Molluscum contagiosum virus (MCV) is a member of the family Poxviridae and 
pathogenic to humans. MCV causes benign epidermal tumors mainly in children and 
young adults and is a common pathogen in immunecompromised individuals. The 
viral DNA polymerase is the essential enzyme involved in the replication of the 
genome of DNA viruses. The identification and characterization of the gene 
encoding the DNA polymerase of molluscum contagiosum virus type 1 (MCV-1) was 
carried out by PCR technology and nucleotide sequence analysis. Computer-aided 
analysis of known amino acid sequences of DNA polymerases from two members of 
the poxvirus family revealed a high amino acid sequence homology of about 49.7% 
as detected between the DNA polymerases of vaccinia virus (genus Orthopoxvirus) 
and fowlpoxvirus (genus Avipoxvirus). Specific oligonucleotide primers were 
designed and synthesized according to the distinct conserved regions of amino 
acid sequences of the DNA polymerases in which the codon usage of the MCV-1 
genome was considered. Using this technology a 228 bp DNA fragment was amplified 
and used as hybridization probe for identifying the corresponding gene of the 
MCV-1 genome. It was found that the PCR product was able to hybridize to the 
BamHI MCV-1 DNA fragment G (9.2 kbp, 0.284 to 0.332 map units). The nucleotide 
sequence of this particular region of the MCV-1 genome (7267 bp) between map 
coordinates 0.284 and 0.315 was determined. The analysis of the DNA sequences 
revealed the presence of 22 open reading frames (ORFs-1 to -22). ORF-13 (3012 
bp; nucleotide positions 6624 to 3612) codes for a putative protein of a 
predicted size of 115 kDa (1004 aa) which shows 40.1% identity and 35% 
similarity to the amino acid sequences of the DNA polymerases of vaccinia, 
variola, and fowlpoxvirus. In addition significant homologies (30% to 55%) were 
found between the amino acid sequences of the ORFs 3, -5, -9, and -14 and the 
amino acid sequences of the E6R, E8R, E10R, and a 7.3 kDa protein of vaccinia 
and variola virus, respectively. Comparative analysis of the genomic positions 
of the loci of the detected viral genes including the DNA polymerases of MCV-1, 
vaccinia, and variola virus revealed a similar gene organization and 
arrangement.