SYNCYTIUM (PLURAL SYNCYTIA)

a mass or clump of cells that fuse together to form one "giant cell." In HIV infection syncytium formation can may lead to direct cell-to-cell infection. Strains of HIV are classified as either syncytium-inducing (SI) or non-syncytium-inducing (NSI). SI strains tend to infect T-cells, whereas NSI strains tend to infect macrophages.