Meeting Abstract
The genus Flavivirus contains at least 70 viruses including both mosquito-borne human pathogens, and non-pathogenic viruses that are limited to insect hosts. The insect-specific flaviviruses are ancestral to mosquito-borne flaviviruses and understanding their diversity and distribution could reveal important evolutionary processes behind the emergence of pathogenic forms. In addition, reports of insect-specific Flaviviruses that have become integrated into the genomes of their hosts, Aedes mosquitoes, reveal important evolutionary routes for host genetic diversification that may ultimately contribute to viral defense. This research seeks to determine whether the insect-specific Flavivirus cell fusing agent virus (CFAV), discovered in field-caught Aedes aegypti mosquito populations from Thailand, represents circulation of this virus in this population or evidence of virus integration into the mosquito genome. Mosquitoes were trapped in central Thailand in 2008 from many sites. Unbiased shotgun sequencing of total RNA revealed the presence of sequences similar to the first half of the CFAV genome. Since the second half of the CFAV genome contains essential genes, their absence may suggest the integration of CFAV into the A. aegypti genome. Alternatively, truncated CFAV might represent differential virus degradation due to host defense mechanisms. Preliminary results on DNA from the Thai samples are positive for CFAV. These RNA viruses are not known to have a DNA stage, suggesting integration into the host genome. This integration event would be novel because CFAV is not found in the sequenced strain of West African A. aegypti, meaning integration occurred after a divergence between African and Asian A. aegypti. Current studies involve genome walking to determine sequence origin adjacent to the known CFAV sequence. A. aegypti sequences would provide evidence for an integration event.
