Fusion of Measles Virus Infected Cells

Measles virus (MV) is a cytopathic virus belonging to family Paramyxoviridae, genus Morbillivirus. Measles virus continues to be an important human pathogen. Although it is largely controlled by immunization in developed countries, it causes significant morbidity and mortality in developing countries. MV particles, of approximately 200 nm diameter, are composed of a helical nucleocapsid enclosed in an envelope that is derived from the host cell plasma membrane, and is studded with virus-coded glycoproteins. MV infects a variety of cell types. The resulting interaction may cause either persistent or lytic infection. In lytic infection, cells may die as a result of virus-induced necrosis or as a result of activation of cellular apoptosis. In vitro, the characteristic cytopathic effect is the formation of multinucleated cells (syncytia) as a result of the interaction between the virus fusion (F) glycoprotein or MV-infected cells, and the host cell plasma membrane. The photographs show cell fusion occurring 2 hours (Figure 1) and 5 hours (Figure 2) after infection of an AV3 (human amnion) cell line with a high input (MOI about 10). Cell nuclei become pyknotic, and by 5 hours, small syncytia fuse into giant ones which show beginning evidence of vacuolation. These syncytia will eventually die and detach from the cell monolayer, leaving behind a visible plaque. These images may be used to help students visualize syncytia.References:Barrett, T. et al. 1991. The Molecular Biology of the Morbilliviruses in D. W. Kingsbury (ed.) The Paramyxoviruses. Plenum Press, New York. Johnston, I.C.D. et al. 1999. A recombinant measles vaccine varis expressing wild type glycoproteins: Consequences for viral spread. J. Virol. 73:6903-6915. Lamb, R.A. and D. Kolakofsky. 1996. Paramyxoviridae: The viruses and their replication in B.N. Fields, D.M. Knipe, and P.M. Howley (eds-in-chief). Fundamental Virology, 3rd. edition, Lippincot-Raven, Philadelphia.Vidalain, P-O. et al. 2000 Measles virus induces functional TRAIL production by human dendritic cells. J. Virol. 74:556-559.