FIG. 3.

Effect of pretreatment with SNAP-generated NO on infectivity of C. ruminantium EBs. (a) The mean number of fluorescing colonies per coverslip was assessed in cultures infected with SNAP-pretreated EBs on days 2 and 4 postinfection on stained indirect fluorescent-antibody test coverslips. This number, which was a reflection of the infectivity of the pretreated EBs, was found to be inversely related to the SNAP concentration. The number was approximately doubled from day 2 to day 4 irrespective of the SNAP concentration used to treat the EBs, indicating similar multiplication rates of the organism once entry into endothelial cell was gained. (b) The rate of infection (percentage of infected cells) was assessed on days 2 and 4 postinfection in Giemsa-stained cultures infected with SNAP-pretreated EBs. There was an increased rate of infection between days 2 and 4 postinfection in both cultures infected with SNAP-pretreated EBs and the controls.