The morphology of plaques induced by Italian, H7N1, low-pathogenic avian influenza (LPAI) viruses belonging to different lineages was investigated in primary chicken, turkey, Muscovy duck, and mallard duck kidney cells and in MDCK cells in the absence of trypsin. LPAI isolates were selected on the basis of the location in the phylogenetic tree: 977/V99 (located at the root, no additional glycosylation site [nAGS]), 2379/V99 (AGS in position 123), and 3675/V99 (AGS in position 149). Different isolates did not induce plaques with a statistically significant different size in MDCK cells. However, in primary cells of different avian origin, the presence or absence of AGS significantly influenced plaque size. Generally speaking, 977/V99 was the least efficient at plaquing in all cells, while 2379/V99 (AGS in position 123) plaqued more efficiently in turkey cells and 3675/V99 (AGS in position 149) in chicken cells. The presence of either AGS induced statistically significant larger plaques in cells of waterfowl origin.