Our results demonstrate that competition between serotypes can affect
virus titers in mixed infections in mosquito cells, suggesting that
competitive suppression could act to decrease transmission. To better
understand the role of inter-serotype competition in emergence of
dengue, future research should aim to identify predictor variables of
suppression, to examine the effects of mixed-serotype infections on
replication throughout both stages of the virus life cycle (vector and
host), and to quantify these effects in an epidemiological framework.
It would also be useful to examine these effects in live mosquitoes.
Recent studies of single strain infections in Aedes aegypti
highlighted that viruses must replicate in, and disseminate to, several
different vector tissues before infecting the salivary glands and
disseminating to the saliva for transmission
The nature of this pathway and our finding that competitive abilities
were uncoupled from performance in single infections highlight that
there is potential for interaction effects between serotypes at several
stages during vector infection, which could complicate prediction of
the effects of mixed serotype infection. Lastly, our results underscore
that within-host competition in the mosquito vector may have dramatic
effects on both emergence and long-term virus persistence, and these
potential effects should be explored in the context of other important
factors of dengue virulence such as the host immune system.