Figure 1.

MDV haplotypes present on the thirteen focal Pennsylvanian poultry farms based on eight marker regions and the respective positions of these markers on the MDV genome. (A) Gray-scale/patterned boxes indicate individual variants or alleles for each marker region. Colored bars represent the haplotype collectively described by the eight marker regions. These colors are used subsequently to indicate haplotypes present on individual farms (Figs 2–4). Numbers in the right-hand column indicate the number of dust samples where that haplotype was detected. Cloning of DNA from one particular dust sample revealed two possible genotypes for marker M4 and three possible genotypes for marker M5. Consequently, this may represent as few as three variants (haplotypes 9, 10, and 11: if the gray or black variants of M4 exist exclusively with one of the three possible M5 variants) or as many as six variants (haplotypes 13, 14, and 15: if both M4 variants exist with all 3 possible M5 variants). (B) The scale bar indicates the length of the MDV genome; TRL (terminal repeat long), UL (unique long), IRL (internal repeat long), IRS (internal repeat short), and US (unique short) mark specific regions of the genome; blue triangles (not to scale) represent the position and orientation (3′–5′) of the eight markers; and the dotted vertical lines represent the limits of the terminal repeat regions where certain markers appear a second time within the genome.