Related Experiment Video
Updated: Jul 7, 2026
Experimental Viral Infection in Adult Mosquitoes by Oral Feeding and Microinjection
Published on: July 28, 2022
Superior infectivity for mosquito vectors contributes to competitive displacement among strains of dengue virus
Kathryn A Hanley1, Jacob T Nelson, Erin E Schirtzinger
1Department of Biology, New Mexico State University, Las Cruces, NM 88003, USA. khanley@nmsu.edu
Background:
Competitive displacement of a weakly virulent pathogen strain by a more virulent strain is one route to disease emergence. However the mechanisms by which pathogens compete for access to hosts are poorly understood. Among vector-borne pathogens, variation in the ability to infect vectors may effect displacement. The current study focused on competitive displacement in dengue virus serotype 3 (DENV3), a mosquito-borne pathogen of humans. In Sri Lanka in the 1980's, a native DENV3 strain associated with relatively mild dengue disease was displaced by an invasive DENV3 strain associated with the most severe disease manifestations, dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS), resulting in an outbreak of DHF/DSS. Here we tested the hypothesis that differences between the invasive and native strain in their infectivity for Aedes aegypti mosquitoes, the primary vector of DENV, contributed to the competitive success of the invasive strain
Results:
To be transmitted by a mosquito, DENV must infect and replicate in the midgut, disseminate into the hemocoel, infect the salivary glands, and be released into the saliva. The ability of the native and invasive DENV3 strains to complete the first three steps of this process in Aedes aegypti mosquitoes was measured in vivo. The invasive strain infected a similar proportion of mosquitoes as the native strain but replicated to significantly higher titers in the midgut and disseminated with significantly greater efficiency than the native strain. In contrast, the native and invasive strain showed no significant difference in replication in cultured mosquito, monkey or human cells.
Conclusion:
The invasive DENV3 strain infects and disseminates in Ae. aegypti more efficiently than the displaced native DENV3 strain, suggesting that the invasive strain is transmitted more efficiently. Replication in cultured cells did not adequately characterize the known phenotypic differences between native and invasive DENV3 strains. Infection dynamics within the vector may have a significant impact on the spread and replacement of dengue virus lineages.
Insights
An invasive dengue virus serotype 3 (DENV3) strain outcompeted a native strain by infecting and disseminating more efficiently in Aedes aegypti mosquitoes. This suggests vector infection dynamics drive dengue virus spread and disease emergence.
Area of Science:
- Virology
- Epidemiology
- Vector-borne diseases
Background:
- Pathogen strains compete for host access, influencing disease emergence.
- Vector infectivity is a key factor in vector-borne pathogen displacement.
- Dengue virus serotype 3 (DENV3) in Sri Lanka saw a native strain replaced by a more virulent invasive strain, leading to severe dengue outbreaks.
Purpose of the Study:
- To investigate if differences in Aedes aegypti mosquito infectivity contributed to the invasive DENV3 strain's competitive success.
- To understand the mechanisms of competitive displacement in dengue virus.
Main Methods:
- In vivo experiments measured the infectivity of native and invasive DENV3 strains in Aedes aegypti mosquitoes.
- Assessed DENV3 replication in mosquito midguts and dissemination to hemocoel.
- Compared DENV3 replication in cultured mosquito, monkey, and human cells.
Main Results:
- The invasive DENV3 strain showed similar initial infection rates but significantly higher midgut replication and dissemination efficiency in Ae. aegypti compared to the native strain.
- No significant differences in replication were observed between native and invasive DENV3 strains in cultured cells.
- Infection and dissemination dynamics within the mosquito vector differed significantly between strains.
Conclusions:
- The invasive DENV3 strain exhibits enhanced infectivity and dissemination in Ae. aegypti, suggesting more efficient transmission.
- In vitro cell culture replication does not fully capture in vivo phenotypic differences between DENV3 strains.
- Vector infection dynamics play a crucial role in the spread and replacement of dengue virus lineages.
