Flu Virus Identification with an RNA Array and Fluorescent Markers

2009 MINI influenza virus. [Courtesy C. S. Goldsmith and A. Balish, CDC.j 

Schematic structure of a generic influenza virus. [Courtesy Dan Higgins, CDC.I 

I nfluenza virus is responsible for 36 000 deaths/yr in the U,S. The virus is clas sified into types A, B, and C, and subtypes C rains ) according to differences in virai proteins. One particular strain of avian virus ( bird flu ) is of particular concern because it has the potentiai to cause widespread human disease. The World Health Organization identifies flu strains so that vaccines can be prepared. Conventional typing methods are expensive and require days or weeks. An RNA array has the potential to reduce cost and time. 

The array above has 15 rows of spots containing synthetic capture RNA covalently attached to a glass slide. Three spots in each row contain identical capture RNA designed to bind to a short section of one strain of viral RNA. The spot at the left in each row is a control that will become fluorescent in every test and serves as an internal standard. Viral RNA extracted from patients is amplified (reproduced into many copies) and digested (cleaved into fragments). Capture RNA on the slide binds selected viral RNA fragments. Another synthetic RNA with a fluorescent tag is designed to bind to a different section of viral RNA. After allowii d ested viral RNA to bind to capture RNA and to fluorescent RNA, excess fluorescent RNA is washed away. Fluorescence intensity in each spot is related to the amount of viral RNA bound at that spot. 

I n this chapter, we describe the components of a spectrophotometer, some of the physical processes that take place when light is absorbed by molecules, and a few important applications of spectrophotometry in analytical chemistry. New analytical instruments and procedures for medicine and biology, such as the RNA array, are being developed by combining sensitive optical methods with biologically specific recognition elements. 

---

Flu Virus Identification with an RNA Array and Fluorescent Markers... 

---