Long-range RNA-RNA interactions circularize the dengue virus genome

Area of Science:

• Virology
• Molecular Biology
• Genetics

Background:

• Viral RNA secondary and tertiary structures regulate key processes like translation and replication.
• Flaviviruses, including dengue virus, are proposed to require RNA-RNA interactions at genome ends for replication.

Purpose of the Study:

• To investigate the RNA-RNA interactions between the 5' and 3' ends of the dengue virus genome.
• To determine the role of specific RNA elements and their complementarity in viral replication.

Main Methods:

• In vitro RNA binding assays to assess RNA element interactions.
• Atomic force microscopy to visualize RNA molecule cyclization.
• Site-directed mutagenesis to disrupt and restore RNA complementarity, followed by viral RNA transfection and replication assays.

Main Results:

• Two RNA elements, 5' and 3' cyclization sequences (CS), interact with high affinity, causing viral RNA cyclization.
• The 5' and 3' upstream AUG regions (UAR) are also essential for RNA-RNA complex formation.
• Mutations disrupting 5'-3' UAR complementarity render dengue virus nonviable, while compensatory mutations restore viability.

Conclusions:

• Sequence complementarity between the 5' and 3' UARs is crucial for dengue virus viability.
• RNA cyclization, mediated by these complementary sequences, is proposed as a required conformation for viral replication.