Novel phycodnavirus genes amplified from Canadian freshwater environments

Abstract

Extant and newly designed primers for the polymerase chain reaction (PCR) were used to amplify phycodnavirus DNA polymerase (polB) gene fragments from numerous samples collected at different times of the year from 3 freshwater environments in Ontario, Canada. Overall, a total of 143 cloned PCR fragments were sequenced and 106 putative phycodnavirus polB gene fragments were identified. Although most of these 106 gene fragments were very closely related (i.e. >97% identical) to polB sequences from chloroviruses, or environmental sequences related to prasi- noviruses, 16 represented 2 new types of phycodnavirus polB genes. More specifically, polB frag- ments that formed a new clade of chloroviruses were amplified from Lake Ontario using newly de- signed Chlorovirus-specific PCR primers, and a polB sequence most closely related to genes from the prymnesioviruses PgV-03T and CbV-PW1 was amplified from a pond sample from Mississauga, On- tario, using the degenerate algal virus-specific PCR primers AVS1 and AVS2. Thus, the results of the present study provide evidence for a new type of Chlorovirus, and the first observation of polB se- quences from freshwater phycodnaviruses that are presumed to infect algae other than chlorophytes.