Aptamer Selection Against BimA protein for Efficient Diagnosis of Melioidosis
Burkholderia pseudomallei is a gram negative bacterium that causes the disease melioidosis, marked by the presence of joint pain, cough, skin infections, lung nodules, and pneumonia. It has a niche in soil and surface water, and as a consequence is endemic in Southeast Asian populations where contact with these environments is essentially inevitable.2 It is most commonly acquired through a break in the skin, or by inhaling the aerosolized form of the bacterium.
Most current diagnostics include a complete screening involving numerous cultures and a throat swab; this is very time consuming, and only adds to the 50% mortality rate. Additionally, rapid discovery methods, such as antibody and antigen detection, have relatively low sensitivities averaging around 70%, and as a consequence are not highly trusted.1 The goal of this experiment, then, would be to develop an aptamer to more efficiently reveal the presence of a B. pseudomallei infection.
There is a particularly interesting target associated with this bacterium that might make it easier to detect. Burkholderia intracellular motility A, or BimA, is a protein the bacterial cell uses to propel itself around a host cell by polymerizing actin.3 If an RNA aptamer could be found to bind this protein, there are two potentially exciting outcomes – the aptamer could work as a competitive inhibitor for the actin and not allow the bacterium to move; additionally, the aptamer could be tagged with green fluorescent protein in order to indicate the bacterial infection. This protein, however, is not available for purchase online, and would need to be targeted within the specific bacterial sample – this could work in conjunction with Umar’s suggestion for a general aptamer against B. pseudomallei.
Figure 1. Illustration of aptamer binding. This aptamer will fluoresce when it binds to the target, in this case BimA. Binding will inhibit actin polymerization, and the bacterium, in theory, would become sessile.
Specific Aim – Target the BimA protein for inhibitory effects of an aptamer. This is very unlikely, due to the complex nature of the bacterium’s membrane. A back up plan would be the general search for an aptamer against the bacterium itself.
Ordering Information – Dr. Kate Brown has samples for us to utilize.
1. Cheng, AC. (2010) “Melioidosis – advances in diagnosis and treatment.” Curr Opin Infect Dis. 6: 554-559.
2. Cheng, AC, Currie, Bart J. (2005) “Melioidosis: Epidemiology, Pathophysiology, and Management.” Clinical Microbiology Reviews. 18: 383-416.
3. Stevens, Joanne M., Ulrich, Ricky L., Taylor, Lowrie A., et al. (2005) “Actin-Binding Proteins from Burkholderia mallei and Burkholderia thailandensis Can Functionally Compensate for the Actin-Based Motility Defect of a Burkholderia pseudomallei bimA Mutant.” Journal of Bacteriology. 187: 7857-7862.