Low linkage disequilibrium indicative of recombination in foot-and-mouth disease virus gene sequence alignments

We have applied tests for detecting recombination to genes of foot-and-mouth disease virus (FMDV). Our approach estimated summary statistics of linkage disequilibrium (LID), which are sensitive to recombination. Using the genealogical relationships, rate heterogeneity and mutation parameters estimated from individual sets of aligned gene sequences, we simulated matching RNA sequence datasets without recombination. These simulated datasets allowed for recurrent mutations at any site to mimic homoplasy in virus sequence data and allow construction of null distributions for LID parameters expected in the absence of recombination. We tested for recombination in two ways: by comparing LID in observed data with corresponding null distributions obtained from simulated data; and by testing for a negative relationship between observed LID between pairs of polymorphic nucleotide sites and inter-site distance. We applied these tests to six FMDV datasets from four serotypes and found some evidence for recombination in all of them.