'We found that the positively selected sites of Spz4 in A. cerana correspond to the glycosyltransferases, which are involved in mucus layer formation and the physical defense system in insects [45,63]. Therefore, we speculate that the Spz4 gene in A. cerana has acquired new functions under positive selection, and affects honeybee immune response to E. faecalis.'

https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1011897#sec015