Viral Quasispecies Assembly via Maximal Clique Enumeration
(A) Example of a read alignment graph based on the insert size criterion. Alignments of read pairs are shown in gray and the corresponding nodes in the graph representation are depicted in blue. The four bottom-most alignment pairs stem from a haplotype harboring a deletion (shown in orange in the reference genome) and therefore display a larger insert size than the remaining alignment pairs. Note that the four deletion-indicating alignment pairs form a max-clique (circled in orange). (B) Illustration of the compatible gaps condition of the sequence similarity criterion. Two reads and are aligned against the reference (left). This induces a direct read-to-read alignment of and (right). Case (1): No gaps in the reference alignments lead to a gapless read-to-read alignment, which renders the pair of reads an edge candidate. Case (2): Gaps in the reference alignment lead to gaps in the read-to-read alignment, excluding the possibility of an edge. See also Figure S6 in the appendix for more complicated cases involving gaps.