A number of viruses, such as HCV, Dengue virus, Ebola virus, SARS coronavirus, West Nile virus, Rift Valley fever virus and Japanese encephalitis virus use N-linked glycans as attachment and entry receptors by interacting with cellular lectins DC-SIGN, L-SIGN, LSECtin, ASGP-R or mannose receptor (Becker et al. 1995; Lin et al. 2003; Lozach et al. 2003; Gramberg et al. 2005; Davis et al. 2006; Miller et al. 2008; Chen et al. 2014; Phoenix et al. 2016; Wang et al. 2016). Mature N-glycans have been suggested to influence Lassa virus binding to cell entry receptor α-dystroglycan (Shrivastava-Ranjan et al. 2016). In addition, specific N-glycans on HIV-1 have been shown to affect CD4 receptor binding on T cells or regulate coreceptor usage (Nakayama et al. 1998; Pollakis et al. 2001; Francois and Balzarini 2011; Lombardi et al. 2015). Systemic functional analysis of HIV-1 gp160 potential N-glycosylation sites has identified a number of additional glycosites affecting infectivity (Wang et al. 2013). In addition, a certain N-glycan on HIV-1 gp41 was shown to have a consistent effect in several viral strains (Mathys and Balzarini 2014). Specific sialylated N-glycans on VZV gB have been identified that are important for interaction with myelin-associated glycoprotein and crucial for cell–cell fusion (Suenaga et al. 2015), and sialylation of virions in general was shown to affect entry of HSV-1 (Teuton and Brandt 2007). Similarly, specific N-linked glycans on HSV-2 gB influenced viral entry (Luo et al. 2015). An N-glycosylation site on IAV HA has also been shown to affect viral entry indirectly by modulating the avidity and specificity for sialosides (Wu et al. 2017). Finally, distinct putative N-glycosylation site mutations on HCV E1 and E2 resulted in diminished entry and altered CD81 binding (Goffard et al. 2005; Falkowska et al. 2007; Helle et al. 2010).