Multiplicity dependent expression of the predominant phosphoprotein pp65 of human cytomegalovirus.

Recent clinical isolates of human cytomegalovirus (HCMV) display considerable quantitative differences in the expression of the structural phosphoprotein pp65. This study shows that a reduced production of pp65 correlates with reduced amounts of its coding transcript in wild-type strains compared to the high level expression in the laboratory strain AD169. The cleavage pattern of the encoding DNAs including the promoter region did not show major differences among the isolates. Therefore the variable expression of pp65 is supposed to be dependent on cell culture conditions. Increasing multiplicities of infection resulted in overproduction of pp65 and this may lead to the increased formation of dense body particles.