Cell surface
carbohydrates play an important role in virus entry and intracellular trafficking. Bovine Adeno-Associated Virus (BAAV) uses plasma membrane
gangliosides for transduction and
infection. In addition, independent of the infectious pathway, BAAV also has the ability to pass through barrier epithelia and endothelia using a transcytosis pathway dependent upon the presence of cell surface
carbohydrates. Thus, in order to better define the
carbohydrate interactions that are necessary for BAAV
infection or transcytosis, a
glycan microarray composed of both natural and synthetic
carbohydrates was probed with HA-tagged BAAV particles. This identified
chitotriose, a trimer of beta-1-4-linked
N-acetyl glucosamine, as having an interaction with BAAV. Competition experiments showed that the BAAV interaction with this
carbohydrate is not necessary for
infection but is instead important in the transcytosis pathway. The beta-1-4-linked
N-acetyl glucosamine modification has been reported on gp96, a
glycoprotein involved in the transcytosis of bacteria and toxins. Significantly, immunoprecipitation and competition experiments with an anti-gp96 antibody and a soluble form of gp96, respectively, showed this
glycoprotein can also interact with BAAV to serve as a receptor for its transcytosis.