The distribution pattern of alpha 2,3-and alpha 2,6-linked sialic acids affects host cell preference in Toxoplasma gondii

摘要

Tachyzoites of Toxoplasma gondii, an obligate intracellular parasite, actively invade almost all types of nucleated cells. However, T. gondii tachyzoites preferentially infect particular types of animal tissue cells. The mechanism underlying the host cell preference of T. gondii is not yet known. In this study, we found that enzymatic removal of alpha 2,3- but not alpha 2,6-linked sialic acids on the surface of Vero cells decreased T. gondii tachyzoite adhesion or invasion to the treated cells. Although Chinese hamster ovary (CHO) cells express only alpha 2,3-linked sialic acid, a genetically modified CHO cell line constructed by transfection with the alpha 2,6-sialiltransferase gene contains subpopulations with a variety of expression patterns of alpha 2,3- and alpha 2,6-linked sialic acids. When T gondii tachyzoites were added to the modified CHO cells, the tachyzoites preferentially attached to cells belonging to a subpopulation of cells that highly expressed alpha 2,3-linked sialic acids. Additionally, multiple regression analysis performed to analyse the relationship between the amount of alpha 2,3-linked/alpha 2,6-linked sialic acids and parasite-expressed fluorescence intensity suggested that more tachyzoites adhered to individual alpha 2,3-linked sialic acid rich-cells than to alpha 2,3-linked sialic acid-poorull cells. The results of confocal laser microscopy confirmed this finding. These results indicate that the host cell preference of T. gondii was, at least partially, affected by the distribution pattern of alpha 2,3-, but almost never alpha 2,6-linked sialic acids on host cells. (C) 2015 Elsevier Inc. All rights reserved.