Posted on by Marc Jouan

VIP

Acronym: VIP Are dengue Defective Interfering Particles truly interfering?
Principal investigator C. Inizan
IPNC focal point C. Inizan / M. Dupont-Rouzeyrol
IPNC collaborators O. O’Connor
Other collaborators
Project total budget 8 275 € Budget devoted to IPNC  NA
Financial support IPNC
Timeline Start: March 2017 End: Feb. 2018
Context
Polymerase errors occurring upon viral replication might give rise to incomplete genomes that are nevertheless encapsidated in Defective Viral Particles (DVP). Replicated and maintained upon co-infection with functional viruses, such DVPs might affect the physiopathology of the infection: inhibition of viral replication, modulation of the host immune response as well as contribution to infection persistence. In the case of dengue virus (DENV), DVPs have been detected in both humans and Aedes mosquitoes. They might represent a natural regulator of viremia in patients, thus impacting infection evolution and resolution.
Objectives
The current study aims at evaluating DVP role in viremia regulation in patients. This project includes (i) the characterization and quantification of DVPs in the sera of dengue patients, in link with viremia and, (ii) the measure of DVP impact on DENV replication in vitro.
Methods
Molecular characterization of DVPs in the sera of dengue patients from New Caledonia:

– Evaluation of patients viremia through in vitro infections and real-time RT-PCT

– Quantification and analysis of DVPs subgenomic RNA profiles in patients’ sera through real-time RT-PCR

– Sequencing of DVPd subgenomic RNAs in patients sera

Measure of the modulation of DENV replication in vitro by DVPs:

– Production and purification of DVPs through in vitro infections and ultracentrifugation

– Quantification of DVP impact on DENV replication in human cells in vitro through real-time RT-PCR
Preliminary results
Viral infectious titers of 50 sera of patients from New Caledonia infected by DENV-1 genotype I have been evaluated through in vitro infections. In parallel, viral RNAs have been extracted from those sera. Molecular analyses are being set up and will soon enable the quantification and sequencing of DVPs subgenomic RNAs.
Perspectives
Through the implementation of DVPs detection and purification tools, the current project opens new avenues for a broader study on DVPs role in DENV natural cycle, aiming at measuring their impact on dengue physiopathology and transmission. This study of the impact of DVPs on viremia might suggest their quantification in patients’ sera as a prognostic tool for infection severity.