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. 2012 Jun 18;7(6):e38630. doi: 10.1371/journal.pone.0038630

Figure 1. Short term kinetic of anti-F1 IgM in R. rattus after inoculation with Y. pestis.

Figure 1

Wild healthy rats (Rattus rattus) were inoculated with different doses of living Y. pestis (0 to 30,000 cfu) and blood sampled over one month. Anti-F1 IgM was detected by a sandwich ELISA. Results were expressed as the ratio of the mean optical density (OD) of the sample on the mean OD obtained for negative control rats +3 SD. Rats are from two villages Ambohimasina and Maromanana. (median; bar: 10% and 90% percentiles) A/Time course of the median OD ratio of each group: OD ratio peaked at Day 13 and decreased rapidly after B/Median of OD ratio obtained at Day13 and Day 25 for the two villages according to the dose inoculated. Rats from Ambohimasina produced a stronger IgM response against Y. pestis than Maromanana rats C/Median fraction of maximal anti-F1 IgM titer (OD ratio, mostly at Day 13) remaining at Day 18 and Day 25 according to the dose inoculated. For each rat the maximal OD ratio is noted as well as the OD ratio at Day 18 and Day 25, the fractions are calculated and the median of each group is plotted according to the dose inoculated. The speed of decay of IgM increases with the dose inoculated. D/Percent of rats remaining seronegative after inoculation. For each dose the fraction of rats remaining negative for anti-F1 IgM at Day 13 and IgG at Day 25 is plotted. It decreases from 15 to 30,000 cfu.