Researchers Uncover Viral Small RNAs in Mosquito Cells

BUSM researchers are now able to provide a new genomics resource that details the small RNA transcriptomes (gene expression) of four bio-medically important mosquito species.

This is the first study to provide a platform for biologists to compare the characteristics of these small RNAs between these four mosquitoes as well as the most widely used insects for genetic experiments, the fruit fly, Drosophila. Although previous studies looked at each of the individual mosquito species separately, this study is the first to allow comparisons between all four species.

“Although mosquitoes are related to Drosophila, they have very different genomes. In addition,  mosquitos bite humans for blood meals that allow them to reproduce and but unfortunately allows serious human pathogens like viruses to infect us and cause diseases like yellow fever virus, dengue fever virus, zika virus and eastern equine encephalitis virus,” explained corresponding author Nelson Lau, PhD, associate professor of biochemistry.

The researchers obtained cell cultures and dissected samples of the mosquito species Anopheles gambiae, Culex quinquefasciatus, Aedes aegypti and Aedes albopictus. They extracted and purified the small RNA molecules, created libraries for high-throughput sequencing, and then developed a special bioinformatics platform to provide thorough genomic analysis of these small RNAs. They provide all this analysis in a public database website .

The four mosquito species have global impacts on human health. Anopheles is the major vector for the parasite causing malaria, but is not known to transmit many viruses. In contrast, Culex and Aedes mosquitoes are well known to pass viruses between humans during mosquito bites, but it is still unknown why there is this difference between mosquito species for this capacity to spread viruses.

According to the researchers this study will allow for better biochemical studies in mosquito cells. “If we can find weaknesses in the small RNA pathways of mosquitoes to make them more intolerant of viruses, perhaps they won’t be so able to pass the virus from biting one human to the next human victim.”

This study was a collaboration between the Lau lab in the Department of Biochemistry and the John Connor and Tonya Colpitts labs of the BU National Emerging Infectious Disease Laboratory (NEIDL) as well as many other mosquito biologists in the USA and the United Kingdom.

The findings appear online in the journal Genome Research.

This work was supported by NIH 4 grants R01-AG052465, R21-HD088792 and R01-GM135215 to NCL; NIH grants R01-5 AI128201, R01-AI116636, and R01-AI150251 to JLR; Defense Advanced Research 6 Project Agency (DARPA) Safe Genes Program Grant (HR0011-17-2- 0047) and an NIH 7 New Innovator Award (1DP2AI152071-01) to OSA; NEIDL Pilot funds and NIH grant 8 R21AI129881 to TMC; NIH grants R21NS101151 and R21AI121933-01 to JHC; the 9 LSTM Director’s Catalyst Fund award to EIP; NIH grants R21AI129507 and 10 R21AI138074), the BBSRC (BB/T001240/1), and a Royal Society Wolfson Fellowship 11 (RSWF\R1\180013) to GLH; grants from BBSRC Network Grant “ANTI-VeC” 12 (AV/PP0020/1) and the Bill & Melinda Gates Foundation to TN. DB was also supported 13 by the Cooperative Agreement Number U01CK000509, funded by the Centers for 14 Disease Control and Prevention.