Characterizing infection of B lymphocytes with vaccine and wild-type strains of measles virus

Abstract Wild-type (w.t.) measles virus (MeV) infection can result in immunosuppression that does not occur following vaccination. A rhesus macaque model indicated that B cells are a target of infection. The role of B cell infection in MeV-induced immune suppression is not fully understood. We characterize the differences in viral replication in human B cells infected with vaccine (Edmonston Zagreb [EZ]) or w.t. virus. B cells from healthy donor blood were infected (MOI 1.0) with a GFP-expressing EZ virus or a w.t. virus to evaluate viral replication after 24 and 48 hours. The number of GFP+ cells (EZ infected) or hemagglutinin (H)+ cells (w.t. infected) was measured via flow cytometry. Transcription of the viral nucleoprotein (N) gene was measured by mRNA-specific cDNA generation and N gene specific qPCR. Production of infectious viral particles was measured via endpoint dilution. In B cells infected with EZ, 30% of cells expressed GFP at 24 hours and 45% of cells expressed GFP at 48 hours. There was a 4.4-fold increase in N gene transcription from 0 to 48 hours. There was no detectable increase in viral titer over input after 48 hours. In B cells infected with w.t. virus, 10% of cells expressed viral H at 24 hours with no increase in H expression at 48 hours. The w.t. virus had a 2.4-fold increase in viral transcription from 0 to 48 hours. There was no detectable increase in viral titer over input after 48 hours. MeV-infected B cells show viral protein production and N gene transcription at 24 and 48 hours. However, w.t. virus replication may be less efficient as shown by lower percentages of H+ cells at 24 and 48 hours and lower levels of N gene transcription at 48 hours. There is no evidence of infectious virus production by either strain of MeV despite evidence of replication.