Figure 4From: Lateral gene transfer of streptococcal ICE element RD2 (region of difference 2) encoding secreted proteinsPCR screen detects multiple or circular copy of RD2. A. Primer combinations used for detection of seven potential arrangements of RD2. Thick black arrows represent RD2 element; thin gray line represents the chromosome. Red, purple, blue, and green arrows represent locations of primer #1, #2, #3, and #4, respectively. Potential arrangement variants are: arrangement as determined by genome sequencing [1], at least two head-to-tail copies of RD2, tail-to-tail, single copy arranged in reverse orientation than the integrative copy determined by genome sequencing, head-to-tail arrangement of copies in reverse orientation than the integrative copy determined by genome sequencing, head-to-head, and circular form. B. PCR screen detects product amplified with primer pairs #1+#2, #3+#4, and #2+#3, corresponding to arrangement variant (head-to-tail) or (circular form), and #1+#4 detecting chromosomal integration site lacking RD2. C. Primers #2+#3 detect arrangement variant 2 or 7 in multiple RD2 positive strains [1]. Serotype M1 strain MGAS5005 (lacks RD2) was used as a negative control of amplification.Back to article page