Replication of Measles Virus in Continuous Lymphoid Cell Lines¹

The replication of measles virus was studied in a T cell-like line, MOLT-4, and a B cell-like line, Raji. Both cell lines supported measles virus replication. The infected lymphoid cells were assayed for infectious virus and expression of measles antigens at timed intervals up to 84 hr after inoculation. At time 0, after a 2-hr adsorption period at 4°C, both cell lines produced a maximum of 3% infectious centers and up to 22% antigen-positive cells. Eventually all cells in both populations became infected during the experimental period. When Raji and MOLT-4 cells were infected under similar conditions 100% infection of cells was achieved 12 hr earlier in Raji than in MOLT-4. Increasing multiplicity of infection (MOI) from 1 to 10 made no significant change in the number of infected cells during the early part of the cycle. Spread of virus was largely due to released virus and not cell to cell transmission. Since only a small proportion of the population adsorbed the virus at any one time, and eventually all cells were infected, it was concluded that the receptors for measles virus were expressed at some phase of the cell cycle.