly higher titers in vitro. In vivo, however, the virulence and replicative capacity of the different HMPV strains did not appear to be solely dependent on the F gene but also on the viral background, with the strains containing the C-85473 background inducing more weight loss as well as increased lung viral titers, pro-inflammatory cytokines and inflammation than strains containing the CAN98-75 background. In conclusion, the F protein is the main determinant of syncytium formation and replication kinetics in vitro, although it is not the only factor implicated in HMPV disease severity in mice.

No MeSH data available.


Related in: MedlinePlus