Effects of Pathogen-Vector Interactions on the Transmission of Dengue Virus

From MicrobeWiki, the student-edited microbiology resource


Viral factors that affect DENV replication and transmission in the mosquito vector


Figure ?. positive correlation between percent of heads infected (arcsin-square root transformation)and the mean body virus titer in mosquitoes infected with DENV-3 strains.[4]


The transmission from vector to host for a particular DENV strain is determined by viral infectivty of mosquito cells, and the rate of viral replication in these cells. Dissemination from the heomocoel to the salivary glands affects disease transmission as well but it is tied directly tied to viral replication rates and viral titers in the hemocoel as seen in figure ?[4].
Replication rate and viral titers are both linked to genotypic differences between DENV strains. Strains belonging to more virulent genotypes have fast rates of viral replication as well as higher virus titers in human and vector hosts[4,23].

Figure ?.Southeast Asian genotype strains had higher viral titers than American genotype strains in human donor dendritic cells 48 hours post-infection.[23]
Figure ?.Invasive DENV-3 strains had higher viral titers in infected mosquitoes than noninvasive strains.[4]

Figure ? shows greater viral output (defined as number of viral genomes over the number of infected cells) in donor dendritic cells 48 hours post-infection. Black bars represent data pooled from tweleve different Southeast Asian genotype strains, white bars represent data pooled from seven different American strains. In figure ? it is clear that the Invassive DENV-3 strains had higher viral titers than noninvassive strains.

Differences in the nontranslated regions of the genome (NTRs) also seem to affect virulence because possible changes in the time it takes to initiate translation because of changes in secondary structure as seen in figure (dengue virus structural… leitmeyer). No specific nucleotide or amino acid differences in either the coding or noncoding region have been correlated with attenuated disease in humans. It is only clear that there are differences at these sights between more virulent strains and less virulent strains.It seems as though mutations within the E envelope glycoprotein responsible for virion binding to the host cell receptor increases the infectivity of a strain.


Figure ?. Predicted secondary RNA structures of the 3’ NTR of; a, an American genotype DENV-2 strain and b, a Southeast Asian DENV-2 strain.[15]