Defective interfering particles of Sendai virus modulate HN expression at the surface of infected BHK cells

The expression of the Sendai viral glycoproteins HN and F0 at the surface of BHK 21 cells was studied during infection with standard virus, with a mixture of standard and defective interfering (DI) particles (mixed virus infection), and during persistent infection. It is shown that by 2 days after infection, the expression of the HN protein at the surface of mixed virus-infected cells is reduced compared to that observed on standard virus-infected cells as estimated by cell surface immune precipitation of iodinated proteins. This reduced expression results from a reduced efficiency of HN insertion in the plasma membrane, as well as from the inaccessibility to antibody of part of the HN present at the membrane. The HN protein is also poorly expressed at the surface of persistently infected cells, originally infected with a mixture of DI and standard virus particles. In contrast, the expression of the F0 protein at the surface of the infected cells is similar regardless of the type of infection.