FIG 5.

An acapsular emm87 strain exhibits shedding titers, intranasal persistence, and transmission rates distinct from those of an encapsulated emm3 strain in CD-1 infant mice. (a and b) Shedding titers of TSPY55 (emm87) from index and contact mice in CD-1 litters inoculated at 1:1 (a) and 1:2 (b) index-to-contact ratios were detected and compared to those detected for MGAS10870 (emm3) in the acute shedding phase (days 1 to 3 postinoculation). The medians and ranges of detected titers are shown to indicate the median shedding titer and rate. (c and d) Intranasal TSPY55 (emm87) GAS tissue burdens in contact and index mice in 1:1 (c) and 1:2 (d) index-to-contact ratio CD-1 litters were assessed at day 3 postinoculation, quantified as streptococcal CFU per milligram of homogenized nasal tissue, and compared to the measured MGAS10870 burden (emm3). (e and f) Intranasal GAS tissue burdens from contact and index mice in litters inoculated at 1:1 (e) and 1:2 (f) index-to-contact ratios were likewise assessed at day 11 postinoculation. The emm3 strain shedding titer and intranasal burden data shown in Fig. 3 are included again here for ease of comparison. The geometric mean intranasal GAS burdens (red lines) are shown to indicate the mean colonization rate and burden. Litters are shown by the strain and inocula (CFU) administered, shown on the x axis. The limit of detection is indicated by a dotted line (shedding titer, 1 CFU; colonization burden, 0.1 CFU/mg). Statistically significant differences were determined by a Mann-Whitney U test (*, P < 0.05; **, P < 0.01; ***, P < 0.001; #, P < 0.0001).