Putative glycoprotein gene of varicella-zoster virus with variable copy numbers of a 42-base-pair repeat sequence has homology to herpes simplex virus glycoprotein C.

A strain variation of varicella-zoster virus that maps to the UL region of the genome was found to be due to different copy numbers of a high GC 42-base-pair repeat. DNA sequence analysis of this variable region showed the sequence to be 5-GCGGGATCGGGCTTTCGGG(A/T)AGCGGCCGAGGTGGGCGCGACG-3. Strains Scott and Webster both contain 7 and 32/42 copies of the repeat, whereas strain Oka has exactly 4 copies less. Microheterogeneity exists within the repeated sequences, depending on the strain and the repeat number. Sequencing of the entire EcoRI P fragment (which contains the repeated sequences) and part of the adjacent EcoRI M and EcoRI Q fragments from strain Scott showed that the repeats are part of a large open reading frame that could code for a polypeptide core with a molecular weight of 66,000. Several potential TATA boxes exist upstream and two polyadenylation signals are found downstream of the open reading frame. The predicted protein bears several characteristics of a glycoprotein. The region is transcriptionally active in varicella-zoster virus-infected cells, specifying at least three RNA species of 1.7, 1.95, and 2.5 kilobases, which are transcribed from the same DNA strand. Part of the predicted protein has a high degree of homology to the herpes simplex virus type 1 glycoprotein gC.