Table 3. Primer combinations used in the amplification assays for the detection of putative intermediate structures.

P1	P2
head (+)	head (+)
head (+)	head (−)
head (−)	head (−)
head (+)	tail (+)
head (+)	tail (−)
head (−)	tail (−)
head (−)	tail (+)
tail (+)	tail (+)
tail (+)	tail (−)
tail (−)	tail (−)

The primers were used in the indicated combinations in order to test for the occurrence of all possible combinations of head-to-tail, tail-to-tail, or head-to-head combinations irrespective of the genome orientation packaged into viral capsid in a given clinical isolate. P1 and P2 correspond to the scheme in figure 2.