Aggressive organ penetration and high vector transmissibility of epidemic dengue virus-2 Cosmopolitan genotype in a transmission mouse model

Abstract

Dengue virus (DENV) causes dengue fever and severe hemorrhagic fever in humans and is primarily transmitted by Aedes aegypti and A. albopictus mosquitoes. The incidence of DENV infection has been gradually increasing in recent years due to global urbanization and international travel. Understanding the virulence determinants in host and vector transmissibility of emerging epidemic DENV will be critical to combat potential outbreaks. The DENV serotype 2 (DENV-2), which caused a widespread utbreak in Taiwan in 2015 (TW2015), is of the Cosmopolitan genotype and is hylogenetically related to the virus strain linked to another large outbreak in Indonesia in 2015. We found that the TW2015 virus was highly virulent in type I and type II interferon-deficient mice, with robust replication in spleen, lung, and intestine. The TW2015 virus also had high transmissibility to Aedes mosquitoes and could be effectively spread in a continuous mosquitoes-mice-mosquitoes-mice transmission cycle. By making 16681-based mutants carrying different segments of the TW2015 virus, we identified structural pre-membrane (prM) and envelope (E) genes as key virulence determinants in the host, with involvement in the high transmissibility of the TW2015 virus in mosquitoes. The transmission mouse model will make a useful platform for evaluation of DENV with high epidemic potential and development of new strategies against dengue outbreaks.

Mechanical transmission of Dengue Virus byAedes aegyptimay influence disease transmission dynamics during outbreaks

“…As for the needlestick experiment, naïve male and female mice bitten by infected mosquitoes could become infected (40% infectivity rate) as evidenced by detectable DENV serum titers (Figure 3B). Successful transmission of DENV was associated with a loss of body weight 12, 22 , as seen in mice that were either infected through MT or through direct tail vein inoculation (Figure 3C). Infected mice also died (Figure 3D), confirming the existence of MT as a lethal method of transmission for DENV.…”

“…The clinical isolate 2015 DENV-2 (TW2015) 12 was propagated in Aedes aegypti and Vero cells, and the viral titer was determined via plaque-formation assay using BHK- 21 C15 cells. Vero cells were grown at 37°C, 5% CO2 in 1× Dulbecco’s modified Eagle’s medium (DMEM) supplemented with 5% fetal bovine serum (FBS), 1× MEM nonessential amino acid solution, and 1× antibiotic-antimycotic solution.…”

“…To investigate the potential of mechanical transmission (MT) of DENV, we conducted experiments using the cosmopolitan strain DENV-2 (TW2015) and immunocompromised AGB6 mice. These mice lack type I and type II interferon receptors 21 , enabling robust replication of the virus in their spleens, lungs, and intestines 12 . Utilising needle-stick assays, we tested whether DENV could be transferred via sharing of contaminated needles (Supplementary Figure 1A).…”

“…The EIP influences the proportion of mosquitoes that become infectious after exposure to DENV, meaning it plays a key role in predicting the magnitude of dengue outbreaks. This property makes it useful for modeling dengue transmission dynamics 10, 11 , though parameter estimates for the EIP are variable 12 .…”

Impact of Intrahost NS5 Nucleotide Variations on Dengue Virus Replication

“…In terms of virulence of dengue virus, two amino acids, E50A and G67A, located within the first transmembrane domain (TMD1) of the NS4A protein was shown to attenuate virus replication, decrease NS4A oligomerization and reduce stability ( Lee et al, 2015 ). Additionally, Lin et al had previously used the Taiwan DENV-22015 outbreak strain and successfully established a full transmission cycle using this virus ( Lin et al, 2021 ). They demonstrated that the pre-membrane and envelope genes were key virulence determinants in the host and had high transmissibility of the Taiwan 2015 strain in mosquitoes.…”