如何手动更改ggplot2中的一个传奇中的关键标签?

I am preparing a plot for publication. I created a stacked box plot to show frequency of patients in each group who were some complicated accumulation of seronegatives versus not. The legend is using the labels from the data frame which are appropriate for us who are working on the project but no for publication. I want to change the names to something more rapidly understood by the reader. I am preparing a plot for publication. I create