Mosquito vector competence for dengue is modulated by insect-specific viruses

Area of Science:

• Medical Entomology
• Virology
• Molecular Biology

Background:

• Aedes aegypti and Aedes albopictus mosquitoes transmit arboviruses like dengue virus (DENV) and Zika virus (ZIKV).
• Understanding factors influencing arbovirus transmission is crucial for public health interventions.
• Viral interactions within the mosquito vector may impact disease transmission dynamics.

Purpose of the Study:

• To investigate the impact of mosquito-specific viruses on arbovirus transmission.
• To identify potential mechanisms by which co-infecting viruses affect arbovirus infectivity and transmissibility.

Main Methods:

• Analysis of viromes from 815 urban Aedes mosquitoes across 12 countries.
• Spatiotemporal analysis of virus circulation in an endemic urban area.
• Laboratory experiments using a mouse model to assess DENV and ZIKV transmission.
• Transcriptomic analysis of DENV-infected mosquitoes with and without co-infecting viruses.

Main Results:

• Phasi Charoen-like virus (PCLV) and Humaita Tubiacanga virus (HTV) were the most abundant mosquito-specific viruses in Aedes aegypti.
• Co-infection with HTV and PCLV was associated with a 200% increase in DENV presence in wild mosquitoes.
• HTV and PCLV presence significantly enhanced DENV and ZIKV transmission by mosquitoes to vertebrate hosts in a mouse model.
• HTV and PCLV were found to inhibit the downregulation of histone H4 in DENV-infected mosquitoes, identifying it as a proviral factor.

Conclusions:

• Mosquito-specific viruses PCLV and HTV play a significant role in enhancing arbovirus transmission.
• The presence of PCLV and HTV increases the efficiency of DENV and ZIKV transmission to vertebrate hosts.
• Blocking histone H4 downregulation by co-infecting viruses is a key mechanism driving enhanced arbovirus transmission.