To further explore genotype/subgenotype differentiation, different HAV strains belonging to the same subgenotype Ib sequence (Fig. 1, group 1) were hybridized to the array. As shown in Fig. (5) , HAV strains HM175 wt, clone 1 and 18f hybridize most efficiently to genotype Ib (consensus group 1) probes (hav1Cb). Lower efficiencies of hybridization are observed for all three targets against all other probe sets. These results reflect a greater target specificity for the probe set that contains target member sequences than for the other genotype Ib derived probe set (hav2b) that does not contain target member sequences (group 2 in Fig. 1) . For all target strains, the remaining probe sets yielded signal intensities equivalent to or less than intensities for probe set hav2b. Thus, in support of the interpretation of results of Fig. (4) , this array has the potential to discriminate viral targets at the level of both their genotype and subgenotype.