UConn BioGrid REU Summer 2008 Primer Design for Multiplex PCR Nikoletta DiGirolamo

Primer Design: The Challenge DPS-HDR MDPSP DPS-HDE MDPSP with Errors NEW New Algorithms for Problems One criteria to achieve highly specific amplification product in MP-PCR reactions is to keep the concentration of amplification primers low. In research, the dilemma associated with the primer minimization is formulated as the Multiple Degenerate Primer Selection Problem (MDPSP).

Primer Design: What is PCR? Primers 3' 5' 3' 5' 3' 5' Denaturation Hybridization Elongation 2 nd round The Polymerase Chain Reaction 5' 3' 5' 3' 5' 3' 5' 3' 3' 5' Targeted DNA 3' 5' 5' 3' The Multiplex Polymerase Chain Reaction

Primer Design: What is a Degenerate Primer? A{C|G}TA{A|G|T}CA:ACTAACA ACTAGCA ACTATCA AGTAACA AGTAGCA AGTATCA Degenerate Positions Degeneracy = 6 Why use degenerate primers?

Primer Design: The Problem The Higher the value of degeneracy, the greater the primers' concentration ! Aim : minimizing the number of degenerate primers bounded degeneracy maximizing coverage (d max )‏

The Multiple Degenerate Primer Selection Problem (MDPSP): Definition 1: Find a set of degenerate primers with the length of l, degeneracy at most d, and maximum coverage that would collectively amplify all the n input sequences. Primer Design : Definition 1

Primer Design: Earlier Works Algorithms: HYDEN: Maximum Coverage DPD ( Linhart and Shamir [2002])‏ MIPS: Multiple Degenerate Primer Design (Souvenir et. Al, [2007])‏ DPS: Maximum Coverage DPDP (Balla et. al, [2007])‏ DPS-HD: Multiple Degenerate Primer Selection Problem (Balla et. al,[2007]) Common goal : maximize coverage at each step of the iteration

Primer Design: Hamming Distance l-mers Hamming Distance (HD): u: ACGTAACT v: ACTTACGT HD uv = 3 # Introduction of DPS-HD L-mer : a substring of sequence n with the length of l (m – l + 1)‏ n l-mers Last l-mer

Primer Design: Algorithm DPS-HDR 1 s1 s1 SnSn k m (m – l + 1)‏ u 1 n HD min = 2 Step #1 Step #2

Primer Design: Algorithm DPS-HDR 2 S 1 k K HD = 0 Step #3 Random v Hd min = 2 u v Degenerate primer : u' v v v v Coverage of u = 2 SnSn

Primer Design: Definition 2 Multiple Degenerate Primer Selection Problem with Errors (MDPSPE)‏ Error ( E ): is an input constant corresponding to the number of mismatches allowed between primer u and the input sequence to be covered. Definition 2 : given n DNA sequences, each with the length of m, and integers d, l, and E, find the set P of degenerate u that would match all the n input sequences with up to E errors (mismatches) such that u ∊ P has l length and at most D degeneracy.

Primer Design: New Algorithms DPS-HDE HD = 2 HD = 4 HD = 0 HD = 5 HD = 3 HD = 5 E = 3 HD <= 3 Coverage of u = 3 *Increases the coverage of the primers *Decreases the cardinality of the final degenerate primer set *Reduction in running time S1S1 SnSn

Primer Design: Results: D = 10000, l = 15 D = , l = 15 DPS-HDR

D = , l = 15 D = 10000, l = 15

Primer Design: Future Work Optimize the efficiency of the Perl program Implement the algorithm not only on random but also on real biological data Initiate collaboration with molecular biologists to validate the algorithms performance in wet-lab experiments

Thank You July 31, 2008

DPS-HD vs. DPS-HDR Primer Design : Set of v s u u' u' with the best coverage Step #3

Primer Design: Comparison MIPS, DPS, DPS-HD D = 10000, l = 15 DPS-HD

Primer Design: Comparison MIPS, DPS, DPS-HD D = , l = 15 DPS-HD