PMNs were critical to control growth of 28/37°C-pregrown Δ<i>yopM-1 Y. pestis</i> in liver but not spleen.

<p>B6 mice were ablated for PMNs (open symbols) by treatment with anti-Ly6G antibody on days -1 and +1 of infection; mock-treated mice (closed symbols) received nonspecific rat IgG. The mice were infected with 400 28/37°C-grown parent (squares) or Δ<i>yopM-1</i> (circles) <i>Y. pestis</i>, and viable numbers (CFU) were determined on d 1, 2, and 3 p.i. Group labels: MM, mock-treated mice infected with Δ<i>yopM-1 Y. pestis</i>; AM, Ablated mice infected with Δ<i>yopM-1 Y. pestis</i>; MP, mock-treated mice infected with the parent strain; AP, ablated mice infected with the parent strain. The data were obtained in two experiments, each with 2 to 3 mice per group, for 4 to 6 mice total for each category. Each symbol gives the bacterial burden of one mouse; the horizontal lines mark the geometric means of the pooled data for each category. Statistically significant differences by Student's <i>t</i> test occurred on d 3 p.i. as indicated: *, P<0.05; **, P<0.01.