Analysis of 94 kb of DNA, located between map positions 88 and 182 kb in the 330-kb chlorella virus PBCV-1 genome, revealed 195 open reading frames (ORFs) 65 codons or longer. One hundred and five of the 195 ORFs were considered major ORFs. Twenty-six of the 105 major ORFs resembled genes in the databases including three chitinases, a chitosanase, three serine/threonine protein kinases, two additional protein kinases, a tyrosine protein phosphatase, two ankyrins, an ornithine decarboxylase, a copper/zinc-superoxide dismutase, a proliferating cell nuclear antigen, a DNA polymerase, a fibronectin-binding protein, the yeast Ski2 protein, an adenine DNA methyltransferase and its corresponding DNA site-specific endonuclease, and an amidase. The genes for the 105 major ORFs were evenly distributed along the genome and, except for one noncoding 1788-nucleotide stretch, the genes were close together. Unexpectedly, a 900-bp region in the 1788-bp noncoding sequence resembled a CpG island.