FIG 9.

Transfer of pVAPN by mating confers virulence to a plasmid-negative R. equi recipient strain. (A) In vivo selection of pVAPN transconjugants in mice. Note the progressive enrichment of the recipient 103S^−RmpR strain upon acquisition of the pVAPN plasmid. Time zero is 60 min after infection. (B) Intracellular proliferation in J774A.1 macrophages. Acquisition of pVAPN (and control pVAPA) promotes intracellular proliferation in the recipient 103S^−RmpR strain. Data are expressed as normalized IGC values (see Materials and Methods). Means of data from three duplicate experiments ± standard errors; P values (determined by 2-way ANOVA and Šidák post hoc multiple-comparison tests) are indicated. ns, not significant.