Initial Events Associated with Virus PBCV-1 Infection of Chlorella NC64A

Chlorella viruses (or chloroviruses) are very large, plaque-forming viruses. The viruses are multilayered structures containing a large double-stranded DNA genome, a lipid bilayered membrane, and an outer icosahedral capsid shell. The viruses replicate in certain isolates of the coccal green alga, Chlorella. Sequence analysis of the 330-kbp genome of Paramecium bursaria Chlorella virus 1 (PBCV-1), the prototype of the virus family Phycodnaviridae, reveals <365 protein-encoding genes and 11 tRNA genes. Products of about 40% of these genes resemble proteins of known function, including many that are unexpected for a virus. Among these is a virus-encoded protein, called Kcv, which forms a functional K(+) channel. This chapter focuses on the initial steps in virus infection and provides a plausible role for the function of the viral K(+) channel in lowering the turgor pressure of the host. This step appears to be a prerequisite for delivery of the viral genome into the host

The Phycodnaviridae: The Story of How Tiny Giants Rule the World

The family Phycodnaviridae encompasses a diverse and rapidly expanding collection of large icosahedral, dsDNA viruses that infect algae. These lytic and lysogenic viruses have genomes ranging from 160 to 560 kb. The family consists of six genera based initially on host range and supported by sequence comparisons. The family is monophyletic with branches for each genus, but the phycodnaviruses have evolutionary roots that connect them with several other families of large DNA viruses, referred to as the nucleocytoplasmic large DNA viruses (NCLDV)