Association of SH with NA2. (A) NA1(−) (lanes 2 to 4) and NA2(−) (lanes 5 to 7) specific PCR products before and, (B), after digestion with SfaN I. The locations of the NA-specific sense primers (NA1 pr., NA2 pr.) and the reverse primer (Reverse pr.) used for PCR amplification of the NA-specific DNA fragments, as well as the cleavage site of the SfaN I enzyme, are illustrated. Restriction fragments were analyzed on 1.5% agarose gel using DNA size standards pBr 328 DNA.BglI + pBr 328 DNA.HinfI (lane 1). Three individuals were tested who were typed as follows: SH(+), NA1(+),NA2(+) (lanes 2 and 5); SH(+), NA1(−),NA2(+) (lanes 3 and 6); SH(−), NA1(+),NA2 (+) (lanes 4 and 7).