IDENTIFICATION OF A HUMAN CYTOMEGALOVIRUS MUTANT IN THE PP150 MATRIX PHOSPHOPROTEIN GENE WITH A GROWTH-DEFECTIVE PHENOTYPE

Following amplification by PCR of a portion of the matrix phosphoprote in pp150 gene, electrophoretic analysis revealed the simultaneous pres ence of two viral variants of human cytomegalovirus in the blood of a heart transplant recipient. Repeated denaturation-annealing cycles dur ing the amplification reaction led to the formation of heteroduplex mo lecules with altered electrophoretic mobility. Sequence analysis of th e amplification products showed the presence of a viral variant carryi ng an in-frame three nucleotide deletion, which caused the absence of an aspartic acid in the corresponding protein. Attempts to plaque-puri fy the deletion mutant were unsuccessful, suggesting that the variant was growth-defective.