Variation in vector competence for dengue viruses does not depend on mosquito midgut binding affinity

Area of Science:

• Virology
• Entomology
• Epidemiology

Background:

• Southeast Asian dengue virus type 2 (DEN-2) genotypes are linked to increased virulence and transmission.
• Genetic variations in dengue viruses may influence binding to the primary vector, Aedes aegypti, affecting transmission.

Purpose of the Study:

• To test if genetic differences in DEN-2 genotypes influence binding to Aedes aegypti midguts.
• To investigate the role of viral binding in DEN-2 transmission and vectorial capacity.

Main Methods:

• Tested binding affinity of four DEN-2 genotypes (Southeast Asian, American, Indian, West African) to Aedes aegypti midguts from Mexican and US populations.
• Compared viral binding rates across different DEN-2 genotypes and mosquito populations.

Main Results:

• All four DEN-2 genotypes exhibited similar binding rates to mosquito midguts in a titer-dependent manner.
• Differences in DEN-2 binding affinity were observed between mosquito colonies from Tapachula, Mexico, and McAllen, USA.
• Previous studies showed Southeast Asian DEN-2 strains disseminated significantly faster in Texas Aedes aegypti.

Conclusions:

• Viral replication, rather than midgut binding affinity, likely explains observed differences in DEN-2 dissemination and vector competence.
• Findings challenge existing models of mosquito infection barriers and transmission dynamics.