Infection of Aedes albopictus Mosquito C6/36 Cells with the w Melpop Strain of Wolbachia Modulates Dengue Virus-Induced Host Cellular Transcripts and Induces Critical Sequence Alterations in the Dengue Viral Genome

• Published in: Journal of virology Vol. 93; no. 15
• Main Authors: Teramoto, Tadahisa, Huang, Xin, Armbruster, Peter A, Padmanabhan, Radhakrishnan
• Format: Journal Article
• Language: English
• Published: United States 01.08.2019
• Subjects: transmembrane proteins; Aedes albopictus; RNAseq analysis; syncytium formation; Wolbachia; dengue virus; wMelPop; World Mosquito Program
• ISSN: 0022-538X; 1098-5514
• DOI: 10.1128/JVI.00581-19

Dengue virus (DENV) causes frequent epidemics infecting ∼390 million people annually in over 100 countries. There are no approved vaccines or antiviral drugs for treatment of infected patients. However, there is a novel approach to control DENV transmission by the mosquito vectors, and , using the symbiont. The MelPop strain of suppresses DENV transmission and shortens the mosquito life span. However, the underlying mechanism is poorly understood. To clarify this mechanism, either naive (C6/36) or MelPop-C6/36 cells were infected with DENV serotype 2 (DENV2). Analysis of host transcript profiles by transcriptome sequencing (RNAseq) revealed that the presence of MelPop dramatically altered the mosquito host cell transcription in response to DENV2 infection. The viral RNA evolved from MelPop-C6/36 cells contained low-frequency mutations (∼25%) within the coding region of transmembrane domain 1 (TMD1) of E protein. Mutations with >97% frequencies were distributed within other regions of E, the NS5 RNA-dependent RNA polymerase (NS5POL) domain, and the TMDs of NS2A, NS2B, and NS4B. Moreover, while DENV2-infected naive C6/36 cells showed syncytium formation, DENV2-infected MelPop-C6/36 cells did not. The -induced mutant DENV2 can readily infect and replicate in naive C6/36 cells, whereas in mutant DENV2-infected BHK-21 or Vero cells, virus replication was delayed. In LLC-MK2 cells, the mutant failed to produce plaques. Additionally, in BHK-21 cells, many mutations in the viral genome reverted to the wild type (WT) and compensatory mutations in NS3 gene appeared. Our results indicate that MelPop impacts significantly the interactions of DENV2 with mosquito and mammalian host cells. Mosquito-borne diseases are of global significance causing considerable morbidity and mortality throughout the world. Dengue virus (DENV; serotypes 1 to 4), a member of the genus of the family, causes millions of infections annually. Development of a safe vaccine is hampered due to absence of cross-protection and increased risk in secondary infections due to antibody-mediated immune enhancement. Infection of vector mosquitoes with bacteria offers a novel countermeasure to suppress DENV transmission, but the mechanisms are poorly understood. In this study, the host transcription profiles and viral RNA sequences were analyzed in naive (C6/36) and MelPop-C6/36 cells by RNAseq. Our results showed that the MelPop symbiont caused profound changes in host transcription profiles and morphology of DENV2-infected C6/36 cells. Accumulation of several mutations throughout DENV2 RNA resulted in loss of infectivity of progeny virions. Our findings offer new insights into the mechanism of -mediated suppression of DENV transmission.