Distribution of ELISpot Response per Clade for Any Antigen and Specific Antigens.

aResponders were defined as those with antigen-stimulated responses significantly greater than twice their background responses as assessed by a bootstrap test (one-tailed α 0.05) after adjusting for the multiple antigens within each clade; additionally, background-subtracted responses had to exceed ten SFC per 200 000 PBMC [3].