Barbour et al. 10.1073/pnas.0605302103. |
Supporting Methods
Bacterial Abundance, Immunity, and Serotype Detection: Assumptions for Fig. 5.
In the antisera-typing study, a serotype was detectable when its proportion was ³1% of a total population of ~107 in the blood of a single mouse (19). At the lower detection limit, this corresponds to variant population size or abundance (x in the Fig. 5 legend) of 105. Empirical data indicate that the level of bacterial abundance at which specific immunity is stimulated (y in the caption of Fig. 3) is at least 10-fold lower than the minimum abundance level for detection by antisera typing (x). In a study 60 adult immunocompetent BALB/c mice were inoculated with ~10 cells of serotype 7 as described. During the courses of infection the bacterial counts in the blood were determined by quantitative PCR, and the specific immune response was quantitatively monitored by whole cell enzyme-linked assay and by agglutination assay. The results of this experiment indicated that specific antibodies began to increase at a time when there were ~103 serotype 7 bacteria in the mouse (Crowder, C., Marcsisin, R., and A.G.B., unpublished work).19. Stoenner HG, Dodd T, Larsen C (1982) J Exp Med 156:1297-1311.